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Correct SHA, SHX, SHY, SHS when page boundary crossed.

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This commit is contained in:
Thomas Harte 2023-09-21 15:31:04 -04:00
parent 4c32fc9b11
commit 873b1122ab
3 changed files with 54 additions and 6 deletions
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10
OSBindings/Mac/Clock SignalTests/NeskellTests.swift
View File

@ -46,7 +46,15 @@ class NeskellTests: XCTestCase {
let stackStart = UInt32(0x101 + machine.value(for: .stackPointer))
let stackLength = UInt32(0x200 - stackStart)
let stackData = machine.data(atAddress: stackStart, length: stackLength)
XCTAssertEqual(stackData, Data(contents));
XCTAssertEqual(stackData.count, contents.count);
if stackData.count != contents.count {
return
}
for c in 0 ..< stackData.count {
XCTAssertEqual(stackData[c], contents[c], "Index \(c)")
}
}
func testAHX_TAS_SHX_SHY() {

1
Processors/6502/6502.hpp
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@ -9,6 +9,7 @@
#ifndef MOS6502_cpp
#define MOS6502_cpp
#include <algorithm>
#include <cassert>
#include <cstdio>
#include <cstdint>

49
Processors/6502/Implementation/6502Implementation.hpp
View File

@ -223,10 +223,45 @@ template <Personality personality, typename T, bool uses_ready_line> void Proces
case OperationSTY: operand_ = y_; continue;
case OperationSTZ: operand_ = 0; continue;
case OperationSAX: operand_ = a_ & x_; continue;
case OperationSHA: operand_ = a_ & x_ & (address_.halves.high+1); continue;
case OperationSHX: operand_ = x_ & (address_.halves.high+1); continue;
case OperationSHY: operand_ = y_ & (address_.halves.high+1); continue;
case OperationSHS: s_ = a_ & x_; operand_ = s_ & (address_.halves.high+1); continue;
// For the next four, intended effect is:
//
// CPU calculates what address would be if a page boundary is crossed. The high byte of that
// takes part in the AND. If the page boundary is actually crossed then the total AND takes
// the place of the intended high byte.
//
// Within this implementation, there's a bit of after-the-effect judgment on whether a page
// boundary was crossed.
case OperationSHA:
if(address_.full != next_address_.full) {
address_.halves.high = operand_ = a_ & x_ & address_.halves.high;
} else {
operand_ = a_ & x_ & (address_.halves.high + 1);
}
continue;
case OperationSHX:
if(address_.full != next_address_.full) {
address_.halves.high = operand_ = x_ & address_.halves.high;
} else {
operand_ = x_ & (address_.halves.high + 1);
}
continue;
case OperationSHY:
if(address_.full != next_address_.full) {
address_.halves.high = operand_ = y_ & address_.halves.high;
} else {
operand_ = y_ & (address_.halves.high + 1);
}
continue;
case OperationSHS:
if(address_.full != next_address_.full) {
s_ = a_ & x_;
address_.halves.high = operand_ = s_ & address_.halves.high;
} else {
s_ = a_ & x_;
operand_ = s_ & (address_.halves.high + 1);
}
continue;
case OperationLXA:
a_ = x_ = (a_ | 0xee) & operand_;
@ -531,7 +566,11 @@ template <Personality personality, typename T, bool uses_ready_line> void Proces
#undef page_crossing_stall_read
case OperationCorrectAddressHigh:
address_.full = next_address_.full;
// Preserve the uncorrected address in next_address_ (albeit that it's
// now a misnomer) as some of the more obscure illegal operations end
// up acting differently if an adjustment was necessary and therefore need
// a crumb trail to test for that.
std::swap(address_.full, next_address_.full);
continue;
case CycleIncrementPCFetchAddressLowFromOperand:
pc_.full++;