codec_g726.c File Reference

codec_g726.c - translate between signed linear and ITU G.726-32kbps (both RFC3551 and AAL2 codeword packing) More...

#include "asterisk.h"
#include "asterisk/lock.h"
#include "asterisk/linkedlists.h"
#include "asterisk/module.h"
#include "asterisk/config.h"
#include "asterisk/translate.h"
#include "asterisk/utils.h"
#include "log2comp.h"
#include "asterisk/slin.h"
#include "ex_g726.h"

Include dependency graph for codec_g726.c:

Go to the source code of this file.

Data Structures
struct	g726_coder_pvt
struct	g726_state

Macros
#define	BUF_SHIFT   5
#define	BUFFER_SAMPLES   8096 /* size for the translation buffers */
#define	WANT_ASM

Functions
static void	__reg_module (void)
static void	__unreg_module (void)
struct ast_module *	AST_MODULE_SELF_SYM (void)
static int	fmult (int an, int srn)
static int	g726_decode (int i, struct g726_state *state_ptr)
static int	g726_encode (int sl, struct g726_state *state_ptr)
static void	g726_init_state (struct g726_state *state_ptr)
static int	g726aal2tolin_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
	decode packed 4-bit G726 values (AAL2 packing) and store in buffer. More...
static int	g726tolin_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
	decode packed 4-bit G726 values (RFC3551 packing) and store in buffer. More...
static int	lintog726_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
	compress and store data (4-bit G726 samples, RFC3551 packing) in outbuf More...
static int	lintog726_new (struct ast_trans_pvt *pvt)
	init a new instance of g726_coder_pvt. More...
static int	lintog726aal2_framein (struct ast_trans_pvt *pvt, struct ast_frame *f)
	compress and store data (4-bit G726 samples, AAL2 packing) in outbuf More...
static int	load_module (void)
static int	predictor_pole (struct g726_state *state_ptr)
static int	predictor_zero (struct g726_state *state_ptr)
static int	quan (int val, int *table, int size)
static int	quantize (int d, int y, int *table, int size)
static int	reconstruct (int sign, int dqln, int y)
static int	step_size (struct g726_state *state_ptr)
static int	unload_module (void)
static void	update (int code_size, int y, int wi, int fi, int dq, int sr, int dqsez, struct g726_state *state_ptr)

Variables
static struct ast_module_info	__mod_info = { .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "ITU G.726-32kbps G726 Transcoder" , .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 = "30ef0c93b36035ec78c9cfd712d36d9b" , .support_level = AST_MODULE_SUPPORT_CORE, .load = load_module, .unload = unload_module, }
static int	_dqlntab [16]
static int	_fitab [16]
static int	_witab [16]
static const struct ast_module_info *	ast_module_info = &__mod_info
static struct ast_translator	g726aal2tolin
static struct ast_translator	g726tolin
static struct ast_translator	lintog726
static struct ast_translator	lintog726aal2
static int	qtab_721 [7] = {-124, 80, 178, 246, 300, 349, 400}

Detailed Description

codec_g726.c - translate between signed linear and ITU G.726-32kbps (both RFC3551 and AAL2 codeword packing)

Definition in file codec_g726.c.

Macro Definition Documentation

BUF_SHIFT

#define BUF_SHIFT   5

Definition at line 60 of file codec_g726.c.

BUFFER_SAMPLES

#define BUFFER_SAMPLES   8096 /* size for the translation buffers */

Definition at line 59 of file codec_g726.c.

WANT_ASM

#define WANT_ASM

Definition at line 43 of file codec_g726.c.

Function Documentation

__reg_module()

static void __reg_module ( void  )

static

Definition at line 903 of file codec_g726.c.

__unreg_module()

static void __unreg_module ( void  )

static

Definition at line 903 of file codec_g726.c.

