Annotation of sys/lib/libkern/arch/sparc/mul.S, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: mul.S,v 1.5 2003/06/02 23:28:09 millert Exp $ */
! 2: /* $NetBSD: mul.S,v 1.2 1994/10/26 06:40:01 cgd Exp $ */
! 3:
! 4: /*
! 5: * Copyright (c) 1992, 1993
! 6: * The Regents of the University of California. All rights reserved.
! 7: *
! 8: * This software was developed by the Computer Systems Engineering group
! 9: * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
! 10: * contributed to Berkeley.
! 11: *
! 12: * Redistribution and use in source and binary forms, with or without
! 13: * modification, are permitted provided that the following conditions
! 14: * are met:
! 15: * 1. Redistributions of source code must retain the above copyright
! 16: * notice, this list of conditions and the following disclaimer.
! 17: * 2. Redistributions in binary form must reproduce the above copyright
! 18: * notice, this list of conditions and the following disclaimer in the
! 19: * documentation and/or other materials provided with the distribution.
! 20: * 3. Neither the name of the University nor the names of its contributors
! 21: * may be used to endorse or promote products derived from this software
! 22: * without specific prior written permission.
! 23: *
! 24: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 25: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 26: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 27: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 28: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 29: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 30: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 31: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 32: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 33: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 34: * SUCH DAMAGE.
! 35: *
! 36: * Header: mul.s,v 1.5 92/06/25 13:24:03 torek Exp
! 37: */
! 38:
! 39: #if defined(LIBC_SCCS) && !defined(lint)
! 40: #ifdef notdef
! 41: .asciz "@(#)mul.s 8.1 (Berkeley) 6/4/93"
! 42: #endif
! 43: .asciz "$OpenBSD: mul.S,v 1.5 2003/06/02 23:28:09 millert Exp $"
! 44: #endif /* LIBC_SCCS and not lint */
! 45:
! 46: /*
! 47: * Signed multiply, from Appendix E of the Sparc Version 8
! 48: * Architecture Manual.
! 49: *
! 50: * Returns %o0 * %o1 in %o1%o0 (i.e., %o1 holds the upper 32 bits of
! 51: * the 64-bit product).
! 52: *
! 53: * This code optimizes short (less than 13-bit) multiplies.
! 54: */
! 55:
! 56: #include "DEFS.h"
! 57: FUNC(.mul)
! 58: mov %o0, %y ! multiplier -> Y
! 59: andncc %o0, 0xfff, %g0 ! test bits 12..31
! 60: be Lmul_shortway ! if zero, can do it the short way
! 61: andcc %g0, %g0, %o4 ! zero the partial product and clear N and V
! 62:
! 63: /*
! 64: * Long multiply. 32 steps, followed by a final shift step.
! 65: */
! 66: mulscc %o4, %o1, %o4 ! 1
! 67: mulscc %o4, %o1, %o4 ! 2
! 68: mulscc %o4, %o1, %o4 ! 3
! 69: mulscc %o4, %o1, %o4 ! 4
! 70: mulscc %o4, %o1, %o4 ! 5
! 71: mulscc %o4, %o1, %o4 ! 6
! 72: mulscc %o4, %o1, %o4 ! 7
! 73: mulscc %o4, %o1, %o4 ! 8
! 74: mulscc %o4, %o1, %o4 ! 9
! 75: mulscc %o4, %o1, %o4 ! 10
! 76: mulscc %o4, %o1, %o4 ! 11
! 77: mulscc %o4, %o1, %o4 ! 12
! 78: mulscc %o4, %o1, %o4 ! 13
! 79: mulscc %o4, %o1, %o4 ! 14
! 80: mulscc %o4, %o1, %o4 ! 15
! 81: mulscc %o4, %o1, %o4 ! 16
! 82: mulscc %o4, %o1, %o4 ! 17
! 83: mulscc %o4, %o1, %o4 ! 18
! 84: mulscc %o4, %o1, %o4 ! 19
! 85: mulscc %o4, %o1, %o4 ! 20
! 86: mulscc %o4, %o1, %o4 ! 21
! 87: mulscc %o4, %o1, %o4 ! 22
! 88: mulscc %o4, %o1, %o4 ! 23
! 89: mulscc %o4, %o1, %o4 ! 24
! 90: mulscc %o4, %o1, %o4 ! 25
! 91: mulscc %o4, %o1, %o4 ! 26
! 92: mulscc %o4, %o1, %o4 ! 27
! 93: mulscc %o4, %o1, %o4 ! 28
! 94: mulscc %o4, %o1, %o4 ! 29
! 95: mulscc %o4, %o1, %o4 ! 30
! 96: mulscc %o4, %o1, %o4 ! 31
! 97: mulscc %o4, %o1, %o4 ! 32
! 98: mulscc %o4, %g0, %o4 ! final shift
! 99:
! 100: ! If %o0 was negative, the result is
! 101: ! (%o0 * %o1) + (%o1 << 32))
! 102: ! We fix that here.
! 103:
! 104: tst %o0
! 105: bge 1f
! 106: rd %y, %o0
! 107:
! 108: ! %o0 was indeed negative; fix upper 32 bits of result by subtracting
! 109: ! %o1 (i.e., return %o4 - %o1 in %o1).
! 110: retl
! 111: sub %o4, %o1, %o1
! 112:
! 113: 1:
! 114: retl
! 115: mov %o4, %o1
! 116:
! 117: Lmul_shortway:
! 118: /*
! 119: * Short multiply. 12 steps, followed by a final shift step.
! 120: * The resulting bits are off by 12 and (32-12) = 20 bit positions,
! 121: * but there is no problem with %o0 being negative (unlike above).
! 122: */
! 123: mulscc %o4, %o1, %o4 ! 1
! 124: mulscc %o4, %o1, %o4 ! 2
! 125: mulscc %o4, %o1, %o4 ! 3
! 126: mulscc %o4, %o1, %o4 ! 4
! 127: mulscc %o4, %o1, %o4 ! 5
! 128: mulscc %o4, %o1, %o4 ! 6
! 129: mulscc %o4, %o1, %o4 ! 7
! 130: mulscc %o4, %o1, %o4 ! 8
! 131: mulscc %o4, %o1, %o4 ! 9
! 132: mulscc %o4, %o1, %o4 ! 10
! 133: mulscc %o4, %o1, %o4 ! 11
! 134: mulscc %o4, %o1, %o4 ! 12
! 135: mulscc %o4, %g0, %o4 ! final shift
! 136:
! 137: /*
! 138: * %o4 has 20 of the bits that should be in the low part of the
! 139: * result; %y has the bottom 12 (as %y's top 12). That is:
! 140: *
! 141: * %o4 %y
! 142: * +----------------+----------------+
! 143: * | -12- | -20- | -12- | -20- |
! 144: * +------(---------+------)---------+
! 145: * --hi-- ----low-part----
! 146: *
! 147: * The upper 12 bits of %o4 should be sign-extended to form the
! 148: * high part of the product (i.e., highpart = %o4 >> 20).
! 149: */
! 150:
! 151: rd %y, %o5
! 152: sll %o4, 12, %o0 ! shift middle bits left 12
! 153: srl %o5, 20, %o5 ! shift low bits right 20, zero fill at left
! 154: or %o5, %o0, %o0 ! construct low part of result
! 155: retl
! 156: sra %o4, 20, %o1 ! ... and extract high part of result
CVSweb
![[BACK]](/icons/back.gif){kind=icon}
Return to mul.S CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / sys / lib / libkern / arch / sparc