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https://github.com/TomHarte/CLK.git
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1469 lines
55 KiB
C++
1469 lines
55 KiB
C++
//
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// 68000Implementation.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 10/03/2019.
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// Copyright © 2019 Thomas Harte. All rights reserved.
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//
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#define get_ccr() \
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( \
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(carry_flag_ ? 0x0001 : 0x0000) | \
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(overflow_flag_ ? 0x0002 : 0x0000) | \
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(zero_result_ ? 0x0000 : 0x0004) | \
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(negative_flag_ ? 0x0008 : 0x0000) | \
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(extend_flag_ ? 0x0010 : 0x0000) \
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)
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#define get_status() \
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( \
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get_ccr() | \
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(interrupt_level_ << 8) | \
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(trace_flag_ ? 0x8000 : 0x0000) | \
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(is_supervisor_ << 13) \
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)
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#define set_ccr(x) \
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carry_flag_ = (x) & 0x0001; \
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overflow_flag_ = (x) & 0x0002; \
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zero_result_ = ((x) & 0x0004) ^ 0x0004; \
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negative_flag_ = (x) & 0x0008; \
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extend_flag_ = (x) & 0x0010;
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#define set_status(x) \
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set_ccr(x) \
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interrupt_level_ = ((x) >> 8) & 7; \
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trace_flag_ = (x) & 0x8000; \
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set_is_supervisor(!!(((x) >> 13) & 1));
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template <class T, bool dtack_is_implicit, bool signal_will_perform> void Processor<T, dtack_is_implicit, signal_will_perform>::run_for(HalfCycles duration) {
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HalfCycles remaining_duration = duration + half_cycles_left_to_run_;
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while(remaining_duration > HalfCycles(0)) {
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/*
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FIND THE NEXT MICRO-OP IF UNKNOWN.
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*/
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if(active_step_->is_terminal()) {
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while(true) {
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// If there are any more micro-operations available, just move onwards.
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if(active_micro_op_ && !active_micro_op_->is_terminal()) {
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++active_micro_op_;
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} else {
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// Either the micro-operations for this instruction have been exhausted, or
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// no instruction was ongoing. Either way, do a standard instruction operation.
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// TODO: unless an interrupt is pending, or the trap flag is set.
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#ifdef LOG_TRACE
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std::cout << std::setfill('0');
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std::cout << (extend_flag_ ? 'x' : '-') << (negative_flag_ ? 'n' : '-') << (zero_result_ ? '-' : 'z');
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std::cout << (overflow_flag_ ? 'v' : '-') << (carry_flag_ ? 'c' : '-') << '\t';
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for(int c = 0; c < 8; ++ c) std::cout << "d" << c << ":" << std::setw(8) << data_[c].full << " ";
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for(int c = 0; c < 8; ++ c) std::cout << "a" << c << ":" << std::setw(8) << address_[c].full << " ";
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if(is_supervisor_) {
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std::cout << "usp:" << std::setw(8) << std::setfill('0') << stack_pointers_[0].full << " ";
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} else {
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std::cout << "ssp:" << std::setw(8) << std::setfill('0') << stack_pointers_[1].full << " ";
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}
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std::cout << '\n';
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#endif
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decoded_instruction_ = prefetch_queue_.halves.high.full;
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if(!instructions[decoded_instruction_].micro_operations) {
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// TODO: once all instructions are implemnted, this should be an instruction error.
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std::cerr << "68000 Abilities exhausted; can't manage instruction " << std::hex << decoded_instruction_ << " from " << (program_counter_.full - 4) << std::endl;
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return;
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} else {
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#ifdef LOG_TRACE
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std::cout << std::hex << (program_counter_.full - 4) << ": " << std::setw(4) << decoded_instruction_ << '\t';
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#endif
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}
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if(signal_will_perform) {
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bus_handler_.will_perform(program_counter_.full - 4, decoded_instruction_);
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}
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active_program_ = &instructions[decoded_instruction_];
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active_micro_op_ = active_program_->micro_operations;
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}
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auto bus_program = active_micro_op_->bus_program;
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switch(active_micro_op_->action) {
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default:
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std::cerr << "Unhandled 68000 micro op action " << std::hex << active_micro_op_->action << std::endl;
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break;
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case int(MicroOp::Action::None): break;
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case int(MicroOp::Action::PerformOperation):
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#define sub_overflow() (source ^ destination) & (destination ^ result)
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#define add_overflow() ~(source ^ destination) & (destination ^ result)
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switch(active_program_->operation) {
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/*
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ABCD adds the lowest bytes form the source and destination using BCD arithmetic,
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obeying the extend flag.
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*/
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case Operation::ABCD: {
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// Pull out the two halves, for simplicity.
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const uint8_t source = active_program_->source->halves.low.halves.low;
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const uint8_t destination = active_program_->destination->halves.low.halves.low;
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// Perform the BCD add by evaluating the two nibbles separately.
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int result = (destination & 0xf) + (source & 0xf) + (extend_flag_ ? 1 : 0);
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if(result > 0x09) result += 0x06;
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result += (destination & 0xf0) + (source & 0xf0);
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if(result > 0x99) result += 0x60;
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// Set all flags essentially as if this were normal addition.
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zero_result_ |= result & 0xff;
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extend_flag_ = carry_flag_ = result & ~0xff;
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negative_flag_ = result & 0x80;
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overflow_flag_ = add_overflow() & 0x80;
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// Store the result.
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active_program_->destination->halves.low.halves.low = uint8_t(result);
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} break;
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// ADD and ADDA add two quantities, the latter sign extending and without setting any flags;
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// ADDQ and SUBQ act as ADD and SUB, but taking the second argument from the instruction code.
