dec_gain.c
上传用户:zhongxx05
上传日期:2007-06-06
资源大小:33641k
文件大小:21k
- /*
- *===================================================================
- * 3GPP AMR Wideband Floating-point Speech Codec
- *===================================================================
- */
- #include "hlxclib/memory.h"
- #include "typedef.h"
- #include "dec_util.h"
- #define L_SUBFR 64 /* Subframe size */
- #define L_LTPHIST 5
- #define ONE_PER_3 10923
- #define ONE_PER_LTPHIST 6554
- #define UP_SAMP 4
- #define L_INTERPOL2 16
- extern const Word16 D_ROM_inter4_2[];
- extern const Word16 D_ROM_pdown_unusable[];
- extern const Word16 D_ROM_pdown_usable[];
- extern const Word16 D_ROM_cdown_unusable[];
- extern const Word16 D_ROM_cdown_usable[];
- extern const Word16 D_ROM_qua_gain6b[];
- extern const Word16 D_ROM_qua_gain7b[];
- /*
- * D_GAIN_init
- *
- * Parameters:
- * mem O: static memory
- *
- * Function:
- * Initialisation of 2nd order quantiser energy predictor.
- *
- * Returns:
- * void
- */
- void D_GAIN_init(Word16 *mem)
- {
- /* 4nd order quantizer energy predictor (init to -14.0 in Q10) */
- mem[0] = -14336; /* past_qua_en[0] */
- mem[1] = -14336; /* past_qua_en[1] */
- mem[2] = -14336; /* past_qua_en[2] */
- mem[3] = -14336; /* past_qua_en[3] */
- /*
- * mem[4] = 0; past_gain_pit
- * mem[5] = 0; past_gain_code
- * mem[6] = 0; prev_gc
- * mem[7 - 11] = 0; pbuf[i]
- * mem[12 - 16] = 0; gbuf[i]
- * mem[17 - 21] = 0; pbuf2[i]
- */
- memset(&mem[4], 0, 18 * sizeof(Word16));
- mem[22] = 21845; /* seed */
- return;
- }
- /*
- * D_GAIN_median
- *
- * Parameters:
- * buf I: previous gains
- *
- * Function:
- * Median of gains
- *
- * Returns:
- * median of 5 previous gains
- */
- static Word16 D_GAIN_median(Word16 x[])
- {
- Word16 x1, x2, x3, x4, x5;
- Word16 tmp;
- x1 = x[ - 2];
- x2 = x[ - 1];
- x3 = x[0];
- x4 = x[1];
- x5 = x[2];
- if(x2 < x1)
- {
- tmp = x1;
- x1 = x2;
- x2 = tmp;
- }
- if(x3 < x1)
- {
- tmp = x1;
- x1 = x3;
- x3 = tmp;
- }
- if(x4 < x1)
- {
- tmp = x1;
- x1 = x4;
- x4 = tmp;
- }
- if(x5 < x1)
- {
- x5 = x1;
- }
- if(x3 < x2)
- {
- tmp = x2;
- x2 = x3;
- x3 = tmp;
- }
- if(x4 < x2)
- {
- tmp = x2;
- x2 = x4;
- x4 = tmp;
- }
- if(x5 < x2)
- {
- x5 = x2;
- }
- if(x4 < x3)
- {
- x3 = x4;
- }
- if(x5 < x3)
- {
- x3 = x5;
- }
- return(x3);
- }
- /*
- * D_GAIN_decode
- *
- * Parameters:
- * index I: Quantization index
- * nbits I: number of bits (6 or 7)
- * code I: Innovative code vector
- * L_subfr I: Subframe size
- * gain_pit O: (Q14) Quantized pitch gain
- * gain_code O: (Q16) Quantized codebook gain
- * bfi I: Bad frame indicator
- * prev_bfi I: Previous BF indicator
- * state I: State of BFH
- * unusable_frame I: UF indicator
- * vad_hist I: number of non-speech frames
- * mem I/O: static memory (4 words)
- *
- *
- * Function:
- * Decoding of pitch and codebook gains
- *
- * Returns:
- * void
- */
- void D_GAIN_decode(Word16 index, Word16 nbits, Word16 code[], Word16 *gain_pit,
- Word32 *gain_cod, Word16 bfi, Word16 prev_bfi,
- Word16 state, Word16 unusable_frame, Word16 vad_hist,
- Word16 *mem)
- {
- Word32 gcode0, qua_ener, L_tmp;
- const Word16 * p;
- Word16 *past_gain_pit, *past_gain_code, *past_qua_en, *prev_gc;
- Word16 *gbuf, *pbuf, *pbuf2;
- Word16 i, tmp, exp, frac, exp_gcode0, gcode_inov;
- Word16 g_code;
- past_qua_en = mem;
- past_gain_pit = mem + 4;
- past_gain_code = mem + 5;
- prev_gc = mem + 6;
- pbuf = mem + 7;
- gbuf = mem + 12;
- pbuf2 = mem + 17;
- /*
- * Find energy of code and compute:
- *
- * L_tmp = 1.0 / sqrt(energy of code/ L_subfr)
- */
- L_tmp = D_UTIL_dot_product12(code, code, L_SUBFR, &exp);
- exp = (Word16)(exp - (18 + 6)); /* exp: -18 (code in Q9), -6 (/L_subfr) */
- D_UTIL_normalised_inverse_sqrt(&L_tmp, &exp);
- if(exp > 3)
- {
- L_tmp <<= (exp - 3);
- }
- else
- {
- L_tmp >>= (3 - exp);
- }
- gcode_inov = (Word16)(L_tmp >>16); /* g_code_inov in Q12 */
- /*
- * Case of erasure.
