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CLK/InstructionSets/M68k/Implementation/PerformImplementation.hpp
Thomas Harte 28093196b9 Convert DIVU/DIVS logic to a template.
2022-10-11 16:16:53 -04:00

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//
// PerformImplementation.hpp
// Clock Signal
//
// Created by Thomas Harte on 28/04/2022.
// Copyright © 2022 Thomas Harte. All rights reserved.
//
#ifndef InstructionSets_M68k_PerformImplementation_h
#define InstructionSets_M68k_PerformImplementation_h
#include "../ExceptionVectors.hpp"
#include <cassert>
#include <cmath>
namespace InstructionSet {
namespace M68k {
#define u_extend16(x) uint32_t(int16_t(x))
#define s_extend16(x) int32_t(int16_t(x))
namespace Primitive {
/// Provides a type alias, @c type, which is an unsigned int bigger than @c IntT.
template <typename IntT> struct BiggerInt {};
template <> struct BiggerInt<uint8_t> {
using type = uint16_t;
};
template <> struct BiggerInt<uint16_t> {
using type = uint32_t;
};
template <> struct BiggerInt<uint32_t> {
using type = uint64_t;
};
/// @returns An int of type @c IntT with only the most-significant bit set.
template <typename IntT> constexpr IntT top_bit() {
static_assert(!std::numeric_limits<IntT>::is_signed);
constexpr IntT max = std::numeric_limits<IntT>::max();
return max - (max >> 1);
}
/// @returns The number of bits in @c IntT.
template <typename IntT> constexpr int bit_count() {
return sizeof(IntT) * 8;
}
/// @returns An int with the top bit indicating whether overflow occurred when @c source and @c destination
/// were either added (if @c is_add is true) or subtracted (if @c is_add is false) and the result was @c result.
/// All other bits will be clear.
template <bool is_add, typename IntT>
static Status::FlagT overflow(IntT source, IntT destination, IntT result) {
const IntT output_changed = result ^ destination;
const IntT input_differed = source ^ destination;
if constexpr (is_add) {
return top_bit<IntT>() & output_changed & ~input_differed;
} else {
return top_bit<IntT>() & output_changed & input_differed;
}
}
/// Performs an add or subtract (as per @c is_add) between @c source and @c destination,
/// updating @c status. @c is_extend indicates whether this is an extend operation (e.g. ADDX)
/// or a plain one (e.g. ADD).
template <bool is_add, bool is_extend, typename IntT>
static void add_sub(IntT source, IntT &destination, Status &status) {
static_assert(!std::numeric_limits<IntT>::is_signed);
const IntT extend = (is_extend && status.extend_flag) ? 1 : 0;
const IntT result = is_add ?
(destination + source + extend) :
(destination - source - extend);
// Extend operations can reset the zero flag only; non-extend operations
// can either set it or reset it. Which in the reverse-logic world of
// zero_result means ORing or storing.
if constexpr (is_extend) {
status.zero_result |= Status::FlagT(result);
} else {
status.zero_result = Status::FlagT(result);
}
status.extend_flag =
status.carry_flag = is_add ? result < destination : result > destination;
status.negative_flag = Status::FlagT(result & top_bit<IntT>());
status.overflow_flag = overflow<is_add>(source, destination, result);
destination = result;
}
/// Performs a compare of @c source to @c destination, setting zero, carry, negative and overflow flags.
template <typename IntT>
static void compare(IntT source, IntT destination, Status &status) {
const IntT result = destination - source;
status.zero_result = result;
status.carry_flag = result > destination;
status.negative_flag = result & top_bit<IntT>();
status.overflow_flag = Primitive::overflow<false>(source, destination, result);
}
/// @returns the name of the bit to be used as a mask for BCLR, BCHG, BSET or BTST for
/// @c instruction given @c source.
inline uint32_t mask_bit(const Preinstruction &instruction, uint32_t source) {
return source & (instruction.mode<1>() == AddressingMode::DataRegisterDirect ? 31 : 7);
}
/// Performs a BCLR, BCHG or BSET as specified by @c operation and described by @c instruction, @c source and @c destination, updating @c destination and @c status.
