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/* * linux/arch/arm26/lib/memzero.S * * Copyright (C) 1995-2000 Russell King * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/linkage.h> #include <asm/assembler.h> .text .align 5 .word 0 /* * Align the pointer in r0. r3 contains the number of bytes that we are * mis-aligned by, and r1 is the number of bytes. If r1 < 4, then we * don't bother; we use byte stores instead. */ 1: subs r1, r1, #4 @ 1 do we have enough blt 5f @ 1 bytes to align with? cmp r3, #2 @ 1 strltb r2, [r0], #1 @ 1 strleb r2, [r0], #1 @ 1 strb r2, [r0], #1 @ 1 add r1, r1, r3 @ 1 (r1 = r1 - (4 - r3)) /* * The pointer is now aligned and the length is adjusted. Try doing the * memzero again. */ ENTRY(__memzero) mov r2, #0 @ 1 ands r3, r0, #3 @ 1 unaligned? bne 1b @ 1 /* * r3 = 0, and we know that the pointer in r0 is aligned to a word boundary. */ cmp r1, #16 @ 1 we can skip this chunk if we blt 4f @ 1 have < 16 bytes /* * We need an extra register for this loop - save the return address and * use the LR */ str lr, [sp, #-4]! @ 1 mov ip, r2 @ 1 mov lr, r2 @ 1 3: subs r1, r1, #64 @ 1 write 32 bytes out per loop stmgeia r0!, {r2, r3, ip, lr} @ 4 stmgeia r0!, {r2, r3, ip, lr} @ 4 stmgeia r0!, {r2, r3, ip, lr} @ 4 stmgeia r0!, {r2, r3, ip, lr} @ 4 bgt 3b @ 1 LOADREGS(eqfd, sp!, {pc}) @ 1/2 quick exit /* * No need to correct the count; we're only testing bits from now on */ tst r1, #32 @ 1 stmneia r0!, {r2, r3, ip, lr} @ 4 stmneia r0!, {r2, r3, ip, lr} @ 4 tst r1, #16 @ 1 16 bytes or more? stmneia r0!, {r2, r3, ip, lr} @ 4 ldr lr, [sp], #4 @ 1 4: tst r1, #8 @ 1 8 bytes or more? stmneia r0!, {r2, r3} @ 2 tst r1, #4 @ 1 4 bytes or more? strne r2, [r0], #4 @ 1 /* * When we get here, we've got less than 4 bytes to zero. We * may have an unaligned pointer as well. */ 5: tst r1, #2 @ 1 2 bytes or more? strneb r2, [r0], #1 @ 1 strneb r2, [r0], #1 @ 1 tst r1, #1 @ 1 a byte left over strneb r2, [r0], #1 @ 1 RETINSTR(mov,pc,lr) @ 1 |