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
  19 ENTRY(mmioset)
  20 ENTRY(memset)
  21 UNWIND( .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  */
  28 1:      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}
  40 UNWIND( .fnend              )
  41 UNWIND( .fnstart            )
  42 UNWIND( .save {r8, lr}      )
  43         mov     r8, r1
  44         mov     lr, r1
  45
  46 2:      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}
  62 UNWIND( .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}
  72 UNWIND( .fnend                 )
  73 UNWIND( .fnstart               )
  74 UNWIND( .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
  96 3:      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}
 107 UNWIND( .fnend                 )
 108
 109 #endif
 110
 111 UNWIND( .fnstart            )
 112 4:      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  */
 120 5:      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
 127 6:      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
 135 UNWIND( .fnend   )
 136 ENDPROC(memset)
 137 ENDPROC(mmioset)