diff options
Diffstat (limited to 'src')
-rw-r--r-- | src/mesa/main/teximage.c | 35 |
1 files changed, 11 insertions, 24 deletions
diff --git a/src/mesa/main/teximage.c b/src/mesa/main/teximage.c index 4ea9a483c92..3e429110ae9 100644 --- a/src/mesa/main/teximage.c +++ b/src/mesa/main/teximage.c @@ -81,31 +81,18 @@ _mesa_free_texmemory(void *m) /* - * Compute floor(log_base_2(n)). - * If n < 0 return -1. + * Returns the floor form of binary logarithm for a 32-bit integer. */ -static int -logbase2( int n ) -{ - GLint i = 1; - GLint log2 = 0; - - if (n < 0) - return -1; - - if (n == 0) - return 0; - - while ( n > i ) { - i *= 2; - log2++; - } - if (i != n) { - return log2 - 1; - } - else { - return log2; - } +static GLuint +logbase2(GLuint n) +{ + GLuint pos = 0; + if (n >= 1<<16) { n >>= 16; pos += 16; } + if (n >= 1<< 8) { n >>= 8; pos += 8; } + if (n >= 1<< 4) { n >>= 4; pos += 4; } + if (n >= 1<< 2) { n >>= 2; pos += 2; } + if (n >= 1<< 1) { pos += 1; } + return pos; } |