AST_MODULE_SELF_SYM()

struct ast_module* AST_MODULE_SELF_SYM

(

void

)

Definition at line 903 of file codec_g726.c.

fmult()

static int fmult ( int  an, int  srn  )

static

Definition at line 205 of file codec_g726.c.

References ilog2(), and retval.

Referenced by predictor_pole(), and predictor_zero().

{
   int      anmag, anexp, anmant;
   int      wanexp, wanmant;
   int      retval;

   anmag = (an > 0) ? an : ((-an) & 0x1FFF);
   anexp = ilog2(anmag) - 5;
   anmant = (anmag == 0) ? 32 :
       (anexp >= 0) ? anmag >> anexp : anmag << -anexp;
   wanexp = anexp + ((srn >> 6) & 0xF) - 13;

   wanmant = (anmant * (srn & 077) + 0x30) >> 4;
   retval = (wanexp >= 0) ? ((wanmant << wanexp) & 0x7FFF) :
       (wanmant >> -wanexp);

   return (((an ^ srn) < 0) ? -retval : retval);
}

g726_decode()

static int g726_decode ( int  i, struct g726_state *  state_ptr  )

static

Definition at line 588 of file codec_g726.c.

References _dqlntab, _fitab, _witab, g726_state::dq, predictor_pole(), predictor_zero(), reconstruct(), g726_state::sr, step_size(), and update().

Referenced by g726aal2tolin_framein(), and g726tolin_framein().

{
   int      sezi, sez, se; /* ACCUM */
   int      y;       /* MIX */
   int      sr;         /* ADDB */
   int      dq;
   int      dqsez;

   i &= 0x0f;        /* mask to get proper bits */
#ifdef NOT_BLI
   sezi = predictor_zero(state_ptr);
   sez = sezi;
   se = sezi + predictor_pole(state_ptr); /* estimated signal */
#else
   sezi = predictor_zero(state_ptr);
   sez = sezi >> 1;
   se = (sezi + predictor_pole(state_ptr)) >> 1;   /* estimated signal */
#endif

   y = step_size(state_ptr);  /* dynamic quantizer step size */

   dq = reconstruct(i & 8, _dqlntab[i], y); /* quantized diff. */

#ifdef NOT_BLI
   sr = se + dq;           /* reconst. signal */
   dqsez = dq + sez;       /* pole prediction diff. */
#else
   sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;   /* reconst. signal */
   dqsez = sr - se + sez;     /* pole prediction diff. */
#endif

   update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);

#ifdef NOT_BLI
   return (sr >> 10);   /* sr was 26-bit dynamic range */
#else
   return (sr << 2); /* sr was 14-bit dynamic range */
#endif
}

g726_encode()

static int g726_encode ( int  sl, struct g726_state *  state_ptr  )

static

Definition at line 634 of file codec_g726.c.

References _dqlntab, _fitab, _witab, d, g726_state::dq, predictor_pole(), predictor_zero(), qtab_721, quantize(), reconstruct(), g726_state::sr, step_size(), and update().

Referenced by lintog726_framein(), and lintog726aal2_framein().

{
   int      sezi, se, sez;    /* ACCUM */
   int      d;       /* SUBTA */
   int      sr;         /* ADDB */
   int      y;       /* MIX */
   int      dqsez;         /* ADDC */
   int      dq, i;

#ifdef NOT_BLI
   sl <<= 10;        /* 26-bit dynamic range */

   sezi = predictor_zero(state_ptr);
   sez = sezi;
   se = sezi + predictor_pole(state_ptr); /* estimated signal */
#else
   sl >>= 2;         /* 14-bit dynamic range */

   sezi = predictor_zero(state_ptr);
   sez = sezi >> 1;
   se = (sezi + predictor_pole(state_ptr)) >> 1;   /* estimated signal */
#endif

   d = sl - se;            /* estimation difference */

   /* quantize the prediction difference */
   y = step_size(state_ptr);     /* quantizer step size */
#ifdef NOT_BLI
   d /= 0x1000;
#endif
   i = quantize(d, y, qtab_721, 7); /* i = G726 code */

   dq = reconstruct(i & 8, _dqlntab[i], y);  /* quantized est diff */

#ifdef NOT_BLI
   sr = se + dq;           /* reconst. signal */
   dqsez = dq + sez;       /* pole prediction diff. */
#else
   sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;   /* reconst. signal */
   dqsez = sr - se + sez;        /* pole prediction diff. */
#endif

   update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);

   return i;
}

g726_init_state()

static void g726_init_state ( struct g726_state *  state_ptr )

static

Definition at line 123 of file codec_g726.c.

