From 4abab5ad6c8465a7528ccdd5f49367da05f78bbd Mon Sep 17 00:00:00 2001 From: Vladimir Azarov Date: Tue, 1 Oct 2024 15:47:05 +0200 Subject: Initial version --- src/math/round.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 src/math/round.c (limited to 'src/math/round.c') diff --git a/src/math/round.c b/src/math/round.c new file mode 100644 index 0000000..130d58d --- /dev/null +++ b/src/math/round.c @@ -0,0 +1,35 @@ +#include "libm.h" + +#if FLT_EVAL_METHOD==0 || FLT_EVAL_METHOD==1 +#define EPS DBL_EPSILON +#elif FLT_EVAL_METHOD==2 +#define EPS LDBL_EPSILON +#endif +static const double_t toint = 1/EPS; + +double round(double x) +{ + union {double f; uint64_t i;} u = {x}; + int e = u.i >> 52 & 0x7ff; + double_t y; + + if (e >= 0x3ff+52) + return x; + if (u.i >> 63) + x = -x; + if (e < 0x3ff-1) { + /* raise inexact if x!=0 */ + FORCE_EVAL(x + toint); + return 0*u.f; + } + y = x + toint - toint - x; + if (y > 0.5) + y = y + x - 1; + else if (y <= -0.5) + y = y + x + 1; + else + y = y + x; + if (u.i >> 63) + y = -y; + return y; +} -- cgit v1.2.3