LXR linux/arch/nios2/lib/memset.c

   1/*
   2 * Copyright (C) 2011 Tobias Klauser <tklauser@distanz.ch>
   3 * Copyright (C) 2004 Microtronix Datacom Ltd
   4 *
   5 * This file is subject to the terms and conditions of the GNU General Public
   6 * License.  See the file "COPYING" in the main directory of this archive
   7 * for more details.
   8 */
   9
  10#include <linux/types.h>
  11#include <linux/string.h>
  12
  13void *memset(void *s, int c, size_t count)
  14{
  15        int destptr, charcnt, dwordcnt, fill8reg, wrkrega;
  16
  17        if (!count)
  18                return s;
  19
  20        c &= 0xFF;
  21
  22        if (count <= 8) {
  23                char *xs = (char *) s;
  24
  25                while (count--)
  26                        *xs++ = c;
  27                return s;
  28        }
  29
  30        __asm__ __volatile__ (
  31                /* fill8 %3, %5 (c & 0xff) */
  32                "       slli    %4, %5, 8\n"
  33                "       or      %4, %4, %5\n"
  34                "       slli    %3, %4, 16\n"
  35                "       or      %3, %3, %4\n"
  36                /* Word-align %0 (s) if necessary */
  37                "       andi    %4, %0, 0x01\n"
  38                "       beq     %4, zero, 1f\n"
  39                "       addi    %1, %1, -1\n"
  40                "       stb     %3, 0(%0)\n"
  41                "       addi    %0, %0, 1\n"
  42                "1:     mov     %2, %1\n"
  43                /* Dword-align %0 (s) if necessary */
  44                "       andi    %4, %0, 0x02\n"
  45                "       beq     %4, zero, 2f\n"
  46                "       addi    %1, %1, -2\n"
  47                "       sth     %3, 0(%0)\n"
  48                "       addi    %0, %0, 2\n"
  49                "       mov     %2, %1\n"
  50                /* %1 and %2 are how many more bytes to set */
  51                "2:     srli    %2, %2, 2\n"
  52                /* %2 is how many dwords to set */
  53                "3:     stw     %3, 0(%0)\n"
  54                "       addi    %0, %0, 4\n"
  55                "       addi    %2, %2, -1\n"
  56                "       bne     %2, zero, 3b\n"
  57                /* store residual word and/or byte if necessary */
  58                "       andi    %4, %1, 0x02\n"
  59                "       beq     %4, zero, 4f\n"
  60                "       sth     %3, 0(%0)\n"
  61                "       addi    %0, %0, 2\n"
  62                /* store residual byte if necessary */
  63                "4:     andi    %4, %1, 0x01\n"
  64                "       beq     %4, zero, 5f\n"
  65                "       stb     %3, 0(%0)\n"
  66                "5:\n"
  67                : "=r" (destptr),       /* %0  Output */
  68                  "=r" (charcnt),       /* %1  Output */
  69                  "=r" (dwordcnt),      /* %2  Output */
  70                  "=r" (fill8reg),      /* %3  Output */
  71                  "=&r" (wrkrega)       /* %4  Output only */
  72                : "r" (c),              /* %5  Input */
  73                  "0" (s),              /* %0  Input/Output */
  74                  "1" (count)           /* %1  Input/Output */
  75                : "memory"              /* clobbered */
  76        );
  77
  78        return s;
  79}
  80