Seth Morabito 731d99cf65 3b2: CMP{W|H|B} instruction fix ...

The WE32100 supports expanded datatypes for its opcodes, allowing an
opcode to override the default size (byte/halfword/word) expected by the
instruction. For example:

        CMPH &0x10000,{uword}-8(%fp)

Without the {uword} marker, this instruction would only compare the
lower 2 bytes of -8(%fp) against the lower two bytes of the constant
value 0x10000, since the CMPH instruction compares halfwords. However,
with the {uword} marker, the CMPH instruction promotes the opcode from a
halfword to an unsigned word, sign extending if appropriate.

The CMP{W|H|B} instruction implementation in the 3B2 simulator was
ignoring any expanded type markers on its opcodes when checking whether
to set the "N" (negative) bit in the PSW, leading to a failure in
compiling GCC. This fix causes the instruction to honor the expanded
datatype in this case.

2019-09-01 11:45:45 -07:00

122 KiB

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