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Alyssa Rosenzweig
dfe0bdd7f2
exhaustively checked against the Intel pseudocode since this is tricky:
def intel(AL, CF, AF):
old_AL = AL
old_CF = CF
CF = False
if (AL & 0x0F) > 9 or AF:
Borrow = AL < 6
AL = (AL - 6) & 0xff
CF = old_CF or Borrow
AF = True
else:
AF = False
if (old_AL > 0x99) or old_CF:
AL = (AL - 0x60) & 0xff
CF = True
return (AL & 0xff, CF, AF)
def fex(AL, CF, AF):
AF = AF | ((AL & 0xf) > 9)
CF = CF | (AL > 0x99)
NewCF = CF | (AF if (AL < 6) else CF)
AL = (AL - 6) if AF else AL
AL = (AL - 0x60) if CF else AL
return (AL & 0xff, NewCF, AF)
for AL in range(256):
for CF in [False, True]:
for AF in [False, True]:
ref = intel(AL, CF, AF)
test = fex(AL, CF, AF)
print(AL, "CF" if CF else "", "AF" if AF else "", ref, test)
assert(ref == test)
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>