References g726_state::a, g726_state::ap, g726_state::b, g726_state::dml, g726_state::dms, g726_state::dq, g726_state::pk, g726_state::sr, g726_state::td, g726_state::yl, and g726_state::yu.

Referenced by lintog726_new().

{
   int      cnta;

   state_ptr->yl = 34816;
   state_ptr->yu = 544;
   state_ptr->dms = 0;
   state_ptr->dml = 0;
   state_ptr->ap = 0;
   for (cnta = 0; cnta < 2; cnta++) {
      state_ptr->a[cnta] = 0;
      state_ptr->pk[cnta] = 0;
#ifdef NOT_BLI
      state_ptr->sr[cnta] = 1;
#else
      state_ptr->sr[cnta] = 32;
#endif
   }
   for (cnta = 0; cnta < 6; cnta++) {
      state_ptr->b[cnta] = 0;
#ifdef NOT_BLI
      state_ptr->dq[cnta] = 1;
#else
      state_ptr->dq[cnta] = 32;
#endif
   }
   state_ptr->td = 0;
}

g726aal2tolin_framein()

static int g726aal2tolin_framein ( struct ast_trans_pvt *  pvt, struct ast_frame *  f  )

static

decode packed 4-bit G726 values (AAL2 packing) and store in buffer.

Definition at line 703 of file codec_g726.c.

References ast_frame::data, ast_frame::datalen, ast_trans_pvt::datalen, g726_coder_pvt::g726, g726_decode(), ast_trans_pvt::i16, ast_trans_pvt::outbuf, ast_frame::ptr, ast_trans_pvt::pvt, ast_frame::samples, ast_trans_pvt::samples, and tmp().

{
   struct g726_coder_pvt *tmp = pvt->pvt;
   unsigned char *src = f->data.ptr;
   int16_t *dst = pvt->outbuf.i16 + pvt->samples;
   unsigned int i;

   for (i = 0; i < f->datalen; i++) {
      *dst++ = g726_decode((src[i] >> 4) & 0xf, &tmp->g726);
      *dst++ = g726_decode(src[i] & 0x0f, &tmp->g726);
   }

   pvt->samples += f->samples;
   pvt->datalen += 2 * f->samples; /* 2 bytes/sample */

   return 0;
}

g726tolin_framein()

static int g726tolin_framein ( struct ast_trans_pvt *  pvt, struct ast_frame *  f  )

static

decode packed 4-bit G726 values (RFC3551 packing) and store in buffer.

Definition at line 744 of file codec_g726.c.

References ast_frame::data, ast_frame::datalen, ast_trans_pvt::datalen, g726_coder_pvt::g726, g726_decode(), ast_trans_pvt::i16, ast_trans_pvt::outbuf, ast_frame::ptr, ast_trans_pvt::pvt, ast_frame::samples, ast_trans_pvt::samples, and tmp().

{
   struct g726_coder_pvt *tmp = pvt->pvt;
   unsigned char *src = f->data.ptr;
   int16_t *dst = pvt->outbuf.i16 + pvt->samples;
   unsigned int i;

   for (i = 0; i < f->datalen; i++) {
      *dst++ = g726_decode(src[i] & 0x0f, &tmp->g726);
      *dst++ = g726_decode((src[i] >> 4) & 0xf, &tmp->g726);
   }

   pvt->samples += f->samples;
   pvt->datalen += 2 * f->samples; /* 2 bytes/sample */

   return 0;
}

lintog726_framein()

static int lintog726_framein ( struct ast_trans_pvt *  pvt, struct ast_frame *  f  )

static

compress and store data (4-bit G726 samples, RFC3551 packing) in outbuf

Definition at line 763 of file codec_g726.c.

