/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╚──────────────────────────────────────────────────────────────────────────────╝
│                                                                              │
│  Musl Libc                                                                   │
│  Copyright © 2005-2014 Rich Felker, et al.                                   │
│                                                                              │
│  Permission is hereby granted, free of charge, to any person obtaining       │
│  a copy of this software and associated documentation files (the             │
│  "Software"), to deal in the Software without restriction, including         │
│  without limitation the rights to use, copy, modify, merge, publish,         │
│  distribute, sublicense, and/or sell copies of the Software, and to          │
│  permit persons to whom the Software is furnished to do so, subject to       │
│  the following conditions:                                                   │
│                                                                              │
│  The above copyright notice and this permission notice shall be              │
│  included in all copies or substantial portions of the Software.             │
│                                                                              │
│  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,             │
│  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF          │
│  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.      │
│  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY        │
│  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,        │
│  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE           │
│  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                      │
│                                                                              │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/math.h"

asm(".ident\t\"\\n\\n\
Musl libc (MIT License)\\n\
Copyright 2005-2014 Rich Felker, et. al.\"");
asm(".include \"libc/disclaimer.inc\"");
/* clang-format off */

static const long double toint = 1/LDBL_EPSILON;

long double modfl(long double x, long double *iptr)
{
	union {
		long double f;
		struct {
			uint64_t m;
			uint16_t se;
		} i;
	} u = {x};
	int e = (u.i.se & 0x7fff) - 0x3fff;
	int s = u.i.se >> 15;
	long double absx;
	long double y;

	/* no fractional part */
	if (e >= LDBL_MANT_DIG-1) {
		*iptr = x;
		if (isnan(x))
			return x;
		return s ? -0.0 : 0.0;
	}

	/* no integral part*/
	if (e < 0) {
		*iptr = s ? -0.0 : 0.0;
		return x;
	}

	/* raises spurious inexact */
	absx = s ? -x : x;
	y = absx + toint - toint - absx;
	if (y == 0) {
		*iptr = x;
		return s ? -0.0 : 0.0;
	}
	if (y > 0)
		y -= 1;
	if (s)
		y = -y;
	*iptr = x + y;
	return -y;
}
