arch/blackfin/lib/strncpy.S

   1 /*
   2  * Copyright 2005-2010 Analog Devices Inc.
   3  *
   4  * Licensed under the Clear BSD license or the GPL-2 (or later)
   5  */
   6
   7 #include <linux/linkage.h>
   8 #include <asm/context.S>
   9
  10 /* void *strncpy(char *dest, const char *src, size_t n);
  11  * R0 = address (dest)
  12  * R1 = address (src)
  13  * R2 = size
  14  * Returns a pointer (R0) to the destination string dest
  15  *  we do this by not changing R0
  16  */
  17
  18 #ifdef CONFIG_STRNCPY_L1
  19 .section .l1.text
  20 #else
  21 .text
  22 #endif
  23
  24 .align 2
  25
  26 ENTRY(_strncpy)
  27         CC = R2 == 0;
  28         if CC JUMP 6f;
  29
  30         P2 = R2 ;       /* size */
  31         P0 = R0 ;       /* dst*/
  32         P1 = R1 ;       /* src*/
  33
  34         LSETUP (1f, 2f) LC0 = P2;
  35 1:
  36         R1 = B [P1++] (Z);
  37         B [P0++] = R1;
  38         CC = R1 == 0;
  39 2:
  40         if CC jump 3f;
  41
  42         RTS;
  43
  44         /* if src is shorter than n, we need to null pad bytes in dest
  45          * but, we can get here when the last byte is zero, and we don't
  46          * want to copy an extra byte at the end, so we need to check
  47          */
  48 3:
  49         R2 = LC0;
  50         CC = R2
  51         if ! CC jump 6f;
  52
  53         /* if the required null padded portion is small, do it here, rather than
  54          * handling the overhead of memset (which is OK when things are big).
  55          */
  56         R3 = 0x20;
  57         CC = R2 < R3;
  58         IF CC jump 4f;
  59
  60         R2 += -1;
  61
  62         /* Set things up for memset
  63          * R0 = address
  64          * R1 = filler byte (this case it's zero, set above)
  65          * R2 = count (set above)
  66          */
  67
  68         I1 = R0;
  69         R0 = RETS;
  70         I0 = R0;
  71         R0 = P0;
  72         pseudo_long_call _memset, p0;
  73         R0 = I0;
  74         RETS = R0;
  75         R0 = I1;
  76         RTS;
  77
  78 4:
  79         LSETUP(5f, 5f) LC0;
  80 5:
  81         B [P0++] = R1;
  82 6:
  83         RTS;
  84
  85 ENDPROC(_strncpy)