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Jessica Hawkwell / kcpu

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Issue #1 opened by

Weird MOVS bug

Memory addresses below 0x0020 seem to be vulnerable to some sort of odd bug in the MOVB/MOVS logic. It is demonstrated with the following:

movs $0 r2
movs 10,16 1

add r0 16
add r2 1
movs $0 r2
jdl r0 512 2a,16

In the output file system.mem (or system.mem.bin), one can see the address 0x0010 is not being stored. The MOVS does initially place the value, but then it gets cleared.

  • @LadySerenaKitty commented
    Master

    Looks more like the ADD instruction is messed up.

    CPU up...
1000 : [      MOVS] 0011 0207 -> 0000 0000 0000 0000         0000 0002
    Writing  0 to 0000
    Writing  0 to 0001
1008 : [      MOVS] 0011 0200 -> 0000 0000 0000 0000         0010 0001
    Writing  1 to 0010
    Writing  0 to 0011
1010 : [       ADD] 0001 0201 -> 0000 0000 0000 0000         0000 0010
    Writing  0 to 0010
    Writing  0 to 0011
  • @LadySerenaKitty commented
    Master

    Bad dereference initially, plus BasicMath wasn't writing the registers back.

  • @LadySerenaKitty

    closed

    closed

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  • @LadySerenaKitty

    assigned to @LadySerenaKitty

    assigned to @LadySerenaKitty

    Toggle commit list
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