/* ** Copyright 2003-2010, VisualOn, Inc. ** ** Licensed under the Apache License, Version 2.0 (the "License"); ** you may not use this file except in compliance with the License. ** You may obtain a copy of the License at ** ** http://www.apache.org/licenses/LICENSE-2.0 ** ** Unless required by applicable law or agreed to in writing, software ** distributed under the License is distributed on an "AS IS" BASIS, ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. ** See the License for the specific language governing permissions and ** limitations under the License. */ /*********************************************************************** * File: isp_az.c * * * * Description:Compute the LPC coefficients from isp (order=M) * * * ************************************************************************/ #include "typedef.h" #include "basic_op.h" #include "oper_32b.h" #include "cnst.h" #define NC (M/2) #define NC16k (M16k/2) /* local function */ static void Get_isp_pol(Word16 * isp, Word32 * f, Word16 n); static void Get_isp_pol_16kHz(Word16 * isp, Word32 * f, Word16 n); void Isp_Az( Word16 isp[], /* (i) Q15 : Immittance spectral pairs */ Word16 a[], /* (o) Q12 : predictor coefficients (order = M) */ Word16 m, Word16 adaptive_scaling /* (i) 0 : adaptive scaling disabled */ /* 1 : adaptive scaling enabled */ ) { Word32 i, j; Word16 hi, lo; Word32 f1[NC16k + 1], f2[NC16k]; Word16 nc; Word32 t0; Word16 q, q_sug; Word32 tmax; nc = (m >> 1); if(nc > 8) { Get_isp_pol_16kHz(&isp[0], f1, nc); for (i = 0; i <= nc; i++) { f1[i] = f1[i] << 2; } } else Get_isp_pol(&isp[0], f1, nc); if (nc > 8) { Get_isp_pol_16kHz(&isp[1], f2, (nc - 1)); for (i = 0; i <= nc - 1; i++) { f2[i] = f2[i] << 2; } } else Get_isp_pol(&isp[1], f2, (nc - 1)); /*-----------------------------------------------------* * Multiply F2(z) by (1 - z^-2) * *-----------------------------------------------------*/ for (i = (nc - 1); i > 1; i--) { f2[i] = vo_L_sub(f2[i], f2[i - 2]); /* f2[i] -= f2[i-2]; */ } /*----------------------------------------------------------* * Scale F1(z) by (1+isp[m-1]) and F2(z) by (1-isp[m-1]) * *----------------------------------------------------------*/ for (i = 0; i < nc; i++) { /* f1[i] *= (1.0 + isp[M-1]); */ hi = f1[i] >> 16; lo = (f1[i] & 0xffff)>>1; t0 = Mpy_32_16(hi, lo, isp[m - 1]); f1[i] = vo_L_add(f1[i], t0); /* f2[i] *= (1.0 - isp[M-1]); */ hi = f2[i] >> 16; lo = (f2[i] & 0xffff)>>1; t0 = Mpy_32_16(hi, lo, isp[m - 1]); f2[i] = vo_L_sub(f2[i], t0); } /*-----------------------------------------------------* * A(z) = (F1(z)+F2(z))/2 * * F1(z) is symmetric and F2(z) is antisymmetric * *-----------------------------------------------------*/ /* a[0] = 1.0; */ a[0] = 4096; tmax = 1; for (i = 1, j = m - 1; i < nc; i++, j--) { /* a[i] = 0.5*(f1[i] + f2[i]); */ t0 = vo_L_add(f1[i], f2[i]); /* f1[i] + f2[i] */ tmax |= L_abs(t0); a[i] = (Word16)(vo_L_shr_r(t0, 12)); /* from Q23 to Q12 and * 0.5 */ /* a[j] = 0.5*(f1[i] - f2[i]); */ t0 = vo_L_sub(f1[i], f2[i]); /* f1[i] - f2[i] */ tmax |= L_abs(t0); a[j] = (Word16)(vo_L_shr_r(t0, 