diff options
| author | Ganesh Ajjanagadde <gajjanagadde@gmail.com> | 2015-12-29 08:18:44 -0800 |
|---|---|---|
| committer | Ganesh Ajjanagadde <gajjanagadde@gmail.com> | 2015-12-30 08:45:19 -0800 |
| commit | b272c3a5aabeafb37d5aeecc4524e8a8aeecf9da (patch) | |
| tree | 8961827080f56c292c29dd27e2bf730c3529ea37 /libavcodec/dsd_tablegen.h | |
| parent | 29bc293297a6edb44114818b3485f50c137d428d (diff) | |
lavc/dsd_tablegen: speed up table generation
Tables are bit identical.
Sample benchmark (Haswell, GNU/Linux+gcc):
old:
814485 decicycles in dsd_ctables_tableinit, 512 runs, 0 skips
new:
356808 decicycles in dsd_ctable_tableinit, 512 runs, 0 skips
Binary size should essentially be identical, and is in fact identical on
the configuration I tested on.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
Diffstat (limited to 'libavcodec/dsd_tablegen.h')
| -rw-r--r-- | libavcodec/dsd_tablegen.h | 19 |
1 files changed, 10 insertions, 9 deletions
diff --git a/libavcodec/dsd_tablegen.h b/libavcodec/dsd_tablegen.h index 6afb4167da..d4ef302188 100644 --- a/libavcodec/dsd_tablegen.h +++ b/libavcodec/dsd_tablegen.h @@ -78,16 +78,17 @@ static float ctables[CTABLES][256]; static av_cold void dsd_ctables_tableinit(void) { - int t, e, m, k; - double acc; - for (t = 0; t < CTABLES; ++t) { - k = FFMIN(HTAPS - t * 8, 8); - for (e = 0; e < 256; ++e) { - acc = 0.0; - for (m = 0; m < k; ++m) - acc += (((e >> (7 - m)) & 1) * 2 - 1) * htaps[t * 8 + m]; - ctables[CTABLES - 1 - t][e] = (float)acc; + int t, e, m, sign; + double acc[CTABLES]; + for (e = 0; e < 256; ++e) { + memset(acc, 0, sizeof(acc)); + for (m = 0; m < 8; ++m) { + sign = (((e >> (7 - m)) & 1) * 2 - 1); + for (t = 0; t < CTABLES; ++t) + acc[t] += sign * htaps[t * 8 + m]; } + for (t = 0; t < CTABLES; ++t) + ctables[CTABLES - 1 - t][e] = acc[t]; } } #endif /* CONFIG_HARDCODED_TABLES */ |