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avcodec/mpegaudiodec: Hardcode tables to save space

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The csa_tables (which always consist of 32 entries of four byte each,
but the type depends upon whether the decoder is fixed or
floating-point) are currently initialized once during decoder
initialization; yet it turns out that this is actually no benefit: The
code used to initialize these tables takes up 153 (fixed point) and 122
(floating point) bytes when compiled with GCC 9.3 with -O3 on x64, so it
is better to just hardcode these tables.

Essentially the same applies to the is_tables: They have a size of 128B
each and the code to initialize them occupies 149 (fixed point) resp.
140 (floating point) bytes. So hardcode them, too.

To make the origin of the tables clear, references to the code used to
create them have been added.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2020-11-18 02:19:53 +01:00
parent 12e941df89
commit ed33bbe678
7 changed files with 58 additions and 46 deletions
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20
libavcodec/mpegaudiodec_fixed.c
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@ -36,6 +36,26 @@
#define OUT_FMT AV_SAMPLE_FMT_S16
#define OUT_FMT_P AV_SAMPLE_FMT_S16P
/* Intensity stereo table. See commit b91d46614df189e7905538e7f5c4ed9c7ed0d274
* (float based mp1/mp2/mp3 decoders.) for how they were created. */
static const int32_t is_table[2][16] = {
{ 0x000000, 0x1B0CB1, 0x2ED9EC, 0x400000, 0x512614, 0x64F34F, 0x800000 },
{ 0x800000, 0x64F34F, 0x512614, 0x400000, 0x2ED9EC, 0x1B0CB1, 0x000000 }
};
/* Antialiasing table. See commit ce4a29c066cddfc180979ed86396812f24337985
* (optimize antialias) for how they were created. */
static const int32_t csa_table[8][4] = {
{ 0x36E129F8, 0xDF128056, 0x15F3AA4E, 0xA831565E },
{ 0x386E75F2, 0xE1CF24A5, 0x1A3D9A97, 0xA960AEB3 },
{ 0x3CC6B73A, 0xEBF19FA6, 0x28B856E0, 0xAF2AE86C },
{ 0x3EEEA054, 0xF45B88BC, 0x334A2910, 0xB56CE868 },
{ 0x3FB6905C, 0xF9F27F18, 0x39A90F74, 0xBA3BEEBC },
{ 0x3FF23F20, 0xFD60D1E4, 0x3D531104, 0xBD6E92C4 },
{ 0x3FFE5932, 0xFF175EE4, 0x3F15B816, 0xBF1905B2 },
{ 0x3FFFE34A, 0xFFC3612F, 0x3FC34479, 0xBFC37DE5 }
};
#include "mpegaudiodec_template.c"
#if CONFIG_MP1_DECODER