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#define addop(a, b) a + b
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#define subop(a, b) a - b
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#define addsubb(a, b, dest, op, overflow) \
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const auto source = a; \
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const auto destination = b; \
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const int result = op(destination, source); \
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\
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zero_result_ = dest = uint8_t(result); \
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extend_flag_ = carry_flag_ = result & ~0xff; \
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negative_flag_ = result & 0x80; \
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overflow_flag_ = overflow() & 0x80;
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#define addsubw(a, b, dest, op, overflow) \
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const auto source = a; \
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const auto destination = b; \
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const int result = op(destination, source); \
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\
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zero_result_ = dest = uint16_t(result); \
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extend_flag_ = carry_flag_ = result & ~0xffff; \
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negative_flag_ = result & 0x8000; \
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overflow_flag_ = overflow() & 0x8000;
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#define addsubl(a, b, dest, op, overflow) \
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const auto source = a; \
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const auto destination = b; \
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const uint64_t result = op(uint64_t(destination), uint64_t(source)); \
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\
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zero_result_ = dest = uint32_t(result); \
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extend_flag_ = carry_flag_ = result >> 32; \
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negative_flag_ = result & 0x80000000; \
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overflow_flag_ = overflow() & 0x80000000;
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#define addb(a, b, dest) addsubb(a, b, dest, addop, add_overflow)
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#define subb(a, b, dest) addsubb(a, b, dest, subop, sub_overflow)
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#define addw(a, b, dest) addsubw(a, b, dest, addop, add_overflow)
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#define subw(a, b, dest) addsubw(a, b, dest, subop, sub_overflow)
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#define addl(a, b, dest) addsubl(a, b, dest, addop, add_overflow)
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#define subl(a, b, dest) addsubl(a, b, dest, subop, sub_overflow)
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#define q() (((decoded_instruction_ >> 9)&7) ? ((decoded_instruction_ >> 9)&7) : 8)
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case Operation::ADDb: {
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addb( active_program_->source->halves.low.halves.low,
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active_program_->destination->halves.low.halves.low,
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active_program_->destination->halves.low.halves.low);
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} break;
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case Operation::ADDQb: {
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addb( q(),
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active_program_->destination->halves.low.halves.low,
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active_program_->destination->halves.low.halves.low);
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} break;
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case Operation::ADDw: {
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addw( active_program_->source->halves.low.full,
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active_program_->destination->halves.low.full,
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active_program_->destination->halves.low.full);
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} break;
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case Operation::ADDQw: {
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addw( q(),
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active_program_->destination->halves.low.full,
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active_program_->destination->halves.low.full);
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} break;
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case Operation::ADDl: {
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addl( active_program_->source->full,
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active_program_->destination->full,
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active_program_->destination->full);
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} break;
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case Operation::ADDQl: {
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addl( q(),
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active_program_->destination->full,
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active_program_->destination->full);
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} break;
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case Operation::SUBb: {
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subb( active_program_->source->halves.low.halves.low,
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active_program_->destination->halves.low.halves.low,
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active_program_->destination->halves.low.halves.low);
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} break;
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case Operation::SUBQb: {
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subb( q(),
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active_program_->destination->halves.low.halves.low,
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active_program_->destination->halves.low.halves.low);
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} break;
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case Operation::SUBw: {
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subw( active_program_->source->halves.low.full,
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active_program_->destination->halves.low.full,
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active_program_->destination->halves.low.full);
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} break;
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case Operation::SUBQw: {
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subw( q(),
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active_program_->destination->halves.low.full,
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active_program_->destination->halves.low.full);
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} break;
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case Operation::SUBl: {
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subl( active_program_->source->full,
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active_program_->destination->full,
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active_program_->destination->full);
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} break;
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case Operation::SUBQl: {
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subl( q(),
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active_program_->destination->full,
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active_program_->destination->full);
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} break;
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case Operation::ADDQAl:
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active_program_->destination->full += q();
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break;
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case Operation::SUBQAl:
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active_program_->destination->full -= q();
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break;
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#undef addl
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#undef addw
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#undef addb
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#undef subl
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#undef subw
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#undef subb
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#undef addsubl
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#undef addsubw
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#undef addsubb
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#undef q
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case Operation::ADDAw:
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active_program_->destination->full += int16_t(active_program_->source->halves.low.full);
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break;
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case Operation::ADDAl:
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active_program_->destination->full += active_program_->source->full;
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break;
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case Operation::SUBAw:
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active_program_->destination->full -= int16_t(active_program_->source->halves.low.full);
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break;
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case Operation::SUBAl:
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active_program_->destination->full -= active_program_->source->full;
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break;
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// BRA: alters the program counter, exclusively via the prefetch queue.
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case Operation::BRA: {
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const int8_t byte_offset = int8_t(prefetch_queue_.halves.high.halves.low);
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// A non-zero offset byte branches by just that amount; otherwise use the word
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// after as an offset. In both cases, treat as signed.
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if(byte_offset) {
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program_counter_.full = (program_counter_.full + byte_offset);
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} else {
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program_counter_.full += int16_t(prefetch_queue_.halves.low.full);
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}
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program_counter_.full -= 2;
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} break;
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// Two BTSTs: set the zero flag according to the value of the destination masked by
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// the bit named in the source modulo the operation size.
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case Operation::BTSTb:
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zero_result_ = active_program_->destination->full & (1 << (active_program_->source->full & 7));
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break;
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case Operation::BTSTl:
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zero_result_ = active_program_->destination->full & (1 << (active_program_->source->full & 31));
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break;
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case Operation::BCLRb:
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zero_result_ = active_program_->destination->full & (1 << (active_program_->source->full & 7));
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active_program_->destination->full &= ~(1 << (active_program_->source->full & 7));
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break;
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case Operation::BCLRl:
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zero_result_ = active_program_->destination->full & (1 << (active_program_->source->full & 31));
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active_program_->destination->full &= ~(1 << (active_program_->source->full & 31));
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// Clearing in the top word requires an extra four cycles.
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active_step_->microcycle.length = HalfCycles(8 + ((active_program_->source->full & 31) / 16) * 4);
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break;
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// Bcc: ordinarily evaluates the relevant condition and displacement size and then:
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// if condition is false, schedules bus operations to get past this instruction;
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// otherwise applies the offset and schedules bus operations to refill the prefetch queue.
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//
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// Special case: the condition code is 1, which is ordinarily false. In that case this
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// is the trailing step of a BSR.
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case Operation::Bcc: {
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// Grab the 8-bit offset.
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const int8_t byte_offset = int8_t(prefetch_queue_.halves.high.halves.low);
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// Check whether this is secretly BSR.
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const bool is_bsr = ((decoded_instruction_ >> 8) & 0xf) == 1;
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// Test the conditional, treating 'false' as true.
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const bool should_branch = is_bsr || evaluate_condition(decoded_instruction_ >> 8);
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// Schedule something appropriate, by rewriting the program for this instruction temporarily.
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if(should_branch) {
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if(byte_offset) {
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program_counter_.full = (program_counter_.full + byte_offset);
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} else {
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program_counter_.full += int16_t(prefetch_queue_.halves.low.full);
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}
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program_counter_.full -= 2;
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bus_program = is_bsr ? bsr_bus_steps_ : branch_taken_bus_steps_;
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} else {
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if(byte_offset) {
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bus_program = branch_byte_not_taken_bus_steps_;
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} else {
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bus_program = branch_word_not_taken_bus_steps_;
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}
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}
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} break;
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case Operation::DBcc: {
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// Decide what sort of DBcc this is.
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if(!evaluate_condition(decoded_instruction_ >> 8)) {
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-- active_program_->source->halves.low.full;
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const auto target_program_counter = program_counter_.full + int16_t(prefetch_queue_.halves.low.full) - 2;
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if(active_program_->source->halves.low.full == 0xffff) {
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// This DBcc will be ignored as the counter has underflowed.
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// Schedule n np np np and continue. Assumed: the first np
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// is from where the branch would have been if taken?
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bus_program = dbcc_condition_false_no_branch_steps_;
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dbcc_false_address_ = target_program_counter;
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} else {
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// Take the branch. Change PC and schedule n np np.
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bus_program = dbcc_condition_false_branch_steps_;
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program_counter_.full = target_program_counter;
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}
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} else {
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// This DBcc will be ignored as the condition is true;
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// perform nn np np and continue.
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bus_program = dbcc_condition_true_steps_;
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}
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} break;
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case Operation::Scc: {
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active_program_->destination->halves.low.halves.low =
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evaluate_condition(decoded_instruction_ >> 8) ? 0xff : 0x00;
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} break;
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/*
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CLRs: store 0 to the destination, set the zero flag, and clear
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negative, overflow and carry.
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*/
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case Operation::CLRb:
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active_program_->destination->halves.low.halves.low = 0;
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negative_flag_ = overflow_flag_ = carry_flag_ = zero_result_ = 0;
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break;
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case Operation::CLRw:
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active_program_->destination->halves.low.full = 0;
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negative_flag_ = overflow_flag_ = carry_flag_ = zero_result_ = 0;
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break;
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case Operation::CLRl:
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active_program_->destination->full = 0;
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negative_flag_ = overflow_flag_ = carry_flag_ = zero_result_ = 0;
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break;
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/*
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CMP.b, CMP.l and CMP.w: sets the condition flags (other than extend) based on a subtraction
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of the source from the destination; the result of the subtraction is not stored.
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*/
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case Operation::CMPb: {
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const uint8_t source = active_program_->source->halves.low.halves.low;
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const uint8_t destination = active_program_->destination->halves.low.halves.low;
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const int result = destination - source;
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zero_result_ = result & 0xff;
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carry_flag_ = result & ~0xff;
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negative_flag_ = result & 0x80;
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overflow_flag_ = sub_overflow() & 0x80;
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} break;
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case Operation::CMPw: {
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const uint16_t source = active_program_->source->halves.low.full;
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const uint16_t destination = active_program_->destination->halves.low.full;
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const int result = destination - source;
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zero_result_ = result & 0xffff;
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carry_flag_ = result & ~0xffff;
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negative_flag_ = result & 0x8000;
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overflow_flag_ = sub_overflow() & 0x8000;
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} break;
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case Operation::CMPl: {
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const uint32_t source = active_program_->source->full;
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const uint32_t destination = active_program_->destination->full;
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const uint64_t result = uint64_t(destination) - uint64_t(source);
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zero_result_ = uint32_t(result);
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carry_flag_ = result >> 32;
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negative_flag_ = result & 0x80000000;
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overflow_flag_ = sub_overflow() & 0x80000000;
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} break;
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// JMP: copies the source to the program counter.