/// Also makes an appropriate notification to the @c flow_controller.
template <Operation operation, typename FlowController>
void bit_manipulate(const Preinstruction &instruction, uint32_t source, uint32_t &destination, Status &status, FlowController &flow_controller) {
static_assert(
operation == Operation::BCLR ||
operation == Operation::BCHG ||
operation == Operation::BSET);
const auto bit = mask_bit(instruction, source);
status.zero_result = destination & (1 << bit);
switch(operation) {
case Operation::BCLR: destination &= ~(1 << bit); break;
case Operation::BCHG: destination ^= (1 << bit); break;
case Operation::BSET: destination |= (1 << bit); break;
}
flow_controller.did_bit_op(int(bit));
}
/// Sets @c destination to 0, clears the overflow, carry and negative flags, sets the zero flag.
template <typename IntT> void clear(IntT &destination, Status &status) {
destination = 0;
status.negative_flag = status.overflow_flag = status.carry_flag = status.zero_result = 0;
}
template <Operation operation, typename FlowController>
void apply_sr_ccr(uint16_t source, Status &status, FlowController &flow_controller) {
static_assert(
operation == Operation::ANDItoSR || operation == Operation::ANDItoCCR ||
operation == Operation::EORItoSR || operation == Operation::EORItoCCR ||
operation == Operation::ORItoSR || operation == Operation::ORItoCCR
);
auto sr = status.status();
switch(operation) {
case Operation::ANDItoSR: case Operation::ANDItoCCR:
sr &= source;
break;
case Operation::EORItoSR: case Operation::EORItoCCR:
sr ^= source;
break;
case Operation::ORItoSR: case Operation::ORItoCCR:
sr |= source;
break;
}
switch(operation) {
case Operation::ANDItoSR:
case Operation::EORItoSR:
case Operation::ORItoSR:
status.set_status(sr);
flow_controller.did_update_status();
break;
case Operation::ANDItoCCR:
case Operation::EORItoCCR:
case Operation::ORItoCCR:
status.set_ccr(sr);
break;
}
}
template <bool is_mulu, typename FlowController>
void multiply(uint16_t source, uint32_t &destination, Status &status, FlowController &flow_controller) {
if constexpr (is_mulu) {
destination = source * uint16_t(destination);
} else {
destination = u_extend16(source) * u_extend16(uint16_t(destination));
}
status.carry_flag = status.overflow_flag = 0;
status.zero_result = destination;
status.negative_flag = status.zero_result & top_bit<uint32_t>();
if constexpr (is_mulu) {
flow_controller.did_mulu(source);
} else {
flow_controller.did_muls(source);
}
}
template <bool is_divu, bool did_overflow, typename IntT, typename FlowController>
void did_divide(IntT dividend, IntT divisor, FlowController &flow_controller) {
if constexpr (is_divu) {
flow_controller.template did_divu<did_overflow>(dividend, divisor);
} else {
flow_controller.template did_divs<did_overflow>(dividend, divisor);
}
}
template <bool is_divu, typename Int16, typename Int32, typename FlowController>
void divide(uint16_t source, uint32_t &destination, Status &status, FlowController &flow_controller) {
status.carry_flag = 0;
const auto dividend = Int32(destination);
const auto divisor = Int32(Int16(source));
if(!divisor) {
status.negative_flag = status.overflow_flag = 0;
status.zero_result = 1;
flow_controller.raise_exception(Exception::IntegerDivideByZero);
did_divide<is_divu, false>(dividend, divisor, flow_controller);
return;
}
const auto quotient = int64_t(dividend) / int64_t(divisor);
if(quotient != Int32(Int16(quotient))) {
status.overflow_flag = 1;
did_divide<is_divu, true>(dividend, divisor, flow_controller);
return;
}
const auto remainder = Int16(dividend % divisor);
destination = uint32_t((uint32_t(remainder) << 16) | uint16_t(quotient));
status.overflow_flag = 0;
status.zero_result = Status::FlagT(quotient);
status.negative_flag = status.zero_result & 0x8000;
did_divide<is_divu, false>(dividend, divisor, flow_controller);
}
}
template <
Model model,
typename FlowController,
Operation operation = Operation::Undefined
> void perform(Preinstruction instruction, CPU::SlicedInt32 &src, CPU::SlicedInt32 &dest, Status &status, FlowController &flow_controller) {
switch((operation != Operation::Undefined) ? operation : instruction.operation) {
/*
ABCD adds the lowest bytes from the source and destination using BCD arithmetic,
obeying the extend flag.
