diff options
| author | Nils Wallménius <nils@rockbox.org> | 2009-12-23 18:05:11 +0000 |
|---|---|---|
| committer | Nils Wallménius <nils@rockbox.org> | 2009-12-23 18:05:11 +0000 |
| commit | 87ecc7020e20b646802992d324d4d60a370b6fe3 (patch) | |
| tree | acb73e93bac766c48ac35c3c7c20defc296dbc68 | |
| parent | 92eb0c184127a04afe3d366ff772e6b71733d746 (diff) | |
Improved bitrev with approach suggested by Jens Arnold, gives 0.5%-1% speedup for tremor decoding on sansa c200 (PP) and a tiny speedup on coldfire as well
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@24102 a1c6a512-1295-4272-9138-f99709370657
| -rw-r--r-- | apps/codecs/libtremor/codebook.c | 30 |
1 files changed, 25 insertions, 5 deletions
diff --git a/apps/codecs/libtremor/codebook.c b/apps/codecs/libtremor/codebook.c index d744f520e5..a4fc9ee6c0 100644 --- a/apps/codecs/libtremor/codebook.c +++ b/apps/codecs/libtremor/codebook.c @@ -140,11 +140,31 @@ int vorbis_staticbook_unpack(oggpack_buffer *opb,static_codebook *s){ be. The first-stage decode table catches most words so that bitreverse is not in the main execution path. */ -static inline ogg_uint32_t bitreverse(register ogg_uint32_t x){ - x= swap32(x); - x= ((x>> 4)&0x0f0f0f0f) | ((x<< 4)&0xf0f0f0f0); - x= ((x>> 2)&0x33333333) | ((x<< 2)&0xcccccccc); - return((x>> 1)&0x55555555) | ((x<< 1)&0xaaaaaaaa); +static inline ogg_uint32_t bitreverse(register ogg_uint32_t x) +{ + unsigned int mask; +#if defined(CPU_ARM) && ARM_ARCH >= 6 + asm ("rev %[x], %[x]" : [x] "+r" (x)); /* swap bytes */ +#else +#if defined(CPU_COLDFIRE) + asm ("swap %[x]" : [x] "+r" (x)); /* swap halfwords */ +#else + x = (x>>16) | (x<<16); +#endif + mask = x&0x00ff00ff; + x ^= mask; + x = (x >> 8) | (mask << 8); /* bytes swapped */ +#endif + mask = x&0x0f0f0f0f; + x ^= mask; + x = (x >> 4) | (mask << 4); /* 4-bit units swapped */ + mask = x&0x33333333; + x ^= mask; + x = (x >> 2) | (mask << 2); /* 2-bit units swapped */ + mask = x&0x55555555; + x ^= mask; + x = (x >> 1) | (mask << 1); /* done */ + return x; } STIN long decode_packed_entry_number(codebook *book, |