1/* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22/* 23 * Copyright (c) 1990, 1991 Sun Microsystems, Inc. 24 */ 25 26#ident "%Z%%M% %I% %E% SMI" 27 28/* 29 * Routine to zero out a section of memory (the tail end of the data segment 30 * upto a page boundary). First nibble off any bytes up to the first double 31 * aligned word, and then clear doubles until the byte count is zero. Note, 32 * this assumes the count specified has been rounded to end on a double word 33 * boundary. 34 * 35 * %o0 = addr, %o1 = len 36 */ 37 38 .seg "text" 39 .global __zero 40__zero: 41 tst %o1 ! Have we any count at all? 42 ba 3f ! Go find out, 43 clr %g1 ! but prepare for long loop 44 45! Byte clearing loop 46 470: 48 inc %o0 ! Bump address 49 deccc %o1 ! Decrement count 503: 51 bz 1f ! If no count left, exit 52 andcc %o0, 7, %g0 ! Is the address less than double-word aligned? 53 bnz,a 0b ! Branch if so 54 clrb [%o0] ! but clear the current byte anyway 55 56! Double clearing loop 57 582: 59 std %g0, [%o0] ! Clear next 8 bytes 60 subcc %o1, 8, %o1 ! Decrement count 61 bnz 2b ! Branch if any left 62 inc 8, %o0 ! but always increment address by 8 631: 64 retl ! Go home 65 nop 66