*/
case Operation::ABCD: {
// Pull out the two halves, for simplicity.
const uint8_t source = src.b;
const uint8_t destination = dest.b;
const int extend = (status.extend_flag ? 1 : 0);
// Perform the BCD add by evaluating the two nibbles separately.
const int unadjusted_result = destination + source + extend;
int result = (destination & 0xf) + (source & 0xf) + extend;
result +=
(destination & 0xf0) +
(source & 0xf0) +
(((9 - result) >> 4) & 0x06); // i.e. ((result > 0x09) ? 0x06 : 0x00)
result += ((0x9f - result) >> 4) & 0x60; // i.e. ((result > 0x9f) ? 0x60 : 0x00)
// Set all flags essentially as if this were normal addition.
status.zero_result |= result & 0xff;
status.extend_flag = status.carry_flag = uint_fast32_t(result & ~0xff);
status.negative_flag = result & 0x80;
status.overflow_flag = ~unadjusted_result & result & 0x80;
// Store the result.
dest.b = uint8_t(result);
} break;
// ADD and ADDA add two quantities, the latter sign extending and without setting any flags;
// ADDQ and SUBQ act as ADD and SUB, but taking the second argument from the instruction code.
case Operation::ADDb: Primitive::add_sub<true, false>(src.b, dest.b, status); break;
case Operation::SUBb: Primitive::add_sub<false, false>(src.b, dest.b, status); break;
case Operation::ADDXb: Primitive::add_sub<true, true>(src.b, dest.b, status); break;
case Operation::SUBXb: Primitive::add_sub<false, true>(src.b, dest.b, status); break;
case Operation::ADDw: Primitive::add_sub<true, false>(src.w, dest.w, status); break;
case Operation::SUBw: Primitive::add_sub<false, false>(src.w, dest.w, status); break;
case Operation::ADDXw: Primitive::add_sub<true, true>(src.w, dest.w, status); break;
case Operation::SUBXw: Primitive::add_sub<false, true>(src.w, dest.w, status); break;
case Operation::ADDl: Primitive::add_sub<true, false>(src.l, dest.l, status); break;
case Operation::SUBl: Primitive::add_sub<false, false>(src.l, dest.l, status); break;
case Operation::ADDXl: Primitive::add_sub<true, true>(src.l, dest.l, status); break;
case Operation::SUBXl: Primitive::add_sub<false, true>(src.l, dest.l, status); break;
case Operation::ADDAw: dest.l += u_extend16(src.w); break;
case Operation::ADDAl: dest.l += src.l; break;
case Operation::SUBAw: dest.l -= u_extend16(src.w); break;
case Operation::SUBAl: dest.l -= src.l; break;
// BTST/BCLR/etc: modulo for the mask depends on whether memory or a data register is the target.
case Operation::BTST:
status.zero_result = dest.l & (1 << Primitive::mask_bit(instruction, src.l));
break;
case Operation::BCLR: Primitive::bit_manipulate<Operation::BCLR>(instruction, src.l, dest.l, status, flow_controller); break;
case Operation::BCHG: Primitive::bit_manipulate<Operation::BCHG>(instruction, src.l, dest.l, status, flow_controller); break;
case Operation::BSET: Primitive::bit_manipulate<Operation::BSET>(instruction, src.l, dest.l, status, flow_controller); break;
case Operation::Bccb:
flow_controller.template complete_bcc<int8_t>(
status.evaluate_condition(instruction.condition()),
int8_t(src.b));
break;
case Operation::Bccw:
flow_controller.template complete_bcc<int16_t>(
status.evaluate_condition(instruction.condition()),
int16_t(src.w));
break;
case Operation::Bccl:
flow_controller.template complete_bcc<int32_t>(
status.evaluate_condition(instruction.condition()),
int32_t(src.l));
break;
case Operation::BSRb:
flow_controller.bsr(uint32_t(int8_t(src.b)));
break;
case Operation::BSRw:
flow_controller.bsr(uint32_t(int16_t(src.w)));
break;
case Operation::BSRl:
flow_controller.bsr(src.l);
break;
case Operation::DBcc: {
const bool matched_condition = status.evaluate_condition(instruction.condition());
bool overflowed = false;
// Classify the dbcc.
if(!matched_condition) {
-- src.w;
overflowed = src.w == 0xffff;
}
// Take the branch.
flow_controller.complete_dbcc(
matched_condition,
overflowed,
int16_t(dest.w));
} break;
case Operation::Scc: {
const bool condition = status.evaluate_condition(instruction.condition());
src.b = condition ? 0xff : 0x00;
flow_controller.did_scc(condition);
} break;
/*
CLRs: store 0 to the destination, set the zero flag, and clear
negative, overflow and carry.
