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 (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22/* 23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27#pragma ident "%Z%%M% %I% %E% SMI" 28 29 .file "%M%" 30 31/* 32 * memset(sp, c, n) 33 * 34 * Set an array of n chars starting at sp to the character c. 35 * Return sp. 36 * 37 * Fast assembler language version of the following C-program for memset 38 * which represents the `standard' for the C-library. 39 * 40 * void * 41 * memset(void *sp1, int c, size_t n) 42 * { 43 * if (n != 0) { 44 * char *sp = sp1; 45 * do { 46 * *sp++ = (char)c; 47 * } while (--n != 0); 48 * } 49 * return (sp1); 50 * } 51 * 52 * 53 * 54 * Algorithm used: 55 * For small stores (6 or fewer bytes), bytes will be stored one at a time. 56 * 57 * When setting 15 or more bytes, there will be at least 8 bytes aligned 58 * on an 8-byte boundary. So, leading bytes will be set, then as many 59 * 8-byte aligned chunks as possible will be set, followed by any trailing 60 * bytes. 61 * 62 * For between 8 and 14 bytes (inclusive), leading odd bytes will be 63 * set, followed by 4-byte chunks, followed by trailing bytes. 64 * 65 * Inputs: 66 * o0: pointer to start of area to be set to a given value 67 * o1: character used to set memory at location in i0 68 * o2: number of bytes to be set 69 * 70 * Outputs: 71 * o0: pointer to start of area set (same as input value in o0) 72 * 73 */ 74 75#include <sys/asm_linkage.h> 76 77 ANSI_PRAGMA_WEAK(memset,function) 78 79 ENTRY(memset) 80 mov %o0, %o5 ! need to return this value 81 cmp %o2, 7 82 blu,pn %xcc, .wrchar ! small count: just set bytes 83 and %o1, 0xff, %o1 84 85 sll %o1, 8, %o4 ! generate 4 bytes filled with char 86 or %o1, %o4, %o1 87 sll %o1, 16, %o4 88 cmp %o2, 15 89 blu,pn %xcc, .walign ! not enough to guarantee 8-byte align 90 or %o1, %o4, %o1 91 92 sllx %o1, 32, %o4 ! now fill the other 4 bytes with char 93 or %o1, %o4, %o1 94 95.dalign: ! Set bytes until 8-byte aligned 96 btst 7, %o5 ! 8-byte aligned? 97 bz,a,pn %icc, .wrdbl 98 andn %o2, 7, %o3 ! o3 has 8-byte multiple 99 100 dec %o2 101 stb %o1, [%o5] ! clear a byte 102 b .dalign ! go see if aligned yet 103 inc %o5 104 105 .align 32 106.wrdbl: 107 stx %o1, [%o5] ! write aligned 8 bytes 108 subcc %o3, 8, %o3 109 bnz,pt %xcc, .wrdbl 110 inc 8, %o5 111 112 b .wrchar ! write the remaining bytes 113 and %o2, 7, %o2 ! leftover count, if any 114 115.walign: ! Set bytes until 4-byte aligned 116 btst 3, %o5 ! if bigger, align to 4 bytes 117 bz,pn %icc, .wrword 118 andn %o2, 3, %o3 ! create word sized count in %o3 119 120 dec %o2 ! decrement count 121 stb %o1, [%o5] ! clear a byte 122 b .walign 123 inc %o5 ! next byte 124 125.wrword: 126 st %o1, [%o5] ! 4-byte writing loop 127 subcc %o3, 4, %o3 128 bnz,pn %xcc, .wrword 129 inc 4, %o5 130 131 and %o2, 3, %o2 ! leftover count, if any 132 133.wrchar: 134 deccc %o2 ! byte clearing loop 135 inc %o5 136 bgeu,a,pt %xcc, .wrchar 137 stb %o1, [%o5 + -1] ! we've already incremented the address 138 139 retl 140 sub %o0, %g0, %o0 141 142 SET_SIZE(memset) 143