include/asterisk/ulaw.h

   1 /*
   2  * Asterisk -- An open source telephony toolkit.
   3  *
   4  * Copyright (C) 1999 - 2005, Digium, Inc.
   5  *
   6  * Mark Spencer <markster@digium.com>
   7  *
   8  * See http://www.asterisk.org for more information about
   9  * the Asterisk project. Please do not directly contact
  10  * any of the maintainers of this project for assistance;
  11  * the project provides a web site, mailing lists and IRC
  12  * channels for your use.
  13  *
  14  * This program is free software, distributed under the terms of
  15  * the GNU General Public License Version 2. See the LICENSE file
  16  * at the top of the source tree.
  17  */
  18
  19 /*! \file
  20  * \brief u-Law to Signed linear conversion
  21  */
  22
  23 #ifndef _ASTERISK_ULAW_H
  24 #define _ASTERISK_ULAW_H
  25
  26 /*! Init the ulaw conversion stuff */
  27 /*!
  28  * To init the ulaw to slinear conversion stuff, this needs to be run.
  29  */
  30 void ast_ulaw_init(void);
  31
  32 /*! converts signed linear to mulaw */
  33 /*!
  34   */
  35 extern unsigned char __ast_lin2mu[16384];
  36
  37 /*! help */
  38 extern short __ast_mulaw[256];
  39
  40 #define AST_LIN2MU(a) (__ast_lin2mu[((unsigned short)(a)) >> 2])
  41 #define AST_MULAW(a) (__ast_mulaw[(a)])
  42
  43 #endif /* _ASTERISK_ULAW_H */