References ast_trans_pvt::c, d, ast_frame::data, ast_trans_pvt::datalen, g726_coder_pvt::g726, g726_encode(), g726_coder_pvt::next_flag, ast_trans_pvt::outbuf, ast_frame::ptr, ast_trans_pvt::pvt, ast_frame::samples, ast_trans_pvt::samples, and tmp().

{
   struct g726_coder_pvt *tmp = pvt->pvt;
   int16_t *src = f->data.ptr;
   unsigned int i;

   for (i = 0; i < f->samples; i++) {
      unsigned char d = g726_encode(src[i], &tmp->g726); /* this sample */

      if (tmp->next_flag & 0x80) {  /* merge with leftover sample */
         pvt->outbuf.c[pvt->datalen++] = (d << 4) | (tmp->next_flag & 0xf);
         pvt->samples += 2;   /* 2 samples per byte */
         tmp->next_flag = 0;
      } else {
         tmp->next_flag = 0x80 | d;
      }
   }

   return 0;
}

lintog726_new()

static int lintog726_new ( struct ast_trans_pvt *  pvt )

static

init a new instance of g726_coder_pvt.

Definition at line 693 of file codec_g726.c.

References g726_coder_pvt::g726, g726_init_state(), ast_trans_pvt::pvt, and tmp().

{
   struct g726_coder_pvt *tmp = pvt->pvt;

   g726_init_state(&tmp->g726);

   return 0;
}

lintog726aal2_framein()

static int lintog726aal2_framein ( struct ast_trans_pvt *  pvt, struct ast_frame *  f  )

static

compress and store data (4-bit G726 samples, AAL2 packing) in outbuf

Definition at line 722 of file codec_g726.c.

References ast_trans_pvt::c, d, ast_frame::data, ast_trans_pvt::datalen, g726_coder_pvt::g726, g726_encode(), g726_coder_pvt::next_flag, ast_trans_pvt::outbuf, ast_frame::ptr, ast_trans_pvt::pvt, ast_frame::samples, ast_trans_pvt::samples, and tmp().

{
   struct g726_coder_pvt *tmp = pvt->pvt;
   int16_t *src = f->data.ptr;
   unsigned int i;

   for (i = 0; i < f->samples; i++) {
      unsigned char d = g726_encode(src[i], &tmp->g726); /* this sample */

      if (tmp->next_flag & 0x80) {  /* merge with leftover sample */
         pvt->outbuf.c[pvt->datalen++] = ((tmp->next_flag & 0xf)<< 4) | d;
         pvt->samples += 2;   /* 2 samples per byte */
         tmp->next_flag = 0;
      } else {
         tmp->next_flag = 0x80 | d;
      }
   }

   return 0;
}

load_module()

static int load_module ( void  )

static

Definition at line 881 of file codec_g726.c.

References AST_MODFLAG_DEFAULT, AST_MODULE_INFO(), AST_MODULE_LOAD_DECLINE, AST_MODULE_LOAD_SUCCESS, AST_MODULE_SUPPORT_CORE, ast_register_translator, ASTERISK_GPL_KEY, and unload_module().

{
   int res = 0;

   res |= ast_register_translator(&g726tolin);
   res |= ast_register_translator(&lintog726);

   res |= ast_register_translator(&g726aal2tolin);
   res |= ast_register_translator(&lintog726aal2);

   if (res) {
      unload_module();
      return AST_MODULE_LOAD_DECLINE;
   }

   return AST_MODULE_LOAD_SUCCESS;
}

predictor_pole()

static int predictor_pole ( struct g726_state *  state_ptr )

static

Definition at line 233 of file codec_g726.c.

