adtools/clib2

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

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

asm("\
    .text\n\
    .align 2\n\
    .globl swab32\n\
    .type swab32,@function\n\
swab32:\n\
    srawi.    %r5,%r5,2\n\
    li            %r6,0\n\
    bc            4,gt,.exit\n\
    mtctr        %r5\n\
.loop:\n\
    lwbrx        %r7,%r6,%r3\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\
");

/* r3=from, r4=to, r5=len/temp, r6=index, r7=load/store temp, r8=cache hint
 *
 * The unrolled, cache-hinting version appears to be about 4.5% faster, but
 * in this case I opted for the smaller implementation. swab64() appears to
 * gain more from cache-hinting - probably because of it using more registers
 * for intermediate storage.
asm("\
    .text\n\
    .align 2\n\
    .globl swab32\n\
    .type swab32,@function\n\
swab32:\n\
    dcbt        0,%r3\n\
    andi.        %r8,%r5,31        # The number of bytes handled in '.pre'. Used for prefetch hint.\n\
    srawi        %r5,%r5,2        # Convert bytes-># of 32-bit words\n\
    andi.        %r7,%r5,7\n\
    li            %r6,0\n\
    bc            4,gt,.preploop\n\
    mtctr        %r7\n\
.pre:                                # One 32-bit word at a time until we have (nLeft%8)==0 \n\
    lwbrx        %r7,%r6,%r3\n\
    stwx        %r7,%r6,%r4\n\
    addi        %r6,%r6,4\n\
    bc            0,lt,.pre\n\
.preploop:\n\
    srawi.    %r5,%r5,3        # Divide by 8 again to get number of loops.\n\
    addi        %r8,%r8,32        # Start address for next loop (from r3).\n\
    bc            4,gt,.exit\n\
    mtctr        %r5\n\
.loop:                            # Loop unrolled 8 times = 32 bytes = 1 cache-line (except on the 970).\n\
    dcbt        %r8,%r3            # Cache hint (prefetch) for the next loop\n\
    lwbrx        %r7,%r6,%r3\n\
    stwx        %r7,%r6,%r4\n\
    addi        %r6,%r6,4\n\
    lwbrx        %r7,%r6,%r3\n\
    stwx        %r7,%r6,%r4\n\
    addi        %r6,%r6,4\n\
    lwbrx        %r7,%r6,%r3\n\
    stwx        %r7,%r6,%r4\n\
    addi        %r6,%r6,4\n\
    lwbrx        %r7,%r6,%r3\n\
    stwx        %r7,%r6,%r4\n\
    addi        %r6,%r6,4\n\
    lwbrx        %r7,%r6,%r3\n\
    stwx        %r7,%r6,%r4\n\
    addi        %r6,%r6,4\n\
    lwbrx        %r7,%r6,%r3\n\
    stwx        %r7,%r6,%r4\n\
    addi        %r6,%r6,4\n\
    lwbrx        %r7,%r6,%r3\n\
    stwx        %r7,%r6,%r4\n\
    addi        %r6,%r6,4\n\
    lwbrx        %r7,%r6,%r3\n\
    stwx        %r7,%r6,%r4\n\
    addi        %r6,%r6,4\n\
    addi        %r8,%r8,32        # Update cache-hint offset\n\
    bc            0,lt,.loop\n\
.exit:\n\
    or            %r3,%r4,%r4\n\
    blr\n\
");
*/

#else

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

void *swab32(void *from,void *to,ssize_t len)
{
int i;
uint32_t *u32in=from,*u32out=to,tmp;

for(i=0;i<(len>>2);i++) {
    tmp=u32in[i];
    u32out[i]=((tmp&0xff)<<24)|
        ((tmp&0xff00)<<8)|
        ((tmp&0xff0000)>>8)|
        ((tmp&0xff000000)>>24);
}

return(to);
}

#endif