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[svn-r4377] Purpose:

Browse Source 
Code improvement
Description:
    The byte swapping routine for data conversion was inefficient.
Solution:
    Applied a number of optimizations which should yield around a 2-3 times
    faster algorithm.
Platforms tested:
    Solaris 2.6 (baldric)
This commit is contained in:
Quincey Koziol 2001-08-17 17:16:11 -05:00
parent 04ca207930
commit 5b83004cfb
1 changed files with 534 additions and 7 deletions

541
src/H5Tconv.c

@ -534,14 +534,541 @@ H5T_conv_order(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
NULL == (dst = H5I_object(dst_id))) {
HRETURN_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
}
md = src->size / 2;
for (i=0; i<nelmts; i++, buf+=buf_stride?buf_stride:src->size) {
for (j=0; j<md; j++) {
tmp = buf[j];
buf[j] = buf[src->size-(j+1)];
buf[src->size-(j+1)] = tmp;
}
}
buf_stride = buf_stride ? buf_stride : src->size;
/* Optimize for popular sizes */
switch(md) {
case 1: /* Swap 2-byte objects */
#ifdef NO_DUFFS_DEVICE
for (i=0; i<nelmts; i++, buf+=buf_stride) {
/* Swap the byte pair */
tmp = buf[0];
buf[0] = buf[1];
buf[1] = tmp;
}
#else /* NO_DUFFS_DEVICE */
{
size_t duff_count = (nelmts + 7) / 8;
switch (duff_count % 8)
{
case 0:
do
{
/* Swap the byte pair */
tmp = buf[0];
buf[0] = buf[1];
buf[1] = tmp;
buf+=buf_stride;
case 7:
/* Swap the byte pair */
tmp = buf[0];
buf[0] = buf[1];
buf[1] = tmp;
buf+=buf_stride;
case 6:
/* Swap the byte pair */
tmp = buf[0];
buf[0] = buf[1];
buf[1] = tmp;
buf+=buf_stride;
case 5:
/* Swap the byte pair */
tmp = buf[0];
buf[0] = buf[1];
buf[1] = tmp;
buf+=buf_stride;
case 4:
/* Swap the byte pair */
tmp = buf[0];
buf[0] = buf[1];
buf[1] = tmp;
buf+=buf_stride;
case 3:
/* Swap the byte pair */
tmp = buf[0];
buf[0] = buf[1];
buf[1] = tmp;
buf+=buf_stride;
case 2:
/* Swap the byte pair */
tmp = buf[0];
buf[0] = buf[1];
buf[1] = tmp;
buf+=buf_stride;
case 1:
/* Swap the byte pair */
tmp = buf[0];
buf[0] = buf[1];
buf[1] = tmp;
buf+=buf_stride;
}
while (--duff_count > 0);
}
}
#endif /* NO_DUFFS_DEVICE */
break;
case 2: /* Swap 4-byte objects */
#ifdef NO_DUFFS_DEVICE
for (i=0; i<nelmts; i++, buf+=buf_stride) {
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[3];
buf[3] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[1];
buf[1] = buf[2];
buf[2] = tmp;
}
#else /* NO_DUFFS_DEVICE */
{
size_t duff_count = (nelmts + 7) / 8;
switch (duff_count % 8)
{
case 0:
do
{
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[3];
buf[3] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[1];
buf[1] = buf[2];
buf[2] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 7:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[3];
buf[3] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[1];
buf[1] = buf[2];
buf[2] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 6:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[3];
buf[3] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[1];
buf[1] = buf[2];
buf[2] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 5:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[3];
buf[3] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[1];
buf[1] = buf[2];
buf[2] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 4:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[3];
buf[3] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[1];
buf[1] = buf[2];
buf[2] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 3:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[3];
buf[3] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[1];
buf[1] = buf[2];
buf[2] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 2:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[3];
buf[3] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[1];
buf[1] = buf[2];
buf[2] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 1:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[3];
buf[3] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[1];
buf[1] = buf[2];
buf[2] = tmp;
/* Advance the pointer */
buf+=buf_stride;
}
while (--duff_count > 0);
}
}
#endif /* NO_DUFFS_DEVICE */
break;
case 4: /* Swap 8-byte objects */
#ifdef NO_DUFFS_DEVICE
for (i=0; i<nelmts; i++, buf+=buf_stride) {
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[7];
buf[7] = tmp;
/* Swap the next-outer pair of bytes */
tmp = buf[1];
buf[1] = buf[6];
buf[6] = tmp;
/* Swap the next-next-outer pair of bytes */
tmp = buf[2];
buf[2] = buf[5];
buf[5] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[3];
buf[3] = buf[4];
buf[4] = tmp;
}
#else /* NO_DUFFS_DEVICE */
{
size_t duff_count = (nelmts + 7) / 8;
switch (duff_count % 8)
{
case 0:
do
{
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[7];
buf[7] = tmp;
/* Swap the next-outer pair of bytes */
tmp = buf[1];
buf[1] = buf[6];
