From bd5969fc876a10b18613302db7087ef3c40f18e1 Mon Sep 17 00:00:00 2001 From: Ian Moffett Date: Thu, 7 Mar 2024 17:28:00 -0500 Subject: lib: Add mlibc Signed-off-by: Ian Moffett --- lib/mlibc/options/ansi/musl-generic-math/fmod.c | 68 +++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 lib/mlibc/options/ansi/musl-generic-math/fmod.c (limited to 'lib/mlibc/options/ansi/musl-generic-math/fmod.c') diff --git a/lib/mlibc/options/ansi/musl-generic-math/fmod.c b/lib/mlibc/options/ansi/musl-generic-math/fmod.c new file mode 100644 index 0000000..6849722 --- /dev/null +++ b/lib/mlibc/options/ansi/musl-generic-math/fmod.c @@ -0,0 +1,68 @@ +#include +#include + +double fmod(double x, double y) +{ + union {double f; uint64_t i;} ux = {x}, uy = {y}; + int ex = ux.i>>52 & 0x7ff; + int ey = uy.i>>52 & 0x7ff; + int sx = ux.i>>63; + uint64_t i; + + /* in the followings uxi should be ux.i, but then gcc wrongly adds */ + /* float load/store to inner loops ruining performance and code size */ + uint64_t uxi = ux.i; + + if (uy.i<<1 == 0 || isnan(y) || ex == 0x7ff) + return (x*y)/(x*y); + if (uxi<<1 <= uy.i<<1) { + if (uxi<<1 == uy.i<<1) + return 0*x; + return x; + } + + /* normalize x and y */ + if (!ex) { + for (i = uxi<<12; i>>63 == 0; ex--, i <<= 1); + uxi <<= -ex + 1; + } else { + uxi &= -1ULL >> 12; + uxi |= 1ULL << 52; + } + if (!ey) { + for (i = uy.i<<12; i>>63 == 0; ey--, i <<= 1); + uy.i <<= -ey + 1; + } else { + uy.i &= -1ULL >> 12; + uy.i |= 1ULL << 52; + } + + /* x mod y */ + for (; ex > ey; ex--) { + i = uxi - uy.i; + if (i >> 63 == 0) { + if (i == 0) + return 0*x; + uxi = i; + } + uxi <<= 1; + } + i = uxi - uy.i; + if (i >> 63 == 0) { + if (i == 0) + return 0*x; + uxi = i; + } + for (; uxi>>52 == 0; uxi <<= 1, ex--); + + /* scale result */ + if (ex > 0) { + uxi -= 1ULL << 52; + uxi |= (uint64_t)ex << 52; + } else { + uxi >>= -ex + 1; + } + uxi |= (uint64_t)sx << 63; + ux.i = uxi; + return ux.f; +} -- cgit v1.2.3