sys/gnu/fpemul/reg_u_mul.s

        .file   "reg_u_mul.S"
/*
 *  reg_u_mul.S
 *
 * Core multiplication routine
 *
 *
 * 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.
 *
 *
 *     $Id: reg_u_mul.s,v 1.2 1994/04/29 21:34:25 gclarkii Exp $
 *
 */

/*---------------------------------------------------------------------------+
 |   Basic multiplication routine.                                           |
 |   Does not check the resulting exponent for overflow/underflow            |
 |                                                                           |
 |   reg_u_mul(FPU_REG *a, FPU_REG *b, FPU_REG *c, unsigned int cw);         |
 |                                                                           |
 |   Internal working is at approx 128 bits.                                 |
 |   Result is rounded to nearest 53 or 64 bits, using "nearest or even".    |
 +---------------------------------------------------------------------------*/

#include "exception.h"
#include "fpu_asm.h"
#include "control_w.h"


.data
        .align 2,0
accum_0:
        .long   0
accum_1:
        .long   0


.text
        .align 2,144

.globl _reg_u_mul
_reg_u_mul:
        pushl   %ebp
        movl    %esp,%ebp
        pushl   %esi
        pushl   %edi
        pushl   %ebx

        movl    PARAM1,%esi
        movl    PARAM2,%edi

#ifdef PARANOID
        testl   $0x80000000,SIGH(%esi)
        jz      L_bugged
        testl   $0x80000000,SIGH(%edi)
        jz      L_bugged
#endif PARANOID

#ifdef DENORM_OPERAND
        movl    EXP(%esi),%eax
        cmpl    EXP_UNDER,%eax
        jg      xOp1_not_denorm

        call    _denormal_operand
        orl     %eax,%eax
        jnz     FPU_Arith_exit

xOp1_not_denorm:
        movl    EXP(%edi),%eax
        cmpl    EXP_UNDER,%eax
        jg      xOp2_not_denorm

        call    _denormal_operand
        orl     %eax,%eax
        jnz     FPU_Arith_exit

xOp2_not_denorm:
#endif DENORM_OPERAND

        xorl    %ecx,%ecx
        xorl    %ebx,%ebx

        movl    SIGL(%esi),%eax
        mull    SIGL(%edi)
        movl    %eax,accum_0
        movl    %edx,accum_1

        movl    SIGL(%esi),%eax
        mull    SIGH(%edi)
        addl    %eax,accum_1
        adcl    %edx,%ebx
/*      adcl    $0,%ecx         *//* overflow here is not possible */

        movl    SIGH(%esi),%eax
        mull    SIGL(%edi)
        addl    %eax,accum_1
        adcl    %edx,%ebx
        adcl    $0,%ecx

        movl    SIGH(%esi),%eax
        mull    SIGH(%edi)
        addl    %eax,%ebx
        adcl    %edx,%ecx

        movl    EXP(%esi),%eax  /* Compute the exponent */
        addl    EXP(%edi),%eax
        subl    EXP_BIAS-1,%eax
/*  Have now finished with the sources */
        movl    PARAM3,%edi     /* Point to the destination */
        movl    %eax,EXP(%edi)

/*  Now make sure that the result is normalized */
        testl   $0x80000000,%ecx
        jnz     LResult_Normalised

        /* Normalize by shifting left one bit */
        shll    $1,accum_0
        rcll    $1,accum_1
        rcll    $1,%ebx
        rcll    $1,%ecx
        decl    EXP(%edi)

LResult_Normalised:
        movl    accum_0,%eax
        movl    accum_1,%edx
        orl     %eax,%eax
        jz      L_extent_zero

        orl     $1,%edx

L_extent_zero:
        movl    %ecx,%eax
        jmp     FPU_round


#ifdef PARANOID
L_bugged:
        pushl   EX_INTERNAL|0x205
        call    EXCEPTION
        pop     %ebx
        jmp     L_exit

L_exit:
        popl    %ebx
        popl    %edi
        popl    %esi
        leave
        ret
#endif PARANOID