buf[6] = tmp;
/* Swap the next-next-outer pair of bytes */
tmp = buf[2];
buf[2] = buf[5];
buf[5] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[3];
buf[3] = buf[4];
buf[4] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 7:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[7];
buf[7] = tmp;
/* Swap the next-outer pair of bytes */
tmp = buf[1];
buf[1] = buf[6];
buf[6] = tmp;
/* Swap the next-next-outer pair of bytes */
tmp = buf[2];
buf[2] = buf[5];
buf[5] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[3];
buf[3] = buf[4];
buf[4] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 6:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[7];
buf[7] = tmp;
/* Swap the next-outer pair of bytes */
tmp = buf[1];
buf[1] = buf[6];
buf[6] = tmp;
/* Swap the next-next-outer pair of bytes */
tmp = buf[2];
buf[2] = buf[5];
buf[5] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[3];
buf[3] = buf[4];
buf[4] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 5:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[7];
buf[7] = tmp;
/* Swap the next-outer pair of bytes */
tmp = buf[1];
buf[1] = buf[6];
buf[6] = tmp;
/* Swap the next-next-outer pair of bytes */
tmp = buf[2];
buf[2] = buf[5];
buf[5] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[3];
buf[3] = buf[4];
buf[4] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 4:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[7];
buf[7] = tmp;
/* Swap the next-outer pair of bytes */
tmp = buf[1];
buf[1] = buf[6];
buf[6] = tmp;
/* Swap the next-next-outer pair of bytes */
tmp = buf[2];
buf[2] = buf[5];
buf[5] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[3];
buf[3] = buf[4];
buf[4] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 3:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[7];
buf[7] = tmp;
/* Swap the next-outer pair of bytes */
tmp = buf[1];
buf[1] = buf[6];
buf[6] = tmp;
/* Swap the next-next-outer pair of bytes */
tmp = buf[2];
buf[2] = buf[5];
buf[5] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[3];
buf[3] = buf[4];
buf[4] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 2:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[7];
buf[7] = tmp;
/* Swap the next-outer pair of bytes */
tmp = buf[1];
buf[1] = buf[6];
buf[6] = tmp;
/* Swap the next-next-outer pair of bytes */
tmp = buf[2];
buf[2] = buf[5];
buf[5] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[3];
buf[3] = buf[4];
buf[4] = tmp;
/* Advance the pointer */
buf+=buf_stride;
case 1:
/* Swap the outer pair of bytes */
tmp = buf[0];
buf[0] = buf[7];
buf[7] = tmp;
/* Swap the next-outer pair of bytes */
tmp = buf[1];
buf[1] = buf[6];
buf[6] = tmp;
/* Swap the next-next-outer pair of bytes */
tmp = buf[2];
buf[2] = buf[5];
buf[5] = tmp;
/* Swap the inner pair of bytes */
tmp = buf[3];
buf[3] = buf[4];
buf[4] = tmp;
/* Advance the pointer */
buf+=buf_stride;
}
while (--duff_count > 0);
}
}
#endif /* NO_DUFFS_DEVICE */
break;
default: /* Swap n-byte objects */
#ifdef NO_DUFFS_DEVICE
for (i=0; i<nelmts; i++, buf+=buf_stride) {
for (j=0; j<md; j++) {
tmp = buf[j];
buf[j] = buf[src->size-(j+1)];
buf[src->size-(j+1)] = tmp;
}
}
#else /* NO_DUFFS_DEVICE */
{
size_t duff_count = (nelmts + 7) / 8;
switch (duff_count % 8)
{
case 0:
do
{
/* Generic byte-swapping loop */
for (j=0; j<md; j++) {
tmp = buf[j];
buf[j] = buf[src->size-(j+1)];
buf[src->size-(j+1)] = tmp;
}
/* Advance the pointer */
buf+=buf_stride;
case 7:
/* Generic byte-swapping loop */
for (j=0; j<md; j++) {
tmp = buf[j];
buf[j] = buf[src->size-(j+1)];
buf[src->size-(j+1)] = tmp;
}
/* Advance the pointer */
buf+=buf_stride;
case 6:
/* Generic byte-swapping loop */
for (j=0; j<md; j++) {
tmp = buf[j];
buf[j] = buf[src->size-(j+1)];
buf[src->size-(j+1)] = tmp;
}
/* Advance the pointer */
buf+=buf_stride;
case 5:
/* Generic byte-swapping loop */
for (j=0; j<md; j++) {
tmp = buf[j];
buf[j] = buf[src->size-(j+1)];
buf[src->size-(j+1)] = tmp;
}
/* Advance the pointer */
buf+=buf_stride;
case 4:
/* Generic byte-swapping loop */
for (j=0; j<md; j++) {
tmp = buf[j];
buf[j] = buf[src->size-(j+1)];
buf[src->size-(j+1)] = tmp;
}
/* Advance the pointer */
buf+=buf_stride;
case 3:
/* Generic byte-swapping loop */
for (j=0; j<md; j++) {
tmp = buf[j];
buf[j] = buf[src->size-(j+1)];
buf[src->size-(j+1)] = tmp;
}
/* Advance the pointer */
buf+=buf_stride;
case 2:
/* Generic byte-swapping loop */
for (j=0; j<md; j++) {
tmp = buf[j];
buf[j] = buf[src->size-(j+1)];
buf[src->size-(j+1)] = tmp;
}
/* Advance the pointer */
buf+=buf_stride;
case 1:
/* Generic byte-swapping loop */
for (j=0; j<md; j++) {
tmp = buf[j];
buf[j] = buf[src->size-(j+1)];
buf[src->size-(j+1)] = tmp;
}
/* Advance the pointer */
buf+=buf_stride;
}
while (--duff_count > 0);
}
}
#endif /* NO_DUFFS_DEVICE */
break;
} /* end switch */
break;
case H5T_CONV_FREE: