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version 2012-09-27

NEG : arithmetic NEGation (2s-complement)

This is an alias of the SUB instruction (-A = 0-A). A "short" form alias is available when the source and the destination are the same register.

Combined with a condition on the Most Significant Bit of the operand (the sign bit), this instruction can emulate the "ABS" (ABSolute) opcode:

  NEG R1 MSB1 R1 ; equivalent of ABS R1 R1

So far, this instruction has no way to handle properly the negation of 8000h (YASEP16) or 80000000h (YASEP32)