1/* 2 * linux/arch/arm/lib/memset.S 3 * 4 * Copyright (C) 1995-2000 Russell King 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * ASM optimised string functions 11 */ 12#include <asm/assembler.h> 13 14 .text 15 .align 5 16 .word 0 17 181: subs r2, r2, #4 @ 1 do we have enough 19 blt 5f @ 1 bytes to align with? 20 cmp r3, #2 @ 1 21 strltb r1, [r0], #1 @ 1 22 strleb r1, [r0], #1 @ 1 23 strb r1, [r0], #1 @ 1 24 add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3)) 25/* 26 * The pointer is now aligned and the length is adjusted. Try doing the 27 * memset again. 28 */ 29 30.globl memset 31memset: 32 ands r3, r0, #3 @ 1 unaligned? 33 bne 1b @ 1 34/* 35 * we know that the pointer in r0 is aligned to a word boundary. 36 */ 37 orr r1, r1, r1, lsl #8 38 orr r1, r1, r1, lsl #16 39 mov r3, r1 40 cmp r2, #16 41 blt 4f 42 43#if ! CALGN(1)+0 44 45/* 46 * We need an extra register for this loop - save the return address and 47 * use the LR 48 */ 49 str lr, [sp, #-4]! 50 mov ip, r1 51 mov lr, r1 52 532: subs r2, r2, #64 54 stmgeia r0!, {r1, r3, ip, lr} @ 64 bytes at a time. 55 stmgeia r0!, {r1, r3, ip, lr} 56 stmgeia r0!, {r1, r3, ip, lr} 57 stmgeia r0!, {r1, r3, ip, lr} 58 bgt 2b 59 ldmeqfd sp!, {pc} @ Now <64 bytes to go. 60/* 61 * No need to correct the count; we're only testing bits from now on 62 */ 63 tst r2, #32 64 stmneia r0!, {r1, r3, ip, lr} 65 stmneia r0!, {r1, r3, ip, lr} 66 tst r2, #16 67 stmneia r0!, {r1, r3, ip, lr} 68 ldr lr, [sp], #4 69 70#else 71 72/* 73 * This version aligns the destination pointer in order to write 74 * whole cache lines at once. 75 */ 76 77 stmfd sp!, {r4-r7, lr} 78 mov r4, r1 79 mov r5, r1 80 mov r6, r1 81 mov r7, r1 82 mov ip, r1 83 mov lr, r1 84 85 cmp r2, #96 86 tstgt r0, #31 87 ble 3f 88 89 and ip, r0, #31 90 rsb ip, ip, #32 91 sub r2, r2, ip 92 movs ip, ip, lsl #(32 - 4) 93 stmcsia r0!, {r4, r5, r6, r7} 94 stmmiia r0!, {r4, r5} 95 tst ip, #(1 << 30) 96 mov ip, r1 97 strne r1, [r0], #4 98 993: subs r2, r2, #64 100 stmgeia r0!, {r1, r3-r7, ip, lr} 101 stmgeia r0!, {r1, r3-r7, ip, lr} 102 bgt 3b 103 ldmeqfd sp!, {r4-r7, pc} 104 105 tst r2, #32 106 stmneia r0!, {r1, r3-r7, ip, lr} 107 tst r2, #16 108 stmneia r0!, {r4-r7} 109 ldmfd sp!, {r4-r7, lr} 110 111#endif 112 1134: tst r2, #8 114 stmneia r0!, {r1, r3} 115 tst r2, #4 116 strne r1, [r0], #4 117/* 118 * When we get here, we've got less than 4 bytes to zero. We 119 * may have an unaligned pointer as well. 120 */ 1215: tst r2, #2 122 strneb r1, [r0], #1 123 strneb r1, [r0], #1 124 tst r2, #1 125 strneb r1, [r0], #1 126 mov pc, lr 127