References g726_state::a, fmult(), and g726_state::sr.

Referenced by g726_decode(), g726_encode(), and quan().

{
   return (fmult(state_ptr->a[1] >> 2, state_ptr->sr[1]) +
         fmult(state_ptr->a[0] >> 2, state_ptr->sr[0]));
}

predictor_zero()

static int predictor_zero ( struct g726_state *  state_ptr )

static

Definition at line 224 of file codec_g726.c.

References g726_state::b, g726_state::dq, and fmult().

Referenced by g726_decode(), g726_encode(), and quan().

{
   int      i;
   int      sezi;
   for (sezi = 0, i = 0; i < 6; i++)         /* ACCUM */
      sezi += fmult(state_ptr->b[i] >> 2, state_ptr->dq[i]);
   return sezi;
}

quan()

static int quan ( int  val, int *  table, int  size  )

static

Definition at line 160 of file codec_g726.c.

References g726_state::a, g726_state::b, g726_state::dq, predictor_pole(), predictor_zero(), g726_state::sr, and table.

Referenced by quantize().

{
   int      i;

   for (i = 0; i < size && val >= *table; ++i, ++table)
      ;
   return i;
}

quantize()

static int quantize ( int  d, int  y, int *  table, int  size  )

static

Definition at line 276 of file codec_g726.c.

References abs, ilog2(), and quan().

Referenced by g726_encode().

{
   int      dqm;  /* Magnitude of 'd' */
   int      exp;  /* Integer part of base 2 log of 'd' */
   int      mant; /* Fractional part of base 2 log */
   int      dl;      /* Log of magnitude of 'd' */
   int      dln;  /* Step size scale factor normalized log */
   int      i;

   /*
    * LOG
    *
    * Compute base 2 log of 'd', and store in 'dl'.
    */
   dqm = abs(d);
   exp = ilog2(dqm);
   if (exp < 0) {
      exp = 0;
   }
   mant = ((dqm << 7) >> exp) & 0x7F;  /* Fractional portion. */
   dl = (exp << 7) | mant;

   /*
    * SUBTB
    *
    * "Divide" by step size multiplier.
    */
   dln = dl - (y >> 2);

   /*
    * QUAN
    *
    * Obtain codword i for 'd'.
    */
   i = quan(dln, table, size);
   if (d < 0) {         /* take 1's complement of i */
      return ((size << 1) + 1 - i);
   } else if (i == 0) {    /* take 1's complement of 0 */
      return ((size << 1) + 1); /* new in 1988 */
   } else {
      return i;
   }
}

reconstruct()

static int reconstruct ( int  sign, int  dqln, int  y  )

static

Definition at line 331 of file codec_g726.c.

References g726_state::dq.

Referenced by bridge_p2p_rtp_write(), g726_decode(), and g726_encode().

{
   int      dql;  /* Log of 'dq' magnitude */
   int      dex;  /* Integer part of log */
   int      dqt;
   int      dq;   /* Reconstructed difference signal sample */

   dql = dqln + (y >> 2);  /* ADDA */

   if (dql < 0) {
#ifdef NOT_BLI
      return (sign) ? -1 : 1;
#else
      return (sign) ? -0x8000 : 0;
#endif
   } else {    /* ANTILOG */
      dex = (dql >> 7) & 15;
      dqt = 128 + (dql & 127);
#ifdef NOT_BLI
      dq = ((dqt << 19) >> (14 - dex));
      return (sign) ? -dq : dq;
#else
      dq = (dqt << 7) >> (14 - dex);
      return (sign) ? (dq - 0x8000) : dq;
#endif
   }
}

step_size()

static int step_size ( struct g726_state *  state_ptr )

static

Definition at line 247 of file codec_g726.c.

References g726_state::ap, g726_state::yl, and g726_state::yu.

Referenced by g726_decode(), g726_encode(), and smb_pitch_shift().