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case Operation::JMP:
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program_counter_.full = active_program_->source->full;
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break;
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/*
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MOVE.b, MOVE.l and MOVE.w: move the least significant byte or word, or the entire long word,
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and set negative, zero, overflow and carry as appropriate.
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*/
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case Operation::MOVEb:
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zero_result_ = active_program_->destination->halves.low.halves.low = active_program_->source->halves.low.halves.low;
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negative_flag_ = zero_result_ & 0x80;
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overflow_flag_ = carry_flag_ = 0;
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break;
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case Operation::MOVEw:
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zero_result_ = active_program_->destination->halves.low.full = active_program_->source->halves.low.full;
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negative_flag_ = zero_result_ & 0x8000;
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overflow_flag_ = carry_flag_ = 0;
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break;
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case Operation::MOVEl:
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zero_result_ = active_program_->destination->full = active_program_->source->full;
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negative_flag_ = zero_result_ & 0x80000000;
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overflow_flag_ = carry_flag_ = 0;
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break;
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|
|
/*
|
|
MOVE.q: a single byte is moved from the current instruction, and sign extended.
|
|
*/
|
|
case Operation::MOVEq:
|
|
zero_result_ = active_program_->destination->full = prefetch_queue_.halves.high.halves.low;
|
|
negative_flag_ = zero_result_ & 0x80;
|
|
overflow_flag_ = carry_flag_ = 0;
|
|
active_program_->destination->full |= negative_flag_ ? 0xffffff00 : 0;
|
|
break;
|
|
|
|
/*
|
|
MOVEA.l: move the entire long word;
|
|
MOVEA.w: move the least significant word and sign extend it.
|
|
Neither sets any flags.
|
|
*/
|
|
case Operation::MOVEAw:
|
|
active_program_->destination->halves.low.full = active_program_->source->halves.low.full;
|
|
active_program_->destination->halves.high.full = (active_program_->destination->halves.low.full & 0x8000) ? 0xffff : 0;
|
|
break;
|
|
|
|
case Operation::MOVEAl:
|
|
active_program_->destination->full = active_program_->source->full;
|
|
break;
|
|
|
|
/*
|
|
Status word moves.
|
|
*/
|
|
|
|
case Operation::MOVEtoSR:
|
|
set_status(active_program_->source->full);
|
|
break;
|
|
|
|
case Operation::MOVEfromSR:
|
|
active_program_->source->halves.low.full = get_status();
|
|
break;
|
|
|
|
case Operation::MOVEtoCCR:
|
|
set_ccr(active_program_->source->full);
|
|
break;
|
|
|
|
/*
|
|
Multiplications.
|
|
*/
|
|
|
|
case Operation::MULU: {
|
|
active_program_->destination->full =
|
|
active_program_->destination->halves.low.full * active_program_->source->halves.low.full;
|
|
carry_flag_ = overflow_flag_ = 0;
|
|
zero_result_ = active_program_->destination->full;
|
|
negative_flag_ = zero_result_ & 0x80000000;
|
|
|
|
// TODO: optimise the below?
|
|
int number_of_ones = 0;
|
|
auto source = active_program_->source->halves.low.full;
|
|
while(source) {
|
|
source >>= 1;
|
|
++number_of_ones;
|
|
}
|
|
|
|
// Time taken = 38 cycles + 2 cycles per 1 in the source.
|
|
active_step_->microcycle.length = HalfCycles(4 * number_of_ones + 38*2);
|
|
} break;
|
|
|
|
case Operation::MULS: {
|
|
active_program_->destination->full =
|
|
int16_t(active_program_->destination->halves.low.full) * int16_t(active_program_->source->halves.low.full);
|
|
carry_flag_ = overflow_flag_ = 0;
|
|
zero_result_ = active_program_->destination->full;
|
|
negative_flag_ = zero_result_ & 0x80000000;
|
|
|
|
// TODO: optimise the below?
|
|
int number_of_pairs = 0;
|
|
int source = active_program_->source->halves.low.full;
|
|
int bit = 0;
|
|
while(source | bit) {
|
|
number_of_pairs += (bit ^ source) & 1;
|
|
bit = source & 1;
|
|
source >>= 1;
|
|
}
|
|
|
|
// Time taken = 38 cycles + 2 cycles per 1 in the source.
|
|
active_step_->microcycle.length = HalfCycles(4 * number_of_pairs + 38*2);
|
|
} break;
|
|
|
|
/*
|
|
MOVEM: multi-word moves.
|
|
*/
|
|
|
|
#define setup_movem(words_per_reg, base) \
|
|
/* Count the number of long words to move. */ \
|
|
size_t total_to_move = 0; \
|
|
auto mask = next_word_; \
|
|
while(mask) { \
|
|
total_to_move += mask&1; \
|
|
mask >>= 1; \
|
|
} \
|
|
\
|
|
/* Twice that many words plus one will need to be moved */ \
|
|
bus_program = base + (64 - total_to_move*words_per_reg)*2; \
|
|
\
|
|
/* Fill in the proper addresses and targets. */ \
|
|
const auto mode = (decoded_instruction_ >> 3) & 7; \
|
|
uint32_t start_address; \
|
|
if(mode <= 4) { \
|
|
start_address = active_program_->destination_address->full; \
|
|
} else { \
|
|
start_address = effective_address_[1].full; \
|
|
} \
|
|
\
|
|
auto step = bus_program; \
|
|
uint32_t *address_storage = precomputed_addresses_; \
|
|
mask = next_word_; \
|
|
int offset = 0;
|
|
|
|
#define inc_action(x, v) x += v
|
|
#define dec_action(x, v) x -= v
|
|
|
|
#define write_address_sequence_long(action, l) \
|
|
while(mask) { \
|
|
if(mask&1) { \
|
|
address_storage[0] = start_address; \
|
|
action(start_address, 2); \
|
|
address_storage[1] = start_address; \
|
|
action(start_address, 2); \
|
|
\
|
|
step[0].microcycle.address = step[1].microcycle.address = address_storage; \
|
|
step[2].microcycle.address = step[3].microcycle.address = address_storage + 1; \
|
|
\
|
|
const auto target = (offset > 7) ? &address_[offset&7] : &data_[offset]; \
|
|
step[l].microcycle.value = step[l+1].microcycle.value = &target->halves.high; \
|
|
step[(l^2)].microcycle.value = step[(l^2)+1].microcycle.value = &target->halves.low; \
|
|
\
|
|
address_storage += 2; \
|
|
step += 4; \
|
|
} \
|
|
mask >>= 1; \
|
|
action(offset, 1); \
|
|
}
|
|
|
|
#define write_address_sequence_word(action) \
|
|
while(mask) { \
|
|
if(mask&1) { \
|
|
address_storage[0] = start_address; \
|
|
action(start_address, 2); \
|
|
\
|
|
step[0].microcycle.address = step[1].microcycle.address = address_storage; \
|
|
\
|
|
const auto target = (offset > 7) ? &address_[offset&7] : &data_[offset]; \
|
|
step[0].microcycle.value = step[1].microcycle.value = &target->halves.low; \
|
|
\
|
|
++ address_storage; \
|
|
step += 2; \
|
|
} \
|
|
mask >>= 1; \
|
|
action(offset, 1); \
|
|
}
|
|
|
|
case Operation::MOVEMtoRl: {
|
|
setup_movem(2, movem_read_steps_);
|
|
|
|
// Everything for move to registers is based on an incrementing
|
|
// address; per M68000PRM:
|
|
//
|
|
// "[If using the postincrement addressing mode then] the incremented address
|
|
// register contains the address of the last operand loaded plus the operand length.
