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This might very well be the 68000's first real gasp: performing an ABCD.

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This commit is contained in:
Thomas Harte 2019-03-14 19:32:15 -04:00
parent bb04981280
commit f9101de956
5 changed files with 142 additions and 13 deletions
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4
OSBindings/Mac/Clock Signal.xcodeproj/project.pbxproj
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@ -616,6 +616,7 @@
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4BD191F52191180E0042E144 /* ScanTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BD191F22191180E0042E144 /* ScanTarget.cpp */; };
4BD388882239E198002D14B5 /* 68000Tests.mm in Sources */ = {isa = PBXBuildFile; fileRef = 4BD388872239E198002D14B5 /* 68000Tests.mm */; };
4BD3A30B1EE755C800B5B501 /* Video.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BD3A3091EE755C800B5B501 /* Video.cpp */; };
4BD424DF2193B5340097291A /* TextureTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BD424DD2193B5340097291A /* TextureTarget.cpp */; };
4BD424E02193B5340097291A /* TextureTarget.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4BD424DD2193B5340097291A /* TextureTarget.cpp */; };
@ -1375,6 +1376,7 @@
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4BD388411FE34E010042B588 /* 9918Base.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; name = 9918Base.hpp; path = 9918/Implementation/9918Base.hpp; sourceTree = "<group>"; };
4BD388872239E198002D14B5 /* 68000Tests.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = 68000Tests.mm; sourceTree = "<group>"; };
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@ -2822,6 +2824,7 @@
4BB73EB51B587A5100552FC2 /* Clock SignalTests */ = {
isa = PBXGroup;
children = (
4BD388872239E198002D14B5 /* 68000Tests.mm */,
4B924E981E74D22700B76AF1 /* AtariStaticAnalyserTests.mm */,
4BB2A9AE1E13367E001A5C23 /* CRCTests.mm */,
4BFF1D3C2235C3C100838EA1 /* EmuTOSTests.mm */,
@ -4024,6 +4027,7 @@
4BB73EB71B587A5100552FC2 /* AllSuiteATests.swift in Sources */,
4B01A6881F22F0DB001FD6E3 /* Z80MemptrTests.swift in Sources */,
4B121F9B1E06293F00BFDA12 /* PCMSegmentEventSourceTests.mm in Sources */,
4BD388882239E198002D14B5 /* 68000Tests.mm in Sources */,
4BA91E1D216D85BA00F79557 /* MasterSystemVDPTests.mm in Sources */,
4B98A0611FFADCDE00ADF63B /* MSXStaticAnalyserTests.mm in Sources */,
4BEF6AAC1D35D1C400E73575 /* DPLLTests.swift in Sources */,

87
OSBindings/Mac/Clock SignalTests/68000Tests.mm Normal file
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@ -0,0 +1,87 @@
//
// 68000Tests.m
// Clock SignalTests
//
// Created by Thomas Harte on 13/03/2019.
// Copyright © 2019 Thomas Harte. All rights reserved.
//
#import <XCTest/XCTest.h>
#include <array>
#include <cassert>
#include "68000.hpp"
/*!
Provides a 68000 with 64kb of RAM in its low address space;
/RESET will put the supervisor stack pointer at 0xFFFF and
begin execution at 0x0400.
*/
class RAM68000: public CPU::MC68000::BusHandler {
public:
RAM68000() : m68000_(*this) {
ram_.resize(32768);
// Setup the /RESET vector.
ram_[0] = 0;
ram_[1] = 0xffff;
ram_[2] = 0;
ram_[3] = 0x0400;
}
void set_program(const std::vector<uint16_t> &program) {
memcpy(&ram_[512], program.data(), program.size() * sizeof(uint16_t));
}
void run_for(HalfCycles cycles) {
m68000_.run_for(cycles);
}
HalfCycles perform_bus_operation(const CPU::MC68000::Microcycle &cycle, int is_supervisor) {
uint32_t address = cycle.address ? (*cycle.address) & 0x00fffffe : 0;
switch(cycle.operation & (CPU::MC68000::Microcycle::LowerData | CPU::MC68000::Microcycle::UpperData)) {
case 0: break;
case CPU::MC68000::Microcycle::LowerData:
cycle.value->halves.low = ram_[address >> 1] >> 8;
break;
case CPU::MC68000::Microcycle::UpperData:
cycle.value->halves.high = ram_[address >> 1] & 0xff;
break;
case CPU::MC68000::Microcycle::UpperData | CPU::MC68000::Microcycle::LowerData:
cycle.value->full = ram_[address >> 1];
break;
}
return HalfCycles(0);
}
private:
CPU::MC68000::Processor<RAM68000, true> m68000_;
std::vector<uint16_t> ram_;
};
@interface M68000Tests : XCTestCase
@end
@implementation M68000Tests {
std::unique_ptr<RAM68000> _machine;
}
- (void)setUp {
_machine.reset(new RAM68000());
}
- (void)tearDown {
_machine.reset();
}
- (void)testABCD {
_machine->set_program({
0xc100 // ABCD D0, D0
});
_machine->run_for(HalfCycles(400));
}
@end

