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[colorforth] ‘?dup’ and ‘drop’


Hi,

I understand that ?dup only compiles a dup if the previous instruction was not a drop. If it was a drop then the drop is removed and no dup is compiled either. Karig, http://www.karig.net/os/cf/c.htm#cdrop explains this.

But how can it be assumed that the TOS (that was to have been dropped) and NOS are identical so that we don't need a drop followed by a dup?

Thanks,
Jason





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