Mon Mar 31 07:38:05 2008

Asterisk developer's documentation


slinfactory.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (C) 2005, Anthony Minessale II.
00005  *
00006  * Anthony Minessale <anthmct@yahoo.com>
00007  *
00008  * See http://www.asterisk.org for more information about
00009  * the Asterisk project. Please do not directly contact
00010  * any of the maintainers of this project for assistance;
00011  * the project provides a web site, mailing lists and IRC
00012  * channels for your use.
00013  *
00014  * This program is free software, distributed under the terms of
00015  * the GNU General Public License Version 2. See the LICENSE file
00016  * at the top of the source tree.
00017  */
00018 
00019 /*! \file
00020  *
00021  * \brief A machine to gather up arbitrary frames and convert them
00022  * to raw slinear on demand.
00023  *
00024  * \author Anthony Minessale <anthmct@yahoo.com>
00025  */
00026 
00027 #include "asterisk.h"
00028 
00029 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
00030 
00031 #include <string.h>
00032 
00033 #include "asterisk/frame.h"
00034 #include "asterisk/slinfactory.h"
00035 #include "asterisk/logger.h"
00036 #include "asterisk/translate.h"
00037 
00038 void ast_slinfactory_init(struct ast_slinfactory *sf) 
00039 {
00040    memset(sf, 0, sizeof(*sf));
00041    sf->offset = sf->hold;
00042 }
00043 
00044 void ast_slinfactory_destroy(struct ast_slinfactory *sf) 
00045 {
00046    struct ast_frame *f;
00047 
00048    if (sf->trans) {
00049       ast_translator_free_path(sf->trans);
00050       sf->trans = NULL;
00051    }
00052 
00053    while ((f = AST_LIST_REMOVE_HEAD(&sf->queue, frame_list)))
00054       ast_frfree(f);
00055 }
00056 
00057 int ast_slinfactory_feed(struct ast_slinfactory *sf, struct ast_frame *f)
00058 {
00059    struct ast_frame *begin_frame = f, *duped_frame = NULL, *frame_ptr;
00060    unsigned int x;
00061 
00062    if (f->subclass != AST_FORMAT_SLINEAR) {
00063       if (sf->trans && f->subclass != sf->format) {
00064          ast_translator_free_path(sf->trans);
00065          sf->trans = NULL;
00066       }
00067 
00068       if (!sf->trans) {
00069          if ((sf->trans = ast_translator_build_path(AST_FORMAT_SLINEAR, f->subclass)) == NULL) {
00070             ast_log(LOG_WARNING, "Cannot build a path from %s to slin\n", ast_getformatname(f->subclass));
00071             return 0;
00072          } else {
00073             sf->format = f->subclass;
00074          }
00075       }
00076 
00077       if (!(begin_frame = ast_translate(sf->trans, f, 0))) 
00078          return 0;
00079       
00080       duped_frame = ast_frdup(begin_frame);
00081 
00082       ast_frfree(begin_frame);
00083 
00084       if (!duped_frame)
00085          return 0;
00086    } else {
00087       if (!(duped_frame = ast_frdup(f)))
00088          return 0;
00089    }
00090 
00091    x = 0;
00092    AST_LIST_TRAVERSE(&sf->queue, frame_ptr, frame_list)
00093       x++;
00094 
00095    AST_LIST_INSERT_TAIL(&sf->queue, duped_frame, frame_list);
00096 
00097    sf->size += duped_frame->samples;
00098 
00099    return x;
00100 }
00101 
00102 int ast_slinfactory_read(struct ast_slinfactory *sf, short *buf, size_t samples) 
00103 {
00104    struct ast_frame *frame_ptr;
00105    unsigned int sofar = 0, ineed, remain;
00106    short *frame_data, *offset = buf;
00107 
00108    while (sofar < samples) {
00109       ineed = samples - sofar;
00110 
00111       if (sf->holdlen) {
00112          if (sf->holdlen <= ineed) {
00113             memcpy(offset, sf->hold, sf->holdlen * sizeof(*offset));
00114             sofar += sf->holdlen;
00115             offset += sf->holdlen;
00116             sf->holdlen = 0;
00117             sf->offset = sf->hold;
00118          } else {
00119             remain = sf->holdlen - ineed;
00120             memcpy(offset, sf->offset, ineed * sizeof(*offset));
00121             sofar += ineed;
00122             sf->offset += ineed;
00123             sf->holdlen = remain;
00124          }
00125          continue;
00126       }
00127       
00128       if ((frame_ptr = AST_LIST_REMOVE_HEAD(&sf->queue, frame_list))) {
00129          frame_data = frame_ptr->data;
00130          
00131          if (frame_ptr->samples <= ineed) {
00132             memcpy(offset, frame_data, frame_ptr->samples * sizeof(*offset));
00133             sofar += frame_ptr->samples;
00134             offset += frame_ptr->samples;
00135          } else {
00136             remain = frame_ptr->samples - ineed;
00137             memcpy(offset, frame_data, ineed * sizeof(*offset));
00138             sofar += ineed;
00139             frame_data += ineed;
00140             memcpy(sf->hold, frame_data, remain * sizeof(*offset));
00141             sf->holdlen = remain;
00142          }
00143          ast_frfree(frame_ptr);
00144       } else {
00145          break;
00146       }
00147    }
00148 
00149    sf->size -= sofar;
00150    return sofar;
00151 }
00152 
00153 unsigned int ast_slinfactory_available(const struct ast_slinfactory *sf)
00154 {
00155    return sf->size;
00156 }

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