Andy McFadden facaa721de Fix AND/ORA imm flag updater ...

The code was making an unwarranted assumption about how the flags
were being set.  For example, ORA #$00 can't know if the previous
contents of the accumulator were nonzero, only that the instruction
hasn't made them nonzero, but instead of marking the Z-flag
"indeterminate" it was leaving the flag in its previous state.  This
produces incorrect results if the previous instruction didn't set
its flags from the accumulator contents, e.g. it was an LDX.

Test 1003-flags-and-branches has been updated to test these states.

2020-05-01 17:29:22 -07:00

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