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stmhal, math: Define _M_LN2 if not already defined.

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Addresses issue #790.
This commit is contained in:
Damien George 2014-08-05 14:13:05 +00:00
parent dd07023cb7
commit 56da07dcfa
1 changed files with 4 additions and 0 deletions
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stmhal/math.c
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@ -102,6 +102,10 @@ float copysignf(float x, float y) {
#ifdef log2f
#undef log2f
#endif
// some compilers have _M_LN2 defined in math.h, some don't
#ifndef _M_LN2
#define _M_LN2 (0.69314718055994530942)
#endif
float log2f(float x) { return logf(x) / (float)_M_LN2; }
static const float _M_LN10 = 2.30258509299404; // 0x40135d8e