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avcodec/wnv1: Move temporary variables from context to stack

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Here it even leads to the complete removal of the context.

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2020-08-29 17:14:18 +02:00
parent 0166b1d1a6
commit 099bc252c6
1 changed files with 17 additions and 23 deletions
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40
libavcodec/wnv1.c
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@ -30,11 +30,6 @@
#include "internal.h"
typedef struct WNV1Context {
int shift;
GetBitContext gb;
} WNV1Context;
static const uint16_t code_tab[16][2] = {
{ 0x17F, 9 }, { 0xBF, 8 }, { 0x5F, 7 }, { 0x2F, 6 }, { 0x17, 5 }, { 0x0B, 4 }, { 0x005, 3 },
{ 0x000, 1 },
@ -45,26 +40,26 @@ static const uint16_t code_tab[16][2] = {
static VLC code_vlc;
/* returns modified base_value */
static inline int wnv1_get_code(WNV1Context *w, int base_value)
static inline int wnv1_get_code(GetBitContext *gb, int shift, int base_value)
{
int v = get_vlc2(&w->gb, code_vlc.table, CODE_VLC_BITS, 1);
int v = get_vlc2(gb, code_vlc.table, CODE_VLC_BITS, 1);
if (v == 15)
return get_bits(&w->gb, 8 - w->shift) << w->shift;
return get_bits(gb, 8 - shift) << shift;
else
return base_value + ((v - 7U) << w->shift);
return base_value + ((v - 7U) << shift);
}
static int decode_frame(AVCodecContext *avctx,
void *data, int *got_frame,
AVPacket *avpkt)
{
WNV1Context * const l = avctx->priv_data;
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
AVFrame * const p = data;
GetBitContext gb;
unsigned char *Y,*U,*V;
int i, j, ret;
int i, j, ret, shift;
int prev_y = 0, prev_u = 0, prev_v = 0;
if (buf_size < 8 + avctx->height * (avctx->width/2)/8) {
@ -76,24 +71,24 @@ static int decode_frame(AVCodecContext *avctx,
return ret;
p->key_frame = 1;
if ((ret = init_get_bits8(&l->gb, buf + 8, buf_size - 8)) < 0)
if ((ret = init_get_bits8(&gb, buf + 8, buf_size - 8)) < 0)
return ret;
if (buf[2] >> 4 == 6)
l->shift = 2;
shift = 2;
else {
l->shift = 8 - (buf[2] >> 4);
if (l->shift > 4) {
shift = 8 - (buf[2] >> 4);
if (shift > 4) {
avpriv_request_sample(avctx,
"Unknown WNV1 frame header value %i",
buf[2] >> 4);
l->shift = 4;
shift = 4;
}
if (l->shift < 1) {
if (shift < 1) {
avpriv_request_sample(avctx,
"Unknown WNV1 frame header value %i",
buf[2] >> 4);
l->shift = 1;
shift = 1;
}
}
@ -102,10 +97,10 @@ static int decode_frame(AVCodecContext *avctx,
V = p->data[2];
for (j = 0; j < avctx->height; j++) {
for (i = 0; i < avctx->width / 2; i++) {
Y[i * 2] = wnv1_get_code(l, prev_y);
prev_u = U[i] = wnv1_get_code(l, prev_u);
prev_y = Y[(i * 2) + 1] = wnv1_get_code(l, Y[i * 2]);
prev_v = V[i] = wnv1_get_code(l, prev_v);
Y[i * 2] = wnv1_get_code(&gb, shift, prev_y);
prev_u = U[i] = wnv1_get_code(&gb, shift, prev_u);
prev_y = Y[(i * 2) + 1] = wnv1_get_code(&gb, shift, Y[i * 2]);
prev_v = V[i] = wnv1_get_code(&gb, shift, prev_v);
}
Y += p->linesize[0];
U += p->linesize[1];
@ -138,7 +133,6 @@ AVCodec ff_wnv1_decoder = {
.long_name = NULL_IF_CONFIG_SMALL("Winnov WNV1"),
.type = AVMEDIA_TYPE_VIDEO,
.id = AV_CODEC_ID_WNV1,
.priv_data_size = sizeof(WNV1Context),
.init = decode_init,
.decode = decode_frame,
.capabilities = AV_CODEC_CAP_DR1,