nexttowardl.s revision 25c28e83beb90e7c80452a7c818c5e6f73a07dc8
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
*/
/*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
.file "nexttowardl.s"
#include "libm.h"
LIBM_ANSI_PRAGMA_WEAK(nexttowardl,function)
#include "libm_synonyms.h"
.section .rodata
.align 4
.LFmaxl: .long 0xffffffff,0xffffffff,0x00007ffe
.LFminl: .long 0x1,0x0,0x0
ENTRY(nexttowardl)
pushl %ebp
movl %esp,%ebp
fldt 20(%ebp) / y
subl $12,%esp
fldt 8(%ebp) / load x
fucom / x : y
fstsw %ax
sahf
jp .LNaN
je .Lequal
fstp %st(1) / x
ja .Lbigger
/ x < y
ftst
movl $1,-12(%ebp) /// -12(%ebp) contains Fminl
movl $0,-8(%ebp)
movl $0,%ecx /// final needs this
movl %ecx,-4(%ebp)
fnstsw %ax
sahf
je .Lfinal
ja .Laddulp
jb .Lsubulp
.Lbigger:
/ x > y
ftst
movl $1,-12(%ebp) /// -12(%ebp) contains -Fminl
movl $0,-8(%ebp)
movl $0x00008000,%ecx /// final needs this
movl %ecx,-4(%ebp)
fnstsw %ax
sahf
je .Lfinal
jb .Laddulp
.Lsubulp:
movl 12(%ebp),%edx / high word of significand of x
movl 16(%ebp),%ecx / x's exponent
andl $0x0000ffff,%ecx
movl %edx,%eax
not %eax
andl $0x80000000,%eax / look at explicit leading bit
orl %ecx,%eax
andl $0x80007fff,%eax
jnz .Lnot_pseudonormal / zero value implies pseudonormal
addl $1,%ecx / if pseudonormal, turn into equivalent normal
.Lnot_pseudonormal:
movl 8(%ebp),%eax / low x
subl $1,%eax / low x - ulp
movl %eax,-12(%ebp)
cmpl $0xffffffff,%eax / this means low x was 0
jz .Lborrow
movl %edx,-8(%ebp)
movl %ecx,-4(%ebp)
jmp .Lfinal
.Lborrow:
cmpl $0x80000000,%edx / look at high x
je .Lsecond_borrow
subl $1,%edx
movl %edx,-8(%ebp)
movl %ecx,-4(%ebp)
jmp .Lfinal
.Lsecond_borrow:
movl %ecx,%eax
andl $0x7fff,%eax / look at exp x without sign bit
cmpl $1,%eax
jbe .Lsubnormal_result / exp > 1 ==> result will be normal
movl $0xffffffff,-8(%ebp)
subl $1,%ecx
movl %ecx,-4(%ebp)
jmp .Lfinal
.Lsubnormal_result:
movl $0x7fffffff,-8(%ebp)
movl %ecx,%eax
andl $0x8000,%eax / look at sign bit
jz .Lpositive
movl $0x8000,%ecx
movl %ecx,-4(%ebp)
jmp .Lfinal
.Lpositive:
movl $0,%ecx
movl %ecx,-4(%ebp)
jmp .Lfinal
.Laddulp:
movl 12(%ebp),%edx / high x
movl 16(%ebp),%ecx / x's exponent
andl $0x0000ffff,%ecx
movl %edx,%eax
not %eax
andl $0x80000000,%eax / look at explicit leading bit
orl %ecx,%eax
andl $0x80007fff,%eax
jnz .Lnot_pseudonormal_2 / zero value implies pseudonormal
addl $1,%ecx
.Lnot_pseudonormal_2:
movl 8(%ebp),%eax / low x
addl $1,%eax / low x + ulp
movl %eax,-12(%ebp)
jz .Lcarry / jump if the content of %eax is 0
movl %edx,-8(%ebp)
movl %ecx,-4(%ebp)
jmp .Lfinal
.Lcarry:
movl %edx,%eax
andl $0x7fffffff,%eax
cmpl $0x7fffffff,%eax / look at high x
je .Lsecond_carry
addl $1,%edx
movl %edx,-8(%ebp)
movl %ecx,-4(%ebp)
jmp .Lfinal
.Lsecond_carry:
movl $0x80000000,-8(%ebp)
addl $1,%ecx
movl %ecx,-4(%ebp)
.Lfinal:
fstp %st(0)
fldt -12(%ebp)
andl $0x00007fff,%ecx
jz .Lunderflow
cmpw $0x7fff,%cx
je .Loverflow
jmp .Lreturn
.Loverflow:
PIC_SETUP(1)
fldt PIC_L(.LFmaxl)
PIC_WRAPUP
fmulp %st,%st(0) / create overflow signal
jmp .Lreturn
.Lunderflow:
PIC_SETUP(2)
fldt PIC_L(.LFminl)
PIC_WRAPUP
fmulp %st,%st(0) / create underflow signal
jmp .Lreturn
.Lequal:
fstp %st(0) / C99 says to return y when x == y
jmp .Lreturn
.LNaN:
faddp %st,%st(1) / x+y,x
.Lreturn:
fwait
leave
ret
.align 4
SET_SIZE(nexttowardl)