{
   int y, dif, al;

   if (state_ptr->ap >= 256) {
      return state_ptr->yu;
   }

   y = state_ptr->yl >> 6;
   dif = state_ptr->yu - y;
   al = state_ptr->ap >> 2;

   if (dif > 0) {
      y += (dif * al) >> 6;
   } else if (dif < 0) {
      y += (dif * al + 0x3F) >> 6;
   }
   return y;
}

unload_module()

static int unload_module ( void  )

static

Definition at line 868 of file codec_g726.c.

References ast_unregister_translator().

Referenced by load_module().

{
   int res = 0;

   res |= ast_unregister_translator(&g726tolin);
   res |= ast_unregister_translator(&lintog726);

   res |= ast_unregister_translator(&g726aal2tolin);
   res |= ast_unregister_translator(&lintog726aal2);

   return res;
}

update()

static void update ( int  code_size, int  y, int  wi, int  fi, int  dq, int  sr, int  dqsez, struct g726_state *  state_ptr  )

static

Definition at line 367 of file codec_g726.c.

References g726_state::a, abs, g726_state::ap, g726_state::b, g726_state::dml, g726_state::dms, g726_state::dq, if(), ilog2(), g726_state::pk, g726_state::sr, g726_state::td, g726_state::yl, and g726_state::yu.

Referenced by ast_bridge_publish_state(), ast_channel_publish_final_snapshot(), ast_channel_publish_snapshot(), AST_TEST_DEFINE(), bridge_publish_state_from_blob(), bridge_snapshot_update(), bridge_snapshot_update_create(), bridge_snapshot_update_dtor(), bridge_topics_destroy(), cache_update(), cache_update_cb(), caching_topic_exec(), cel_snapshot_update_cb(), channel_snapshot_update(), channel_snapshot_update_create(), channel_snapshot_update_dtor(), config_device(), config_line(), connectedline_write(), endpoint_cache_clear(), find_route(), g726_decode(), g726_encode(), handle_bridge_enter_message(), handle_bridge_leave_message(), handle_channel_snapshot_update_message(), load_module(), load_pktccops_config(), redirecting_write(), stasis_cache_update_dtor(), sub_bridge_update_handler(), sub_channel_update_handler(), sub_endpoint_update_handler(), unload_module(), update_create(), and updates().

{
   int      cnt;
   int      mag;     /* Adaptive predictor, FLOAT A */
#ifndef NOT_BLI
   int      exp;
#endif
   int      a2p=0;      /* LIMC */
   int      a1ul;    /* UPA1 */
   int      pks1;    /* UPA2 */
   int      fa1;
   int      tr;         /* tone/transition detector */
   int      ylint, thr2, dqthr;
   int      ylfrac, thr1;
   int      pk0;

   pk0 = (dqsez < 0) ? 1 : 0; /* needed in updating predictor poles */

#ifdef NOT_BLI
   mag = abs(dq / 0x1000); /* prediction difference magnitude */
#else
   mag = dq & 0x7FFF;      /* prediction difference magnitude */
#endif
   /* TRANS */
   ylint = state_ptr->yl >> 15;  /* exponent part of yl */
   ylfrac = (state_ptr->yl >> 10) & 0x1F; /* fractional part of yl */
   thr1 = (32 + ylfrac) << ylint;      /* threshold */
   thr2 = (ylint > 9) ? 31 << 10 : thr1;  /* limit thr2 to 31 << 10 */
   dqthr = (thr2 + (thr2 >> 1)) >> 1;  /* dqthr = 0.75 * thr2 */
   if (state_ptr->td == 0) {     /* signal supposed voice */
      tr = 0;
   } else if (mag <= dqthr) {    /* supposed data, but small mag */
      tr = 0;        /* treated as voice */
   } else {          /* signal is data (modem) */
      tr = 1;
   }
   /*
    * Quantizer scale factor adaptation.
    */