|
|
// If the addressing register is also loaded from memory, the memory value is ignored
|
|
// and the register is written with the postincremented effective address."
|
|
//
|
|
// The latter part is dealt with by MicroOp::Action::MOVEMtoRComplete, which also
|
|
// does any necessary sign extension.
|
|
write_address_sequence_long(inc_action, 0);
|
|
|
|
// MOVEM to R always reads one word too many.
|
|
address_storage[0] = start_address;
|
|
step[0].microcycle.address = step[1].microcycle.address = address_storage;
|
|
step[0].microcycle.value = step[1].microcycle.value = &throwaway_value_;
|
|
movem_final_address_ = start_address;
|
|
} break;
|
|
|
|
case Operation::MOVEMtoRw: {
|
|
setup_movem(1, movem_read_steps_);
|
|
write_address_sequence_word(inc_action);
|
|
|
|
// MOVEM to R always reads one word too many.
|
|
address_storage[0] = start_address;
|
|
step[0].microcycle.address = step[1].microcycle.address = address_storage;
|
|
step[0].microcycle.value = step[1].microcycle.value = &throwaway_value_;
|
|
movem_final_address_ = start_address;
|
|
} break;
|
|
|
|
case Operation::MOVEMtoMl: {
|
|
setup_movem(2, movem_write_steps_);
|
|
|
|
// MOVEM to M counts downwards and enumerates the registers in reverse order
|
|
// if subject to the predecrementing mode; otherwise it counts upwards and
|
|
// operates exactly as does MOVEM to R.
|
|
//
|
|
// Note also: "The MC68000 and MC68010 write the initial register value
|
|
// (not decremented) [when writing a register that is providing
|
|
// pre-decrementing addressing]."
|
|
//
|
|
// Hence the decrementing register (if any) is updated
|
|
// by MicroOp::Action::MOVEMtoMComplete.
|
|
if(mode == 4) {
|
|
offset = 15;
|
|
start_address -= 2;
|
|
write_address_sequence_long(dec_action, 2);
|
|
movem_final_address_ = start_address + 2;
|
|
} else {
|
|
write_address_sequence_long(inc_action, 0);
|
|
}
|
|
} break;
|
|
|
|
case Operation::MOVEMtoMw: {
|
|
setup_movem(1, movem_write_steps_);
|
|
|
|
if(mode == 4) {
|
|
offset = 15;
|
|
start_address -= 2;
|
|
write_address_sequence_word(dec_action);
|
|
} else {
|
|
write_address_sequence_word(inc_action);
|
|
}
|
|
} break;
|
|
|
|
#undef setup_movem
|
|
#undef write_address_sequence_long
|
|
#undef write_address_sequence_word
|
|
#undef inc_action
|
|
#undef dec_action
|
|
|
|
// TRAP, which is a nicer form of ILLEGAL.
|
|
case Operation::TRAP: {
|
|
// Select the trap steps as next.
|
|
bus_program = trap_steps_;
|
|
|
|
// Fill in the status word value.
|
|
destination_bus_data_[0].full = get_status();
|
|
|
|
// Switch to supervisor mode.
|
|
set_is_supervisor(true);
|
|
|
|
// Pick a vector.
|
|
effective_address_[0].full = ((decoded_instruction_ & 15) + 32) << 2;
|
|
|
|
// Schedule the proper stack activity.
|
|
precomputed_addresses_[0] = address_[7].full - 2;
|
|
precomputed_addresses_[1] = address_[7].full - 6;
|
|
precomputed_addresses_[2] = address_[7].full - 4;
|
|
address_[7].full -= 6;
|
|
|
|
// The program counter to push is actually one slot ago.
|
|
program_counter_.full -= 2;
|
|
} break;
|
|
|
|
/*
|
|
NEGs: negatives the destination, setting the zero,
|
|
negative, overflow and carry flags appropriate, and extend.
|
|
*/
|
|
case Operation::NEGb: {
|
|
const int source = 0;
|
|
const int destination = active_program_->destination->halves.low.halves.low;
|
|
const int result = source - destination;
|
|
active_program_->destination->halves.low.halves.low = result;
|
|
|
|
zero_result_ = result & 0xff;
|
|
extend_flag_ = carry_flag_ = result & ~0xff;
|
|
negative_flag_ = result & 0x80;
|
|
overflow_flag_ = sub_overflow() & 0x80;
|
|
} break;
|
|
|
|
case Operation::NEGw: {
|
|
const int source = 0;
|
|
const int destination = active_program_->destination->halves.low.full;
|
|
const int result = source - destination;
|
|
active_program_->destination->halves.low.full = result;
|
|
|
|
zero_result_ = result & 0xffff;
|
|
extend_flag_ = carry_flag_ = result & ~0xffff;
|
|
negative_flag_ = result & 0x8000;
|
|
overflow_flag_ = sub_overflow() & 0x8000;
|
|
} break;
|
|
|
|
case Operation::NEGl: {
|
|
const int source = 0;
|
|
const int destination = active_program_->destination->full;
|
|
int64_t result = source - destination;
|
|
active_program_->destination->full = uint32_t(result);
|
|
|
|
zero_result_ = uint_fast32_t(result);
|
|
extend_flag_ = carry_flag_ = result >> 32;
|
|
negative_flag_ = result & 0x80000000;
|
|
overflow_flag_ = sub_overflow() & 0x80000000;
|
|
} break;
|
|
|
|
/*
|
|
NEGXs: NEG, with extend.
|
|
*/
|
|
case Operation::NEGXb: {
|
|
const int source = 0;
|
|
const int destination = active_program_->destination->halves.low.halves.low;
|
|
const int result = source - destination - (extend_flag_ ? 1 : 0);
|
|
active_program_->destination->halves.low.halves.low = result;
|
|
|
|
zero_result_ = result & 0xff;
|
|
extend_flag_ = carry_flag_ = result & ~0xff;
|
|
negative_flag_ = result & 0x80;
|
|
overflow_flag_ = sub_overflow() & 0x80;
|
|
} break;
|
|
|
|
case Operation::NEGXw: {
|
|
const int source = 0;
|
|
const int destination = active_program_->destination->halves.low.full;
|
|
const int result = source - destination - (extend_flag_ ? 1 : 0);
|
|
active_program_->destination->halves.low.full = result;
|
|
|
|
zero_result_ = result & 0xffff;
|
|
extend_flag_ = carry_flag_ = result & ~0xffff;
|
|
negative_flag_ = result & 0x8000;
|
|
overflow_flag_ = sub_overflow() & 0x8000;
|
|
} break;
|
|
|
|
case Operation::NEGXl: {
|
|
const int source = 0;
|
|
const int destination = active_program_->destination->full;
|
|
int64_t result = source - destination - (extend_flag_ ? 1 : 0);
|
|
active_program_->destination->full = uint32_t(result);
|
|
|
|
zero_result_ = uint_fast32_t(result);
|
|
extend_flag_ = carry_flag_ = result >> 32;
|
|
negative_flag_ = result & 0x80000000;
|
|
overflow_flag_ = sub_overflow() & 0x80000000;
|
|
} break;
|
|
|
|
/*
|
|
The no-op.
|
|
*/
|
|
case Operation::None:
|
|
break;
|
|
|
|
/*
|
|
Bitwise operators: AND, OR and EOR. All three clear the overflow and carry flags,
|
|
and set zero and negative appropriately.
