On Wed, 29 Oct 1997 10:50:06 -0500, you wrote:

>There hasn't been a "programming challenge" lately.  Here's a problem I'm
>looking at:  I have a 7 bit ASCII character which was transmitted
>serially LSB first, but received MSB first.  Thus, I need to reverse the
>order of the bits (I can't change the receiver, since other parts of the
>data are transmitted MSB first).  For example, 0011010 should come out as
>0101100.  The routine should be a subroutine which gets the input value
>in W and returns the result in W.  It is OK to assume the high bit of W
>will be 0, and the high bit of the result must be 0 (the routine works
>only on the low 7 bits)


>Each ROM location used : 8 points
>Each RAM location used : 30 points
>Each instruction cycle (to convert once): 1 point
>Uses less than 25 instruction cycles: -40 points
>
 
Compact version : 9 rom, 2 ram, 40 cycles - 172 points

 movwf temp
 movlw 2           ; end marker 
 movwf temp2
loop 
  rrf temp
  rlf temp2
  skpc 
  goto loop ; loop until bit falls out end
 movf temp2,w
 return


Fast & low RAM version  :  17 rom, 1 ram, 18 cycles - 144 points

 movwf temp
 clrw
 btfsc temp,0
 iorlw 040
 btfsc temp,1
 iorlw 020
 btfsc temp,2
 iorlw 010
 btfsc temp,3
 iorlw 008
 btfsc temp,4
 iorlw 004
 btfsc temp,5
 iorlw 002
 btfsc temp,6
 iorlw 001
 return