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avcodec/smacker: Don't zero-initialize unnecessarily

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With the possible exception of the "last" values when decoding video,
only the part that is actually initialized with values derived from the
bitstream is used afterwards, so it is unnecessary to zero everything at
the beginning. This is also no problem for the "last" values at all,
because they are reset for every frame anyway.

While at it, use sizeof(variable) instead of sizeof(type).

Performance increased slightly: For GCC, from 2068389 decicycles per call
to smka_decode_frame() when decoding the sample from ticket #2425 to 2053758
decicycles; for Clang, from 1534188 to 1523153 decicycles.

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt
2020-06-25 16:59:13 +02:00
parent 2db38ae734
commit 77c9507253
1 changed files with 8 additions and 7 deletions
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15
libavcodec/smacker.c
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@@ -197,14 +197,15 @@ static int smacker_decode_header_tree(SmackVContext *smk, GetBitContext *gb, int
for (int i = 0; i < 2; i++) {
h[i].length = 256;
h[i].current = 0;
h[i].bits = av_mallocz(256 * sizeof(h[i].bits[0]));
h[i].lengths = av_mallocz(256 * sizeof(h[i].lengths[0]));
h[i].values = av_mallocz(256 * sizeof(h[i].values[0]));
h[i].bits = av_malloc(256 * sizeof(h[i].bits[0]));
h[i].lengths = av_malloc(256 * sizeof(h[i].lengths[0]));
h[i].values = av_malloc(256 * sizeof(h[i].values[0]));
if (!h[i].bits || !h[i].lengths || !h[i].values) {
err = AVERROR(ENOMEM);
goto error;
}
if (!get_bits1(gb)) {
h[i].values[0] = 0;
av_log(smk->avctx, AV_LOG_ERROR, "Skipping %s bytes tree\n",
i ? "high" : "low");
continue;
@@ -242,7 +243,7 @@ static int smacker_decode_header_tree(SmackVContext *smk, GetBitContext *gb, int
huff.length = (size + 3) >> 2;
huff.current = 0;
huff.values = av_mallocz_array(huff.length + 3, sizeof(huff.values[0]));
huff.values = av_malloc_array(huff.length + 3, sizeof(huff.values[0]));
if (!huff.values) {
err = AVERROR(ENOMEM);
goto error;
@@ -645,9 +646,9 @@ static int smka_decode_frame(AVCodecContext *avctx, void *data,
for(i = 0; i < (1 << (bits + stereo)); i++) {
h[i].length = 256;
h[i].current = 0;
h[i].bits = av_mallocz(256 * 4);
h[i].lengths = av_mallocz(256 * sizeof(int));
h[i].values = av_mallocz(256 * sizeof(int));
h[i].bits = av_malloc(256 * sizeof(h[i].bits));
h[i].lengths = av_malloc(256 * sizeof(h[i].lengths));
h[i].values = av_malloc(256 * sizeof(h[i].values));
if (!h[i].bits || !h[i].lengths || !h[i].values) {
ret = AVERROR(ENOMEM);
goto error;