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authorBrian Paul <[email protected]>2012-08-31 08:33:31 -0600
committerBrian Paul <[email protected]>2012-09-01 07:41:26 -0600
commit36f3f7ebfa345460bfd89d6e471b655385efc739 (patch)
tree7e28a774ff337b7918844ff2db4fd9e5b6840a95 /src/mesa/main/imports.h
parentc8a86f717f8e30204c615d06bcec159410ac06c5 (diff)
mesa: clean-up LOG2() function
Diffstat (limited to 'src/mesa/main/imports.h')
-rw-r--r--src/mesa/main/imports.h34
1 files changed, 16 insertions, 18 deletions
diff --git a/src/mesa/main/imports.h b/src/mesa/main/imports.h
index d851ee56a46..2f854e57400 100644
--- a/src/mesa/main/imports.h
+++ b/src/mesa/main/imports.h
@@ -164,41 +164,39 @@ static inline int isblank(int ch) { return ch == ' ' || ch == '\t'; }
/***
*** LOG2: Log base 2 of float
***/
-#ifdef USE_IEEE
-#if 0
-/* This is pretty fast, but not accurate enough (only 2 fractional bits).
- * Based on code from http://www.stereopsis.com/log2.html
- */
static inline GLfloat LOG2(GLfloat x)
{
+#ifdef USE_IEEE
+#if 0
+ /* This is pretty fast, but not accurate enough (only 2 fractional bits).
+ * Based on code from http://www.stereopsis.com/log2.html
+ */
const GLfloat y = x * x * x * x;
const GLuint ix = *((GLuint *) &y);
const GLuint exp = (ix >> 23) & 0xFF;
const GLint log2 = ((GLint) exp) - 127;
return (GLfloat) log2 * (1.0 / 4.0); /* 4, because of x^4 above */
-}
#endif
-/* Pretty fast, and accurate.
- * Based on code from http://www.flipcode.com/totd/
- */
-static inline GLfloat LOG2(GLfloat val)
-{
+ /* Pretty fast, and accurate.
+ * Based on code from http://www.flipcode.com/totd/
+ */
fi_type num;
GLint log_2;
- num.f = val;
+ num.f = x;
log_2 = ((num.i >> 23) & 255) - 128;
num.i &= ~(255 << 23);
num.i += 127 << 23;
num.f = ((-1.0f/3) * num.f + 2) * num.f - 2.0f/3;
return num.f + log_2;
-}
#else
-/*
- * NOTE: log_base_2(x) = log(x) / log(2)
- * NOTE: 1.442695 = 1/log(2).
- */
-#define LOG2(x) ((GLfloat) (log(x) * 1.442695F))
+ /*
+ * NOTE: log_base_2(x) = log(x) / log(2)
+ * NOTE: 1.442695 = 1/log(2).
+ */
+ return (GLfloat) (log(x) * 1.442695F);
#endif
+}
+
/***