codec_gsm.c File Reference

Translate between signed linear and Global System for Mobile Communications (GSM). More...

#include "asterisk.h"
#include "asterisk/translate.h"
#include "asterisk/config.h"
#include "asterisk/module.h"
#include "asterisk/utils.h"
#include "../formats/msgsm.h"
#include "asterisk/slin.h"
#include "ex_gsm.h"

Include dependency graph for codec_gsm.c:

Go to the source code of this file.

Data Structures

struct  gsm_translator_pvt

Defines

#define BUFFER_SAMPLES   8000
#define GSM_FRAME_LEN   33
#define GSM_SAMPLES   160
#define MSGSM_FRAME_LEN   65

Functions

static void __reg_module (void)
static void __unreg_module (void)
static void gsm_destroy_stuff (struct ast_trans_pvt *pvt)
static int gsm_new (struct ast_trans_pvt *pvt)
static int gsmtolin_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
 decode and store in outbuf.
static int lintogsm_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
 store samples into working buffer for later decode
static struct ast_framelintogsm_frameout (struct ast_trans_pvt *pvt)
 encode and produce a frame
static int load_module (void)
static int unload_module (void)

Variables

static struct ast_module_info __mod_info = { .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "GSM Coder/Decoder" , .key = "This paragraph is copyright (c) 2006 by Digium, Inc. \In order for your module to load, it must return this \key via a function called \"key\". Any code which \includes this paragraph must be licensed under the GNU \General Public License version 2 or later (at your \option). In addition to Digium's general reservations \of rights, Digium expressly reserves the right to \allow other parties to license this paragraph under \different terms. Any use of Digium, Inc. trademarks or \logos (including \"Asterisk\" or \"Digium\") without \express written permission of Digium, Inc. is prohibited.\n" , .buildopt_sum = AST_BUILDOPT_SUM, .support_level = AST_MODULE_SUPPORT_CORE, .load = load_module, .unload = unload_module, }
static struct ast_module_infoast_module_info = &__mod_info
static struct ast_translator gsmtolin
static struct ast_translator lintogsm


Detailed Description

Translate between signed linear and Global System for Mobile Communications (GSM).

Definition in file codec_gsm.c.


Define Documentation

#define BUFFER_SAMPLES   8000

Definition at line 51 of file codec_gsm.c.

#define GSM_FRAME_LEN   33

Definition at line 53 of file codec_gsm.c.

Referenced by gsmtolin_framein(), and lintogsm_frameout().

#define GSM_SAMPLES   160

#define MSGSM_FRAME_LEN   65

Definition at line 54 of file codec_gsm.c.

Referenced by gsmtolin_framein().


Function Documentation

static void __reg_module ( void   )  [static]

Definition at line 243 of file codec_gsm.c.

static void __unreg_module ( void   )  [static]

Definition at line 243 of file codec_gsm.c.

static void gsm_destroy_stuff ( struct ast_trans_pvt pvt  )  [static]

Definition at line 163 of file codec_gsm.c.

References gsm_translator_pvt::gsm, ast_trans_pvt::pvt, and tmp().

00164 {
00165    struct gsm_translator_pvt *tmp = pvt->pvt;
00166    if (tmp->gsm)
00167       gsm_destroy(tmp->gsm);
00168 }

static int gsm_new ( struct ast_trans_pvt pvt  )  [static]

Definition at line 65 of file codec_gsm.c.

References gsm_translator_pvt::gsm, ast_trans_pvt::pvt, and tmp().

00066 {
00067    struct gsm_translator_pvt *tmp = pvt->pvt;
00068    
00069    return (tmp->gsm = gsm_create()) ? 0 : -1;
00070 }

static int gsmtolin_framein ( struct ast_trans_pvt pvt,
struct ast_frame f 
) [static]

decode and store in outbuf.

Definition at line 73 of file codec_gsm.c.

References ast_log, BUFFER_SAMPLES, conv65(), ast_frame::data, ast_trans_pvt::datalen, ast_frame::datalen, gsm_translator_pvt::gsm, GSM_FRAME_LEN, GSM_SAMPLES, ast_trans_pvt::i16, len(), LOG_WARNING, MSGSM_FRAME_LEN, ast_trans_pvt::outbuf, ast_frame::ptr, ast_trans_pvt::pvt, ast_trans_pvt::samples, and tmp().

00074 {
00075    struct gsm_translator_pvt *tmp = pvt->pvt;
00076    int x;
00077    int16_t *dst = pvt->outbuf.i16;
00078    /* guess format from frame len. 65 for MSGSM, 33 for regular GSM */
00079    int flen = (f->datalen % MSGSM_FRAME_LEN == 0) ?
00080       MSGSM_FRAME_LEN : GSM_FRAME_LEN;
00081 
00082    for (x=0; x < f->datalen; x += flen) {
00083       unsigned char data[2 * GSM_FRAME_LEN];
00084       unsigned char *src;
00085       int len;
00086       if (flen == MSGSM_FRAME_LEN) {
00087          len = 2*GSM_SAMPLES;
00088          src = data;
00089          /* Translate MSGSM format to Real GSM format before feeding in */
00090          /* XXX what's the point here! we should just work
00091           * on the full format.
00092           */
00093          conv65(f->data.ptr + x, data);
00094       } else {
00095          len = GSM_SAMPLES;
00096          src = f->data.ptr + x;
00097       }
00098       /* XXX maybe we don't need to check */
00099       if (pvt->samples + len > BUFFER_SAMPLES) {   
00100          ast_log(LOG_WARNING, "Out of buffer space\n");
00101          return -1;
00102       }
00103       if (gsm_decode(tmp->gsm, src, dst + pvt->samples)) {
00104          ast_log(LOG_WARNING, "Invalid GSM data (1)\n");
00105          return -1;
00106       }
00107       pvt->samples += GSM_SAMPLES;
00108       pvt->datalen += 2 * GSM_SAMPLES;
00109       if (flen == MSGSM_FRAME_LEN) {
00110          if (gsm_decode(tmp->gsm, data + GSM_FRAME_LEN, dst + pvt->samples)) {
00111             ast_log(LOG_WARNING, "Invalid GSM data (2)\n");
00112             return -1;
00113          }
00114          pvt->samples += GSM_SAMPLES;
00115          pvt->datalen += 2 * GSM_SAMPLES;
00116       }
00117    }
00118    return 0;
00119 }

