projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
1 | /* |
| 2 | * linux/arch/arm/lib/memzero.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 | #include <linux/linkage.h> | |
| 11 | #include <asm/assembler.h> | |
| 12 | ||
| 13 | .text | |
| 14 | .align 5 | |
| 15 | .word 0 | |
| 16 | /* | |
| 17 | * Align the pointer in r0. r3 contains the number of bytes that we are | |
| 18 | * mis-aligned by, and r1 is the number of bytes. If r1 < 4, then we | |
| 19 | * don't bother; we use byte stores instead. | |
| 20 | */ | |
| 21 | 1: subs r1, r1, #4 @ 1 do we have enough | |
| 22 | blt 5f @ 1 bytes to align with? | |
| 23 | cmp r3, #2 @ 1 | |
| 24 | strltb r2, [r0], #1 @ 1 | |
| 25 | strleb r2, [r0], #1 @ 1 | |
| 26 | strb r2, [r0], #1 @ 1 | |
| 27 | add r1, r1, r3 @ 1 (r1 = r1 - (4 - r3)) | |
| 28 | /* | |
| 29 | * The pointer is now aligned and the length is adjusted. Try doing the | |
| 30 | * memzero again. | |
| 31 | */ | |
| 32 | ||
| 33 | ENTRY(__memzero) | |
| 34 | mov r2, #0 @ 1 | |
| 35 | ands r3, r0, #3 @ 1 unaligned? | |
| 36 | bne 1b @ 1 | |
| 37 | /* | |
| 38 | * r3 = 0, and we know that the pointer in r0 is aligned to a word boundary. | |
| 39 | */ | |
| 40 | cmp r1, #16 @ 1 we can skip this chunk if we | |
| 41 | blt 4f @ 1 have < 16 bytes | |
| 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]! @ 1 | |
| 47 | mov ip, r2 @ 1 | |
| 48 | mov lr, r2 @ 1 | |
| 49 | ||
| 50 | 3: subs r1, r1, #64 @ 1 write 32 bytes out per loop | |
| 51 | stmgeia r0!, {r2, r3, ip, lr} @ 4 | |
| 52 | stmgeia r0!, {r2, r3, ip, lr} @ 4 | |
| 53 | stmgeia r0!, {r2, r3, ip, lr} @ 4 | |
| 54 | stmgeia r0!, {r2, r3, ip, lr} @ 4 | |
| 55 | bgt 3b @ 1 | |
| 1b93a717 | 56 | ldmeqfd sp!, {pc} @ 1/2 quick exit |
| 1da177e4 LT |
57 | /* |
| 58 | * No need to correct the count; we're only testing bits from now on | |
| 59 | */ | |
| 60 | tst r1, #32 @ 1 | |
| 61 | stmneia r0!, {r2, r3, ip, lr} @ 4 | |
| 62 | stmneia r0!, {r2, r3, ip, lr} @ 4 | |
| 63 | tst r1, #16 @ 1 16 bytes or more? | |
| 64 | stmneia r0!, {r2, r3, ip, lr} @ 4 | |
| 65 | ldr lr, [sp], #4 @ 1 | |
| 66 | ||
| 67 | 4: tst r1, #8 @ 1 8 bytes or more? | |
| 68 | stmneia r0!, {r2, r3} @ 2 | |
| 69 | tst r1, #4 @ 1 4 bytes or more? | |
| 70 | strne r2, [r0], #4 @ 1 | |
| 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 r1, #2 @ 1 2 bytes or more? | |
| 76 | strneb r2, [r0], #1 @ 1 | |
| 77 | strneb r2, [r0], #1 @ 1 | |
| 78 | tst r1, #1 @ 1 a byte left over | |
| 79 | strneb r2, [r0], #1 @ 1 | |
| 7999d8d7 | 80 | mov pc, lr @ 1 |