diff options
Diffstat (limited to 'src/gallium/auxiliary/util/u_math.h')
| -rw-r--r-- | src/gallium/auxiliary/util/u_math.h | 33 |
1 files changed, 27 insertions, 6 deletions
diff --git a/src/gallium/auxiliary/util/u_math.h b/src/gallium/auxiliary/util/u_math.h index 9ed1ab6d8e..a5cd6574c0 100644 --- a/src/gallium/auxiliary/util/u_math.h +++ b/src/gallium/auxiliary/util/u_math.h @@ -499,11 +499,15 @@ util_bitcount(unsigned n) #if defined(PIPE_CC_GCC) return __builtin_popcount(n); #else - /* XXX there are more clever ways of doing this */ + /* K&R classic bitcount. + * + * For each iteration, clear the LSB from the bitfield. + * Requires only one iteration per set bit, instead of + * one iteration per bit less than highest set bit. + */ unsigned bits = 0; - while (n) { - bits += (n & 1); - n = n >> 1; + for (bits; n; bits++) { + n &= n - 1; } return bits; #endif @@ -511,6 +515,23 @@ util_bitcount(unsigned n) /** + * Reverse byte order of a 32 bit word. + */ +static INLINE uint32_t +util_bswap32(uint32_t n) +{ +#if defined(PIPE_CC_GCC) + return __builtin_bswap32(n); +#else + return (n >> 24) | + ((n >> 8) & 0x0000ff00) | + ((n << 8) & 0x00ff0000) | + (n << 24); +#endif +} + + +/** * Clamp X to [MIN, MAX]. * This is a macro to allow float, int, uint, etc. types. */ @@ -530,9 +551,9 @@ align(int value, int alignment) } static INLINE unsigned -minify(unsigned value) +u_minify(unsigned value, unsigned levels) { - return MAX2(1, value >> 1); + return MAX2(1, value >> levels); } #ifndef COPY_4V |