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/*
 * String handling functions for PowerPC.
 *
 * Copyright (C) 1996 Paul Mackerras.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */
#include <asm/ppc_asm.tmpl>
#include <asm/processor.h>
#include <asm/errno.h>

_GLOBAL(strcpy)
        addi    r5,r3,-1
        addi    r4,r4,-1
1:      lbzu    r0,1(r4)
        cmpwi   0,r0,0
        stbu    r0,1(r5)
        bne     1b
        blr

_GLOBAL(strncpy)
        cmpwi   0,r5,0
        beqlr
        mtctr   r5
        addi    r6,r3,-1
        addi    r4,r4,-1
1:      lbzu    r0,1(r4)
        cmpwi   0,r0,0
        stbu    r0,1(r6)
        bdnzf   2,1b            /* dec ctr, branch if ctr != 0 && !cr0.eq */
        blr

_GLOBAL(strcat)
        addi    r5,r3,-1
        addi    r4,r4,-1
1:      lbzu    r0,1(r5)
        cmpwi   0,r0,0
        bne     1b
        addi    r5,r5,-1
1:      lbzu    r0,1(r4)
        cmpwi   0,r0,0
        stbu    r0,1(r5)
        bne     1b
        blr

_GLOBAL(strcmp)
        addi    r5,r3,-1
        addi    r4,r4,-1
1:      lbzu    r3,1(r5)
        cmpwi   1,r3,0
        lbzu    r0,1(r4)
        subf.   r3,r0,r3
        beqlr   1
        beq     1b
        blr

_GLOBAL(strlen)
        addi    r4,r3,-1
1:      lbzu    r0,1(r4)
        cmpwi   0,r0,0
        bne     1b
        subf    r3,r3,r4
        blr

_GLOBAL(memset)
        rlwimi  r4,r4,8,16,23
        rlwimi  r4,r4,16,0,15
        addi    r6,r3,-4
        cmplwi  0,r5,4
        blt     7f
        stwu    r4,4(r6)
        beqlr
        andi.   r0,r6,3
        add     r5,r0,r5
        subf    r6,r0,r6
        srwi    r0,r5,2
        mtctr   r0
        bdz     6f
1:      stwu    r4,4(r6)
        bdnz    1b
6:      andi.   r5,r5,3
7:      cmpwi   0,r5,0
        beqlr
        mtctr   r5
        addi    r6,r6,3
8:      stbu    r4,1(r6)
        bdnz    8b
        blr

_GLOBAL(memmove)
        cmplw   0,r3,r4
        bgt     .backwards_memcpy
        b       .memcpy

_GLOBAL(backwards_memcpy)
        rlwinm. r7,r5,32-3,3,31         /* r0 = r5 >> 3 */
        add     r6,r3,r5
        add     r4,r4,r5
        beq     2f
        andi.   r0,r6,3
        mtctr   r7
        bne     5f
1:      lwz     r7,-4(r4)
        lwzu    r8,-8(r4)
        stw     r7,-4(r6)
        stwu    r8,-8(r6)
        bdnz    1b
        andi.   r5,r5,7
2:      cmplwi  0,r5,4
        blt     3f
        lwzu    r0,-4(r4)
        subi    r5,r5,4
        stwu    r0,-4(r6)
3:      cmpwi   0,r5,0
        beqlr
        mtctr   r5
4:      lbzu    r0,-1(r4)
        stbu    r0,-1(r6)
        bdnz    4b
        blr
5:      mtctr   r0
6:      lbzu    r7,-1(r4)
        stbu    r7,-1(r6)
        bdnz    6b
        subf    r5,r0,r5
        rlwinm. r7,r5,32-3,3,31
        beq     2b
        mtctr   r7
        b       1b
        
_GLOBAL(memcmp)
        cmpwi   0,r5,0
        ble-    2f
        mtctr   r5
        addi    r6,r3,-1
        addi    r4,r4,-1
1:      lbzu    r3,1(r6)
        lbzu    r0,1(r4)
        subf.   r3,r0,r3
        bdnzt   2,1b
        blr
2:      li      r3,0
        blr

_GLOBAL(memchr)
        cmpwi   0,r5,0
        ble-    2f
        mtctr   r5
        addi    r3,r3,-1
1:      lbzu    r0,1(r3)
        cmpw    0,r0,r4
        bdnzf   2,1b
        beqlr
2:      li      r3,0
        blr

_GLOBAL(__clear_user)
        addi    r6,r3,-4
        li      r3,0
        li      r5,0
        cmplwi  0,r4,4
        blt     7f
        /* clear a single word */
11:     stwu    r5,4(r6)
        beqlr
        /* clear word sized chunks */
        andi.   r0,r6,3
        add     r4,r0,r4
        subf    r6,r0,r6
        srwi    r0,r4,2
        andi.   r4,r4,3
        mtctr   r0
        bdz     7f
1:      stwu    r5,4(r6)
        bdnz    1b
        /* clear byte sized chunks */
7:      cmpwi   0,r4,0
        beqlr
        mtctr   r4
        addi    r6,r6,3
8:      stbu    r5,1(r6)
        bdnz    8b
        blr
90:     mr      r3,r4
        blr
91:     mfctr   r3
        slwi    r3,r3,2
        add     r3,r3,r4
        blr
92:     mfctr   r3
        blr

        .section __ex_table,"a"
        .align  3
        .llong  11b,90b
        .llong  1b,91b
        .llong  8b,92b
        .text

_GLOBAL(__strncpy_from_user)
        addi    r6,r3,-1
        addi    r4,r4,-1
        cmpwi   0,r5,0
        beq     2f
        mtctr   r5
1:      lbzu    r0,1(r4)
        cmpwi   0,r0,0
        stbu    r0,1(r6)
        bdnzf   2,1b            /* dec ctr, branch if ctr != 0 && !cr0.eq */
        beq     3f
2:      addi    r6,r6,1
3:      subf    r3,r3,r6
        blr
99:     li      r3,-EFAULT
        blr

        .section __ex_table,"a"
        .align  3
        .llong  1b,99b
        .text

/* r3 = str, r4 = len (> 0), r5 = top (highest addr) */
_GLOBAL(__strnlen_user)
        addi    r7,r3,-1
        subf    r6,r7,r5        /* top+1 - str */
        cmplw   0,r4,r6
        bge     0f
        mr      r6,r4
0:      mtctr   r6              /* ctr = min(len, top - str) */
1:      lbzu    r0,1(r7)        /* get next byte */
        cmpwi   0,r0,0
        bdnzf   2,1b            /* loop if --ctr != 0 && byte != 0 */
        addi    r7,r7,1
        subf    r3,r3,r7        /* number of bytes we have looked at */
        beqlr                   /* return if we found a 0 byte */
        cmpw    0,r3,r4         /* did we look at all len bytes? */
        blt     99f             /* if not, must have hit top */
        addi    r3,r4,1         /* return len + 1 to indicate no null found */
        blr
99:     li      r3,0            /* bad address, return 0 */
        blr

        .section __ex_table,"a"
        .align  3
        .llong  1b,99b