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/*
 *  linux/arch/arm/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