1/* $OpenBSD: memset.S,v 1.2 2004/02/01 05:47:10 drahn Exp $ */ 2/* $NetBSD: memset.S,v 1.1 2000/12/29 20:51:57 bjh21 Exp $ */ 3 4/* 5 * Copyright (c) 1995 Mark Brinicombe. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by Mark Brinicombe. 19 * 4. The name of the company nor the name of the author may be used to 20 * endorse or promote products derived from this software without specific 21 * prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 24 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 25 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26 * IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 27 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 28 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 29 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36#include <machine/asm.h> 37 38/* 39 * Sets a block of memory to the specified value 40 * 41 * On entry: 42 * r0 - dest address 43 * r1 - byte to write 44 * r2 - number of bytes to write 45 * 46 * On exit: 47 * r0 - dest address 48 */ 49 50ENTRY(memset) 51 stmfd sp!, {r0} /* Remember address for return value */ 52 and r1, r1, #0x000000ff /* We write bytes */ 53 54 cmp r2, #0x00000004 /* Do we have less than 4 bytes */ 55 blt Lmemset_lessthanfour 56 57 /* Ok first we will word align the address */ 58 59 ands r3, r0, #0x00000003 /* Get the bottom two bits */ 60 beq Lmemset_addraligned /* The address is word aligned */ 61 62 rsb r3, r3, #0x00000004 63 sub r2, r2, r3 64 cmp r3, #0x00000002 65 strb r1, [r0], #0x0001 /* Set 1 byte */ 66 strgeb r1, [r0], #0x0001 /* Set another byte */ 67 strgtb r1, [r0], #0x0001 /* and a third */ 68 69 cmp r2, #0x00000004 70 blt Lmemset_lessthanfour 71 72 /* Now we must be word aligned */ 73 74Lmemset_addraligned: 75 76 orr r3, r1, r1, lsl #8 /* Repeat the byte into a word */ 77 orr r3, r3, r3, lsl #16 78 79 /* We know we have at least 4 bytes ... */ 80 81 cmp r2, #0x00000020 /* If less than 32 then use words */ 82 blt Lmemset_lessthan32 83 84 /* We have at least 32 so lets use quad words */ 85 86 stmfd sp!, {r4-r6} /* Store registers */ 87 mov r4, r3 /* Duplicate data */ 88 mov r5, r3 89 mov r6, r3 90 91Lmemset_loop16: 92 stmia r0!, {r3-r6} /* Store 16 bytes */ 93 sub r2, r2, #0x00000010 /* Adjust count */ 94 cmp r2, #0x00000010 /* Still got at least 16 bytes ? */ 95 bgt Lmemset_loop16 96 97 ldmfd sp!, {r4-r6} /* Restore registers */ 98 99 /* Do we need to set some words as well ? */ 100 101 cmp r2, #0x00000004 102 blt Lmemset_lessthanfour 103 104 /* Have either less than 16 or less than 32 depending on route taken */ 105 106Lmemset_lessthan32: 107 108 /* We have at least 4 bytes so copy as words */ 109 110Lmemset_loop4: 111 str r3, [r0], #0x0004 112 sub r2, r2, #0x0004 113 cmp r2, #0x00000004 114 bge Lmemset_loop4 115 116Lmemset_lessthanfour: 117 cmp r2, #0x00000000 118 ldmeqfd sp!, {r0} 119#ifdef __APCS_26__ 120 moveqs pc, lr /* Zero length so exit */ 121#else 122 moveq pc, lr /* Zero length so exit */ 123#endif 124 125 cmp r2, #0x00000002 126 strb r1, [r0], #0x0001 /* Set 1 byte */ 127 strgeb r1, [r0], #0x0001 /* Set another byte */ 128 strgtb r1, [r0], #0x0001 /* and a third */ 129 130 ldmfd sp!, {r0} 131#ifdef __APCS_26__ 132 movs pc, lr /* Exit */ 133#else 134 mov pc, lr /* Exit */ 135#endif 136