diff options
author | Jean-Marc Valin <jmvalin@jmvalin.ca> | 2014-01-21 01:32:16 +0400 |
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committer | Jean-Marc Valin <jmvalin@jmvalin.ca> | 2014-01-21 01:32:16 +0400 |
commit | ec5d01cbe486ebc29f0c03423f9a253a1655df7f (patch) | |
tree | 404d0d2115393a427553efb90817b554934bf59f /celt | |
parent | 379af35fd4293d34f3b0b5c15576d6d7a61324cb (diff) |
Using a table on ARM for unsigned division by small (<=256) integers.
Saves 0.6% for 64 kb/s and 1.8% for 128 kb/s when decoding on arm7tdmi.
Diffstat (limited to 'celt')
-rw-r--r-- | celt/entcode.c | 38 | ||||
-rw-r--r-- | celt/entcode.h | 22 | ||||
-rw-r--r-- | celt/entdec.c | 2 | ||||
-rw-r--r-- | celt/entenc.c | 2 |
4 files changed, 62 insertions, 2 deletions
diff --git a/celt/entcode.c b/celt/entcode.c index fa5d7c7c..edb7ef90 100644 --- a/celt/entcode.c +++ b/celt/entcode.c @@ -91,3 +91,41 @@ opus_uint32 ec_tell_frac(ec_ctx *_this){ } return nbits-l; } + +#ifdef USE_SMALL_DIV_TABLE +/* Result of 2^32/(2*i+1), except for i=0. */ +const opus_uint32 SMALL_DIV_TABLE[129] = { + 0xFFFFFFFF, 0x55555555, 0x33333333, 0x24924924, + 0x1C71C71C, 0x1745D174, 0x13B13B13, 0x11111111, + 0x0F0F0F0F, 0x0D79435E, 0x0C30C30C, 0x0B21642C, + 0x0A3D70A3, 0x097B425E, 0x08D3DCB0, 0x08421084, + 0x07C1F07C, 0x07507507, 0x06EB3E45, 0x06906906, + 0x063E7063, 0x05F417D0, 0x05B05B05, 0x0572620A, + 0x05397829, 0x05050505, 0x04D4873E, 0x04A7904A, + 0x047DC11F, 0x0456C797, 0x04325C53, 0x04104104, + 0x03F03F03, 0x03D22635, 0x03B5CC0E, 0x039B0AD1, + 0x0381C0E0, 0x0369D036, 0x03531DEC, 0x033D91D2, + 0x0329161F, 0x03159721, 0x03030303, 0x02F14990, + 0x02E05C0B, 0x02D02D02, 0x02C0B02C, 0x02B1DA46, + 0x02A3A0FD, 0x0295FAD4, 0x0288DF0C, 0x027C4597, + 0x02702702, 0x02647C69, 0x02593F69, 0x024E6A17, + 0x0243F6F0, 0x0239E0D5, 0x02302302, 0x0226B902, + 0x021D9EAD, 0x0214D021, 0x020C49BA, 0x02040810, + 0x01FC07F0, 0x01F44659, 0x01ECC07B, 0x01E573AC, + 0x01DE5D6E, 0x01D77B65, 0x01D0CB58, 0x01CA4B30, + 0x01C3F8F0, 0x01BDD2B8, 0x01B7D6C3, 0x01B20364, + 0x01AC5701, 0x01A6D01A, 0x01A16D3F, 0x019C2D14, + 0x01970E4F, 0x01920FB4, 0x018D3018, 0x01886E5F, + 0x0183C977, 0x017F405F, 0x017AD220, 0x01767DCE, + 0x01724287, 0x016E1F76, 0x016A13CD, 0x01661EC6, + 0x01623FA7, 0x015E75BB, 0x015AC056, 0x01571ED3, + 0x01539094, 0x01501501, 0x014CAB88, 0x0149539E, + 0x01460CBC, 0x0142D662, 0x013FB013, 0x013C995A, + 0x013991C2, 0x013698DF, 0x0133AE45, 0x0130D190, + 0x012E025C, 0x012B404A, 0x01288B01, 0x0125E227, + 0x01234567, 0x0120B470, 0x011E2EF3, 0x011BB4A4, + 0x01194538, 0x0116E068, 0x011485F0, 0x0112358E, + 0x010FEF01, 0x010DB20A, 0x010B7E6E, 0x010953F3, + 0x01073260, 0x0105197F, 0x0103091B, 0x01010101 +}; +#endif diff --git a/celt/entcode.h b/celt/entcode.h index dd13e49e..c10fe8d7 100644 --- a/celt/entcode.h +++ b/celt/entcode.h @@ -34,6 +34,12 @@ # include <stddef.h> # include "ecintrin.h" +extern const opus_uint32 SMALL_DIV_TABLE[129]; + +#ifdef OPUS_ARM_ASM +#define USE_SMALL_DIV_TABLE +#endif + /*OPT: ec_window must be at least 32 bits, but if you have fast arithmetic on a larger type, you can speed up the decoder by using it here.*/ typedef opus_uint32 ec_window; @@ -114,4 +120,20 @@ static OPUS_INLINE int ec_tell(ec_ctx *_this){ rounding error is in the positive direction).*/ opus_uint32 ec_tell_frac(ec_ctx *_this); +/* Tested exhaustively for all n and for 1<=d<=256 */ +static OPUS_INLINE opus_uint32 celt_udiv(opus_uint32 n, opus_uint32 d) { +#ifdef USE_SMALL_DIV_TABLE + if (d>256) + return n/d; + else { + opus_uint32 t, q; + t = EC_ILOG(d&-d); + q = (opus_uint64)SMALL_DIV_TABLE[d>>t]*(n>>(t-1))>>32; + return q+(n-q*d >= d); + } +#else + return n/d; +#endif +} + #endif diff --git a/celt/entdec.c b/celt/entdec.c index 3c264685..0b3433ed 100644 --- a/celt/entdec.c +++ b/celt/entdec.c @@ -138,7 +138,7 @@ void ec_dec_init(ec_dec *_this,unsigned char *_buf,opus_uint32 _storage){ unsigned ec_decode(ec_dec *_this,unsigned _ft){ unsigned s; - _this->ext=_this->rng/_ft; + _this->ext=celt_udiv(_this->rng,_ft); s=(unsigned)(_this->val/_this->ext); return _ft-EC_MINI(s+1,_ft); } diff --git a/celt/entenc.c b/celt/entenc.c index a7e34ece..271e4d30 100644 --- a/celt/entenc.c +++ b/celt/entenc.c @@ -127,7 +127,7 @@ void ec_enc_init(ec_enc *_this,unsigned char *_buf,opus_uint32 _size){ void ec_encode(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned _ft){ opus_uint32 r; - r=_this->rng/_ft; + r=celt_udiv(_this->rng,_ft); if(_fl>0){ _this->val+=_this->rng-IMUL32(r,(_ft-_fl)); _this->rng=IMUL32(r,(_fh-_fl)); |