*/
case Operation::CLRb: Primitive::clear(src.b, status); break;
case Operation::CLRw: Primitive::clear(src.w, status); break;
case Operation::CLRl: Primitive::clear(src.l, status); break;
/*
CMP.b, CMP.l and CMP.w: sets the condition flags (other than extend) based on a subtraction
of the source from the destination; the result of the subtraction is not stored.
*/
case Operation::CMPb: Primitive::compare(src.b, dest.b, status); break;
case Operation::CMPw: Primitive::compare(src.w, dest.w, status); break;
case Operation::CMPAw: Primitive::compare(u_extend16(src.w), dest.l, status); break;
case Operation::CMPAl:
case Operation::CMPl: Primitive::compare(src.l, dest.l, status); break;
// JMP: copies EA(0) to the program counter.
case Operation::JMP:
flow_controller.jmp(src.l);
break;
// JSR: jump to EA(0), pushing the current PC to the stack.
case Operation::JSR:
flow_controller.jsr(src.l);
break;
/*
MOVE.b, MOVE.l and MOVE.w: move the least significant byte or word, or the entire long word,
and set negative, zero, overflow and carry as appropriate.
*/
case Operation::MOVEb:
status.zero_result = dest.b = src.b;
status.negative_flag = status.zero_result & 0x80;
status.overflow_flag = status.carry_flag = 0;
break;
case Operation::MOVEw:
status.zero_result = dest.w = src.w;
status.negative_flag = status.zero_result & 0x8000;
status.overflow_flag = status.carry_flag = 0;
break;
case Operation::MOVEl:
status.zero_result = dest.l = src.l;
status.negative_flag = status.zero_result & 0x80000000;
status.overflow_flag = status.carry_flag = 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:
dest.l = u_extend16(src.w);
break;
case Operation::MOVEAl:
dest.l = src.l;
break;
case Operation::LEA:
dest.l = src.l;
break;
case Operation::PEA:
flow_controller.pea(src.l);
break;
/*
Status word moves and manipulations.
*/
case Operation::MOVEtoSR:
status.set_status(src.w);
flow_controller.did_update_status();
break;
case Operation::MOVEfromSR:
src.w = status.status();
break;
case Operation::MOVEtoCCR:
status.set_ccr(src.w);
break;
case Operation::MOVEtoUSP:
flow_controller.move_to_usp(src.l);
break;
case Operation::MOVEfromUSP:
flow_controller.move_from_usp(src.l);
break;
case Operation::EXTbtow:
src.w = uint16_t(int8_t(src.b));
status.overflow_flag = status.carry_flag = 0;
status.zero_result = src.w;
status.negative_flag = status.zero_result & 0x8000;
break;
case Operation::EXTwtol:
src.l = u_extend16(src.w);
status.overflow_flag = status.carry_flag = 0;
status.zero_result = src.l;
status.negative_flag = status.zero_result & 0x80000000;
break;
case Operation::ANDItoSR: Primitive::apply_sr_ccr<Operation::ANDItoSR>(src.w, status, flow_controller); break;
case Operation::EORItoSR: Primitive::apply_sr_ccr<Operation::EORItoSR>(src.w, status, flow_controller); break;
case Operation::ORItoSR: Primitive::apply_sr_ccr<Operation::ORItoSR>(src.w, status, flow_controller); break;
case Operation::ANDItoCCR: Primitive::apply_sr_ccr<Operation::ANDItoCCR>(src.w, status, flow_controller); break;
case Operation::EORItoCCR: Primitive::apply_sr_ccr<Operation::EORItoCCR>(src.w, status, flow_controller); break;
case Operation::ORItoCCR: Primitive::apply_sr_ccr<Operation::ORItoCCR>(src.w, status, flow_controller); break;
/*
Multiplications.
*/
case Operation::MULU: Primitive::multiply<true>(src.w, dest.l, status, flow_controller); break;
case Operation::MULS: Primitive::multiply<false>(src.w, dest.l, status, flow_controller); break;
/*
Divisions.
