c8_31pf.cpp

实现3GPP的GSM中AMR语音的CODECS。

 When the code is written for a specific target processor the
 the resources used should be documented below.

 HEAP MEMORY USED: x bytes

 STACK MEMORY USED: x bytes

 CLOCK CYCLES: (cycle count equation for this function) + (variable
                used to represent cycle count for each subroutine
                called)
     where: (cycle count variable) = cycle count for [subroutine
                                     name]

------------------------------------------------------------------------------
 CAUTION [optional]
 [State any special notes, constraints or cautions for users of this function]

------------------------------------------------------------------------------
*/

static Word16 compress10(
    Word16 pos_indxA,  /* i : signs of 4 pulses (signs only)             */
    Word16 pos_indxB,  /* i : position index of 8 pulses (pos only)      */
    Word16 pos_indxC,  /* i : position and sign of 8 pulses (compressed) */
    Flag  *pOverflow)  /* o : Flag set when overflow occurs              */
{
    Word16 indx;
    Word16 ia;
    Word16 ib;
    Word16 ic;

    Word32 tempWord32;

    OSCL_UNUSED_ARG(pOverflow);

    ia = pos_indxA >> 1;

    ib = pos_indxB >> 1;

    tempWord32 = ((Word32) ib * 5) << 1;

    tempWord32 = tempWord32 >> 1;

    ib = (Word16) tempWord32;

    ic = pos_indxC >> 1;

    tempWord32 = ((Word32) ic * 25) << 1;

    tempWord32 = tempWord32 >> 1;

    ic = (Word16) tempWord32;

    ib += ic;

    ib += ia;

    indx = ib << 3;

    ia = pos_indxA & 1;

    ib = ((Word16)(pos_indxB & 1)) << 1;

    ic = ((Word16)(pos_indxC & 1)) << 2;

    ib += ic;

    ib += ia;

    indx += ib;

    return indx;

}

/****************************************************************************/

/*
------------------------------------------------------------------------------
 FUNCTION NAME: compress_code()
------------------------------------------------------------------------------
 INPUT AND OUTPUT DEFINITIONS

 Inputs:
    sign_indx   Array of type Word16 -- signs of 4 pulses (signs only)
    pos_indx    Array of type Word16 -- position index of 8 pulses
                                            (position only)

 Outputs:
    indx         Array of type Word16 -- position and sign of 8 pulses
                                            (compressed)
    pOverflow    Pointer to Flag      -- set when overflow occurs

 Returns:
    None

 Global Variables Used:
    None

 Local Variables Needed:
    None

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

 PURPOSE: compression of the linear codewords to 4+three indeces
          one bit from each pulse is made robust to errors by
          minimizing the phase shift of a bit error.
          4 signs (one for each track)
          i0,i4,i1 => one index (7+3) bits, 3   LSBs more robust
          i2,i6,i5 => one index (7+3) bits, 3   LSBs more robust
          i3,i7    => one index (5+2) bits, 2-3 LSbs more robust

------------------------------------------------------------------------------
 REQUIREMENTS

 None

------------------------------------------------------------------------------
 REFERENCES

 [1] c3_14pf.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001

------------------------------------------------------------------------------
 PSEUDO-CODE

------------------------------------------------------------------------------
 RESOURCES USED [optional]

 When the code is written for a specific target processor the
 the resources used should be documented below.

 HEAP MEMORY USED: x bytes

 STACK MEMORY USED: x bytes

 CLOCK CYCLES: (cycle count equation for this function) + (variable
                used to represent cycle count for each subroutine
                called)
     where: (cycle count variable) = cycle count for [subroutine
                                     name]

------------------------------------------------------------------------------
 CAUTION [optional]
 [State any special notes, constraints or cautions for users of this function]

------------------------------------------------------------------------------
*/

static void compress_code(
    Word16 sign_indx[], /* i : signs of 4 pulses (signs only)             */
    Word16 pos_indx[],  /* i : position index of 8 pulses (position only) */
    Word16 indx[],      /* o : position and sign of 8 pulses (compressed) */
    Flag  *pOverflow)   /* o : Flag set when overflow occurs              */
{
    Word16 i;
    Word16 ia;
    Word16 ib;
    Word16 ic;

    Word16 *p_indx = &indx[0];
    Word16 *p_sign_indx = &sign_indx[0];

    Word32 tempWord32;

    for (i = 0; i < NB_TRACK_MR102; i++)
    {
        *(p_indx++) = *(p_sign_indx++);
    }

    /* First index
      indx[NB_TRACK] = (ia/2+(ib/2)*5 +(ic/2)*25)*8 + ia%2 + (ib%2)*2 + (ic%2)*4; */

    indx[NB_TRACK_MR102] =
        compress10(
            pos_indx[0],
            pos_indx[4],
            pos_indx[1],
            pOverflow);

    /* Second index
      indx[NB_TRACK+1] = (ia/2+(ib/2)*5 +(ic/2)*25)*8 + ia%2 + (ib%2)*2 + (ic%2)*4; */

    indx[NB_TRACK_MR102+1] =
        compress10(
            pos_indx[2],
            pos_indx[6],
            pos_indx[5],
            pOverflow);

