MS/CW-style inline assembly for GCC

[Robert Dewar]

Neil Booth wrote:

Robert Dewar wrote:-


Robert Dewar wrote:


For reference, the code on the x86 should look something like
(in Intel syntax):
   lp:   mov  eax, [ebx]
         adc  eax, [ecx]
         inc  ebx
         inc  ecx
         loop lp
that's the code that was wrong, should be


    lp:   mov  eax, [ebx]
          adc  eax, [ecx]
          lea  ebx, [ebx+4]
          lea  ecx, [ecx+4]
          loop lp


Except that loop decrements ecx and loops if non-zero, so I
think you've still got some work to do 8-)
OK, well I did say look something like :-)
Yes indeed we need to use some other register
than ecx for the second index register. Might
also be nice to store the result :-) Just goes to show
that dashing off code in email is a hazzardous
occupation. How about
         lp:   lodsw
               adc     eax, [ebx]
               lea     ebx, [ebx+4]
               stosw
               loop    lp
Here source registers are esi,ebx and destination register is edi

Did someone check what GCC generates for the C code?