*/
case Operation::DIVU: Primitive::divide<true, uint16_t, uint32_t>(src.w, dest.l, status, flow_controller); break;
case Operation::DIVS: Primitive::divide<false, int16_t, int32_t>(src.w, dest.l, status, flow_controller); break;
// TRAP, which is a nicer form of ILLEGAL.
case Operation::TRAP:
flow_controller.template raise_exception<false>(int(src.l + Exception::TrapBase));
break;
case Operation::TRAPV: {
if(status.overflow_flag) {
flow_controller.template raise_exception<false>(Exception::TRAPV);
}
} break;
case Operation::CHK: {
const bool is_under = s_extend16(dest.w) < 0;
const bool is_over = s_extend16(dest.w) > s_extend16(src.w);
status.overflow_flag = status.carry_flag = 0;
status.zero_result = dest.w;
// Test applied for N:
//
// if Dn < 0, set negative flag;
// otherwise, if Dn > <ea>, reset negative flag.
if(is_over) status.negative_flag = 0;
if(is_under) status.negative_flag = 1;
// No exception is the default course of action; deviate only if an
// exception is necessary.
flow_controller.did_chk(is_under, is_over);
if(is_under || is_over) {
flow_controller.template raise_exception<false>(Exception::CHK);
}
} break;
/*
NEGs: negatives the destination, setting the zero,
negative, overflow and carry flags appropriate, and extend.
NB: since the same logic as SUB is used to calculate overflow,
and SUB calculates `destination - source`, the NEGs deliberately
label 'source' and 'destination' differently from Motorola.
*/
case Operation::NEGb: {
const int destination = 0;
const int source = src.b;
const auto result = destination - source;
src.b = uint8_t(result);
status.zero_result = result & 0xff;
status.extend_flag = status.carry_flag = Status::FlagT(result & ~0xff);
status.negative_flag = result & 0x80;
status.overflow_flag = Primitive::overflow<false>(uint8_t(source), uint8_t(destination), uint8_t(result));
} break;
case Operation::NEGw: {
const int destination = 0;
const int source = src.w;
const auto result = destination - source;
src.w = uint16_t(result);
status.zero_result = result & 0xffff;
status.extend_flag = status.carry_flag = Status::FlagT(result & ~0xffff);
status.negative_flag = result & 0x8000;
status.overflow_flag = Primitive::overflow<false>(uint16_t(source), uint16_t(destination), uint16_t(result));
} break;
case Operation::NEGl: {
const uint64_t destination = 0;
const uint64_t source = src.l;
const auto result = destination - source;
src.l = uint32_t(result);
status.zero_result = uint_fast32_t(result);
status.extend_flag = status.carry_flag = result >> 32;
status.negative_flag = result & 0x80000000;
status.overflow_flag = Primitive::overflow<false>(uint32_t(source), uint32_t(destination), uint32_t(result));
} break;
/*
NEGXs: NEG, with extend.
*/
case Operation::NEGXb: {
const int source = src.b;
const int destination = 0;
const auto result = destination - source - (status.extend_flag ? 1 : 0);
src.b = uint8_t(result);
status.zero_result |= result & 0xff;
status.extend_flag = status.carry_flag = Status::FlagT(result & ~0xff);
status.negative_flag = result & 0x80;
status.overflow_flag = Primitive::overflow<false>(uint8_t(source), uint8_t(destination), uint8_t(result));
} break;
case Operation::NEGXw: {
const int source = src.w;
const int destination = 0;
const auto result = destination - source - (status.extend_flag ? 1 : 0);
src.w = uint16_t(result);
status.zero_result |= result & 0xffff;
status.extend_flag = status.carry_flag = Status::FlagT(result & ~0xffff);
status.negative_flag = result & 0x8000;
status.overflow_flag = Primitive::overflow<false>(uint16_t(source), uint16_t(destination), uint16_t(result));
} break;
case Operation::NEGXl: {
const uint64_t source = src.l;
const uint64_t destination = 0;
const auto result = destination - source - (status.extend_flag ? 1 : 0);
src.l = uint32_t(result);
status.zero_result |= uint_fast32_t(result);
status.extend_flag = status.carry_flag = result >> 32;
status.negative_flag = result & 0x80000000;
status.overflow_flag = Primitive::overflow<false>(uint32_t(source), uint32_t(destination), uint32_t(result));
} break;
/*
The no-op.
*/
case Operation::NOP: break;
/*
LINK and UNLINK help with stack frames, allowing a certain
amount of stack space to be allocated or deallocated.
*/
case Operation::LINKw:
flow_controller.link(instruction, uint32_t(int16_t(dest.w)));
break;
case Operation::UNLINK:
flow_controller.unlink(src.l);
break;
/*
TAS: sets zero and negative depending on the current value of the destination,
and sets the high bit, using a specialised atomic bus cycle.
*/
case Operation::TAS:
flow_controller.tas(instruction, src.l);
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); \
status.overflow_flag = status.carry_flag = 0; \
status.zero_result = dest; \
status.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(src.b, dest.b, 0x80); break; \
case Operation::name##w: op(src.w, dest.w, 0x8000); break; \
case Operation::name##l: op(src.l, dest.l, 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:
src.b ^= 0xff;
status.zero_result = src.b;
status.negative_flag = status.zero_result & 0x80;
status.overflow_flag = status.carry_flag = 0;
break;
case Operation::NOTw:
src.w ^= 0xffff;
status.zero_result = src.w;
status.negative_flag = status.zero_result & 0x8000;
status.overflow_flag = status.carry_flag = 0;
break;
case Operation::NOTl:
src.l ^= 0xffffffff;
status.zero_result = src.l;
status.negative_flag = status.zero_result & 0x80000000;
status.overflow_flag = status.carry_flag = 0;
break;
#define sbcd(d) \
const int extend = (status.extend_flag ? 1 : 0); \
const int unadjusted_result = destination - source - extend; \
\
const int top = (destination & 0xf0) - (source & 0xf0) - (0x60 & (unadjusted_result >> 4)); \
\
int result = (destination & 0xf) - (source & 0xf) - extend; \
const int low_adjustment = 0x06 & (result >> 4); \
status.extend_flag = status.carry_flag = Status::FlagT( \
(unadjusted_result - low_adjustment) & 0x300 \
); \
result = result + top - low_adjustment; \
\
/* Store the result. */ \
d = uint8_t(result); \
\
/* Set all remaining flags essentially as if this were normal subtraction. */ \
status.zero_result |= d; \
status.negative_flag = result & 0x80; \
status.overflow_flag = unadjusted_result & ~result & 0x80; \
/*
SBCD subtracts the lowest byte of the source from that of the destination using
BCD arithmetic, obeying the extend flag.
*/
case Operation::SBCD: {
const uint8_t source = src.b;
const uint8_t destination = dest.b;
sbcd(dest.b);
} break;
/*
NBCD is like SBCD except that the result is 0 - source rather than
destination - source.
*/
case Operation::NBCD: {
const uint8_t source = src.b;
const uint8_t destination = 0;
sbcd(src.b);
} break;
#undef sbcd
// EXG and SWAP exchange/swap words or long words.
case Operation::EXG: {
const auto temporary = src.l;
src.l = dest.l;
dest.l = temporary;
} break;
case Operation::SWAP: {
uint16_t *const words = reinterpret_cast<uint16_t *>(&src.l);
const auto temporary = words[0];
words[0] = words[1];
words[1] = temporary;
status.zero_result = src.l;
status.negative_flag = temporary & 0x8000;
status.overflow_flag = status.carry_flag = 0;
} break;
/*
Shifts and rotates.
*/
#define set_neg_zero(v, m) \
status.zero_result = Status::FlagT(v); \
status.negative_flag = status.zero_result & Status::FlagT(m);
#define set_neg_zero_overflow(v, m) \
set_neg_zero(v, m); \
status.overflow_flag = (Status::FlagT(value) ^ status.zero_result) & Status::FlagT(m);
#define decode_shift_count(type) \
int shift_count = src.l & 63; \
flow_controller.template did_shift<type>(shift_count);
#define set_flags_w(t) set_flags(src.w, 0x8000, t)
#define asl(destination, size) {\
decode_shift_count(decltype(destination)); \
const auto value = destination; \
\
if(!shift_count) { \
status.carry_flag = status.overflow_flag = 0; \
} else { \
destination = (shift_count < size) ? decltype(destination)(value << shift_count) : 0; \
status.extend_flag = status.carry_flag = Status::FlagT(value) & Status::FlagT( (1u << (size - 1)) >> (shift_count - 1) ); \
\
if(shift_count >= size) status.overflow_flag = value && (value != decltype(value)(-1)); \
else { \
const auto mask = decltype(destination)(0xffffffff << (size - shift_count)); \
status.overflow_flag = mask & value && ((mask & value) != mask); \
} \
} \
\
set_neg_zero(destination, 1 << (size - 1)); \
}
case Operation::ASLm: {
const auto value = src.w;
src.w = uint16_t(value << 1);
status.extend_flag = status.carry_flag = value & 0x8000;