|
|
*/
|
|
#define op_and(x, y) x &= y
|
|
#define op_or(x, y) x |= y
|
|
#define op_eor(x, y) x ^= y
|
|
|
|
#define bitwise(source, dest, sign_mask, operator) \
|
|
operator(dest, source); \
|
|
overflow_flag_ = carry_flag_ = 0; \
|
|
zero_result_ = dest; \
|
|
negative_flag_ = dest & sign_mask;
|
|
|
|
#define andx(source, dest, sign_mask) bitwise(source, dest, sign_mask, op_and)
|
|
#define eorx(source, dest, sign_mask) bitwise(source, dest, sign_mask, op_eor)
|
|
#define orx(source, dest, sign_mask) bitwise(source, dest, sign_mask, op_or)
|
|
|
|
#define op_bwl(name, op) \
|
|
case Operation::name##b: op(active_program_->source->halves.low.halves.low, active_program_->destination->halves.low.halves.low, 0x80); break; \
|
|
case Operation::name##w: op(active_program_->source->halves.low.full, active_program_->destination->halves.low.full, 0x8000); break; \
|
|
case Operation::name##l: op(active_program_->source->full, active_program_->destination->full, 0x80000000); break;
|
|
|
|
op_bwl(AND, andx);
|
|
op_bwl(EOR, eorx);
|
|
op_bwl(OR, orx);
|
|
|
|
#undef op_bwl
|
|
#undef orx
|
|
#undef eorx
|
|
#undef andx
|
|
#undef bitwise
|
|
#undef op_eor
|
|
#undef op_or
|
|
#undef op_and
|
|
|
|
// NOTs: take the logical inverse, affecting the negative and zero flags.
|
|
case Operation::NOTb:
|
|
active_program_->destination->halves.low.halves.low ^= 0xff;
|
|
zero_result_ = active_program_->destination->halves.low.halves.low;
|
|
negative_flag_ = zero_result_ & 0x80;
|
|
break;
|
|
|
|
case Operation::NOTw:
|
|
active_program_->destination->halves.low.full ^= 0xffff;
|
|
zero_result_ = active_program_->destination->halves.low.full;
|
|
negative_flag_ = zero_result_ & 0x8000;
|
|
break;
|
|
|
|
case Operation::NOTl:
|
|
active_program_->destination->full ^= 0xffffffff;
|
|
zero_result_ = active_program_->destination->full;
|
|
negative_flag_ = zero_result_ & 0x80000000;
|
|
break;
|
|
|
|
/*
|
|
SBCD subtracts the lowest byte of the source from that of the destination using
|
|
BCD arithmetic, obeying the extend flag.
|
|
*/
|
|
case Operation::SBCD: {
|
|
// Pull out the two halves, for simplicity.
|
|
const uint8_t source = active_program_->source->halves.low.halves.low;
|
|
const uint8_t destination = active_program_->destination->halves.low.halves.low;
|
|
|
|
// Perform the BCD add by evaluating the two nibbles separately.
|
|
int result = (destination & 0xf) - (source & 0xf) - (extend_flag_ ? 1 : 0);
|
|
if(result > 0x09) result -= 0x06;
|
|
result += (destination & 0xf0) - (source & 0xf0);
|
|
if(result > 0x99) result -= 0x60;
|
|
|
|
// Set all flags essentially as if this were normal subtraction.
|
|
zero_result_ |= result & 0xff;
|
|
extend_flag_ = carry_flag_ = result & ~0xff;
|
|
negative_flag_ = result & 0x80;
|
|
overflow_flag_ = sub_overflow() & 0x80;
|
|
|
|
// Store the result.
|
|
active_program_->destination->halves.low.halves.low = uint8_t(result);
|
|
} break;
|
|
|
|
// EXG and SWAP exchange/swap words or long words.
|
|
|
|
case Operation::EXG: {
|
|
const auto temporary = active_program_->source->full;
|
|
active_program_->source->full = active_program_->destination->full;
|
|
active_program_->destination->full = temporary;
|
|
} break;
|
|
|
|
case Operation::SWAP: {
|
|
const auto temporary = active_program_->destination->halves.low.full;
|
|
active_program_->destination->halves.low.full = active_program_->destination->halves.high.full;
|
|
active_program_->destination->halves.high.full = temporary;
|
|
|
|
zero_result_ = active_program_->destination->full;
|
|
negative_flag_ = temporary & 0x8000;
|
|
} break;
|
|
|
|
/*
|
|
Shifts and rotates.
|
|
*/
|
|
#define set_neg_zero_overflow(v, m) \
|
|
zero_result_ = (v); \
|
|
negative_flag_ = zero_result_ & (m); \
|
|
overflow_flag_ = (value ^ zero_result_) & (m);
|
|
|
|
#define set_flags(v, m, t) \
|
|
set_neg_zero_overflow(v, m) \
|
|
extend_flag_ = carry_flag_ = value & (t);
|
|
|
|
#define decode_shift_count() \
|
|
int shift_count = (decoded_instruction_ & 32) ? data_[(decoded_instruction_ >> 9) & 7].full&63 : ( ((decoded_instruction_ >> 9)&7) ? ((decoded_instruction_ >> 9)&7) : 8) ; \
|
|
active_step_->microcycle.length = HalfCycles(4 * shift_count);
|
|
|
|
#define set_flags_b(t) set_flags(active_program_->destination->halves.low.halves.low, 0x80, t)
|
|
#define set_flags_w(t) set_flags(active_program_->destination->halves.low.full, 0x8000, t)
|
|
#define set_flags_l(t) set_flags(active_program_->destination->full, 0x80000000, t)
|
|
|
|
#define shift_op(name, op, mb, mw, ml) \
|
|
case Operation::name##b: { \
|
|
decode_shift_count(); \
|
|
const auto value = active_program_->destination->halves.low.halves.low; \
|
|
op(active_program_->destination->halves.low.halves.low, shift_count, 0xff, 7); \
|
|
set_flags_b(mb); \
|
|
} break; \
|
|
\
|
|
case Operation::name##w: { \
|
|
decode_shift_count(); \
|
|
const auto value = active_program_->destination->halves.low.full; \
|
|
op(active_program_->destination->halves.low.full, shift_count, 0xffff, 15); \
|
|
set_flags_w(mw); \
|
|
} break; \
|
|
\
|
|
case Operation::name##l: { \
|
|
decode_shift_count(); \
|
|
const auto value = active_program_->destination->full; \
|
|
op(active_program_->destination->full, shift_count, 0xffffffff, 31); \
|
|
set_flags_l(ml); \
|
|
} break; \
|
|
\
|
|
case Operation::name##m: { \
|
|
const auto value = active_program_->destination->halves.low.full; \
|
|
op(active_program_->destination->halves.low.full, 1, 0xffff, 15); \
|
|
set_flags_w(mw); \
|
|
} break;
|
|
|
|
#define lsl(x, c, m, d) x <<= c
|
|
#define lsr(x, c, m, d) x >>= c
|
|
#define asl(x, c, m, d) x <<= c
|
|
#define asr(x, c, m, d) x = (x >> c) | (((value >> d) & 1) * (m ^ (m >> c)))
|
|
|
|
// TODO: carry/extend is incorrect for shifts of greater than one digit.