- */
- if(bfi != 0)
- {
- tmp = D_GAIN_median(&pbuf[2]);
- *past_gain_pit = tmp;
- if(*past_gain_pit > 15565)
- {
- *past_gain_pit = 15565; /* 0.95 in Q14 */
- }
- if(unusable_frame != 0)
- {
- *gain_pit =
- (Word16)((D_ROM_pdown_unusable[state] * *past_gain_pit) >> 15);
- }
- else
- {
- *gain_pit =
- (Word16)((D_ROM_pdown_usable[state] * *past_gain_pit) >> 15);
- }
- tmp = D_GAIN_median(&gbuf[2]);
- if(vad_hist > 2)
- {
- *past_gain_code = tmp;
- }
- else
- {
- if(unusable_frame != 0)
- {
- *past_gain_code =
- (Word16)((D_ROM_cdown_unusable[state] * tmp) >> 15);
- }
- else
- {
- *past_gain_code =
- (Word16)((D_ROM_cdown_usable[state] * tmp) >> 15);
- }
- }
- /* update table of past quantized energies */
- L_tmp = past_qua_en[0] + past_qua_en[1]+ past_qua_en[2] + past_qua_en[3];
- qua_ener = L_tmp >> 2;
- qua_ener = qua_ener - 3072; /* -3 in Q10 */
- if(qua_ener < - 14336)
- {
- qua_ener = -14336; /* -14 in Q10 */
- }
- past_qua_en[3] = past_qua_en[2];
- past_qua_en[2] = past_qua_en[1];
- past_qua_en[1] = past_qua_en[0];
- past_qua_en[0] = (Word16)qua_ener;
- for(i = 1; i < 5; i++)
- {
- gbuf[i - 1] = gbuf[i];
- }
- gbuf[4] = *past_gain_code;
- for(i = 1; i < 5; i++)
- {
- pbuf[i - 1] = pbuf[i];
- }
- pbuf[4] = *past_gain_pit;
- /* adjust gain according to energy of code */
- /* past_gain_code(Q3) * gcode_inov(Q12) => Q16 */
- *gain_cod = (*past_gain_code * gcode_inov) << 1;
- return;
- }
- /*
- * Compute gcode0.