   /* FUNCTW & FILTD & DELAY */
   /* update non-steady state step size multiplier */
   state_ptr->yu = y + ((wi - y) >> 5);

   /* LIMB */
   if (state_ptr->yu < 544) { /* 544 <= yu <= 5120 */
      state_ptr->yu = 544;
   } else if (state_ptr->yu > 5120) {
      state_ptr->yu = 5120;
   }

   /* FILTE & DELAY */
   /* update steady state step size multiplier */
   state_ptr->yl += state_ptr->yu + ((-state_ptr->yl) >> 6);

   /*
    * Adaptive predictor coefficients.
    */
   if (tr == 1) {       /* reset a's and b's for modem signal */
      state_ptr->a[0] = 0;
      state_ptr->a[1] = 0;
      state_ptr->b[0] = 0;
      state_ptr->b[1] = 0;
      state_ptr->b[2] = 0;
      state_ptr->b[3] = 0;
      state_ptr->b[4] = 0;
      state_ptr->b[5] = 0;
   } else {       /* update a's and b's */
      pks1 = pk0 ^ state_ptr->pk[0];      /* UPA2 */

      /* update predictor pole a[1] */
      a2p = state_ptr->a[1] - (state_ptr->a[1] >> 7);
      if (dqsez != 0) {
         fa1 = (pks1) ? state_ptr->a[0] : -state_ptr->a[0];
         if (fa1 < -8191) {   /* a2p = function of fa1 */
            a2p -= 0x100;
         } else if (fa1 > 8191) {
            a2p += 0xFF;
         } else {
            a2p += fa1 >> 5;
         }

         if (pk0 ^ state_ptr->pk[1]) {
            /* LIMC */
            if (a2p <= -12160) {
               a2p = -12288;
            } else if (a2p >= 12416) {
               a2p = 12288;
            } else {
               a2p -= 0x80;
            }
         } else if (a2p <= -12416) {
            a2p = -12288;
         } else if (a2p >= 12160) {
            a2p = 12288;
         } else {
            a2p += 0x80;
         }
      }

      /* TRIGB & DELAY */
      state_ptr->a[1] = a2p;

      /* UPA1 */
      /* update predictor pole a[0] */
      state_ptr->a[0] -= state_ptr->a[0] >> 8;
      if (dqsez != 0) {
         if (pks1 == 0)
            state_ptr->a[0] += 192;
         else
            state_ptr->a[0] -= 192;
      }
      /* LIMD */
      a1ul = 15360 - a2p;
      if (state_ptr->a[0] < -a1ul) {
         state_ptr->a[0] = -a1ul;
      } else if (state_ptr->a[0] > a1ul) {
         state_ptr->a[0] = a1ul;
      }

      /* UPB : update predictor zeros b[6] */
      for (cnt = 0; cnt < 6; cnt++) {
         if (code_size == 5) {      /* for 40Kbps G.723 */
            state_ptr->b[cnt] -= state_ptr->b[cnt] >> 9;
         } else {       /* for G.721 and 24Kbps G.723 */
            state_ptr->b[cnt] -= state_ptr->b[cnt] >> 8;
         }
         if (mag) {  /* XOR */
            if ((dq ^ state_ptr->dq[cnt]) >= 0) {
               state_ptr->b[cnt] += 128;
            } else {
               state_ptr->b[cnt] -= 128;
            }
         }
      }
   }

   for (cnt = 5; cnt > 0; cnt--)
      state_ptr->dq[cnt] = state_ptr->dq[cnt-1];
#ifdef NOT_BLI
   state_ptr->dq[0] = dq;
#else
   /* FLOAT A : convert dq[0] to 4-bit exp, 6-bit mantissa f.p. */
   if (mag == 0) {
      state_ptr->dq[0] = (dq >= 0) ? 0x20 : 0x20 - 0x400;
   } else {
      exp = ilog2(mag) + 1;
      state_ptr->dq[0] = (dq >= 0) ?
          (exp << 6) + ((mag << 6) >> exp) :
          (exp << 6) + ((mag << 6) >> exp) - 0x400;
   }
#endif

