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authorAlex Converse <aconverse@google.com>2015-10-26 17:05:00 +0000
committerGerrit Code Review <noreply-gerritcodereview@google.com>2015-10-26 17:05:00 +0000
commite34c7e3f59ad7bf398c457865ca06af958c89f87 (patch)
tree2b20b619ac7cb0e8f2e7f7be8c758bb4037513bb
parente1a056e163dfb8217dc55ce77c5ba66087f1a822 (diff)
parent171fd8999fe8fdf04b5e836ff4eb0106ac6d7501 (diff)
downloadlibvpx-e34c7e3f59ad7bf398c457865ca06af958c89f87.tar.gz
Merge "palette: Replace rand() call with custom LCG."
-rw-r--r--vp10/encoder/palette.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/vp10/encoder/palette.c b/vp10/encoder/palette.c
index b6fd6533e..fd5f402d8 100644
--- a/vp10/encoder/palette.c
+++ b/vp10/encoder/palette.c
@@ -39,12 +39,20 @@ void vp10_calc_indices(const double *data, const double *centroids,
}
}
+// Generate a random number in the range [0, 32768).
+static unsigned int lcg_rand16(unsigned int *state) {
+ *state = *state * 1103515245 + 12345;
+ return *state / 65536 % 32768;
+}
+
static void calc_centroids(const double *data, double *centroids,
const uint8_t *indices, int n, int k, int dim) {
int i, j, index;
int count[PALETTE_MAX_SIZE];
+ unsigned int rand_state = data[0];
+
+ assert(n <= 32768);
- srand((unsigned int) data[0]);
memset(count, 0, sizeof(count[0]) * k);
memset(centroids, 0, sizeof(centroids[0]) * k * dim);
@@ -59,8 +67,7 @@ static void calc_centroids(const double *data, double *centroids,
for (i = 0; i < k; ++i) {
if (count[i] == 0) {
- // TODO(huisu): replace rand() with something else.
- memcpy(centroids + i * dim, data + (rand() % n) * dim,
+ memcpy(centroids + i * dim, data + (lcg_rand16(&rand_state) % n) * dim,
sizeof(centroids[0]) * dim);
} else {
const double norm = 1.0 / count[i];