6502/py65
1
0
Fork 0
mirror of https://github.com/mnaberez/py65.git synced 2025-01-04 01:30:18 +00:00
Code Issues Projects Releases Wiki Activity

fix two failing BCD tests: now passes the Bruce Clark exhaustive test for all flags

Browse Source
This commit is contained in:
Ed Spittles 2010-12-15 20:22:48 +00:00
parent 4bd92cf80e
commit f4fba9b06a
1 changed files with 6 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
src/py65/devices/mpu6502.py
View File

@ -292,9 +292,13 @@ class MPU:
nibble1 = ((data >> 4) & 0xf) + ((self.a >> 4) & 0xf) + halfcarry
if nibble1 > 9:
adjust1 = 6
decimalcarry = 1 # may be a little more complicated than this
decimalcarry = 1
# the ALU outputs are not decimally adjusted
nibble0 = nibble0 & 0xf
nibble1 = nibble1 & 0xf
aluresult = (nibble1 << 4) + nibble0
# the final A contents will be decimally adjusted
nibble0 = (nibble0 + adjust0) & 0xf
nibble1 = (nibble1 + adjust1) & 0xf
@ -403,7 +407,7 @@ class MPU:
self.p |= aluresult & self.NEGATIVE
if decimalcarry == 1:
self.p |= self.CARRY
if ( ~(self.a ^ data) & (self.a ^ aluresult) ) & 0x80:
if ( (self.a ^ data) & (self.a ^ aluresult) ) & 0x80:
self.p |= self.OVERFLOW
self.a = (nibble1 << 4) + nibble0
else: