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 .file "memset.s" 28 29/* 30 * memset(sp, c, n) 31 * 32 * Set an array of n chars starting at sp to the character c. 33 * Return sp. 34 * 35 * Fast assembler language version of the following C-program for memset 36 * which represents the `standard' for the C-library. 37 * 38 * void * 39 * memset(void *sp1, int c, size_t n) 40 * { 41 * if (n != 0) { 42 * char *sp = sp1; 43 * do { 44 * *sp++ = (char)c; 45 * } while (--n != 0); 46 * } 47 * return (sp1); 48 * } 49 * 50 * 51 * 52 * Algorithm used: 53 * For small stores (6 or fewer bytes), bytes will be stored one at a time. 54 * 55 * When setting 15 or more bytes, there will be at least 8 bytes aligned 56 * on an 8-byte boundary. So, leading bytes will be set, then as many 57 * 8-byte aligned chunks as possible will be set, followed by any trailing 58 * bytes. 59 * 60 * For between 8 and 14 bytes (inclusive), leading odd bytes will be 61 * set, followed by 4-byte chunks, followed by trailing bytes. 62 * 63 * Inputs: 64 * o0: pointer to start of area to be set to a given value 65 * o1: character used to set memory at location in i0 66 * o2: number of bytes to be set 67 * 68 * Outputs: 69 * o0: pointer to start of area set (same as input value in o0) 70 * 71 */ 72 73#include <sys/asm_linkage.h> 74 75 ANSI_PRAGMA_WEAK(memset,function) 76 77 ENTRY(memset) 78 mov %o0, %o5 ! need to return this value 79 cmp %o2, 7 80 blu,pn %xcc, .wrchar ! small count: just set bytes 81 and %o1, 0xff, %o1 82 83 sll %o1, 8, %o4 ! generate 4 bytes filled with char 84 or %o1, %o4, %o1 85 sll %o1, 16, %o4 86 cmp %o2, 15 87 blu,pn %xcc, .walign ! not enough to guarantee 8-byte align 88 or %o1, %o4, %o1 89 90 sllx %o1, 32, %o4 ! now fill the other 4 bytes with char 91 or %o1, %o4, %o1 92 93.dalign: ! Set bytes until 8-byte aligned 94 btst 7, %o5 ! 8-byte aligned? 95 bz,a,pn %icc, .wrdbl 96 andn %o2, 7, %o3 ! o3 has 8-byte multiple 97 98 dec %o2 99 stb %o1, [%o5] ! clear a byte 100 b .dalign ! go see if aligned yet 101 inc %o5 102 103 .align 32 104.wrdbl: 105 stx %o1, [%o5] ! write aligned 8 bytes 106 subcc %o3, 8, %o3 107 bnz,pt %xcc, .wrdbl 108 inc 8, %o5 109 110 b .wrchar ! write the remaining bytes 111 and %o2, 7, %o2 ! leftover count, if any 112 113.walign: ! Set bytes until 4-byte aligned 114 btst 3, %o5 ! if bigger, align to 4 bytes 115 bz,pn %icc, .wrword 116 andn %o2, 3, %o3 ! create word sized count in %o3 117 118 dec %o2 ! decrement count 119 stb %o1, [%o5] ! clear a byte 120 b .walign 121 inc %o5 ! next byte 122 123.wrword: 124 st %o1, [%o5] ! 4-byte writing loop 125 subcc %o3, 4, %o3 126 bnz,pn %xcc, .wrword 127 inc 4, %o5 128 129 and %o2, 3, %o2 ! leftover count, if any 130 131.wrchar: 132 deccc %o2 ! byte clearing loop 133 inc %o5 134 bgeu,a,pt %xcc, .wrchar 135 stb %o1, [%o5 + -1] ! we've already incremented the address 136 137 retl 138 sub %o0, %g0, %o0 139 140 SET_SIZE(memset) 141