|
|
|
|
shift_op(LSL, lsl, 0x80, 0x8000, 0x80000000);
|
|
shift_op(ASL, lsl, 0x80, 0x8000, 0x80000000);
|
|
shift_op(LSR, lsr, 0x01, 0x0001, 0x00000001);
|
|
shift_op(ASR, asr, 0x01, 0x0001, 0x00000001);
|
|
|
|
#undef set_flags
|
|
#define set_flags(v, m, t) \
|
|
zero_result_ = v; \
|
|
negative_flag_ = zero_result_ & (m); \
|
|
overflow_flag_ = 0; \
|
|
carry_flag_ = value & (t);
|
|
|
|
#define rol(destination, size) { \
|
|
decode_shift_count(); \
|
|
const auto value = destination; \
|
|
\
|
|
if(!shift_count) { \
|
|
carry_flag_ = 0; \
|
|
} else { \
|
|
shift_count &= (size - 1); \
|
|
destination = \
|
|
(value << shift_count) | \
|
|
(value >> (size - shift_count)); \
|
|
carry_flag_ = destination & 1; \
|
|
} \
|
|
\
|
|
set_neg_zero_overflow(destination, 1 << (size - 1)); \
|
|
}
|
|
|
|
case Operation::ROLm: {
|
|
const auto value = active_program_->destination->halves.low.full;
|
|
active_program_->destination->halves.low.full = (value << 1) | (value >> 15);
|
|
carry_flag_ = active_program_->destination->halves.low.full & 1;
|
|
set_neg_zero_overflow(active_program_->destination->halves.low.full, 0x8000);
|
|
} break;
|
|
case Operation::ROLb: rol(active_program_->destination->halves.low.halves.low, 8); break;
|
|
case Operation::ROLw: rol(active_program_->destination->halves.low.full, 16); break;
|
|
case Operation::ROLl: rol(active_program_->destination->full, 32); break;
|
|
|
|
#undef rol
|
|
|
|
#define ror(destination, size) { \
|
|
decode_shift_count(); \
|
|
const auto value = destination; \
|
|
\
|
|
if(!shift_count) { \
|
|
carry_flag_ = 0; \
|
|
} else { \
|
|
shift_count &= (size - 1); \
|
|
destination = \
|
|
(value >> shift_count) | \
|
|
(value << (size - shift_count)); \
|
|
carry_flag_ = destination & (1 << (size - 1)); \
|
|
} \
|
|
\
|
|
set_neg_zero_overflow(destination, 1 << (size - 1)); \
|
|
}
|
|
|
|
case Operation::RORm: {
|
|
const auto value = active_program_->destination->halves.low.full;
|
|
active_program_->destination->halves.low.full = (value >> 1) | (value << 15);
|
|
carry_flag_ = active_program_->destination->halves.low.full & 0x8000;
|
|
set_neg_zero_overflow(active_program_->destination->halves.low.full, 0x8000);
|
|
} break;
|
|
case Operation::RORb: ror(active_program_->destination->halves.low.halves.low, 8); break;
|
|
case Operation::RORw: ror(active_program_->destination->halves.low.full, 16); break;
|
|
case Operation::RORl: ror(active_program_->destination->full, 32); break;
|
|
|
|
#undef ror
|
|
|
|
#define roxl(destination, size) { \
|
|
decode_shift_count(); \
|
|
const auto value = destination; \
|
|
\
|
|
if(!shift_count) { \
|
|
carry_flag_ = extend_flag_; \
|
|
} else { \
|
|
shift_count %= (size + 1); \
|
|
destination = \
|
|
(value << shift_count) | \
|
|
(value >> (size + 1 - shift_count)) | \
|
|
((extend_flag_ ? (1 << (size - 1)) : 0) >> (size - shift_count)); \
|
|
carry_flag_ = extend_flag_ = destination & 1; \
|
|
} \
|
|
\
|
|
set_neg_zero_overflow(destination, 1 << (size - 1)); \
|
|
}
|
|
|
|
case Operation::ROXLm: {
|
|
const auto value = active_program_->destination->halves.low.full;
|
|
active_program_->destination->halves.low.full = (value << 1) | (extend_flag_ ? 0x0001 : 0x0000);
|
|
extend_flag_ = value & 0x8000;
|
|
set_flags_w(0x8000);
|
|
} break;
|
|
case Operation::ROXLb: roxl(active_program_->destination->halves.low.halves.low, 8); break;
|
|
case Operation::ROXLw: roxl(active_program_->destination->halves.low.full, 16); break;
|
|
case Operation::ROXLl: roxl(active_program_->destination->full, 32); break;
|
|
|
|
#undef roxl
|
|
|
|
#define roxr(destination, size) { \
|
|
decode_shift_count(); \
|
|
const auto value = destination; \
|
|
\
|
|
if(!shift_count) { \
|
|
carry_flag_ = extend_flag_; \
|
|
} else { \
|
|
shift_count %= (size + 1); \
|
|
destination = \
|
|
(value >> shift_count) | \
|
|
(value << (size + 1 - shift_count)) | \
|
|
((extend_flag_ ? 1 : 0) << (size - shift_count)); \
|
|
carry_flag_ = extend_flag_ = destination & 1; \
|
|
} \
|
|
\
|
|
set_neg_zero_overflow(destination, 1 << (size - 1)); \
|
|
}
|
|
|
|
case Operation::ROXRm: {
|
|
const auto value = active_program_->destination->halves.low.full;
|
|
active_program_->destination->halves.low.full = (value >> 1) | (extend_flag_ ? 0x8000 : 0x0000);
|
|
extend_flag_ = value & 0x0001;
|
|
set_flags_w(0x0001);
|
|
} break;
|
|
case Operation::ROXRb: roxr(active_program_->destination->halves.low.halves.low, 8); break;
|
|
case Operation::ROXRw: roxr(active_program_->destination->halves.low.full, 16); break;
|
|
case Operation::ROXRl: roxr(active_program_->destination->full, 32); break;
|
|
|
|
#undef roxr
|
|
|
|
#undef set_flags
|
|
#undef decode_shift_count
|
|
#undef set_flags_b
|
|
#undef set_flags_w
|
|
#undef set_flags_l
|
|
#undef set_neg_zero_overflow
|
|
/*
|
|
RTE and RTR share an implementation.
|
|
*/
|
|
case Operation::RTE_RTR:
|
|
// If this is RTR, patch out the is_supervisor bit.
|
|
if(decoded_instruction_ == 0x4e77) {
|
|
source_bus_data_[0].full =
|
|
(source_bus_data_[0].full & ~(1 << 13)) |
|
|
(is_supervisor_ << 13);
|
|
}
|
|
set_status(source_bus_data_[0].full);
|
|
break;
|
|
|
|
/*
|
|
TSTs: compare to zero.
|
|
*/
|
|
|
|
case Operation::TSTb:
|
|
carry_flag_ = overflow_flag_ = 0;
|
|
zero_result_ = active_program_->source->halves.low.halves.low;
|
|
negative_flag_ = zero_result_ & 0x80;
|
|
break;
|
|
|
|
case Operation::TSTw:
|
|
carry_flag_ = overflow_flag_ = 0;
|
|
zero_result_ = active_program_->source->halves.low.full;
|
|
negative_flag_ = zero_result_ & 0x8000;
|
|
break;
|
|
|
|
case Operation::TSTl:
|
|
carry_flag_ = overflow_flag_ = 0;
|
|
zero_result_ = active_program_->source->full;
|
|
negative_flag_ = zero_result_ & 0x80000000;
|
|
break;
|
|
|
|
/*
|
|
Development period debugging.
|
|
*/
|
|
default:
|
|
std::cerr << "Should do something with program operation " << int(active_program_->operation) << std::endl;
|
|
break;
|
|
}
|
|
#undef sub_overflow
|
|
#undef add_overflow
|
|
break;
|
|
|
|
case int(MicroOp::Action::MOVEMtoRComplete): {
|
|
// If this was a word-sized move, perform sign extension.
|
|
if(active_program_->operation == Operation::MOVEMtoRw) {
|
|
auto mask = next_word_;
|
|
int offset = 0;
|
|
while(mask) {
|
|
if(mask&1) {
|
|
const auto target = (offset > 7) ? &address_[offset&7] : &data_[offset];
|
|
target->halves.high.full = (target->halves.low.full & 0x8000) ? 0xffff : 0x0000;
|
|
}
|
|
mask >>= 1;
|
|
++offset;
|
|
}
|
|
}
|
|
|
|
// If the post-increment mode was used, overwrite the source register.
