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/* $OpenBSD: reg_norm.s,v 1.1 1996/08/27 10:33:00 downsj Exp $ */
/*
* reg_norm.s
*
* Normalize the value in a FPU_REG.
*
* Call from C as:
* void normalize(FPU_REG *n)
*
* void normalize_nuo(FPU_REG *n)
*
*
* Copyright (C) 1992,1993,1994
* W. Metzenthen, 22 Parker St, Ormond, Vic 3163,
* Australia. E-mail billm@vaxc.cc.monash.edu.au
* All rights reserved.
*
* This copyright notice covers the redistribution and use of the
* FPU emulator developed by W. Metzenthen. It covers only its use
* in the 386BSD, FreeBSD and NetBSD operating systems. Any other
* use is not permitted under this copyright.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must include information specifying
* that source code for the emulator is freely available and include
* either:
* a) an offer to provide the source code for a nominal distribution
* fee, or
* b) list at least two alternative methods whereby the source
* can be obtained, e.g. a publically accessible bulletin board
* and an anonymous ftp site from which the software can be
* downloaded.
* 3. All advertising materials specifically mentioning features or use of
* this emulator must acknowledge that it was developed by W. Metzenthen.
* 4. The name of W. Metzenthen may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*
* The purpose of this copyright, based upon the Berkeley copyright, is to
* ensure that the covered software remains freely available to everyone.
*
* The software (with necessary differences) is also available, but under
* the terms of the GNU copyleft, for the Linux operating system and for
* the djgpp ms-dos extender.
*
* W. Metzenthen June 1994.
*
*
* $FreeBSD: reg_norm.s,v 1.3 1994/06/10 07:44:54 rich Exp $
*
*/
#include <machine/asm.h>
#include <gnu/arch/i386/fpemul/fpu_asm.h>
.text
.align 2,144
.globl _normalize
_normalize:
pushl %ebp
movl %esp,%ebp
pushl %ebx
movl PARAM1,%ebx
movl SIGH(%ebx),%edx
movl SIGL(%ebx),%eax
orl %edx,%edx /* ms bits */
js L_done /* Already normalized */
jnz L_shift_1 /* Shift left 1 - 31 bits */
orl %eax,%eax
jz L_zero /* The contents are zero */
/* L_shift_32: */
movl %eax,%edx
xorl %eax,%eax
subl $32,EXP(%ebx) /* This can cause an underflow */
/* We need to shift left by 1 - 31 bits */
L_shift_1:
bsrl %edx,%ecx /* get the required shift in %ecx */
subl $31,%ecx
negl %ecx
shld %cl,%eax,%edx
shl %cl,%eax
subl %ecx,EXP(%ebx) /* This can cause an underflow */
movl %edx,SIGH(%ebx)
movl %eax,SIGL(%ebx)
L_done:
cmpl EXP_OVER,EXP(%ebx)
jge L_overflow
cmpl EXP_UNDER,EXP(%ebx)
jle L_underflow
L_exit:
popl %ebx
leave
ret
L_zero:
movl EXP_UNDER,EXP(%ebx)
movb TW_Zero,TAG(%ebx)
jmp L_exit
L_underflow:
push %ebx
call _arith_underflow
pop %ebx
jmp L_exit
L_overflow:
push %ebx
call _arith_overflow
pop %ebx
jmp L_exit
/* Normalise without reporting underflow or overflow */
.align 2,144
.globl _normalize_nuo
_normalize_nuo:
pushl %ebp
movl %esp,%ebp
pushl %ebx
movl PARAM1,%ebx
movl SIGH(%ebx),%edx
movl SIGL(%ebx),%eax
orl %edx,%edx /* ms bits */
js L_exit /* Already normalized */
jnz L_nuo_shift_1 /* Shift left 1 - 31 bits */
orl %eax,%eax
jz L_zero /* The contents are zero */
/* L_nuo_shift_32: */
movl %eax,%edx
xorl %eax,%eax
subl $32,EXP(%ebx) /* This can cause an underflow */
/* We need to shift left by 1 - 31 bits */
L_nuo_shift_1:
bsrl %edx,%ecx /* get the required shift in %ecx */
subl $31,%ecx
negl %ecx
shld %cl,%eax,%edx
shl %cl,%eax
subl %ecx,EXP(%ebx) /* This can cause an underflow */
movl %edx,SIGH(%ebx)
movl %eax,SIGL(%ebx)
jmp L_exit
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