/ swab.s (emx+gcc) -- Copyright (c) 1992-1993 by Eberhard Mattes

        .globl _swab

/ void swab (const void *src, void *dst, size_t n)
/ {
/   char *s, *d;
/ 
/   if (n & 1) return;
/   while (n > 0)
/     {
/       d[0] = s[1];
/       d[1] = s[0];
/       d += 2; s += 2; n -= 2;
/     }
/ }

/ assumes ds=es!

        .text

        .align  2, 0x90

_swab:
        pushl   %esi
        pushl   %edi
        movl    3*4(%esp), %esi         / src
        movl    4*4(%esp), %edi         / dst
        movl    5*4(%esp), %ecx         / n
        shrl    $1, %ecx
        jc      9f
        .align  2, 0x90
1:      lodsw
        xchgb   %al, %ah
        stosw
        loop    1b
9:      popl    %edi
        popl    %esi
        ret