static int lintogsm_framein ( struct ast_trans_pvt pvt,
struct ast_frame f 
) [static]

store samples into working buffer for later decode

Definition at line 122 of file codec_gsm.c.

References ast_log, gsm_translator_pvt::buf, BUFFER_SAMPLES, ast_frame::data, ast_frame::datalen, LOG_WARNING, ast_frame::ptr, ast_trans_pvt::pvt, ast_frame::samples, ast_trans_pvt::samples, and tmp().

00123 {
00124    struct gsm_translator_pvt *tmp = pvt->pvt;
00125 
00126    /* XXX We should look at how old the rest of our stream is, and if it
00127       is too old, then we should overwrite it entirely, otherwise we can
00128       get artifacts of earlier talk that do not belong */
00129    if (pvt->samples + f->samples > BUFFER_SAMPLES) {
00130       ast_log(LOG_WARNING, "Out of buffer space\n");
00131       return -1;
00132    }
00133    memcpy(tmp->buf + pvt->samples, f->data.ptr, f->datalen);
00134    pvt->samples += f->samples;
00135    return 0;
00136 }

static struct ast_frame* lintogsm_frameout ( struct ast_trans_pvt pvt  )  [static, read]

encode and produce a frame

Definition at line 139 of file codec_gsm.c.

References ast_trans_frameout(), gsm_translator_pvt::buf, ast_trans_pvt::c, gsm_translator_pvt::gsm, GSM_FRAME_LEN, GSM_SAMPLES, NULL, ast_trans_pvt::outbuf, ast_trans_pvt::pvt, ast_trans_pvt::samples, and tmp().

00140 {
00141    struct gsm_translator_pvt *tmp = pvt->pvt;
00142    int datalen = 0;
00143    int samples = 0;
00144 
00145    /* We can't work on anything less than a frame in size */
00146    if (pvt->samples < GSM_SAMPLES)
00147       return NULL;
00148    while (pvt->samples >= GSM_SAMPLES) {
00149       /* Encode a frame of data */
00150       gsm_encode(tmp->gsm, tmp->buf + samples, (gsm_byte *) pvt->outbuf.c + datalen);
00151       datalen += GSM_FRAME_LEN;
00152       samples += GSM_SAMPLES;
00153       pvt->samples -= GSM_SAMPLES;
00154    }
00155 
00156    /* Move the data at the end of the buffer to the front */
00157    if (pvt->samples)
00158       memmove(tmp->buf, tmp->buf + samples, pvt->samples * 2);
00159 
00160    return ast_trans_frameout(pvt, datalen, samples);
00161 }

static int load_module ( void   )  [static]

Definition at line 224 of file codec_gsm.c.

References AST_MODULE_LOAD_FAILURE, AST_MODULE_LOAD_SUCCESS, ast_register_translator, and unload_module.

00225 {
00226    int res;
00227 
00228    res = ast_register_translator(&gsmtolin);
00229    res |= ast_register_translator(&lintogsm);
00230 
00231    if (res) {
00232       unload_module();
00233       return AST_MODULE_LOAD_FAILURE;
00234    }
00235 
00236    return AST_MODULE_LOAD_SUCCESS;
00237 }

static int unload_module ( void   )  [static]

Definition at line 214 of file codec_gsm.c.

References ast_unregister_translator().

00215 {
00216    int res;
00217 
00218    res = ast_unregister_translator(&lintogsm);
00219    res |= ast_unregister_translator(&gsmtolin);
00220 
00221    return res;
00222 }


Variable Documentation

struct ast_module_info __mod_info = { .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "GSM Coder/Decoder" , .key = "This paragraph is copyright (c) 2006 by Digium, Inc. \In order for your module to load, it must return this \key via a function called \"key\". Any code which \includes this paragraph must be licensed under the GNU \General Public License version 2 or later (at your \option). In addition to Digium's general reservations \of rights, Digium expressly reserves the right to \allow other parties to license this paragraph under \different terms. Any use of Digium, Inc. trademarks or \logos (including \"Asterisk\" or \"Digium\") without \express written permission of Digium, Inc. is prohibited.\n" , .buildopt_sum = AST_BUILDOPT_SUM, .support_level = AST_MODULE_SUPPORT_CORE, .load = load_module, .unload = unload_module, } [static]

Definition at line 243 of file codec_gsm.c.

Definition at line 243 of file codec_gsm.c.

struct ast_translator gsmtolin [static]

Definition at line 170 of file codec_gsm.c.

struct ast_translator lintogsm [static]

Definition at line 192 of file codec_gsm.c.


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