In SX Microcontrollers, SX/B Compiler and SX-Key Tool, natpie wrote:

It sounds to me like you don't want XOR.   If you want to keep bits 0 to 3 as they are and clear 4 to seven you would AND 00001111.   Xor (exclusive or)  sets a bit as 1 ONLY if ONE and ONLY ONE of the bits is 1.   1 XOR 1 = 0

0 XOR 0 = 0

1 XOR 0 = 1

0 XOR 1 = 1

 

AND on the other hand requires both bits to be 1.  So...

 

1 AND 1 = 1

0 AND 0 = 0

1 AND 0 = 0

0 AND 1 = 0

Also in your code you did an 

xor     $12, #%00001111      ;"1" to Copy the Bit, "0" clears the Bit
        mov    rc, W


This will ALWAYS put %00001111 in rc.    The way you used XOR is not supporterd by the chip so the assymbler brakes this into two instructions.

 

 

MOV W, #%0000111

XOR $12, W

 

 

At this point $12 contains the new XORed value, and W contains %00001111.

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