LXR linux/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
  26ENTRY(_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;
  351:
  36        R1 = B [P1++] (Z);
  37        B [P0++] = R1;
  38        CC = R1 == 0;
  392:
  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         */
  483:
  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
  784:
  79        LSETUP(5f, 5f) LC0;
  805:
  81        B [P0++] = R1;
  826:
  83        RTS;
  84
  85ENDPROC(_strncpy)
  86