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Rewrite the DAA instruction

This commit is contained in:
Maximilian Mader 2018-07-22 18:36:24 +02:00
parent f7b882f0e8
commit a36dd791ec
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GPG Key ID: F71D56A3151C4FB3
1 changed files with 22 additions and 37 deletions
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59
Core/z80_cpu.c
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@ -464,54 +464,39 @@ static void jr_cc_r8(GB_gameboy_t *gb, uint8_t opcode)
static void daa(GB_gameboy_t *gb, uint8_t opcode) static void daa(GB_gameboy_t *gb, uint8_t opcode)
{ {
/* This function is UGLY and UNREADABLE! But it passes Blargg's daa test! */ int16_t result = gb->registers[GB_REGISTER_AF] >> 8;
gb->registers[GB_REGISTER_AF] &= ~GB_ZERO_FLAG;
gb->registers[GB_REGISTER_AF] &= ~(0xFF00 | GB_ZERO_FLAG);
if (gb->registers[GB_REGISTER_AF] & GB_SUBSTRACT_FLAG) { if (gb->registers[GB_REGISTER_AF] & GB_SUBSTRACT_FLAG) {
if (gb->registers[GB_REGISTER_AF] & GB_HALF_CARRY_FLAG) { if (gb->registers[GB_REGISTER_AF] & GB_HALF_CARRY_FLAG) {
gb->registers[GB_REGISTER_AF] &= ~GB_HALF_CARRY_FLAG; result = (result - 0x06) & 0xFF;
}
if (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) { if (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) {
gb->registers[GB_REGISTER_AF] += 0x9A00; result -= 0x60;
}
else {
gb->registers[GB_REGISTER_AF] += 0xFA00;
}
}
else if(gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) {
gb->registers[GB_REGISTER_AF] += 0xA000;
} }
} }
else { else {
if (gb->registers[GB_REGISTER_AF] & GB_HALF_CARRY_FLAG) { if ((gb->registers[GB_REGISTER_AF] & GB_HALF_CARRY_FLAG) || (result & 0x0F) > 0x09) {
uint16_t number = gb->registers[GB_REGISTER_AF] >> 8; result += 0x06;
if (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) {
number += 0x100;
} }
gb->registers[GB_REGISTER_AF] = 0;
number += 0x06; if ((gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) || result > 0x9F) {
if (number >= 0xa0) { result += 0x60;
number -= 0xa0;
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
gb->registers[GB_REGISTER_AF] |= number << 8;
}
else {
uint16_t number = gb->registers[GB_REGISTER_AF] >> 8;
if (gb->registers[GB_REGISTER_AF] & GB_CARRY_FLAG) {
number += 0x100;
}
if (number > 0x99) {
number += 0x60;
}
number = (number & 0x0F) + ((number & 0x0F) > 9 ? 6 : 0) + (number & 0xFF0);
gb->registers[GB_REGISTER_AF] = number << 8;
if (number & 0xFF00) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
} }
} }
}
if ((gb->registers[GB_REGISTER_AF] & 0xFF00) == 0) { if ((result & 0xFF) == 0) {
gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG; gb->registers[GB_REGISTER_AF] |= GB_ZERO_FLAG;
} }
if ((result & 0x100) == 0x100) {
gb->registers[GB_REGISTER_AF] |= GB_CARRY_FLAG;
}
gb->registers[GB_REGISTER_AF] &= ~GB_HALF_CARRY_FLAG;
gb->registers[GB_REGISTER_AF] |= result << 8;
} }
static void cpl(GB_gameboy_t *gb, uint8_t opcode) static void cpl(GB_gameboy_t *gb, uint8_t opcode)