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This commit is contained in:
Justine Tunney 2020-06-15 07:18:57 -07:00
commit c91b3c5006
14915 changed files with 590219 additions and 0 deletions
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32
libc/math/scalbn.c Normal file
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#include "libc/math/math.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;
}