    /*
      Third index
      if ((ib/2)%2 == 1)
        indx[NB_TRACK+2] = ((((4-ia/2) + (ib/2)*5)*32+12)/25)*4 + ia%2 + (ib%2)*2;
      else
        indx[NB_TRACK+2] = ((((ia/2) +   (ib/2)*5)*32+12)/25)*4 + ia%2 + (ib%2)*2;
        */

    ib = pos_indx[7] >> 1;

    ib &= 1;

    ia = pos_indx[3] >> 1;

    if (ib == 1)
    {
        ia = 4 - ia;
    }

    ib = pos_indx[7] >> 1;

    tempWord32 = ((Word32) ib * 5) << 1;

    tempWord32 = tempWord32 >> 1;

    ib = (Word16) tempWord32;

    ib += ia;

    ib <<= 5;

    ib += 12;

    ic = (Word16)(((Word32) ib * 1311) >> 15);

    ic <<= 2;

    ia = pos_indx[3] & 1;

    ib = ((Word16)(pos_indx[7] & 1)) << 1;

    ib += ic;

    ib += ia;

    indx[NB_TRACK_MR102+2] = ib;

} /* compress_code */


/****************************************************************************/

/*
------------------------------------------------------------------------------
 FUNCTION NAME: code_8i40_31bits()
------------------------------------------------------------------------------
 INPUT AND OUTPUT DEFINITIONS

 Inputs:
    x   Array of type Word16 -- target vector
    cn  Array of type Word16 -- residual after long term prediction
    h   Array of type Word16 -- impulse response of weighted synthesis filter


 Outputs:
    cod Array of type Word16 -- algebraic (fixed) codebook excitation
    y   Array of type Word16 -- filtered fixed codebook excitation
    indx Array of type Word16 -- index of 8 pulses (signs+positions)
    pOverflow    Pointer to Flag      -- set when overflow occurs

 Returns:
    None

 Global Variables Used:
    None

 Local Variables Needed:
    None

------------------------------------------------------------------------------
 FUNCTION DESCRIPTION

 FUNCTION:

 PURPOSE:  Searches a 31 bit algebraic codebook containing 8 pulses
           in a frame of 40 samples.

 DESCRIPTION:
   The code contains 8 nonzero pulses: i0...i7.
   All pulses can have two possible amplitudes: +1 or -1.
   The 40 positions in a subframe are divided into 4 tracks of
   interleaved positions. Each track contains two pulses.
   The pulses can have the following possible positions:

      i0, i4 :  0, 4, 8,  12, 16, 20, 24, 28, 32, 36
      i1, i5 :  1, 5, 9,  13, 17, 21, 25, 29, 33, 37
      i2, i6 :  2, 6, 10, 14, 18, 22, 26, 30, 34, 38
      i3, i7 :  3, 7, 11, 15, 19, 23, 27, 31, 35, 39

   Each pair of pulses require 1 bit for their signs. The positions
   are encoded together 3,3 and 2 resulting in
   (7+3) + (7+3) + (5+2) bits for their
   positions. This results in a 31 (4 sign and 27 pos) bit codebook.
   The function determines the optimal pulse signs and positions, builds
   the codevector, and computes the filtered codevector.

------------------------------------------------------------------------------
 REQUIREMENTS

 None

------------------------------------------------------------------------------
 REFERENCES

 [1] c8_31pf.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001

------------------------------------------------------------------------------
 PSEUDO-CODE

------------------------------------------------------------------------------
 RESOURCES USED [optional]

 When the code is written for a specific target processor the
 the resources used should be documented below.

 HEAP MEMORY USED: x bytes

 STACK MEMORY USED: x bytes

 CLOCK CYCLES: (cycle count equation for this function) + (variable
                used to represent cycle count for each subroutine
                called)
     where: (cycle count variable) = cycle count for [subroutine
                                     name]

------------------------------------------------------------------------------
 CAUTION [optional]
 [State any special notes, constraints or cautions for users of this function]

------------------------------------------------------------------------------
*/
void code_8i40_31bits(
    Word16 x[],        /* i : target vector                                  */
    Word16 cn[],       /* i : residual after long term prediction            */
    Word16 h[],        /* i : impulse response of weighted synthesis
                             filter                                         */
    Word16 cod[],      /* o : algebraic (fixed) codebook excitation          */
    Word16 y[],        /* o : filtered fixed codebook excitation             */
    Word16 indx[],     /* o : 7 Word16, index of 8 pulses (signs+positions)  */
    Flag  *pOverflow   /* o : Flag set when overflow occurs                  */
)
{
    Word16 ipos[NB_PULSE];
    Word16 pos_max[NB_TRACK_MR102];
    Word16 codvec[NB_PULSE];

    Word16 dn[L_CODE];
    Word16 sign[L_CODE];

    Word16 rr[L_CODE][L_CODE];
    Word16 linear_signs[NB_TRACK_MR102];
    Word16 linear_codewords[NB_PULSE];

    cor_h_x2(
        h,
        x,
        dn,
        2,
        NB_TRACK_MR102,
        STEP_MR102,
        pOverflow);

    /* 2 = use GSMEFR scaling */

    set_sign12k2(
        dn,
        cn,
        sign,
        pos_max,
        NB_TRACK_MR102,
        ipos,
        STEP_MR102,
        pOverflow);

    /* same setsign alg as GSM-EFR new constants though*/

    cor_h(
        h,
        sign,
        rr,
        pOverflow);

    search_10and8i40(
        NB_PULSE,
        STEP_MR102,
        NB_TRACK_MR102,
        dn,
        rr,
        ipos,
        pos_max,
        codvec,
        pOverflow);

    build_code(
        codvec,
        sign,
        cod,
        h,
        y,
        linear_signs,
        linear_codewords,
        pOverflow);

    compress_code(
        linear_signs,
        linear_codewords,
        indx,
        pOverflow);

} /* code_8i40_31bits */