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Refactor the DEC/X/Y tests a bit for clarity

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This commit is contained in:
Peter Evans 2018-04-30 21:37:20 -05:00
parent ad4014ced4
commit 635ff624e7
1 changed files with 11 additions and 8 deletions
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19
src/mos6502/arith.c
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@ -154,14 +154,15 @@ DEFINE_INST(cpy)
*/ */
DEFINE_INST(dec) DEFINE_INST(dec)
{ {
oper--;
MOS_CHECK_NZ(oper);
if (cpu->addr_mode == ACC) { if (cpu->addr_mode == ACC) {
MOS_CHECK_NZ(cpu->A - 1); cpu->A = oper;
cpu->A--;
return; return;
} }
MOS_CHECK_NZ(oper - 1); mos6502_set(cpu, cpu->eff_addr, oper);
mos6502_set(cpu, cpu->eff_addr, oper - 1);
} }
/* /*
@ -169,8 +170,9 @@ DEFINE_INST(dec)
*/ */
DEFINE_INST(dex) DEFINE_INST(dex)
{ {
MOS_CHECK_NZ(cpu->X - 1); oper--;
cpu->X--; MOS_CHECK_NZ(oper);
cpu->X = oper;
} }
/* /*
@ -178,8 +180,9 @@ DEFINE_INST(dex)
*/ */
DEFINE_INST(dey) DEFINE_INST(dey)
{ {
MOS_CHECK_NZ(cpu->Y - 1); oper--;
cpu->Y--; MOS_CHECK_NZ(oper);
cpu->Y = oper;
} }
/* /*