Apple-2-Tools/bradgrantham-apple2e
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another SBC

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This commit is contained in:
Brad Grantham 2016-11-13 12:41:13 -08:00
parent 20863ee77c
commit 3765decf3a
1 changed files with 10 additions and 0 deletions
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10
apple2e.cpp
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@ -862,6 +862,16 @@ struct CPU6502
break;
}
case 0xFD: { // SBC abs, X
int addr = read_pc_inc(bus) + read_pc_inc(bus) * 256 + x;
unsigned char m = bus.read(addr);
int borrow = isset(C) ? 0 : 1;
flag_change(C, !(a < (m + borrow)));
flag_change(V, sbc_overflow(a, m, borrow));
set_flags(N | Z, a = a - (m + borrow));
break;
}
case 0xED: { // SBC abs
int addr = read_pc_inc(bus) + read_pc_inc(bus) * 256;
unsigned char m = bus.read(addr);