   state_ptr->sr[1] = state_ptr->sr[0];
#ifdef NOT_BLI
   state_ptr->sr[0] = sr;
#else
   /* FLOAT B : convert sr to 4-bit exp., 6-bit mantissa f.p. */
   if (sr == 0) {
      state_ptr->sr[0] = 0x20;
   } else if (sr > 0) {
      exp = ilog2(sr) + 1;
      state_ptr->sr[0] = (exp << 6) + ((sr << 6) >> exp);
   } else if (sr > -0x8000) {
      mag = -sr;
      exp = ilog2(mag) + 1;
      state_ptr->sr[0] =  (exp << 6) + ((mag << 6) >> exp) - 0x400;
   } else
      state_ptr->sr[0] = 0x20 - 0x400;
#endif

   /* DELAY A */
   state_ptr->pk[1] = state_ptr->pk[0];
   state_ptr->pk[0] = pk0;

   /* TONE */
   if (tr == 1) {    /* this sample has been treated as data */
      state_ptr->td = 0;   /* next one will be treated as voice */
   } else if (a2p < -11776) { /* small sample-to-sample correlation */
      state_ptr->td = 1;   /* signal may be data */
   } else {          /* signal is voice */
      state_ptr->td = 0;
   }

   /*
    * Adaptation speed control.
    */
   state_ptr->dms += (fi - state_ptr->dms) >> 5;      /* FILTA */
   state_ptr->dml += (((fi << 2) - state_ptr->dml) >> 7);   /* FILTB */

   if (tr == 1) {
      state_ptr->ap = 256;
   } else if (y < 1536) {              /* SUBTC */
      state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
   } else if (state_ptr->td == 1) {
      state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
   } else if (abs((state_ptr->dms << 2) - state_ptr->dml) >=
       (state_ptr->dml >> 3)) {
      state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
   } else {
      state_ptr->ap += (-state_ptr->ap) >> 4;
   }
}

Variable Documentation

__mod_info

struct ast_module_info __mod_info = { .name = AST_MODULE, .flags = AST_MODFLAG_DEFAULT , .description = "ITU G.726-32kbps G726 Transcoder" , .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 = "30ef0c93b36035ec78c9cfd712d36d9b" , .support_level = AST_MODULE_SUPPORT_CORE, .load = load_module, .unload = unload_module, }

static

Definition at line 903 of file codec_g726.c.

_dqlntab

int _dqlntab[16]

static

Initial value:

= {-2048, 4, 135, 213, 273, 323, 373, 425,
            425, 373, 323, 273, 213, 135, 4, -2048}

Definition at line 101 of file codec_g726.c.

Referenced by g726_decode(), and g726_encode().

_fitab

int _fitab[16]

static

Initial value:

= {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00,
            0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0}

Definition at line 112 of file codec_g726.c.

Referenced by g726_decode(), and g726_encode().

_witab

int _witab[16]

static

Initial value:

= {-12, 18, 41, 64, 112, 198, 355, 1122,
            1122, 355, 198, 112, 64, 41, 18, -12}

Definition at line 105 of file codec_g726.c.

Referenced by g726_decode(), and g726_encode().

ast_module_info

const struct ast_module_info* ast_module_info = &__mod_info

static

Definition at line 903 of file codec_g726.c.

g726aal2tolin

struct ast_translator g726aal2tolin

static

Definition at line 826 of file codec_g726.c.

g726tolin

struct ast_translator g726tolin

static

Definition at line 784 of file codec_g726.c.

lintog726

struct ast_translator lintog726

static

Definition at line 805 of file codec_g726.c.

lintog726aal2

struct ast_translator lintog726aal2

static

Definition at line 847 of file codec_g726.c.

qtab_721

int qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400}

static

Definition at line 96 of file codec_g726.c.

Referenced by g726_encode().