|
|
const auto mode = (decoded_instruction_ >> 3) & 7;
|
|
if(mode == 3) {
|
|
const auto reg = decoded_instruction_ & 7;
|
|
address_[reg] = movem_final_address_;
|
|
}
|
|
} break;
|
|
|
|
case int(MicroOp::Action::MOVEMtoMComplete): {
|
|
const auto mode = (decoded_instruction_ >> 3) & 7;
|
|
if(mode == 4) {
|
|
const auto reg = decoded_instruction_ & 7;
|
|
address_[reg] = movem_final_address_;
|
|
}
|
|
} break;
|
|
|
|
case int(MicroOp::Action::PrepareJSR): {
|
|
const auto mode = (decoded_instruction_ >> 3) & 7;
|
|
// Determine the proper resumption address.
|
|
switch(mode) {
|
|
case 2: destination_bus_data_[0].full = program_counter_.full - 2; break; /* (An) */
|
|
default:
|
|
destination_bus_data_[0].full = program_counter_.full; /* Everything other than (An) */
|
|
break;
|
|
}
|
|
destination_bus_data_[0].full = program_counter_.full;
|
|
address_[7].full -= 4;
|
|
effective_address_[1].full = address_[7].full;
|
|
} break;
|
|
|
|
case int(MicroOp::Action::PrepareBSR):
|
|
destination_bus_data_[0].full = (decoded_instruction_ & 0xff) ? program_counter_.full - 2 : program_counter_.full;
|
|
address_[7].full -= 4;
|
|
effective_address_[1].full = address_[7].full;
|
|
break;
|
|
|
|
case int(MicroOp::Action::PrepareRTS):
|
|
effective_address_[0].full = address_[7].full;
|
|
address_[7].full += 4;
|
|
break;
|
|
|
|
case int(MicroOp::Action::PrepareRTE_RTR):
|
|
precomputed_addresses_[0] = address_[7].full + 2;
|
|
precomputed_addresses_[1] = address_[7].full;
|
|
precomputed_addresses_[2] = address_[7].full + 4;
|
|
address_[7].full += 6;
|
|
break;
|
|
|
|
case int(MicroOp::Action::CopyNextWord):
|
|
next_word_ = prefetch_queue_.halves.low.full;
|
|
break;
|
|
|
|
// Increments and decrements.
|
|
#define Adjust(op, quantity) \
|
|
case int(op) | MicroOp::SourceMask: active_program_->source_address->full += quantity; break; \
|
|
case int(op) | MicroOp::DestinationMask: active_program_->destination_address->full += quantity; break; \
|
|
case int(op) | MicroOp::SourceMask | MicroOp::DestinationMask: \
|
|
active_program_->destination_address->full += quantity; \
|
|
active_program_->source_address->full += quantity; \
|
|
break;
|
|
|
|
Adjust(MicroOp::Action::Decrement1, -1);
|
|
Adjust(MicroOp::Action::Decrement2, -2);
|
|
Adjust(MicroOp::Action::Decrement4, -4);
|
|
Adjust(MicroOp::Action::Increment1, 1);
|
|
Adjust(MicroOp::Action::Increment2, 2);
|
|
Adjust(MicroOp::Action::Increment4, 4);
|
|
|
|
#undef Adjust
|
|
|
|
case int(MicroOp::Action::SignExtendWord):
|
|
if(active_micro_op_->action & MicroOp::SourceMask) {
|
|
active_program_->source->halves.high.full =
|
|
(active_program_->source->halves.low.full & 0x8000) ? 0xffff : 0x0000;
|
|
}
|
|
if(active_micro_op_->action & MicroOp::DestinationMask) {
|
|
active_program_->destination->halves.high.full =
|
|
(active_program_->destination->halves.low.full & 0x8000) ? 0xffff : 0x0000;
|
|
}
|
|
break;
|
|
|
|
case int(MicroOp::Action::SignExtendByte):
|
|
if(active_micro_op_->action & MicroOp::SourceMask) {
|
|
active_program_->source->full = (active_program_->source->full & 0xff) |
|
|
(active_program_->source->full & 0x80) ? 0xffffff : 0x000000;
|
|
}
|
|
if(active_micro_op_->action & MicroOp::DestinationMask) {
|
|
active_program_->destination->full = (active_program_->destination->full & 0xff) |
|
|
(active_program_->destination->full & 0x80) ? 0xffffff : 0x000000;
|
|
}
|
|
break;
|
|
|
|
// 16-bit offset addressing modes.
|
|
|
|
case int(MicroOp::Action::CalcD16PC) | MicroOp::SourceMask:
|
|
// The address the low part of the prefetch queue was read from was two bytes ago, hence
|
|
// the subtraction of 2.
|
|
effective_address_[0] = int16_t(prefetch_queue_.halves.low.full) + program_counter_.full - 2;
|
|
break;
|
|
|
|
case int(MicroOp::Action::CalcD16PC) | MicroOp::DestinationMask:
|
|
effective_address_[1] = int16_t(prefetch_queue_.halves.low.full) + program_counter_.full - 2;
|
|
break;
|
|
|
|
case int(MicroOp::Action::CalcD16PC) | MicroOp::SourceMask | MicroOp::DestinationMask:
|
|
// Similar logic applies here to above, but the high part of the prefetch queue was four bytes
|
|
// ago rather than merely two.
|
|
effective_address_[0] = int16_t(prefetch_queue_.halves.high.full) + program_counter_.full - 4;
|
|
effective_address_[1] = int16_t(prefetch_queue_.halves.low.full) + program_counter_.full - 2;
|
|
break;
|
|
|
|
case int(MicroOp::Action::CalcD16An) | MicroOp::SourceMask:
|
|
effective_address_[0] = int16_t(prefetch_queue_.halves.low.full) + active_program_->source_address->full;
|
|
break;
|
|
|
|
case int(MicroOp::Action::CalcD16An) | MicroOp::DestinationMask:
|
|
effective_address_[1] = int16_t(prefetch_queue_.halves.low.full) + active_program_->destination_address->full;
|
|
break;
|
|
|
|
case int(MicroOp::Action::CalcD16An) | MicroOp::SourceMask | MicroOp::DestinationMask:
|
|
effective_address_[0] = int16_t(prefetch_queue_.halves.high.full) + active_program_->source_address->full;
|
|
effective_address_[1] = int16_t(prefetch_queue_.halves.low.full) + active_program_->destination_address->full;
|
|
break;
|
|
|
|
#define CalculateD8AnXn(data, source, target) {\
|
|
const auto register_index = (data.full >> 12) & 7; \
|
|
const RegisterPair32 &displacement = (data.full & 0x8000) ? address_[register_index] : data_[register_index]; \
|
|
target.full = int8_t(data.halves.low) + source; \
|
|
\
|
|
if(data.full & 0x800) { \
|
|
target.full += int16_t(displacement.halves.low.full); \
|
|
} else { \
|
|
target.full += displacement.full; \
|
|
} \
|
|
}
|
|
case int(MicroOp::Action::CalcD8AnXn) | MicroOp::SourceMask: {
|
|
CalculateD8AnXn(prefetch_queue_.halves.low, active_program_->source_address->full, effective_address_[0]);
|
|
} break;
|
|
|
|
case int(MicroOp::Action::CalcD8AnXn) | MicroOp::DestinationMask: {
|
|
CalculateD8AnXn(prefetch_queue_.halves.low, active_program_->destination_address->full, effective_address_[1]);
|
|
} break;
|
|
|
|
case int(MicroOp::Action::CalcD8AnXn) | MicroOp::SourceMask | MicroOp::DestinationMask: {
|
|
CalculateD8AnXn(prefetch_queue_.halves.high, active_program_->source_address->full, effective_address_[0]);
|
|
CalculateD8AnXn(prefetch_queue_.halves.low, active_program_->destination_address->full, effective_address_[1]);
|
|
} break;
|
|
|
|
case int(MicroOp::Action::CalcD8PCXn) | MicroOp::SourceMask: {
|
|
CalculateD8AnXn(prefetch_queue_.halves.low, program_counter_.full - 2, effective_address_[0]);
|
|
} break;
|
|
|
|
case int(MicroOp::Action::CalcD8PCXn) | MicroOp::DestinationMask: {
|
|
CalculateD8AnXn(prefetch_queue_.halves.low, program_counter_.full - 2, effective_address_[1]);
|
|
} break;
|
|
|
|
case int(MicroOp::Action::CalcD8PCXn) | MicroOp::SourceMask | MicroOp::DestinationMask: {
|
|
CalculateD8AnXn(prefetch_queue_.halves.high, program_counter_.full - 4, effective_address_[0]);
|
|
CalculateD8AnXn(prefetch_queue_.halves.low, program_counter_.full - 2, effective_address_[1]);
|
|
} break;
|
|
|
|
#undef CalculateD8AnXn
|
|
|
|
case int(MicroOp::Action::AssembleWordAddressFromPrefetch) | MicroOp::SourceMask:
|
|
// Assumption: this will be assembling right at the start of the instruction.
