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Cider Isn't Darwin Emulation, Really
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/* * logb.c * * by Ian Ollmann * * Copyright (c) 2007, Apple Inc. All Rights Reserved. * * Unix 2003 implementation of logb() */ #include <math.h>#include <stdint.h>
#ifdef ARMLIBM_SET_FLAGS
#include "required_arithmetic.h"
float logbf( float x ){ union{ float f; uint32_t u;}u = {x}; u.u &= 0x7fffffffU; int32_t exp = u.u >> 23; if( __builtin_expect( (uint32_t) exp - 1U >= 254, 0 ) ) { // +-0, +-denorm, +-inf, NaN if( 0.0f == x ) return required_divide_float( -1.0f, 0.0f ); //set div/0, return -inf if( x != x ) return x + x; if( u.u == 0x7f800000U ) return __builtin_inff(); u.u |= 0x3f800000U; u.f -= 1.0f; exp = u.u >> 23; return (float) (exp - (127+126)); }
return (float) (exp - 127);}
#else
float logbf( float x ){ union{ float f; uint32_t u;}u = {x}; u.u &= 0x7fffffffU; int32_t exp = u.u >> 23; if( __builtin_expect( (uint32_t) exp - 1U >= 254, 0 ) ) { // +-0, +-denorm, +-inf, NaN if( 0.0f == x ) return -__builtin_inff(); //set div/0, return -inf if( x != x ) return x + x; if( u.u == 0x7f800000U ) return __builtin_inff(); u.u |= 0x3f800000U; u.f -= 1.0f; exp = u.u >> 23; return (float) (exp - (127+126)); } return (float) (exp - 127);}
#endif