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Knocks SBC into producing likely results; disables Lorenz testing.

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This commit is contained in:
Thomas Harte 2020-10-10 17:13:16 -04:00
parent da4702851f
commit 0fe09cd1e4
2 changed files with 38 additions and 15 deletions
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10
OSBindings/Mac/Clock SignalTests/WolfgangLorenzTests.swift
View File

@ -220,12 +220,10 @@ class WolfgangLorenzTests: XCTestCase, CSTestMachineTrapHandler {
func testFlagManipulation65816() {
testFlagManipulation(processor: .processor65816)
}
func testADC65816() {
runTest("adc", suffixes: ["b", "z", "zx", "a", "ax", "ay", "ix", "iy"], processor: .processor65816)
}
func testSBC65816() {
runTest("sbc", suffixes: ["b", "z", "zx", "a", "ax", "ay", "ix", "iy"], processor: .processor65816)
}
/*
ADC and SBC tests don't apply, as the 65816 follows the 65C02 in setting flags based on the outcome of decimal
results, whereas Lorenzz's tests expect the original 6502 behaviour of setting flags based an intermediate value.
*/
// MARK: - Collections

43
Processors/65816/Implementation/65816Implementation.hpp
View File

@ -715,6 +715,34 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
#undef cp
case SBC:
if(flags_.decimal) {
// I've yet to manage to find a rational way to map this to an ADC,
// hence the yucky repetition of code here.
const uint16_t a = a_.full & m_masks_[1];
unsigned int result = 0;
unsigned int borrow = flags_.carry ^ 1;
#define nibble(mask, adjustment, carry) \
result += (a & mask) - (data_buffer_.value & mask) - borrow; \
if(result > mask) result -= adjustment;\
borrow = (result > mask) ? carry : 0; \
result &= (carry - 1);
nibble(0x000f, 0x0006, 0x00010);
nibble(0x00f0, 0x0060, 0x00100);
nibble(0x0f00, 0x0600, 0x01000);
nibble(0xf000, 0x6000, 0x10000);
#undef nibble
flags_.overflow = ~(( (result ^ a_.full) & (result ^ data_buffer_.value) ) >> (1 + m_shift_))&0x40;
flags_.set_nz(result, m_shift_);
flags_.carry = ((borrow >> 16)&1)^1;
LD(a_, result, m_masks_);
break;
}
data_buffer_.value = ~data_buffer_.value & m_masks_[1];
[[fallthrough]];
@ -724,18 +752,15 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
if(flags_.decimal) {
result = flags_.carry;
const int nibble_adjustment = (active_instruction_->operation == SBC) ? 0xa : 0x6;
// TODO: this still isn't quite correct for SBC as the limit test is wrong, I think.
#define nibble(mask, limit, addition, carry) \
#define nibble(mask, limit, adjustment, carry) \
result += (a & mask) + (data_buffer_.value & mask); \
if(result >= limit) result = ((result + (addition)) & (carry - 1)) + carry;
if(result >= limit) result = ((result + (adjustment)) & (carry - 1)) + carry;
nibble(0x000f, 0x000a, nibble_adjustment << 0, 0x00010);
nibble(0x00f0, 0x00a0, nibble_adjustment << 4, 0x00100);
nibble(0x0f00, 0x0a00, nibble_adjustment << 8, 0x01000);
nibble(0xf000, 0xa000, nibble_adjustment << 12, 0x10000);
nibble(0x000f, 0x000a, 0x0006, 0x00010);
nibble(0x00f0, 0x00a0, 0x0060, 0x00100);
nibble(0x0f00, 0x0a00, 0x0600, 0x01000);
nibble(0xf000, 0xa000, 0x6000, 0x10000);
#undef nibble