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[svn-r20896] I added some comments.

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Tested on jam - very simple change.
This commit is contained in:
Raymond Lu 2011-05-24 16:51:41 -05:00
parent 0418b80b22
commit 48dc2ca2fc
1 changed files with 15 additions and 0 deletions
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15
src/H5Tconv.c
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@ -2614,6 +2614,15 @@ H5T_conv_enum_init(H5T_t *src, H5T_t *dst, H5T_cdata_t *cdata)
* a native integer type as an index into the `val2dst'. The values of
* that array are the index numbers in the destination type or negative
* if the entry is unused.
*
* (This optimized algorithm doesn't work when the byte orders are different.
* The code such as "n = *((int*)(src->shared->u.enumer.value+i*src->shared->size));"
* can change the value significantly. i.g. if the source value is big-endian 0x0000000f,
* executing the casting on little-endian machine will get a big number 0x0f000000.
* Then it can't meet the condition
* "if(src->shared->u.enumer.nmembs<2 || (double)length/src->shared->u.enumer.nmembs<1.2)"
* Because this is the optimized code, we won't fix it. It should still work in some
* situations. SLU - 2011/5/24)
*/
if (1==src->shared->size || sizeof(short)==src->shared->size || sizeof(int)==src->shared->size) {
for (i=0; i<src->shared->u.enumer.nmembs; i++) {
@ -2796,6 +2805,12 @@ H5T_conv_enum(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, size_t nelmts,
for(i = 0; i < nelmts; i++, s += src_delta, d += dst_delta) {
if(priv->length) {
/* Use O(1) lookup */
/* (The casting won't work when the byte orders are different. i.g. if the source value
* is big-endian 0x0000000f, the direct casting "n = *((int*)s);" will make it a big
* number 0x0f000000 on little-endian machine. But we won't fix it because it's an
* optimization code. Please also see the comment in the H5T_conv_enum_init() function.
* SLU - 2011/5/24)
*/
if(1 == src->shared->size)
n = *((signed char*)s);
else if(sizeof(short) == src->shared->size)