set_neg_zero_overflow(src.w, 0x8000);
} break;
case Operation::ASLb: asl(dest.b, 8); break;
case Operation::ASLw: asl(dest.w, 16); break;
case Operation::ASLl: asl(dest.l, 32); break;
#define asr(destination, size) {\
decode_shift_count(decltype(destination)); \
const auto value = destination; \
\
if(!shift_count) { \
status.carry_flag = 0; \
} else { \
destination = (shift_count < size) ? \
decltype(destination)(\
(value >> shift_count) | \
((value & decltype(value)(1 << (size - 1)) ? 0xffffffff : 0x000000000) << (size - shift_count)) \
) : \
decltype(destination)( \
(value & decltype(value)(1 << (size - 1))) ? 0xffffffff : 0x000000000 \
); \
status.extend_flag = status.carry_flag = Status::FlagT(value) & Status::FlagT(1 << (shift_count - 1)); \
} \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::ASRm: {
const auto value = src.w;
src.w = (value&0x8000) | (value >> 1);
status.extend_flag = status.carry_flag = value & 1;
set_neg_zero_overflow(src.w, 0x8000);
} break;
case Operation::ASRb: asr(dest.b, 8); break;
case Operation::ASRw: asr(dest.w, 16); break;
case Operation::ASRl: asr(dest.l, 32); break;
#undef set_neg_zero_overflow
#define set_neg_zero_overflow(v, m) \
set_neg_zero(v, m); \
status.overflow_flag = 0;
#undef set_flags
#define set_flags(v, m, t) \
status.zero_result = v; \
status.negative_flag = status.zero_result & (m); \
status.overflow_flag = 0; \
status.carry_flag = value & (t);
#define lsl(destination, size) {\
decode_shift_count(decltype(destination)); \
const auto value = destination; \
\
if(!shift_count) { \
status.carry_flag = 0; \
} else { \
destination = (shift_count < size) ? decltype(destination)(value << shift_count) : 0; \
status.extend_flag = status.carry_flag = Status::FlagT(value) & Status::FlagT( (1u << (size - 1)) >> (shift_count - 1) ); \
} \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::LSLm: {
const auto value = src.w;
src.w = uint16_t(value << 1);
status.extend_flag = status.carry_flag = value & 0x8000;
set_neg_zero_overflow(src.w, 0x8000);
} break;
case Operation::LSLb: lsl(dest.b, 8); break;
case Operation::LSLw: lsl(dest.w, 16); break;
case Operation::LSLl: lsl(dest.l, 32); break;
#define lsr(destination, size) {\
decode_shift_count(decltype(destination)); \
const auto value = destination; \
\
if(!shift_count) { \
status.carry_flag = 0; \
} else { \
destination = (shift_count < size) ? (value >> shift_count) : 0; \
status.extend_flag = status.carry_flag = value & Status::FlagT(1 << (shift_count - 1)); \
} \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::LSRm: {
const auto value = src.w;
src.w = value >> 1;
status.extend_flag = status.carry_flag = value & 1;
set_neg_zero_overflow(src.w, 0x8000);
} break;
case Operation::LSRb: lsr(dest.b, 8); break;
case Operation::LSRw: lsr(dest.w, 16); break;
case Operation::LSRl: lsr(dest.l, 32); break;
#define rol(destination, size) { \
decode_shift_count(decltype(destination)); \
const auto value = destination; \
\
if(!shift_count) { \
status.carry_flag = 0; \
} else { \
shift_count &= (size - 1); \
destination = decltype(destination)( \
(value << shift_count) | \
(value >> (size - shift_count)) \
); \
status.carry_flag = Status::FlagT(destination & 1); \
} \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::ROLm: {
const auto value = src.w;
src.w = uint16_t((value << 1) | (value >> 15));
status.carry_flag = src.w & 1;
set_neg_zero_overflow(src.w, 0x8000);
} break;
case Operation::ROLb: rol(dest.b, 8); break;
case Operation::ROLw: rol(dest.w, 16); break;
case Operation::ROLl: rol(dest.l, 32); break;
#define ror(destination, size) { \
decode_shift_count(decltype(destination)); \
const auto value = destination; \
\
if(!shift_count) { \
status.carry_flag = 0; \
} else { \
shift_count &= (size - 1); \
destination = decltype(destination)(\
(value >> shift_count) | \
(value << (size - shift_count)) \
);\
