usr/src/lib/libc/amd64/gen/wslen.s

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27         .file   "wslen.s"
  28
  29 /*
  30  * Wide character wcslen() implementation
  31  *
  32  * size_t
  33  * wcslen(const wchar_t *s)
  34  *{
  35  *      const wchar_t *s0 = s + 1;
  36  *      while (*s++)
  37  *              ;
  38  *      return (s - s0);
  39  *}
  40  */
  41
  42 #include <sys/asm_linkage.h>
  43
  44         ANSI_PRAGMA_WEAK(wcslen,function)
  45         ANSI_PRAGMA_WEAK(wslen,function)
  46
  47         ENTRY(wcslen)           /* (wchar_t *) */
  48         xorl    %eax,%eax
  49
  50         .align  8
  51 .loop:
  52         cmpl    $0,(%rdi)
  53         je      .out0
  54         cmpl    $0,4(%rdi)
  55         je      .out1
  56         cmpl    $0,8(%rdi)
  57         je      .out2
  58         cmpl    $0,12(%rdi)
  59         je      .out3
  60         addq    $4,%rax
  61         addq    $16,%rdi
  62         jmp     .loop
  63
  64         .align  4
  65 .out1:
  66         incq    %rax
  67 .out0:
  68         ret
  69
  70         .align  4
  71 .out2:
  72         addq    $2,%rax
  73         ret
  74
  75         .align  4
  76 .out3:
  77         addq    $3, %rax
  78         ret
  79         SET_SIZE(wcslen)
  80
  81         ENTRY(wslen)
  82         jmp     wcslen          / tail call into wcslen
  83         SET_SIZE(wslen)