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libgsmhr1 RxFE: store CN R0+LPC separately from speech In the original GSM 06.06 code the ECU for speech mode is entirely separate from the CN generator, maintaining separate state. (The main intertie between them is the speech vs CN state variable, distinguishing between speech and CN BFIs, in addition to the CN-specific function of distinguishing between initial and update SIDs.) In the present RxFE implementation I initially thought that we could use the same saved_frame buffer for both ECU and CN, overwriting just the first 4 params (R0 and LPC) when a valid SID comes in. However, I now realize it was a bad idea: the original code has a corner case (long sequence of speech-mode BFIs to put the ECU in state 6, then SID and CN-mode BFIs, then a good speech frame) that would be broken by that buffer reuse approach. We could eliminate this corner case by resetting the ECU state when passing through a CN insertion period, but doing so would needlessly increase the behavioral diffs between GSM 06.06 and our version. Solution: use a separate CN-specific buffer for CN R0+LPC parameters, and match the behavior of GSM 06.06 code in this regard.
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 13 Feb 2025 10:02:45 +0000
parents 9beb01439a90
children
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/*
 * This module holds the bitno[] table (intermodule linkage)
 * and the set of static per-mode tables referenced from it,
 * originally in bitno.tab in 3GPP reference source.
 */

#include "typedef.h"
#include "namespace.h"
#include "int_defs.h"

/* parameter sizes (# of bits), one table per mode */

static const Word16 bitno_MR475[PRMNO_MR475] = {
   8, 8, 7,                                 /* LSP VQ          */
   8, 7, 2, 8,                              /* first subframe  */
   4, 7, 2,                                 /* second subframe */
   4, 7, 2, 8,                              /* third subframe  */
   4, 7, 2,                                 /* fourth subframe */
};

static const Word16 bitno_MR515[PRMNO_MR515] = {
   8, 8, 7,                                 /* LSP VQ          */
   8, 7, 2, 6,                              /* first subframe  */
   4, 7, 2, 6,                              /* second subframe */
   4, 7, 2, 6,                              /* third subframe  */
   4, 7, 2, 6,                              /* fourth subframe */
};

static const Word16 bitno_MR59[PRMNO_MR59] = {
   8, 9, 9,                                 /* LSP VQ          */
   8, 9, 2, 6,                              /* first subframe  */
   4, 9, 2, 6,                              /* second subframe */
   8, 9, 2, 6,                              /* third subframe  */
   4, 9, 2, 6,                              /* fourth subframe */
};

static const Word16 bitno_MR67[PRMNO_MR67] = {
   8, 9, 9,                                 /* LSP VQ          */
   8, 11, 3, 7,                             /* first subframe  */
   4, 11, 3, 7,                             /* second subframe */
   8, 11, 3, 7,                             /* third subframe  */
   4, 11, 3, 7,                             /* fourth subframe */
};

static const Word16 bitno_MR74[PRMNO_MR74] = {
   8, 9, 9,                                 /* LSP VQ          */
   8, 13, 4, 7,                             /* first subframe  */
   5, 13, 4, 7,                             /* second subframe */
   8, 13, 4, 7,                             /* third subframe  */
   5, 13, 4, 7,                             /* fourth subframe */
};

static const Word16 bitno_MR795[PRMNO_MR795] = {
   9, 9, 9,                                 /* LSP VQ          */
   8, 13, 4, 4, 5,                          /* first subframe  */
   6, 13, 4, 4, 5,                          /* second subframe */
   8, 13, 4, 4, 5,                          /* third subframe  */
   6, 13, 4, 4, 5,                          /* fourth subframe */
};

static const Word16 bitno_MR102[PRMNO_MR102] = {
   8, 9, 9,                                 /* LSP VQ          */
   8, 1, 1, 1, 1, 10, 10, 7, 7,             /* first subframe  */
   5, 1, 1, 1, 1, 10, 10, 7, 7,             /* second subframe */
   8, 1, 1, 1, 1, 10, 10, 7, 7,             /* third subframe  */
   5, 1, 1, 1, 1, 10, 10, 7, 7,             /* fourth subframe */
};

static const Word16 bitno_MR122[PRMNO_MR122] = {
   7, 8, 9, 8, 6,                           /* LSP VQ          */
   9, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 5,   /* first subframe  */
   6, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 5,   /* second subframe */
   9, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 5,   /* third subframe  */
   6, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 5    /* fourth subframe */
};

static const Word16 bitno_MRDTX[PRMNO_MRDTX] = {
  3,
  8, 9, 9,
  6
};

/* overall table with all parameter sizes for all modes */
const Word16 * const bitno[9] = {
   bitno_MR475,
   bitno_MR515,
   bitno_MR59,
   bitno_MR67,
   bitno_MR74,
   bitno_MR795,
   bitno_MR102,
   bitno_MR122,
   bitno_MRDTX
};