/* ix87 specific implementation of exp(x)-1.

   Copyright (C) 1996-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   Based on code by John C. Bowman <bowman@ipp-garching.mpg.de>.

   Corrections by H.J. Lu (hjl@gnu.ai.mit.edu), 1997.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

	/* Using: e^x - 1 = 2^(x * log2(e)) - 1 */

#include <sysdep.h>

#include <machine/asm.h>

#include <i386-math-asm.h>

#include <libm-alias-double.h>

	.section .rodata

	.align ALIGNARG(4)

	.type minus1,@object

minus1:	.double -1.0

	ASM_SIZE_DIRECTIVE(minus1)

	.type one,@object

one:	.double 1.0

	ASM_SIZE_DIRECTIVE(one)

	.type l2e,@object

l2e:	.tfloat 1.442695040888963407359924681002

	ASM_SIZE_DIRECTIVE(l2e)

DEFINE_DBL_MIN

#ifdef PIC

#define MO(op) op##@GOTOFF(%edx)

#else

#define MO(op) op

#endif

	.text

ENTRY(__expm1)

	movzwl	4+6(%esp), %eax

	xorb	$0x80, %ah	// invert sign bit (now 1 is "positive")

	cmpl	$0xc086, %eax	// is num >= 704?

	jae	HIDDEN_JUMPTARGET (__exp)

	fldl	4(%esp)		// x

	fxam			// Is NaN, +-Inf or +-0?

	xorb	$0x80, %ah

	cmpl	$0xc043, %eax	// is num <= -38.0?

	fstsw	%ax

	movb	$0x45, %ch

	jb	4f

	// Below -38.0 (may be -NaN or -Inf).

	andb	%ah, %ch

#ifdef	PIC

	LOAD_PIC_REG (dx)

#endif

	cmpb	$0x01, %ch

	je	5f		// If -NaN, jump.

	jmp	2f		// -large, possibly -Inf.

4:	// In range -38.0 to 704.0 (may be +-0 but not NaN or +-Inf).

	andb	%ah, %ch

	cmpb	$0x40, %ch

	je	3f		// If +-0, jump.

#ifdef	PIC

	LOAD_PIC_REG (dx)

#endif

5:	fldt	MO(l2e)		// log2(e) : x

	fmulp			// log2(e)*x

	fld	%st		// log2(e)*x : log2(e)*x

	// Set round-to-nearest temporarily.

	subl	$8, %esp

	cfi_adjust_cfa_offset (8)

	fstcw	4(%esp)

	movl	$0xf3ff, %ecx

	andl	4(%esp), %ecx

	movl	%ecx, (%esp)

	fldcw	(%esp)

	frndint			// int(log2(e)*x) : log2(e)*x

	fldcw	4(%esp)

	addl	$8, %esp

	cfi_adjust_cfa_offset (-8)

	fsubr	%st, %st(1)	// int(log2(e)*x) : fract(log2(e)*x)

	fxch			// fract(log2(e)*x) : int(log2(e)*x)

	f2xm1			// 2^fract(log2(e)*x)-1 : int(log2(e)*x)

	fscale			// 2^(log2(e)*x)-2^int(log2(e)*x) : int(log2(e)*x)

	fxch			// int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)

	fldl	MO(one)		// 1 : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)

	fscale			// 2^int(log2(e)*x) : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)

	fsubrl	MO(one)		// 1-2^int(log2(e)*x) : int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)

	fstp	%st(1)		// 1-2^int(log2(e)*x) : 2^(log2(e)*x)-2^int(log2(e)*x)

	fsubrp	%st, %st(1)	// 2^(log2(e)*x)

	DBL_CHECK_FORCE_UFLOW

	ret

2:	fstp	%st

	fldl	MO(minus1)	// Set result to -1.0.

3:	ret

END(__expm1)

libm_alias_double (__expm1, expm1)