#include <limits.h> | |
#include "libm.h" | |
int ilogbf(float x) { | |
PRAGMA_STDC_FENV_ACCESS_ON | |
union { | |
float f; | |
uint32_t i; | |
} u = {x}; | |
uint32_t i = u.i; | |
int e = i >> 23 & 0xff; | |
if (!e) { | |
i <<= 9; | |
if (i == 0) { | |
FORCE_EVAL(0 / 0.0f); | |
return FP_ILOGB0; | |
} | |
/* subnormal x */ | |
for (e = -0x7f; i >> 31 == 0; e--, i <<= 1) | |
; | |
return e; | |
} | |
if (e == 0xff) { | |
FORCE_EVAL(0 / 0.0f); | |
return i << 9 ? FP_ILOGBNAN : INT_MAX; | |
} | |
return e - 0x7f; | |
} |