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Starts forming an Atari ST memory map.

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This commit is contained in:
Thomas Harte 2019-10-04 22:38:46 -04:00
parent a8a34497ff
commit 3f45cd2380
3 changed files with 67 additions and 4 deletions
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59
Machines/AtariST/AtariST.cpp
View File

@ -15,6 +15,9 @@
#include "Video.hpp"
#include "../../ClockReceiver/JustInTime.hpp"
#include "../Utility/MemoryPacker.hpp"
#include "../Utility/MemoryFuzzer.hpp"
namespace Atari {
namespace ST {
@ -31,7 +34,8 @@ class ConcreteMachine:
mc68000_(*this) {
set_clock_rate(CLOCK_RATE);
ram_.resize(512 * 1024);
ram_.resize(512 * 512);
Memory::Fuzz(ram_);
std::vector<ROMMachine::ROM> rom_descriptions = {
{"AtariST", "the TOS ROM", "tos100.img", 192*1024, 0x1a586c64}
@ -40,7 +44,7 @@ class ConcreteMachine:
if(!roms[0]) {
throw ROMMachine::Error::MissingROMs;
}
rom_ = *roms[0];
Memory::PackBigEndian16(*roms[0], rom_);
}
// MARK: CRTMachine::Machine
@ -57,7 +61,54 @@ class ConcreteMachine:
}
// MARK: MC68000::BusHandler
using Microcycle = CPU::MC68000::Microcycle;
HalfCycles perform_bus_operation(const CPU::MC68000::Microcycle &cycle, int is_supervisor) {
// Advance time.
video_ += cycle.length;
// A null cycle leaves nothing else to do.
if(!(cycle.operation & (Microcycle::NewAddress | Microcycle::SameAddress))) return HalfCycles(0);
auto address = cycle.word_address();
uint16_t *memory;
if(address < 4) {
memory = rom_.data();
} else if(address < 0x700000) {
memory = ram_.data();
address &= ram_.size() - 1;
// TODO: align with the next access window.
} else if(address < 0x780000) { // TOS 2.0+ address
memory = rom_.data();
address &= rom_.size() - 1;
} else if(address >= 0x7e0000 && address < 0x7f8000) { // TOS 1.0 address
memory = rom_.data();
address &= rom_.size() - 1;
} else {
assert(false);
}
// If control has fallen through to here, the access is either a read from ROM, or a read or write to RAM.
switch(cycle.operation & (Microcycle::SelectWord | Microcycle::SelectByte | Microcycle::Read)) {
default:
break;
case Microcycle::SelectWord | Microcycle::Read:
cycle.value->full = memory[address];
break;
case Microcycle::SelectByte | Microcycle::Read:
cycle.value->halves.low = uint8_t(memory[address] >> cycle.byte_shift());
break;
case Microcycle::SelectWord:
memory[address] = cycle.value->full;
break;
case Microcycle::SelectByte:
memory[address] = uint16_t(
(cycle.value->halves.low << cycle.byte_shift()) |
(memory[address] & cycle.untouched_byte_mask())
);
break;
}
return HalfCycles(0);
}
@ -65,8 +116,8 @@ class ConcreteMachine:
CPU::MC68000::Processor<ConcreteMachine, true> mc68000_;
JustInTimeActor<Video, HalfCycles> video_;
std::vector<uint8_t> ram_;
std::vector<uint8_t> rom_;
std::vector<uint16_t> ram_;
std::vector<uint16_t> rom_;
};

5
Machines/Utility/MemoryPacker.cpp
View File

@ -13,3 +13,8 @@ void Memory::PackBigEndian16(const std::vector<uint8_t> &source, uint16_t *targe
target[c >> 1] = uint16_t(source[c] << 8) | uint16_t(source[c+1]);
}
}
void Memory::PackBigEndian16(const std::vector<uint8_t> &source, std::vector<uint16_t> &target) {
target.resize(source.size() >> 1);
PackBigEndian16(source, target.data());
}

7
Machines/Utility/MemoryPacker.hpp
View File

@ -20,5 +20,12 @@ namespace Memory {
*/
void PackBigEndian16(const std::vector<uint8_t> &source, uint16_t *target);
/*!
Copies the bytes from @c source into @c target, interpreting them
as big-endian 16-bit data. @c target will be resized to the proper size
exactly to contain the contents of @c source.
*/
void PackBigEndian16(const std::vector<uint8_t> &source, std::vector<uint16_t> &target);
}
#endif /* MemoryPacker_hpp */