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remove one malloc from TraceBackwards()

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Change-Id: I4f77c0240ca2ece86e8beab11d02c74277409921
This commit is contained in:
skal 2013-02-05 19:43:43 +01:00
parent 7c732e59f4
commit f3a44dcd83
1 changed files with 17 additions and 33 deletions
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50
src/enc/backward_references.c
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@ -597,33 +597,23 @@ Error:
return ok;
}
static int TraceBackwards(const uint32_t* const dist_array,
int dist_array_size,
uint32_t** const chosen_path,
int* const chosen_path_size) {
int i;
// Count how many.
int count = 0;
for (i = dist_array_size - 1; i >= 0; ) {
int k = dist_array[i];
assert(k >= 1);
++count;
i -= k;
// We pack the path at the end of *dist_array and return
// a pointer to this part of the array. Example:
// dist_array = [1x2xx3x2] => packed [1x2x1232], chosen_path = [1232]
static void TraceBackwards(uint32_t* const dist_array,
int dist_array_size,
uint32_t** const chosen_path,
int* const chosen_path_size) {
uint32_t* path = dist_array + dist_array_size;
uint32_t* cur = dist_array + dist_array_size - 1;
while (cur >= dist_array) {
const int k = *cur;
--path;
*path = k;
cur -= k;
}
// Allocate.
*chosen_path_size = count;
*chosen_path =
(uint32_t*)WebPSafeMalloc((uint64_t)count, sizeof(**chosen_path));
if (*chosen_path == NULL) return 0;
// Write in reverse order.
for (i = dist_array_size - 1; i >= 0; ) {
int k = dist_array[i];
assert(k >= 1);
(*chosen_path)[--count] = k;
i -= k;
}
return 1;
*chosen_path = path;
*chosen_path_size = dist_array + dist_array_size - path;
}
static int BackwardReferencesHashChainFollowChosenPath(
@ -722,12 +712,7 @@ static int BackwardReferencesTraceBackwards(int xsize, int ysize,
dist_array)) {
goto Error;
}
if (!TraceBackwards(dist_array, dist_array_size,
&chosen_path, &chosen_path_size)) {
goto Error;
}
free(dist_array); // no need to retain this memory any longer
dist_array = NULL;
TraceBackwards(dist_array, dist_array_size, &chosen_path, &chosen_path_size);
if (!BackwardReferencesHashChainFollowChosenPath(
xsize, ysize, argb, quality, cache_bits, chosen_path, chosen_path_size,
refs)) {
@ -735,7 +720,6 @@ static int BackwardReferencesTraceBackwards(int xsize, int ysize,
}
ok = 1;
Error:
free(chosen_path);
free(dist_array);
return ok;
}