root
/
xz
mirror of https://git.tukaani.org/xz.git
1
0
Fork 0
Code Issues Releases Wiki Activity

Take advantage of arithmetic right shift in range decoder.

This commit is contained in:
Lasse Collin 2008-03-22 14:39:34 +02:00
parent 03e0e8a0d7
commit ad999efd27
1 changed files with 37 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
src/liblzma/rangecoder/range_decoder.h
View File

@ -121,6 +121,17 @@ do { \
} while (0)
#ifdef HAVE_ARITHMETIC_RSHIFT
# define rc_decode_direct(dest, count) \
do { \
rc_normalize(); \
rc.range >>= 1; \
rc.code -= rc.range; \
rc_bound = (uint32_t)((int32_t)(rc.code) >> 31); \
dest = (dest << 1) + (rc_bound + 1); \
rc.code += rc.range & rc_bound; \
} while (--count > 0)
#else
# define rc_decode_direct(dest, count) \
do { \
rc_normalize(); \
@ -129,6 +140,7 @@ do { \
rc.code -= rc.range & (rc_bound - 1); \
dest = ((dest) << 1) | (1 - rc_bound);\
} while (--count > 0)
#endif
// Dummy versions don't update prob or dest.
@ -143,6 +155,15 @@ do { \
} while (0)
#ifdef HAVE_ARITHMETIC_RSHIFT
# define rc_decode_direct_dummy(count) \
do { \
rc_normalize(); \
rc.range >>= 1; \
rc.code -= rc.range; \
rc.code += rc.range & ((uint32_t)((int32_t)(rc.code) >> 31)); \
} while (--count > 0)
#else
# define rc_decode_direct_dummy(count) \
do { \
rc_normalize(); \
@ -150,6 +171,7 @@ do { \
rc_bound = (rc.code - rc.range) >> 31; \
rc.code -= rc.range & (rc_bound - 1); \
} while (--count > 0)
#endif
///////////////////////