12)); /* from Q23 to Q12 and * 0.5 */ } /* rescale data if overflow has occured and reprocess the loop */ if(adaptive_scaling == 1) q = 4 - norm_l(tmax); /* adaptive scaling enabled */ else q = 0; /* adaptive scaling disabled */ if (q > 0) { q_sug = (12 + q); for (i = 1, j = m - 1; i < nc; i++, j--) { /* a[i] = 0.5*(f1[i] + f2[i]); */ t0 = vo_L_add(f1[i], f2[i]); /* f1[i] + f2[i] */ a[i] = (Word16)(vo_L_shr_r(t0, q_sug)); /* from Q23 to Q12 and * 0.5 */ /* a[j] = 0.5*(f1[i] - f2[i]); */ t0 = vo_L_sub(f1[i], f2[i]); /* f1[i] - f2[i] */ a[j] = (Word16)(vo_L_shr_r(t0, q_sug)); /* from Q23 to Q12 and * 0.5 */ } a[0] = shr(a[0], q); } else { q_sug = 12; q = 0; } /* a[NC] = 0.5*f1[NC]*(1.0 + isp[M-1]); */ hi = f1[nc] >> 16; lo = (f1[nc] & 0xffff)>>1; t0 = Mpy_32_16(hi, lo, isp[m - 1]); t0 = vo_L_add(f1[nc], t0); a[nc] = (Word16)(L_shr_r(t0, q_sug)); /* from Q23 to Q12 and * 0.5 */ /* a[m] = isp[m-1]; */ a[m] = vo_shr_r(isp[m - 1], (3 + q)); /* from Q15 to Q12 */ return; } /*-----------------------------------------------------------* * procedure Get_isp_pol: * * ~~~~~~~~~~~ * * Find the polynomial F1(z) or F2(z) from the ISPs. * * This is performed by expanding the product polynomials: * * * * F1(z) = product ( 1 - 2 isp_i z^-1 + z^-2 ) * * i=0,2,4,6,8 * * F2(z) = product ( 1 - 2 isp_i z^-1 + z^-2 ) * * i=1,3,5,7 * * * * where isp_i are the ISPs in the cosine domain. * *-----------------------------------------------------------* * * * Parameters: * * isp[] : isp vector (cosine domaine) in Q15 * * f[] : the coefficients of F1 or F2 in Q23 * * n : == NC for F1(z); == NC-1 for F2(z) * *-----------------------------------------------------------*/ static void Get_isp_pol(Word16 * isp, Word32 * f, Word16 n) { Word16 hi, lo; Word32 i, j, t0; /* All computation in Q23 */ f[0] = vo_L_mult(4096, 1024); /* f[0] = 1.0; in Q23 */ f[1] = vo_L_mult(isp[0], -256); /* f[1] = -2.0*isp[0] in Q23 */ f += 2; /* Advance f pointer */ isp += 2; /* Advance isp pointer */ for (i = 2; i <= n; i++) { *f = f[-2]; for (j = 1; j < i; j++, f--) { hi = f[-1]>>16; lo = (f[-1] & 0xffff)>>1; t0 = Mpy_32_16(hi, lo, *isp); /* t0 = f[-1] * isp */ t0 = t0 << 1; *f = vo_L_sub(*f, t0); /* *f -= t0 */ *f = vo_L_add(*f, f[-2]); /* *f += f[-2] */ } *f -= (*isp << 9); /* *f -= isp<<8 */ f += i; /* Advance f pointer */ isp += 2; /* Advance isp pointer */ } return; } static void Get_isp_pol_16kHz(Word16 * isp, Word32 * f, Word16 n) { Word16 hi, lo; Word32 i, j, t0; /* All computation in Q23 */ f[0] = L_mult(4096, 256); /* f[0] = 1.0; in Q23 */ f[1] = L_mult(isp[0], -64); /* f[1] = -2.0*isp[0] in Q23 */ f += 2; /* Advance f pointer */ isp += 2; /* Advance isp pointer */ for (i = 2; i <= n; i++) { *f = f[-2]; for (j = 1; j < i; j++, f--) { VO_L_Extract(f[-1], &hi, &lo); t0 = Mpy_32_16(hi, lo, *isp); /* t0 = f[-1] * isp */ t0 = L_shl2(t0, 1); *f = L_sub(*f, t0); /* *f -= t0 */ *f = L_add(*f, f[-2]); /* *f += f[-2] */ } *f = L_msu(*f, *isp, 64); /* *f -= isp<<8 */ f += i; /* Advance f pointer */ isp += 2; /* Advance isp pointer */ } return; }