- * = Sum(i=0,1) pred[i]*past_qua_en[i] + mean_ener - ener_code
- */
- /* MEAN_ENER in Q24 = 0x1e000000 */
- /* MA prediction coeff = {0.5, 0.4, 0.3, 0.2} in Q13 */
- L_tmp = 0xF000000 + (4096 * past_qua_en[0]); /* Q13*Q10 -> Q24 */
- L_tmp = L_tmp + (3277 * past_qua_en[1]); /* Q13*Q10 -> Q24 */
- L_tmp = L_tmp + (2458 * past_qua_en[2]); /* Q13*Q10 -> Q24 */
- L_tmp = L_tmp + (1638 * past_qua_en[3]); /* Q13*Q10 -> Q24 */
- gcode0 = L_tmp >> 15; /* From Q24 to Q8 */
- /*
- * gcode0 = pow(10.0, gcode0/20)
- * = pow(2, 3.321928*gcode0/20)
- * = pow(2, 0.166096*gcode0)
- */
- L_tmp = (gcode0 * 5443) >> 7;
- /* *0.166096 in Q15 -> Q24, From Q24 to Q16 */
- D_UTIL_l_extract(L_tmp, &exp_gcode0, &frac);
- /* Extract exponant of gcode0 */
- gcode0 = D_UTIL_pow2(14, frac); /* Put 14 as exponant so that */
- /*
- * output of Pow2() will be:
- * 16384 < Pow2() <= 32767
- */
- exp_gcode0 = (Word16)(exp_gcode0 - 14);
- /* Read the quantized gains */
- if(nbits == 6)
- {
- p = &D_ROM_qua_gain6b[(index << 1)];
- }
- else
- {
- p = &D_ROM_qua_gain7b[(index << 1)];
- }
- *gain_pit = *p++; /* selected pitch gain in Q14 */
- g_code = *p++; /* selected code gain in Q11 */
- L_tmp = g_code * gcode0;
- exp_gcode0 += 5;
- if(exp_gcode0 >= 0)
- {
- *gain_cod = L_tmp << exp_gcode0; /* gain of code in Q16 */
- }
- else
- {
- *gain_cod = L_tmp >> -exp_gcode0; /* gain of code in Q16 */
- }
- if(prev_bfi == 1)
- {
- L_tmp = (*prev_gc * 5120) << 1; /* prev_gc(Q3) * 1.25(Q12) = Q16 */
- /* if((*gain_cod > ((*prev_gc) * 1.25)) && (*gain_cod > 100.0)) */
- if((*gain_cod > L_tmp) & (*gain_cod > 6553600))
- {
- *gain_cod = L_tmp;
- }
- }
- /* keep past gain code in Q3 for frame erasure (can saturate) */
- L_tmp = (*gain_cod + 0x1000) >> 13;
- if(L_tmp < 32768)
- {
- *past_gain_code = (Word16)L_tmp;
- }
- else
- {
- *past_gain_code = 32767;
- }
- *past_gain_pit = *gain_pit;
- *prev_gc = *past_gain_code;
- for(i = 1; i < 5; i++)
- {
- gbuf[i - 1] = gbuf[i];
- }
- gbuf[4] = *past_gain_code;
- for(i = 1; i < 5; i++)
- {
- pbuf[i - 1] = pbuf[i];
- }
- pbuf[4] = *past_gain_pit;
- for(i = 1; i < 5; i++)
- {
- pbuf2[i - 1] = pbuf2[i];
- }
- pbuf2[4] = *past_gain_pit;
- /* adjust gain according to energy of code */
- D_UTIL_l_extract(*gain_cod, &exp, &frac);
- L_tmp = D_UTIL_mpy_32_16(exp, frac, gcode_inov);
- if(L_tmp < 0xFFFFFFF)
- {
- *gain_cod = (L_tmp << 3); /* gcode_inov in Q12 */
- }
- else
- {
- *gain_cod = 0x7FFFFFFF;
- }
- /*
- * qua_ener = 20*log10(g_code)
- * = 6.0206*log2(g_code)
- * = 6.0206*(log2(g_codeQ11) - 11)
- */
- L_tmp = (Word32)(g_code);
- D_UTIL_log2(L_tmp, &exp, &frac);
- exp = (Word16)(exp - 11);
- L_tmp = D_UTIL_mpy_32_16(exp, frac, 24660); /* x 6.0206 in Q12 */
- qua_ener = L_tmp >>3; /* result in Q10 */
- /* update table of past quantized energies */
- past_qua_en[3] = past_qua_en[2];
- past_qua_en[2] = past_qua_en[1];
- past_qua_en[1] = past_qua_en[0];
- past_qua_en[0] = (Word16)qua_ener;
- return;
- }
- /*
- * D_GAIN_adaptive_control
- *
- * Parameters:
- * sig_in I: postfilter input signal
- * sig_out I/O: postfilter output signal
- * l_trm I: subframe size
- *
- * Function:
- * Adaptive gain control is used to compensate for
- * the gain difference between the non-emphasized excitation and
- * emphasized excitation.
