1#include <limits.h> 2#include <fenv.h> 3#include <math.h> 4#include "libm.h" 5 6/* 7If the result cannot be represented (overflow, nan), then 8lrint raises the invalid exception. 9 10Otherwise if the input was not an integer then the inexact 11exception is raised. 12 13C99 is a bit vague about whether inexact exception is 14allowed to be raised when invalid is raised. 15(F.9 explicitly allows spurious inexact exceptions, F.9.6.5 16does not make it clear if that rule applies to lrint, but 17IEEE 754r 7.8 seems to forbid spurious inexact exception in 18the ineger conversion functions) 19 20So we try to make sure that no spurious inexact exception is 21raised in case of an overflow. 22 23If the bit size of long > precision of double, then there 24cannot be inexact rounding in case the result overflows, 25otherwise LONG_MAX and LONG_MIN can be represented exactly 26as a double. 27*/ 28 29#if LONG_MAX < 1U<<53 && defined(FE_INEXACT) 30#include <float.h> 31#include <stdint.h> 32#if FLT_EVAL_METHOD==0 || FLT_EVAL_METHOD==1 33#define EPS DBL_EPSILON 34#elif FLT_EVAL_METHOD==2 35#define EPS LDBL_EPSILON 36#endif 37#ifdef __GNUC__ 38/* avoid stack frame in lrint */ 39__attribute__((noinline)) 40#endif 41static long lrint_slow(double x) 42{ 43 #pragma STDC FENV_ACCESS ON 44 int e; 45 46 e = fetestexcept(FE_INEXACT); 47 x = rint(x); 48 if (!e && (x > LONG_MAX || x < LONG_MIN)) 49 feclearexcept(FE_INEXACT); 50 /* conversion */ 51 return x; 52} 53 54long lrint(double x) 55{ 56 uint32_t abstop = asuint64(x)>>32 & 0x7fffffff; 57 uint64_t sign = asuint64(x) & (1ULL << 63); 58 59 if (abstop < 0x41dfffff) { 60 /* |x| < 0x7ffffc00, no overflow */ 61 double_t toint = asdouble(asuint64(1/EPS) | sign); 62 double_t y = x + toint - toint; 63 return (long)y; 64 } 65 return lrint_slow(x); 66} 67#else 68long lrint(double x) 69{ 70 return rint(x); 71} 72#endif 73