>         incf    W, 0                  ; W = W + 1

The other thing that I have not yet seen explained to you, and would have
helped you catch this error. Use W and F as the destinations of these
mnemonics, instead of using 0 and 1. This is the purpose for which W and F
are defined.

Your code would then have looked like this

         incf    W, W                  ; W = W + 1

which should have flagged an error in your mind, as you have used the W in
two places in the same instruction.

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