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view usr/src/lib/libc/i386/gen/_mul64.s @ 7298:b69e27387f74
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author | Mark J. Nelson <Mark.J.Nelson@Sun.COM> |
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date | Wed, 06 Aug 2008 16:29:39 -0600 |
parents | 68f95e015346 |
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/* * 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 2004 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ .file "_mul64.s" / / function __mul64(A,B:Longint):Longint; / {Overflow is not checked} / / We essentially do multiply by longhand, using base 2**32 digits. / a b parameter A / x c d parameter B / --------- / ad bd / ac bc / ----------------- / ac ad+bc bd / / We can ignore ac and top 32 bits of ad+bc: if <> 0, overflow happened. / #include "SYS.h" ENTRY(__mul64) push %ebp mov %esp,%ebp pushl %esi mov 12(%ebp),%eax / A.hi (a) mull 16(%ebp) / Multiply A.hi by B.lo (produces ad) xchg %ecx,%eax / ecx = bottom half of ad. movl 8(%ebp),%eax / A.Lo (b) movl %eax,%esi / Save A.lo for later mull 16(%ebp) / Multiply A.Lo by B.LO (dx:ax = bd.) addl %edx,%ecx / cx is ad xchg %eax,%esi / esi is bd, eax = A.lo (d) mull 20(%ebp) / Multiply A.lo * B.hi (producing bc) addl %ecx,%eax / Produce ad+bc movl %esi,%edx xchg %eax,%edx popl %esi movl %ebp,%esp popl %ebp ret $16 SET_SIZE(__mul64)