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 <linux/linkage.h> 13 #include <asm/assembler.h> 14 15 .text 16 .align 5 17 18 ENTRY(memset) 19 ands r3, r0, #3 @ 1 unaligned? 20 mov ip, r0 @ preserve r0 as return value 21 bne 6f @ 1 22 /* 23 * we know that the pointer in ip is aligned to a word boundary. 24 */ 25 1: orr r1, r1, r1, lsl #8 26 orr r1, r1, r1, lsl #16 27 mov r3, r1 28 cmp r2, #16 29 blt 4f 30 31 #if ! CALGN(1)+0 32 33 /* 34 * We need 2 extra registers for this loop - use r8 and the LR 35 */ 36 stmfd sp!, {r8, lr} 37 mov r8, r1 38 mov lr, r1 39 40 2: subs r2, r2, #64 41 stmgeia ip!, {r1, r3, r8, lr} @ 64 bytes at a time. 42 stmgeia ip!, {r1, r3, r8, lr} 43 stmgeia ip!, {r1, r3, r8, lr} 44 stmgeia ip!, {r1, r3, r8, lr} 45 bgt 2b 46 ldmeqfd sp!, {r8, pc} @ Now <64 bytes to go. 47 /* 48 * No need to correct the count; we're only testing bits from now on 49 */ 50 tst r2, #32 51 stmneia ip!, {r1, r3, r8, lr} 52 stmneia ip!, {r1, r3, r8, lr} 53 tst r2, #16 54 stmneia ip!, {r1, r3, r8, lr} 55 ldmfd sp!, {r8, lr} 56 57 #else 58 59 /* 60 * This version aligns the destination pointer in order to write 61 * whole cache lines at once. 62 */ 63 64 stmfd sp!, {r4-r8, lr} 65 mov r4, r1 66 mov r5, r1 67 mov r6, r1 68 mov r7, r1 69 mov r8, r1 70 mov lr, r1 71 72 cmp r2, #96 73 tstgt ip, #31 74 ble 3f 75 76 and r8, ip, #31 77 rsb r8, r8, #32 78 sub r2, r2, r8 79 movs r8, r8, lsl #(32 - 4) 80 stmcsia ip!, {r4, r5, r6, r7} 81 stmmiia ip!, {r4, r5} 82 tst r8, #(1 << 30) 83 mov r8, r1 84 strne r1, [ip], #4 85 86 3: subs r2, r2, #64 87 stmgeia ip!, {r1, r3-r8, lr} 88 stmgeia ip!, {r1, r3-r8, lr} 89 bgt 3b 90 ldmeqfd sp!, {r4-r8, pc} 91 92 tst r2, #32 93 stmneia ip!, {r1, r3-r8, lr} 94 tst r2, #16 95 stmneia ip!, {r4-r7} 96 ldmfd sp!, {r4-r8, lr} 97 98 #endif 99 100 4: tst r2, #8 101 stmneia ip!, {r1, r3} 102 tst r2, #4 103 strne r1, [ip], #4 104 /* 105 * When we get here, we've got less than 4 bytes to zero. We 106 * may have an unaligned pointer as well. 107 */ 108 5: tst r2, #2 109 strneb r1, [ip], #1 110 strneb r1, [ip], #1 111 tst r2, #1 112 strneb r1, [ip], #1 113 mov pc, lr 114 115 6: subs r2, r2, #4 @ 1 do we have enough 116 blt 5b @ 1 bytes to align with? 117 cmp r3, #2 @ 1 118 strltb r1, [ip], #1 @ 1 119 strleb r1, [ip], #1 @ 1 120 strb r1, [ip], #1 @ 1 121 add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3)) 122 b 1b 123 ENDPROC(memset) 124
