From: Mike Keitz. There is a trick method that works for 4 bits. It replaces a 2-bit number in a variable with a 4-bit mask:
incf BitP, W ;W = 0001 0010 0011 0100 btfsc BitP, 1 ;If 0 or 1, result is almost correct now. iorwf BitP, F ;BitP = [0000] [0001] 0011 0111 incf BitP, F ;BitP = 0001 0010 0100 1000
It could be the core of an 8-bit routine thus:
; Convert 3-bit number (0-7) in INDEX to a 8-bit mask (00000001 ... ; 10000000) in BitP. movfw INDEX andlw b'00000011' ;Start with half of the mask. movwf BitP incf BitP, W ;The 4-bit converter btfsc BitP, 1 iorwf BitP, F incf BitP, F btfsc INDEX, 2 ;Is it high 4 bits? swapf BitP, F
file: /Techref/scenix/lib/math/bit/mask.htm, 1KB, , updated: 2004/6/10 14:40, local time: 2024/8/17 02:13,
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