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vp9_dsubexp: remove clamp in inv_remap_prob()

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the max value of the lookup in expanded form is:
(((1 << 7) - 1) << 1) - 65 + 1 + 64 = 254

remove the clamp [0, 253] and add one table entry

Change-Id: I0b5d0c66702fdb0b8f1cc9ab9b0dac66326e85a6
This commit is contained in:
James Zern
2015-06-30 15:09:48 -07:00
parent fc5f3b8f4f
commit 8aaf5ec4c7
1 changed files with 5 additions and 5 deletions
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10
vp9/decoder/vp9_dsubexp.c
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@@ -8,6 +8,8 @@
* be found in the AUTHORS file in the root of the source tree. * be found in the AUTHORS file in the root of the source tree.
*/ */
#include <assert.h>
#include "vp9/common/vp9_entropy.h" #include "vp9/common/vp9_entropy.h"
#include "vp9/decoder/vp9_dsubexp.h" #include "vp9/decoder/vp9_dsubexp.h"
@@ -27,7 +29,7 @@ static int decode_uniform(vp9_reader *r) {
} }
static int inv_remap_prob(int v, int m) { static int inv_remap_prob(int v, int m) {
static int inv_map_table[MAX_PROB - 1] = { static int inv_map_table[MAX_PROB] = {
6, 19, 32, 45, 58, 71, 84, 97, 110, 123, 136, 149, 162, 175, 188, 6, 19, 32, 45, 58, 71, 84, 97, 110, 123, 136, 149, 162, 175, 188,
201, 214, 227, 240, 253, 0, 1, 2, 3, 4, 5, 7, 8, 9, 10, 201, 214, 227, 240, 253, 0, 1, 2, 3, 4, 5, 7, 8, 9, 10,
11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26,
@@ -44,11 +46,9 @@ static int inv_remap_prob(int v, int m) {
190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 202, 203, 204, 205, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 202, 203, 204, 205,
206, 207, 208, 209, 210, 211, 212, 213, 215, 216, 217, 218, 219, 220, 221, 206, 207, 208, 209, 210, 211, 212, 213, 215, 216, 217, 218, 219, 220, 221,
222, 223, 224, 225, 226, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 222, 223, 224, 225, 226, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237,
238, 239, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252 238, 239, 241, 242, 243, 244, 245, 246, 247, 248, 249, 250, 251, 252, 252
}; };
// The clamp is not necessary for conforming VP9 stream, it is added to assert(v < (int)(sizeof(inv_map_table) / sizeof(inv_map_table[0])));
// prevent out of bound access for bad input data
v = clamp(v, 0, 253);
v = inv_map_table[v]; v = inv_map_table[v];
m--; m--;
if ((m << 1) <= MAX_PROB) { if ((m << 1) <= MAX_PROB) {