- *
- * Returns:
- * void
- */
- void D_GAIN_adaptive_control(Word16 *sig_in, Word16 *sig_out, Word16 l_trm)
- {
- Word32 s, temp, i, exp;
- Word32 gain_in, gain_out, g0;
- /* calculate gain_out with exponent */
- temp = sig_out[0] >> 2;
- s = temp * temp;
- for(i = 1; i < l_trm; i++)
- {
- temp = sig_out[i] >> 2;
- s += temp * temp;
- }
- s <<= 1;
- if(s == 0)
- {
- return;
- }
- exp = (D_UTIL_norm_l(s) - 1);
- if(exp >= 0)
- {
- gain_out = ((s << exp) + 0x8000) >> 16;
- }
- else
- {
- gain_out = ((s >> -exp) + 0x8000) >> 16;
- }
- /* calculate gain_in with exponent */
- temp = sig_in[0] >> 2;
- s = temp * temp;
- for(i = 1; i < l_trm; i++)
- {
- temp = sig_in[i] >> 2;
- s += temp * temp;
- }
- s <<= 1;
- if(s == 0)
- {
- g0 = 0;
- }
- else
- {
- i = D_UTIL_norm_l(s);
- s = ((s << i) + 0x8000) >> 16;
- if((s < 32768) & (s > 0))
- {
- gain_in = s;
- }
- else
- {
- gain_in = 32767;
- }
- exp = exp - i;
- /*
- * g0 = sqrt(gain_in/gain_out)
- */
- s = (gain_out << 15) / gain_in;
- s = s << (7 - exp); /* s = gain_out / gain_in */
- s = D_UTIL_inverse_sqrt(s);
- g0 = ((s << 9) + 0x8000) >> 16;
- }
- /* sig_out(n) = gain(n) sig_out(n) */
- for(i = 0; i < l_trm; i++)
- {
- s = (sig_out[i] * g0) >> 13;
- sig_out[i] = D_UTIL_saturate(s);
- }
- return;
- }
- /*
- * D_GAIN_insert_lag
- *
- * Parameters:
- * array I/O: pitch lag history
- * n I: history size
- * x I: lag value
- *
- * Function:
- * Insert lag into correct location
- *
- * Returns:
- * void
- */
- static void D_GAIN_insert_lag(Word16 array[], Word32 n, Word16 x)
- {
- Word32 i;
- for(i = n - 1; i >= 0; i--)
- {
- if(x < array[i])
- {
- array[i + 1] = array[i];
- }
- else
- {
- break;
- }
- }
- array[i + 1] = x;
- }
- /*
- * D_GAIN_sort_lag
- *
- * Parameters:
- * array I/O: pitch lag history
- * n I: history size
- *
- * Function:
- * Sorting of the lag history
- *
- * Returns:
- * void
- */
- static void D_GAIN_sort_lag(Word16 array[], Word16 n)
- {
- Word32 i;
- for(i = 0; i < n; i++)
- {
- D_GAIN_insert_lag(array, i, array[i]);
- }
- }
- /*
- * D_GAIN_lag_concealment_init
- *
- * Parameters:
- * lag_hist O: pitch lag history
- *
- * Function:
- * Initialise lag history to 64
- *
- * Returns:
- * void
- */
- void D_GAIN_lag_concealment_init(Word16 lag_hist[])
- {
- Word32 i;
- for(i = 0; i < L_LTPHIST; i++)
- {
- lag_hist[i] = 64;
- }
- }
- /*
- * D_GAIN_lag_concealment
- *
- * Parameters:
- * gain_hist I: gain history
- * lag_hist I: pitch lag history
- * T0 O: current lag
- * old_T0 I: previous lag
- * seed I/O: seed for random
- * unusable_frame I: lost frame
- *
- * Function:
- * Concealment of LTP lags during bad frames
- *
- * Returns:
- * void
- */
- void D_GAIN_lag_concealment(Word16 gain_hist[], Word16 lag_hist[],
- Word32 *T0, Word16 *old_T0, Word16 *seed,
- Word16 unusable_frame)
- {
- Word32 i, lagDif, tmp, tmp2, D2, meanLag = 0;
- Word16 lag_hist2[L_LTPHIST] = {0};
- Word16 maxLag, minLag, lastLag;
- Word16 minGain, lastGain, secLastGain;
- Word16 D;
- /*
- * Is lag index such that it can be aplied directly
- * or does it has to be subtituted
- */
- lastGain = gain_hist[4];
- secLastGain = gain_hist[3];
- lastLag = lag_hist[0];
- /* SMALLEST history lag */
- minLag = lag_hist[0];
- for(i = 1; i < L_LTPHIST; i++)
- {
- if(lag_hist[i] < minLag)
