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/scalbn.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) create mode 100644 src/math/scalbn.c (limited to 'src/math/scalbn.c') diff --git a/src/math/scalbn.c b/src/math/scalbn.c new file mode 100644 index 0000000..182f561 --- /dev/null +++ b/src/math/scalbn.c @@ -0,0 +1,33 @@ +#include +#include + +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; +} -- cgit v1.2.3