Asterisk.org: Developer Documentation (28 Oct 2009)

Wed Oct 28 15:47:54 2009

## Asterisk developer's documentation

# format_sln.c

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    00001 /*
    00002  * Asterisk -- An open source telephony toolkit.
    00003  *
    00004  * Copyright (C) 1999 - 2005, Anthony Minessale
    00005  * Anthony Minessale (anthmct@yahoo.com)
    00006  *
    00007  * See http://www.asterisk.org for more information about
    00008  * the Asterisk project. Please do not directly contact
    00009  * any of the maintainers of this project for assistance;
    00010  * the project provides a web site, mailing lists and IRC
    00011  * channels for your use.
    00012  *
    00013  * This program is free software, distributed under the terms of
    00014  * the GNU General Public License Version 2. See the LICENSE file
    00015  * at the top of the source tree.
    00016  */
    00017
    00018 /*! \file
    00019  *
    00020  * \brief RAW SLINEAR Format
    00021  * \arg File name extensions: sln, raw
    00022  * \ingroup formats
    00023  */
    00024
    00025 #include <unistd.h>
    00026 #include <netinet/in.h>
    00027 #include <arpa/inet.h>
    00028 #include <stdlib.h>
    00029 #include <sys/time.h>
    00030 #include <stdio.h>
    00031 #include <errno.h>
    00032 #include <string.h>
    00033
    00034 #include "asterisk.h"
    00035
    00036 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 10487 $")
    00037
    00038 #include "asterisk/lock.h"
    00039 #include "asterisk/channel.h"
    00040 #include "asterisk/file.h"
    00041 #include "asterisk/logger.h"
    00042 #include "asterisk/sched.h"
    00043 #include "asterisk/module.h"
    00044 #include "asterisk/endian.h"
    00045
    00046 #define BUF_SIZE 320    /* 320 samples */
    00047
    00048 struct ast_filestream {
    00049    void *reserved[AST_RESERVED_POINTERS];
    00050    /* This is what a filestream means to us */
    00051    FILE *f; /* Descriptor */
    00052    struct ast_channel *owner;
    00053    struct ast_frame fr;          /* Frame information */
    00054    char waste[AST_FRIENDLY_OFFSET]; /* Buffer for sending frames, etc */
    00055    char empty;                   /* Empty character */
    00056    unsigned char buf[BUF_SIZE];           /* Output Buffer */
    00057    struct timeval last;
    00058 };
    00059
    00060
    00061 AST_MUTEX_DEFINE_STATIC(slinear_lock);
    00062 static int glistcnt = 0;
    00063
    00064 static char *name = "sln";
    00065 static char *desc = "Raw Signed Linear Audio support (SLN)";
    00066 static char *exts = "sln|raw";
    00067
    00068 static struct ast_filestream *slinear_open(FILE *f)
    00069 {
    00070    /* We don't have any header to read or anything really, but
    00071       if we did, it would go here.  We also might want to check
    00072       and be sure it's a valid file.  */
    00073    struct ast_filestream *tmp;
    00074    if ((tmp = malloc(sizeof(struct ast_filestream)))) {
    00075       memset(tmp, 0, sizeof(struct ast_filestream));
    00076       if (ast_mutex_lock(&slinear_lock)) {
    00077          ast_log(LOG_WARNING, "Unable to lock slinear list\n");
    00078          free(tmp);
    00079          return NULL;
    00080       }
    00081       tmp->f = f;
    00082       tmp->fr.data = tmp->buf;
    00083       tmp->fr.frametype = AST_FRAME_VOICE;
    00084       tmp->fr.subclass = AST_FORMAT_SLINEAR;
    00085       /* datalen will vary for each frame */
    00086       tmp->fr.src = name;
    00087       tmp->fr.mallocd = 0;
    00088       glistcnt++;
    00089       ast_mutex_unlock(&slinear_lock);
    00090       ast_update_use_count();
    00091    }
    00092    return tmp;
    00093 }
    00094
    00095 static struct ast_filestream *slinear_rewrite(FILE *f, const char *comment)
    00096 {
    00097    /* We don't have any header to read or anything really, but
    00098       if we did, it would go here.  We also might want to check
    00099       and be sure it's a valid file.  */
    00100    struct ast_filestream *tmp;
    00101    if ((tmp = malloc(sizeof(struct ast_filestream)))) {
    00102       memset(tmp, 0, sizeof(struct ast_filestream));
    00103       if (ast_mutex_lock(&slinear_lock)) {
    00104          ast_log(LOG_WARNING, "Unable to lock slinear list\n");
    00105          free(tmp);
    00106          return NULL;
    00107       }
    00108       tmp->f = f;
    00109       glistcnt++;
    00110       ast_mutex_unlock(&slinear_lock);
