Subversion Repositories openrisc_2011-10-31

/*

 * strlen.c -- strlen function.  On at least some MIPS chips, a simple

 * strlen is faster than the 'optimized' C version.

 *

 * Copyright (c) 2001, 2002 Red Hat, Inc.

 *

 * The authors hereby grant permission to use, copy, modify, distribute,

 * and license this software and its documentation for any purpose, provided

 * that existing copyright notices are retained in all copies and that this

 * notice is included verbatim in any distributions. No written agreement,

 * license, or royalty fee is required for any of the authorized uses.

 * Modifications to this software may be copyrighted by their authors

 * and need not follow the licensing terms described here, provided that

 * the new terms are clearly indicated on the first page of each file where

 * they apply.

 */

#include <stddef.h>

#include <string.h>

/* MIPS16 needs to come first.  */

#if defined(__mips16)

size_t

strlen (const char *str)

{

  const char *start = str;

  while (*str++ != '\0')

    ;

  return str - start - 1;

}

#elif defined(__mips64)

__asm__(""                      /* 64-bit MIPS targets */

        "       .set    noreorder\n"

        "       .set    nomacro\n"

        "       .globl  strlen\n"

        "       .ent    strlen\n"

        "strlen:\n"

        "       daddiu  $2,$4,1\n"

        "\n"

        "1:     lbu     $3,0($4)\n"

        "       bnez    $3,1b\n"

        "       daddiu  $4,$4,1\n"

        "\n"

        "       jr      $31\n"

        "       dsubu   $2,$4,$2\n"

        "       .end    strlen\n"

        "       .set    macro\n"

        "       .set    reorder\n");

#else

__asm__(""                      /* 32-bit MIPS targets */

        "       .set    noreorder\n"

        "       .set    nomacro\n"

        "       .globl  strlen\n"

        "       .ent    strlen\n"

        "strlen:\n"

        "       addiu   $2,$4,1\n"

        "\n"

        "1:     lbu     $3,0($4)\n"

        "       bnez    $3,1b\n"

        "       addiu   $4,$4,1\n"

        "\n"

        "       jr      $31\n"

        "       subu    $2,$4,$2\n"

        "       .end    strlen\n"

        "       .set    macro\n"

        "       .set    reorder\n");

#endif