LXR linux/arch/arm/lib/memset.S

   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#include <asm/unwind.h>
  15
  16        .text
  17        .align  5
  18
  19ENTRY(mmioset)
  20ENTRY(memset)
  21UNWIND( .fnstart         )
  22        ands    r3, r0, #3              @ 1 unaligned?
  23        mov     ip, r0                  @ preserve r0 as return value
  24        bne     6f                      @ 1
  25/*
  26 * we know that the pointer in ip is aligned to a word boundary.
  27 */
  281:      orr     r1, r1, r1, lsl #8
  29        orr     r1, r1, r1, lsl #16
  30        mov     r3, r1
  31        cmp     r2, #16
  32        blt     4f
  33
  34#if ! CALGN(1)+0
  35
  36/*
  37 * We need 2 extra registers for this loop - use r8 and the LR
  38 */
  39        stmfd   sp!, {r8, lr}
  40UNWIND( .fnend              )
  41UNWIND( .fnstart            )
  42UNWIND( .save {r8, lr}      )
  43        mov     r8, r1
  44        mov     lr, r1
  45
  462:      subs    r2, r2, #64
  47        stmgeia ip!, {r1, r3, r8, lr}   @ 64 bytes at a time.
  48        stmgeia ip!, {r1, r3, r8, lr}
  49        stmgeia ip!, {r1, r3, r8, lr}
  50        stmgeia ip!, {r1, r3, r8, lr}
  51        bgt     2b
  52        ldmeqfd sp!, {r8, pc}           @ Now <64 bytes to go.
  53/*
  54 * No need to correct the count; we're only testing bits from now on
  55 */
  56        tst     r2, #32
  57        stmneia ip!, {r1, r3, r8, lr}
  58        stmneia ip!, {r1, r3, r8, lr}
  59        tst     r2, #16
  60        stmneia ip!, {r1, r3, r8, lr}
  61        ldmfd   sp!, {r8, lr}
  62UNWIND( .fnend              )
  63
  64#else
  65
  66/*
  67 * This version aligns the destination pointer in order to write
  68 * whole cache lines at once.
  69 */
  70
  71        stmfd   sp!, {r4-r8, lr}
  72UNWIND( .fnend                 )
  73UNWIND( .fnstart               )
  74UNWIND( .save {r4-r8, lr}      )
  75        mov     r4, r1
  76        mov     r5, r1
  77        mov     r6, r1
  78        mov     r7, r1
  79        mov     r8, r1
  80        mov     lr, r1
  81
  82        cmp     r2, #96
  83        tstgt   ip, #31
  84        ble     3f
  85
  86        and     r8, ip, #31
  87        rsb     r8, r8, #32
  88        sub     r2, r2, r8
  89        movs    r8, r8, lsl #(32 - 4)
  90        stmcsia ip!, {r4, r5, r6, r7}
  91        stmmiia ip!, {r4, r5}
  92        tst     r8, #(1 << 30)
  93        mov     r8, r1
  94        strne   r1, [ip], #4
  95
  963:      subs    r2, r2, #64
  97        stmgeia ip!, {r1, r3-r8, lr}
  98        stmgeia ip!, {r1, r3-r8, lr}
  99        bgt     3b
 100        ldmeqfd sp!, {r4-r8, pc}
 101
 102        tst     r2, #32
 103        stmneia ip!, {r1, r3-r8, lr}
 104        tst     r2, #16
 105        stmneia ip!, {r4-r7}
 106        ldmfd   sp!, {r4-r8, lr}
 107UNWIND( .fnend                 )
 108
 109#endif
 110
 111UNWIND( .fnstart            )
 1124:      tst     r2, #8
 113        stmneia ip!, {r1, r3}
 114        tst     r2, #4
 115        strne   r1, [ip], #4
 116/*
 117 * When we get here, we've got less than 4 bytes to zero.  We
 118 * may have an unaligned pointer as well.
 119 */
 1205:      tst     r2, #2
 121        strneb  r1, [ip], #1
 122        strneb  r1, [ip], #1
 123        tst     r2, #1
 124        strneb  r1, [ip], #1
 125        ret     lr
 126
 1276:      subs    r2, r2, #4              @ 1 do we have enough
 128        blt     5b                      @ 1 bytes to align with?
 129        cmp     r3, #2                  @ 1
 130        strltb  r1, [ip], #1            @ 1
 131        strleb  r1, [ip], #1            @ 1
 132        strb    r1, [ip], #1            @ 1
 133        add     r2, r2, r3              @ 1 (r2 = r2 - (4 - r3))
 134        b       1b
 135UNWIND( .fnend   )
 136ENDPROC(memset)
 137ENDPROC(mmioset)
 138