| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | .word 0 |
| 18 | |
| 19 | 1: subs r2, r2, #4 @ 1 do we have enough |
| 20 | blt 5f @ 1 bytes to align with? |
| 21 | cmp r3, #2 @ 1 |
| 22 | strltb r1, [r0], #1 @ 1 |
| 23 | strleb r1, [r0], #1 @ 1 |
| 24 | strb r1, [r0], #1 @ 1 |
| 25 | add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3)) |
| 26 | /* |
| 27 | * The pointer is now aligned and the length is adjusted. Try doing the |
| 28 | * memzero again. |
| 29 | */ |
| 30 | |
| 31 | ENTRY(memset) |
| 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 | * We need an extra register for this loop - save the return address and |
| 44 | * use the LR |
| 45 | */ |
| 46 | str lr, [sp, #-4]! |
| 47 | mov ip, r1 |
| 48 | mov lr, r1 |
| 49 | |
| 50 | 2: subs r2, r2, #64 |
| 51 | stmgeia r0!, {r1, r3, ip, lr} @ 64 bytes at a time. |
| 52 | stmgeia r0!, {r1, r3, ip, lr} |
| 53 | stmgeia r0!, {r1, r3, ip, lr} |
| 54 | stmgeia r0!, {r1, r3, ip, lr} |
| 55 | bgt 2b |
| Russell King | 1b93a71 | 2006-06-25 11:23:45 +0100 | [diff] [blame] | 56 | ldmeqfd sp!, {pc} @ Now <64 bytes to go. |
| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 57 | /* |
| 58 | * No need to correct the count; we're only testing bits from now on |
| 59 | */ |
| 60 | tst r2, #32 |
| 61 | stmneia r0!, {r1, r3, ip, lr} |
| 62 | stmneia r0!, {r1, r3, ip, lr} |
| 63 | tst r2, #16 |
| 64 | stmneia r0!, {r1, r3, ip, lr} |
| 65 | ldr lr, [sp], #4 |
| 66 | |
| 67 | 4: tst r2, #8 |
| 68 | stmneia r0!, {r1, r3} |
| 69 | tst r2, #4 |
| 70 | strne r1, [r0], #4 |
| 71 | /* |
| 72 | * When we get here, we've got less than 4 bytes to zero. We |
| 73 | * may have an unaligned pointer as well. |
| 74 | */ |
| 75 | 5: tst r2, #2 |
| 76 | strneb r1, [r0], #1 |
| 77 | strneb r1, [r0], #1 |
| 78 | tst r2, #1 |
| 79 | strneb r1, [r0], #1 |
| Russell King | 7999d8d | 2006-06-25 11:17:23 +0100 | [diff] [blame] | 80 | mov pc, lr |