Source code
Revision control
Copy as Markdown
Other Tools
/*
* Copyright (c) 2005-2020 Rich Felker, et al.
*
* SPDX-License-Identifier: MIT
*
* for all contributors to musl.
*/
#include <float.h>
#include <stdint.h>
#include "math_private.h"
double scalbn(double x, int n)
{
union {double f; uint64_t i;} u;
double_t y = x;
if (n > 1023) {
y *= 0x1p1023;
n -= 1023;
if (n > 1023) {
y *= 0x1p1023;
n -= 1023;
if (n > 1023)
n = 1023;
}
} else if (n < -1022) {
/* make sure final n < -53 to avoid double
rounding in the subnormal range */
y *= 0x1p-1022 * 0x1p53;
n += 1022 - 53;
if (n < -1022) {
y *= 0x1p-1022 * 0x1p53;
n += 1022 - 53;
if (n < -1022)
n = -1022;
}
}
u.i = (uint64_t)(0x3ff+n)<<52;
x = y * u.f;
return x;
}