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authorBrian Paul <brian.paul@tungstengraphics.com>2008-11-14 12:55:05 -0700
committerBrian Paul <brian.paul@tungstengraphics.com>2008-11-14 12:58:12 -0700
commit7e584a70c492698be18bf4d6372b50d1a1c38385 (patch)
tree05f9ca9d5fa10246bc45766dd4e6e419a28a16a4
parent6afab9001e5ebe5a970810b0e12dbfac0d9abe14 (diff)
gallium: increase table size for fast log/pow functions
The various conformance tests pass now.
-rw-r--r--src/gallium/auxiliary/util/u_math.c2
-rw-r--r--src/gallium/auxiliary/util/u_math.h8
2 files changed, 6 insertions, 4 deletions
diff --git a/src/gallium/auxiliary/util/u_math.c b/src/gallium/auxiliary/util/u_math.c
index d1571cd1fc..2811475fa0 100644
--- a/src/gallium/auxiliary/util/u_math.c
+++ b/src/gallium/auxiliary/util/u_math.c
@@ -52,7 +52,7 @@ init_log2_table(void)
{
unsigned i;
for (i = 0; i < LOG2_TABLE_SIZE; i++)
- log2_table[i] = (float) log2(1.0 + i * (1.0 / LOG2_TABLE_SIZE));
+ log2_table[i] = (float) log2(1.0 + i * (1.0 / LOG2_TABLE_SCALE));
}
diff --git a/src/gallium/auxiliary/util/u_math.h b/src/gallium/auxiliary/util/u_math.h
index aee69ab7ba..ac11d7001b 100644
--- a/src/gallium/auxiliary/util/u_math.h
+++ b/src/gallium/auxiliary/util/u_math.h
@@ -246,8 +246,9 @@ util_fast_exp(float x)
}
-#define LOG2_TABLE_SIZE_LOG2 8
-#define LOG2_TABLE_SIZE (1 << LOG2_TABLE_SIZE_LOG2)
+#define LOG2_TABLE_SIZE_LOG2 16
+#define LOG2_TABLE_SCALE (1 << LOG2_TABLE_SIZE_LOG2)
+#define LOG2_TABLE_SIZE (LOG2_TABLE_SCALE + 1)
extern float log2_table[LOG2_TABLE_SIZE];
@@ -258,7 +259,8 @@ util_fast_log2(float x)
float epart, mpart;
num.f = x;
epart = (float)(((num.i & 0x7f800000) >> 23) - 127);
- mpart = log2_table[(num.i & 0x007fffff) >> (23 - LOG2_TABLE_SIZE_LOG2)];
+ /* mpart = log2_table[mantissa*LOG2_TABLE_SCALE + 0.5] */
+ mpart = log2_table[((num.i & 0x007fffff) + (1 << (22 - LOG2_TABLE_SIZE_LOG2))) >> (23 - LOG2_TABLE_SIZE_LOG2)];
return epart + mpart;
}