adtools/clib2

#if defined(__GNUC__) && defined(__PPC__)

/* r3=from, r4=to, r5=len/count, r6=index, r7=load/store/temp */

asm("\
    .text\n\
    .align 2\n\
    .globl swab\n\
    .type swab,@function\n\
swab:\n\
    dcbt        0,%r3\n\
    srawi.    %r5,%r5,1\n\
    bc            4,gt,.exit\n\
    andi.        %r7,%r3,3        # Check if we start on an address evenly divisible by 4.\n\
    li            %r6,0\n\
    bc            4,gt,.preploop\n\
    lhbrx        %r7,%r6,%r3        # Fix alignment if needed.\n\
    sthx        %r7,%r6,%r4\n\
    addi        %r6,%r6,2\n\
    subi        %r5,%r5,1\n\
.preploop:\n\
    andi.        %r7,%r5,1        # Check if even or odd number of 16-bit words.\n\
    srawi        %r5,%r5,1        # Number of 32-bit words to half-swap.\n\
    mtctr        %r5\n\
    bc            12,gt,.oddloop    # Jump to loop for odd number of 16-bit words.\n\
.loop:                            # Loop is 'unrolled' by reading/writing 32-bit words.\n\
    lwbrx        %r7,%r6,%r3\n\
    rotlwi    %r7,%r7,16\n\
    stwx        %r7,%r6,%r4\n\
    addi        %r6,%r6,4\n\
    bc            0,lt,.loop\n\
.exit:\n\
    or            %r3,%r4,%r4\n\
    blr\n\
.oddloop:\n\
    lwbrx        %r7,%r6,%r3\n\
    rotlwi    %r7,%r7,16\n\
    stwx        %r7,%r6,%r4\n\
    addi        %r6,%r6,4\n\
    bc            0,lt,.oddloop\n\
    sub        %r6,%r6,2\n\
    lhbrx        %r7,%r6,%r3        # Fix last 16-bit word.\n\
    sthx        %r7,%r6,%r4\n\
    or            %r3,%r4,%r4\n\
    blr\n\
");

#else

#include <sys/types.h>
#include <stdint.h>

void *swab(void *from,void *to,ssize_t len)
{
int i;
uint16_t u16,*u16in=from,*u16out=to;

for(i=0;i<(len>>1);i++) {
    u16=u16in[i];
    u16out[i]=u16>>8|u16<<8;
}

return(u16out);
}

#endif