|
|
effective_address_[0] = prefetch_queue_.halves.low.full;
|
|
break;
|
|
|
|
case int(MicroOp::Action::AssembleWordAddressFromPrefetch) | MicroOp::DestinationMask:
|
|
effective_address_[1] = prefetch_queue_.halves.low.full;
|
|
break;
|
|
|
|
case int(MicroOp::Action::AssembleLongWordAddressFromPrefetch) | MicroOp::SourceMask:
|
|
effective_address_[0] = prefetch_queue_.full;
|
|
break;
|
|
|
|
case int(MicroOp::Action::AssembleLongWordAddressFromPrefetch) | MicroOp::DestinationMask:
|
|
effective_address_[1] = prefetch_queue_.full;
|
|
break;
|
|
|
|
case int(MicroOp::Action::AssembleWordDataFromPrefetch) | MicroOp::SourceMask:
|
|
// Assumption: this will be assembling right at the start of the instruction.
|
|
source_bus_data_[0] = prefetch_queue_.halves.low.full;
|
|
break;
|
|
|
|
case int(MicroOp::Action::AssembleWordDataFromPrefetch) | MicroOp::DestinationMask:
|
|
destination_bus_data_[0] = prefetch_queue_.halves.low.full;
|
|
break;
|
|
|
|
case int(MicroOp::Action::AssembleLongWordDataFromPrefetch) | MicroOp::SourceMask:
|
|
source_bus_data_[0] = prefetch_queue_.full;
|
|
break;
|
|
|
|
case int(MicroOp::Action::AssembleLongWordDataFromPrefetch) | MicroOp::DestinationMask:
|
|
destination_bus_data_[0] = prefetch_queue_.full;
|
|
break;
|
|
|
|
case int(MicroOp::Action::CopyToEffectiveAddress) | MicroOp::SourceMask:
|
|
effective_address_[0] = *active_program_->source_address;
|
|
break;
|
|
|
|
case int(MicroOp::Action::CopyToEffectiveAddress) | MicroOp::DestinationMask:
|
|
effective_address_[1] = *active_program_->destination_address;
|
|
break;
|
|
|
|
case int(MicroOp::Action::CopyToEffectiveAddress) | MicroOp::SourceMask | MicroOp::DestinationMask:
|
|
effective_address_[0] = *active_program_->source_address;
|
|
effective_address_[1] = *active_program_->destination_address;
|
|
break;
|
|
}
|
|
|
|
// If we've got to a micro-op that includes bus steps, break out of this loop.
|
|
if(!active_micro_op_->is_terminal()) {
|
|
active_step_ = bus_program;
|
|
if(!active_step_->is_terminal())
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
PERFORM THE CURRENT BUS STEP'S MICROCYCLE.
|
|
*/
|
|
// Check for DTack if this isn't being treated implicitly.
|
|
if(!dtack_is_implicit) {
|
|
if(active_step_->microcycle.data_select_active() && !dtack_) {
|
|
// TODO: perform wait state.
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// TODO: synchronous bus.
|
|
|
|
// TODO: check for bus error.
|
|
|
|
// Perform the microcycle.
|
|
remaining_duration -=
|
|
active_step_->microcycle.length +
|
|
bus_handler_.perform_bus_operation(active_step_->microcycle, is_supervisor_);
|
|
|
|
#ifdef LOG_TRACE
|
|
if(!(active_step_->microcycle.operation & Microcycle::IsProgram)) {
|
|
switch(active_step_->microcycle.operation & (Microcycle::SelectWord | Microcycle::SelectByte | Microcycle::Read)) {
|
|
default: break;
|
|
|
|
case Microcycle::SelectWord | Microcycle::Read:
|
|
printf("[%08x -> %04x] ", *active_step_->microcycle.address, active_step_->microcycle.value->full);
|
|
break;
|
|
case Microcycle::SelectByte | Microcycle::Read:
|
|
printf("[%08x -> %02x] ", *active_step_->microcycle.address, active_step_->microcycle.value->halves.low);
|
|
break;
|
|
case Microcycle::SelectWord:
|
|
printf("{%04x -> %08x} ", active_step_->microcycle.value->full, *active_step_->microcycle.address);
|
|
break;
|
|
case Microcycle::SelectByte:
|
|
printf("{%02x -> %08x} ", active_step_->microcycle.value->halves.low, *active_step_->microcycle.address);
|
|
break;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
PERFORM THE BUS STEP'S ACTION.
|
|
*/
|
|
switch(active_step_->action) {
|
|
default:
|
|
std::cerr << "Unimplemented 68000 bus step action: " << int(active_step_->action) << std::endl;
|
|
return;
|
|
break;
|
|
|
|
case BusStep::Action::None: break;
|
|
|
|
case BusStep::Action::IncrementEffectiveAddress0: effective_address_[0].full += 2; break;
|
|
case BusStep::Action::IncrementEffectiveAddress1: effective_address_[1].full += 2; break;
|
|
case BusStep::Action::DecrementEffectiveAddress0: effective_address_[0].full -= 2; break;
|
|
case BusStep::Action::DecrementEffectiveAddress1: effective_address_[1].full -= 2; break;
|
|
case BusStep::Action::IncrementProgramCounter: program_counter_.full += 2; break;
|
|
|
|
case BusStep::Action::AdvancePrefetch:
|
|
prefetch_queue_.halves.high = prefetch_queue_.halves.low;
|
|
break;
|
|
}
|
|
|
|
// Move to the next bus step.
|
|
++ active_step_;
|
|
}
|
|
|
|
half_cycles_left_to_run_ = remaining_duration;
|
|
}
|
|
|
|
template <class T, bool dtack_is_implicit, bool signal_will_perform> ProcessorState Processor<T, dtack_is_implicit, signal_will_perform>::get_state() {
|
|
write_back_stack_pointer();
|
|
|
|
State state;
|
|
memcpy(state.data, data_, sizeof(state.data));
|
|
memcpy(state.address, address_, sizeof(state.address));
|
|
state.user_stack_pointer = stack_pointers_[0].full;
|
|
state.supervisor_stack_pointer = stack_pointers_[1].full;
|
|
|
|
state.status = get_status();
|
|
|
|
return state;
|
|
}
|
|
|
|
template <class T, bool dtack_is_implicit, bool signal_will_perform> void Processor<T, dtack_is_implicit, signal_will_perform>::set_state(const ProcessorState &state) {
|
|
memcpy(data_, state.data, sizeof(state.data));
|
|
memcpy(address_, state.address, sizeof(state.address));
|
|
stack_pointers_[0].full = state.user_stack_pointer;
|
|
stack_pointers_[1].full = state.supervisor_stack_pointer;
|
|
|
|
set_status(state.status);
|
|
|
|
address_[7] = stack_pointers_[is_supervisor_];
|
|
}
|
|
|
|
#undef get_status
|
|
#undef set_status
|
|
#undef set_ccr
|
|
#undef get_ccr
|