- {
- minLag = lag_hist[i];
- }
- }
- /* BIGGEST history lag */
- maxLag = lag_hist[0];
- for(i = 1; i < L_LTPHIST; i++)
- {
- if(lag_hist[i] > maxLag)
- {
- maxLag = lag_hist[i];
- }
- }
- /* SMALLEST history gain */
- minGain = gain_hist[0];
- for(i = 1; i < L_LTPHIST; i++)
- {
- if(gain_hist[i] < minGain)
- {
- minGain = gain_hist[i];
- }
- }
- /* Difference between MAX and MIN lag */
- lagDif = maxLag - minLag;
- if(unusable_frame != 0)
- {
- /*
- * LTP-lag for RX_SPEECH_LOST
- * Recognition of the LTP-history
- */
- if((minGain > 8192) & (lagDif < 10))
- {
- *T0 = *old_T0;
- }
- else if((lastGain > 8192) && (secLastGain > 8192))
- {
- *T0 = lag_hist[0];
- }
- else
- {
- /*
- * SORT
- * The sorting of the lag history
- */
- for(i = 0; i < L_LTPHIST; i++)
- {
- lag_hist2[i] = lag_hist[i];
- }
- D_GAIN_sort_lag(lag_hist2, 5);
- /*
- * Lag is weighted towards bigger lags
- * and random variation is added
- */
- lagDif = (lag_hist2[4] - lag_hist2[2]);
- if(lagDif > 40)
- {
- lagDif = 40;
- }
- D = D_UTIL_random(seed); /* D={-1, ...,1} */
- /* D2={-lagDif/2..lagDif/2} */
- tmp = lagDif >> 1;
- D2 = (tmp * D) >> 15;
- tmp = (lag_hist2[2] + lag_hist2[3]) + lag_hist2[4];
- *T0 = ((tmp * ONE_PER_3) >> 15) + D2;
- }
- /* New lag is not allowed to be bigger or smaller than last lag values */
- if(*T0 > maxLag)
- {
- *T0 = maxLag;
- }
- if(*T0 < minLag)
- {
- *T0 = minLag;
- }
- }
- else
- {
- /*
- * LTP-lag for RX_BAD_FRAME
- * MEAN lag
- */
- meanLag = 0;
- for(i = 0; i < L_LTPHIST; i++)
- {
- meanLag = meanLag + lag_hist[i];
- }
- meanLag = (meanLag * ONE_PER_LTPHIST) >> 15;
- tmp = *T0 - maxLag;
- tmp2 = *T0 - lastLag;
- if((lagDif < 10) & (*T0 > (minLag - 5)) & (tmp < 5))
- {
- *T0 = *T0;
- }
- else if((lastGain > 8192) & (secLastGain > 8192) & ((tmp2 > - 10)
- & (tmp2 < 10)))
- {
- *T0 = *T0;
- }
- else if((minGain < 6554) & (lastGain == minGain) & ((*T0 > minLag)
- & (*T0 < maxLag)))
- {
- *T0 = *T0;
- }
- else if((lagDif < 70) & (*T0 > minLag) & (*T0 < maxLag))
- {
- *T0 = *T0;
- }
- else if((*T0 > meanLag) & (*T0 < maxLag))
- {
- *T0 = *T0;
- }
- else
- {
- if((minGain > 8192) & (lagDif < 10))
- {
- *T0 = lag_hist[0];
- }
- else if((lastGain > 8192) & (secLastGain > 8192))
- {
- *T0 = lag_hist[0];
- }
- else
- {
- /*
- * SORT
- * The sorting of the lag history
- */
- for(i = 0; i < L_LTPHIST; i++)
- {
- lag_hist2[i] = lag_hist[i];
- }
- D_GAIN_sort_lag(lag_hist2, 5);
- /*
- * Lag is weighted towards bigger lags
- * and random variation is added
- */
- lagDif = lag_hist2[4] - lag_hist2[2];
- if(lagDif > 40)
- {
- lagDif = 40;
- }
- D = D_UTIL_random(seed); /* D={-1,.., 1} */
- /* D2={-lagDif/2..lagDif/2} */
- tmp = lagDif >> 1;
- D2 = (tmp * D) >> 15;
- tmp = (lag_hist2[2] + lag_hist2[3]) + lag_hist2[4];
- *T0 = ((tmp * ONE_PER_3) >> 15) + D2;
- }
- /*
- * New lag is not allowed to be bigger or
- * smaller than last lag values
- */
- if(*T0 > maxLag)
- {
- *T0 = maxLag;
- }
- if(*T0 < minLag)
- {
- *T0 = minLag;
- }
- }
- }
- }
- /*
- * D_GAIN_adaptive_codebook_excitation
- *
- * Parameters:
- * exc I/O: excitation buffer
- * T0 I: integer pitch lag
- * frac I: fraction of lag
- *
- * Function:
- * Compute the result of Word32 term prediction with fractional
- * interpolation of resolution 1/4.