49
Processors/68000/Implementation/68000Implementation.hpp
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@ -15,12 +15,36 @@ template <class T, bool dtack_is_implicit> void Processor<T, dtack_is_implicit>:
// for interrupts).
if(active_step_->action == BusStep::Action::ScheduleNextProgram) {
if(active_micro_op_) {
++active_micro_op_;
switch(active_micro_op_->action) {
case MicroOp::Action::None: break;
case MicroOp::Action::PerformOperation:
std::cerr << "Should do something with program operation " << int(active_program_->operation) << std::endl;
switch(active_program_->operation) {
case Operation::ABCD: {
// 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 = (source & 0xf) + (destination & 0xf) + (extend_flag_ ? 1 : 0);
if(result > 0x9) result += 0x06;
result += (source & 0xf0) + (destination & 0xf0);
if(result > 0x90) result += 0x60;
// Set all flags essentially as if this were normal addition.
zero_flag_ |= result & 0xff;
extend_flag_ = carry_flag_ = result & ~0xff;
negative_flag_ = result & 0x80;
overflow_flag_ = ~(source ^ destination) & (source ^ result) & 0x80;
// Store the result.
active_program_->destination->halves.low.halves.low = uint8_t(result);
} break;
default:
std::cerr << "Should do something with program operation " << int(active_program_->operation) << std::endl;
break;
}
break;
case MicroOp::Action::PredecrementSourceAndDestination1:
@ -28,22 +52,33 @@ template <class T, bool dtack_is_implicit> void Processor<T, dtack_is_implicit>:
-- active_program_->destination->full;
break;
case MicroOp::Action::PredecrementSourceAndDestination1:
case MicroOp::Action::PredecrementSourceAndDestination2:
active_program_->source->full -= 2;
active_program_->destination->full -= 2;
break;
case MicroOp::Action::PredecrementSourceAndDestination1:
case MicroOp::Action::PredecrementSourceAndDestination4:
active_program_->source->full -= 4;
active_program_->destination->full -= 4;
break;
}
}
if(active_micro_op_) {
++active_micro_op_;
active_step_ = active_micro_op_->bus_program;
}
if(!active_step_) {
std::cerr << "68000 Abilities exhausted; should schedule an instruction or something?" << std::endl;
return;
if(!active_step_ || !active_micro_op_) {
const uint16_t next_instruction = prefetch_queue_[0].full;
if(!instructions[next_instruction].micro_operations) {
std::cerr << "68000 Abilities exhausted; should schedule an instruction or something?" << std::endl;
return;
}
active_program_ = &instructions[next_instruction];
active_micro_op_ = active_program_->micro_operations;
active_step_ = active_micro_op_->bus_program;
}
}

6
Processors/68000/Implementation/68000Storage.cpp
View File

@ -219,7 +219,7 @@ void ProcessorStorage::install_instructions(const BusStepCollection &bus_step_co
std::vector<size_t> micro_op_pointers(65536, std::numeric_limits<size_t>::max());
// Perform a linear search of the mappings above for this instruction.
for(size_t instruction = 0; instruction < 65536; ++instruction) {
for(size_t instruction = 0; instruction < 65536; ++instruction) {
for(const auto &mapping: mappings) {
if((instruction & mapping.mask) == mapping.value) {
// Install the operation and make a note of where micro-ops begin.
@ -228,11 +228,9 @@ void ProcessorStorage::install_instructions(const BusStepCollection &bus_step_co
switch(mapping.decoder) {
case Decoder::Decimal: {
const int destination = (instruction >> 8) & 7;
const int destination = (instruction >> 9) & 7;
const int source = instruction & 7;
all_micro_ops_.emplace_back();
if(instruction & 8) {
// Install source and destination.
instructions[instruction].source = &bus_data_[0];

9
Processors/68000/Implementation/68000Storage.hpp
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@ -26,6 +26,11 @@ class ProcessorStorage {
// Various status bits.
int is_supervisor_;
int zero_flag_; // The zero flag is set if this value is zero.
int carry_flag_; // The carry flag is set if this value is non-zero.
int extend_flag_; // The extend flag is set if this value is non-zero.
int overflow_flag_; // The overflow flag is set if this value is non-zero.
int negative_flag_; // The negative flag is set if this value is non-zero.
// Generic sources and targets for memory operations.
uint32_t effective_address_;
@ -88,8 +93,8 @@ class ProcessorStorage {
*/
struct Program {
MicroOp *micro_operations = nullptr;
RegisterPair32 *source;
RegisterPair32 *destination;
RegisterPair32 *source = nullptr;
RegisterPair32 *destination = nullptr;
Operation operation;
};