status.carry_flag = destination & Status::FlagT(1 << (size - 1)); \
} \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::RORm: {
const auto value = src.w;
src.w = uint16_t((value >> 1) | (value << 15));
status.carry_flag = src.w & 0x8000;
set_neg_zero_overflow(src.w, 0x8000);
} break;
case Operation::RORb: ror(dest.b, 8); break;
case Operation::RORw: ror(dest.w, 16); break;
case Operation::RORl: ror(dest.l, 32); break;
#define roxl(destination, size) { \
decode_shift_count(decltype(destination)); \
\
shift_count %= (size + 1); \
uint64_t compound = uint64_t(destination) | (status.extend_flag ? (1ull << size) : 0); \
compound = \
(compound << shift_count) | \
(compound >> (size + 1 - shift_count)); \
status.carry_flag = status.extend_flag = Status::FlagT((compound >> size) & 1); \
destination = decltype(destination)(compound); \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::ROXLm: {
const auto value = src.w;
src.w = uint16_t((value << 1) | (status.extend_flag ? 0x0001 : 0x0000));
status.extend_flag = value & 0x8000;
set_flags_w(0x8000);
} break;
case Operation::ROXLb: roxl(dest.b, 8); break;
case Operation::ROXLw: roxl(dest.w, 16); break;
case Operation::ROXLl: roxl(dest.l, 32); break;
#define roxr(destination, size) { \
decode_shift_count(decltype(destination)); \
\
shift_count %= (size + 1); \
uint64_t compound = uint64_t(destination) | (status.extend_flag ? (1ull << size) : 0); \
compound = \
(compound >> shift_count) | \
(compound << (size + 1 - shift_count)); \
status.carry_flag = status.extend_flag = Status::FlagT((compound >> size) & 1); \
destination = decltype(destination)(compound); \
\
set_neg_zero_overflow(destination, 1 << (size - 1)); \
}
case Operation::ROXRm: {
const auto value = src.w;
src.w = (value >> 1) | (status.extend_flag ? 0x8000 : 0x0000);
status.extend_flag = value & 0x0001;
set_flags_w(0x0001);
} break;
case Operation::ROXRb: roxr(dest.b, 8); break;
case Operation::ROXRw: roxr(dest.w, 16); break;
case Operation::ROXRl: roxr(dest.l, 32); break;
#undef roxr
#undef roxl
#undef ror
#undef rol
#undef asr
#undef lsr
#undef lsl
#undef asl
#undef set_flags
#undef decode_shift_count
#undef set_flags_w
#undef set_neg_zero_overflow
#undef set_neg_zero
case Operation::MOVEPl:
flow_controller.template movep<uint32_t>(instruction, src.l, dest.l);
break;
case Operation::MOVEPw:
flow_controller.template movep<uint16_t>(instruction, src.l, dest.l);
break;
case Operation::MOVEMtoRl:
flow_controller.template movem_toR<uint32_t>(instruction, src.l, dest.l);
break;
case Operation::MOVEMtoMl:
flow_controller.template movem_toM<uint32_t>(instruction, src.l, dest.l);
break;
case Operation::MOVEMtoRw:
flow_controller.template movem_toR<uint16_t>(instruction, src.l, dest.l);
break;
case Operation::MOVEMtoMw:
flow_controller.template movem_toM<uint16_t>(instruction, src.l, dest.l);
break;
/*
RTE and RTR share an implementation.
*/
case Operation::RTR:
flow_controller.rtr();
break;
case Operation::RTE:
flow_controller.rte();
break;
case Operation::RTS:
flow_controller.rts();
break;
/*
TSTs: compare to zero.
*/
case Operation::TSTb:
status.carry_flag = status.overflow_flag = 0;
status.zero_result = src.b;
status.negative_flag = status.zero_result & 0x80;
break;
case Operation::TSTw:
status.carry_flag = status.overflow_flag = 0;
status.zero_result = src.w;
status.negative_flag = status.zero_result & 0x8000;
break;
case Operation::TSTl:
status.carry_flag = status.overflow_flag = 0;
status.zero_result = src.l;
status.negative_flag = status.zero_result & 0x80000000;
break;
case Operation::STOP:
status.set_status(src.w);
flow_controller.did_update_status();
flow_controller.stop();
break;
case Operation::RESET:
flow_controller.reset();
break;
/*
Development period debugging.
*/
default:
assert(false);
break;
}
#undef u_extend16
#undef s_extend16
}
}
}
#endif /* InstructionSets_M68k_PerformImplementation_h */
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