FFmpeg/libavcodec/lossless_videodsp.c
Michael Niedermayer ed1a687856 avcodec/lossless_videodsp: add_hfyu_left_prediction_int16_c: fix harmless integer overflow
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
2014-02-15 16:51:33 +01:00

129 lines
3.9 KiB
C

/*
* Lossless video DSP utils
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avcodec.h"
#include "lossless_videodsp.h"
#include "libavcodec/mathops.h"
static void add_int16_c(uint16_t *dst, const uint16_t *src, unsigned mask, int w){
long i;
unsigned long pw_lsb = (mask >> 1) * 0x0001000100010001ULL;
unsigned long pw_msb = pw_lsb + 0x0001000100010001ULL;
for (i = 0; i <= w - (int)sizeof(long)/2; i += sizeof(long)/2) {
long a = *(long*)(src+i);
long b = *(long*)(dst+i);
*(long*)(dst+i) = ((a&pw_lsb) + (b&pw_lsb)) ^ ((a^b)&pw_msb);
}
for(; i<w; i++)
dst[i] = (dst[i] + src[i]) & mask;
}
static void diff_int16_c(uint16_t *dst, const uint16_t *src1, const uint16_t *src2, unsigned mask, int w){
long i;
#if !HAVE_FAST_UNALIGNED
if((long)src2 & (sizeof(long)-1)){
for(i=0; i+3<w; i+=4){
dst[i+0] = (src1[i+0]-src2[i+0]) & mask;
dst[i+1] = (src1[i+1]-src2[i+1]) & mask;
dst[i+2] = (src1[i+2]-src2[i+2]) & mask;
dst[i+3] = (src1[i+3]-src2[i+3]) & mask;
}
}else
#endif
{
unsigned long pw_lsb = (mask >> 1) * 0x0001000100010001ULL;
unsigned long pw_msb = pw_lsb + 0x0001000100010001ULL;
for (i = 0; i <= w - (int)sizeof(long)/2; i += sizeof(long)/2) {
long a = *(long*)(src1+i);
long b = *(long*)(src2+i);
*(long*)(dst+i) = ((a|pw_msb) - (b&pw_lsb)) ^ ((a^b^pw_msb)&pw_msb);
}
}
for (; i<w; i++)
dst[i] = (src1[i] - src2[i]) & mask;
}
static void add_hfyu_median_prediction_int16_c(uint16_t *dst, const uint16_t *src, const uint16_t *diff, unsigned mask, int w, int *left, int *left_top){
int i;
uint16_t l, lt;
l = *left;
lt = *left_top;
for(i=0; i<w; i++){
l = (mid_pred(l, src[i], (l + src[i] - lt) & mask) + diff[i]) & mask;
lt = src[i];
dst[i] = l;
}
*left = l;
*left_top = lt;
}
static void sub_hfyu_median_prediction_int16_c(uint16_t *dst, const uint16_t *src1, const uint16_t *src2, unsigned mask, int w, int *left, int *left_top){
int i;
uint16_t l, lt;
l = *left;
lt = *left_top;
for(i=0; i<w; i++){
const int pred = mid_pred(l, src1[i], (l + src1[i] - lt) & mask);
lt = src1[i];
l = src2[i];
dst[i] = (l - pred) & mask;
}
*left = l;
*left_top = lt;
}
static int add_hfyu_left_prediction_int16_c(uint16_t *dst, const uint16_t *src, unsigned mask, int w, unsigned acc){
int i;
for(i=0; i<w-1; i++){
acc+= src[i];
dst[i]= acc & mask;
i++;
acc+= src[i];
dst[i]= acc & mask;
}
for(; i<w; i++){
acc+= src[i];
dst[i]= acc & mask;
}
return acc;
}
void ff_llviddsp_init(LLVidDSPContext *c, AVCodecContext *avctx)
{
c->add_int16 = add_int16_c;
c->diff_int16= diff_int16_c;
c->add_hfyu_left_prediction_int16 = add_hfyu_left_prediction_int16_c;
c->add_hfyu_median_prediction_int16 = add_hfyu_median_prediction_int16_c;
c->sub_hfyu_median_prediction_int16 = sub_hfyu_median_prediction_int16_c;
if (ARCH_X86)
ff_llviddsp_init_x86(c, avctx);
}