    00111       ast_update_use_count();
    00112    } else
    00113       ast_log(LOG_WARNING, "Out of memory\n");
    00114    return tmp;
    00115 }
    00116
    00117 static void slinear_close(struct ast_filestream *s)
    00118 {
    00119    if (ast_mutex_lock(&slinear_lock)) {
    00120       ast_log(LOG_WARNING, "Unable to lock slinear list\n");
    00121       return;
    00122    }
    00123    glistcnt--;
    00124    ast_mutex_unlock(&slinear_lock);
    00125    ast_update_use_count();
    00126    fclose(s->f);
    00127    free(s);
    00128    s = NULL;
    00129 }
    00130
    00131 static struct ast_frame *slinear_read(struct ast_filestream *s, int *whennext)
    00132 {
    00133    int res;
    00134    int delay;
    00135    /* Send a frame from the file to the appropriate channel */
    00136
    00137    s->fr.frametype = AST_FRAME_VOICE;
    00138    s->fr.subclass = AST_FORMAT_SLINEAR;
    00139    s->fr.offset = AST_FRIENDLY_OFFSET;
    00140    s->fr.mallocd = 0;
    00141    s->fr.data = s->buf;
    00142    if ((res = fread(s->buf, 1, BUF_SIZE, s->f)) < 1) {
    00143       if (res)
    00144          ast_log(LOG_WARNING, "Short read (%d) (%s)!\n", res, strerror(errno));
    00145       return NULL;
    00146    }
    00147    s->fr.samples = res/2;
    00148    s->fr.datalen = res;
    00149    delay = s->fr.samples;
    00150    *whennext = delay;
    00151    return &s->fr;
    00152 }
    00153
    00154 static int slinear_write(struct ast_filestream *fs, struct ast_frame *f)
    00155 {
    00156    int res;
    00157    if (f->frametype != AST_FRAME_VOICE) {
    00158       ast_log(LOG_WARNING, "Asked to write non-voice frame!\n");
    00159       return -1;
    00160    }
    00161    if (f->subclass != AST_FORMAT_SLINEAR) {
    00162       ast_log(LOG_WARNING, "Asked to write non-slinear frame (%d)!\n", f->subclass);
    00163       return -1;
    00164    }
    00165    if ((res = fwrite(f->data, 1, f->datalen, fs->f)) != f->datalen) {
    00166          ast_log(LOG_WARNING, "Bad write (%d/%d): %s\n", res, f->datalen, strerror(errno));
    00167          return -1;
    00168    }
    00169    return 0;
    00170 }
    00171
    00172 static int slinear_seek(struct ast_filestream *fs, long sample_offset, int whence)
    00173 {
    00174    off_t offset=0,min,cur,max;
    00175
    00176    min = 0;
    00177    sample_offset <<= 1;
    00178    cur = ftell(fs->f);
    00179    fseek(fs->f, 0, SEEK_END);
    00180    max = ftell(fs->f);
    00181    if (whence == SEEK_SET)
    00182       offset = sample_offset;
    00183    else if (whence == SEEK_CUR || whence == SEEK_FORCECUR)
    00184       offset = sample_offset + cur;
    00185    else if (whence == SEEK_END)
    00186       offset = max - sample_offset;
    00187    if (whence != SEEK_FORCECUR) {
    00188       offset = (offset > max)?max:offset;
    00189    }
    00190    /* always protect against seeking past begining. */
    00191    offset = (offset < min)?min:offset;
    00192    return fseek(fs->f, offset, SEEK_SET);
    00193 }
    00194
    00195 static int slinear_trunc(struct ast_filestream *fs)
    00196 {
    00197    return ftruncate(fileno(fs->f), ftell(fs->f));
    00198 }
    00199
    00200 static long slinear_tell(struct ast_filestream *fs)
    00201 {
    00202    off_t offset;
    00203    offset = ftell(fs->f);
    00204    return offset / 2;
    00205 }
    00206
    00207 static char *slinear_getcomment(struct ast_filestream *s)
    00208 {
    00209    return NULL;
    00210 }
    00211
    00212 int load_module()
    00213 {
    00214    return ast_format_register(name, exts, AST_FORMAT_SLINEAR,
    00215                         slinear_open,
    00216                         slinear_rewrite,
    00217                         slinear_write,
    00218                         slinear_seek,
    00219                         slinear_trunc,
    00220                         slinear_tell,
    00221                         slinear_read,
    00222                         slinear_close,
    00223                         slinear_getcomment);
    00224
    00225
    00226 }
    00227
    00228 int unload_module()
    00229 {
    00230    return ast_format_unregister(name);
    00231 }
    00232
    00233 int usecount()
    00234 {
    00235    return glistcnt;
    00236 }
    00237
    00238 char *description()
    00239 {
    00240    return desc;
    00241 }
    00242
    00243
    00244 char *key()
    00245 {
    00246    return ASTERISK_GPL_KEY;
    00247 }