6502/CLK
1
0
Fork 0
mirror of https://github.com/TomHarte/CLK.git synced 2024-12-27 16:31:31 +00:00
Code Issues Projects Releases Wiki Activity

Implements enough of ADC and SBC for the Dormann test definitively to fail.

Browse Source
This commit is contained in:
Thomas Harte 2020-10-07 18:36:17 -04:00
parent 7439a326a6
commit eac722cf59
1 changed files with 38 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
Processors/65816/Implementation/65816Implementation.hpp
View File

@ -594,8 +594,45 @@ template <typename BusHandler> void Processor<BusHandler>::run_for(const Cycles
#undef cp
case SBC:
if(flags_.decimal) {
assert(false);
break;
}
// Implement non-decimal SBC by falling through to ADC;
// TODO: what do I need to invert to be able to fall through in both cases? And does it matter?
data_buffer_.value = ~data_buffer_.value;
[[fallthrough]];
case ADC: {
int result;
if(flags_.decimal) {
result = flags_.carry;
#define nibble(mask, limit, addition, carry) \
result += (a_.full & mask) + (data_buffer_.value & mask); \
if(result >= limit) result = ((result + addition) & (carry - 1)) + carry;
nibble(0x000f, 0x000a, 0x0006, 0x00010);
nibble(0x00f0, 0x00a0, 0x0060, 0x00100);
nibble(0x0f00, 0x0a00, 0x0600, 0x01000);
nibble(0xf000, 0xa000, 0x6000, 0x10000);
#undef nibble
} else {
result = a_.full + data_buffer_.value + flags_.carry;
}
flags_.overflow = (( (result ^ a_.full) & (result ^ data_buffer_.value) ) >> (1 + m_shift_))&0x40;
flags_.set_nz(result, m_shift_);
flags_.carry = (result >> (8 + m_shift_))&1;
LD(a_, result, m_masks_);
} break;
// TODO:
// ADC, SBC,
// PLP,
// PHP, PHD, PHK,
// TRB, TSB,