- *
- * Returns:
- * interpolated signal (adaptive codebook excitation)
- */
- void D_GAIN_adaptive_codebook_excitation(Word16 exc[], Word32 T0, Word32 frac)
- {
- Word32 i, j, k, sum;
- Word16 *x;
- x = &exc[ - T0];
- frac = -(frac);
- if(frac < 0)
- {
- frac = (frac + UP_SAMP);
- x--;
- }
- x = x - L_INTERPOL2 + 1;
- for(j = 0; j < L_SUBFR + 1; j++)
- {
- sum = 0L;
- for(i = 0, k = ((UP_SAMP - 1) - frac); i < 2 * L_INTERPOL2; i++,
- k += UP_SAMP)
- {
- sum += x[i] * D_ROM_inter4_2[k];
- }
- sum = (sum + 0x2000) >> 14;
- exc[j] = D_UTIL_saturate(sum);
- x++;
- }
- return;
- }
- /*
- * D_GAIN_pitch_sharpening
- *
- * Parameters:
- * x I/O: impulse response (or algebraic code)
- * pit_lag I: pitch lag
- * sharp I: (Q15) pitch sharpening factor
- *
- * Function:
- * Performs Pitch sharpening routine for one subframe.
- *
- * Returns:
- * void
- */
- void D_GAIN_pitch_sharpening(Word16 *x, Word32 pit_lag, Word16 sharp)
- {
- Word32 i;
- Word32 tmp;
- for(i = pit_lag; i < L_SUBFR; i++)
- {
- tmp = x[i] << 15;
- tmp += x[i - pit_lag] * sharp;
- x[i] = (Word16)((tmp + 0x4000) >> 15);
- }
- return;
- }
- /*
- * D_GAIN_find_voice_factor
- *
- * Parameters:
- * exc I: pitch excitation
- * Q_exc I: exc format
- * gain_pit I: (Q14) gain of pitch
- * code I: (Q9) fixed codebook excitation
- * gain_code I: (Q0) gain of code
- * L_subfr I: subframe length
- *
- * Function:
- * Find the voicing factor.
- *
- * Returns:
- * (Q15) 1=voice to -1=unvoiced
- */
- Word16 D_GAIN_find_voice_factor(Word16 exc[], Word16 Q_exc,
- Word16 gain_pit, Word16 code[],
- Word16 gain_code, Word16 L_subfr)
- {
- Word32 tmp, ener1, ener2, i;
- Word16 exp, exp1, exp2;
- ener1 = (D_UTIL_dot_product12(exc, exc, L_subfr, &exp1)) >> 16;
- exp1 = (Word16)(exp1 - (Q_exc + Q_exc));
- tmp = (gain_pit * gain_pit) << 1;
- exp = D_UTIL_norm_l(tmp);
- tmp = (tmp << exp) >> 16;
- ener1 = (ener1 * tmp) >> 15;
- exp1 = (Word16)((exp1 - exp) - 10); /* 10 -> gain_pit Q14 to Q9 */
- ener2 = D_UTIL_dot_product12(code, code, L_subfr, &exp2) >> 16;
- exp = D_UTIL_norm_s(gain_code);
- tmp = gain_code << exp;
- tmp = (tmp * tmp) >> 15;
- ener2 = (ener2 * tmp) >> 15;
- exp2 = (Word16)(exp2 - (exp << 1));
- i = exp1 - exp2;
- if(i >= 0)
- {
- ener1 = ener1 >> 1;
- ener2 = ener2 >> (i + 1);
- }
- else if(i > (-16))
- {
- ener1 = ener1 >> (1 - i);
- ener2 = ener2 >> 1;
- }
- else
- {
- ener1 = 0;
- ener2 = ener2 >> 1;
- }
- tmp = ener1 - ener2;
- ener1 = (ener1 + ener2) + 1;
- tmp = (tmp << 15) / ener1;
- return((Word16)tmp);
- }