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4 modification, are permitted provided that the following conditions
5 are met:
6 - Redistributions of source code must retain the above copyright notice,
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16 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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26 ***********************************************************************/
27
28 #ifdef HAVE_CONFIG_H
29 #include "config.h"
30 #endif
31
32 #include "SigProc_FIX.h"
33 #include "define.h"
34 #include "tuning_parameters.h"
35 #include "pitch.h"
36
37 #define MAX_FRAME_SIZE 384 /* subfr_length * nb_subfr = ( 0.005 * 16000 + 16 ) * 4 = 384 */
38
39 #define QA 25
40 #define N_BITS_HEAD_ROOM 2
41 #define MIN_RSHIFTS -16
42 #define MAX_RSHIFTS (32 - QA)
43
44 /* Compute reflection coefficients from input signal */
silk_burg_modified_c(opus_int32 * res_nrg,opus_int * res_nrg_Q,opus_int32 A_Q16[],const opus_int16 x[],const opus_int32 minInvGain_Q30,const opus_int subfr_length,const opus_int nb_subfr,const opus_int D,int arch)45 void silk_burg_modified_c(
46 opus_int32 *res_nrg, /* O Residual energy */
47 opus_int *res_nrg_Q, /* O Residual energy Q value */
48 opus_int32 A_Q16[], /* O Prediction coefficients (length order) */
49 const opus_int16 x[], /* I Input signal, length: nb_subfr * ( D + subfr_length ) */
50 const opus_int32 minInvGain_Q30, /* I Inverse of max prediction gain */
51 const opus_int subfr_length, /* I Input signal subframe length (incl. D preceding samples) */
52 const opus_int nb_subfr, /* I Number of subframes stacked in x */
53 const opus_int D, /* I Order */
54 int arch /* I Run-time architecture */
55 )
56 {
57 opus_int k, n, s, lz, rshifts, reached_max_gain;
58 opus_int32 C0, num, nrg, rc_Q31, invGain_Q30, Atmp_QA, Atmp1, tmp1, tmp2, x1, x2;
59 const opus_int16 *x_ptr;
60 opus_int32 C_first_row[ SILK_MAX_ORDER_LPC ];
61 opus_int32 C_last_row[ SILK_MAX_ORDER_LPC ];
62 opus_int32 Af_QA[ SILK_MAX_ORDER_LPC ];
63 opus_int32 CAf[ SILK_MAX_ORDER_LPC + 1 ];
64 opus_int32 CAb[ SILK_MAX_ORDER_LPC + 1 ];
65 opus_int32 xcorr[ SILK_MAX_ORDER_LPC ];
66 opus_int64 C0_64;
67
68 silk_assert( subfr_length * nb_subfr <= MAX_FRAME_SIZE );
69
70 /* Compute autocorrelations, added over subframes */
71 C0_64 = silk_inner_prod16_aligned_64( x, x, subfr_length*nb_subfr, arch );
72 lz = silk_CLZ64(C0_64);
73 rshifts = 32 + 1 + N_BITS_HEAD_ROOM - lz;
74 if (rshifts > MAX_RSHIFTS) rshifts = MAX_RSHIFTS;
75 if (rshifts < MIN_RSHIFTS) rshifts = MIN_RSHIFTS;
76
77 if (rshifts > 0) {
78 C0 = (opus_int32)silk_RSHIFT64(C0_64, rshifts );
79 } else {
80 C0 = silk_LSHIFT32((opus_int32)C0_64, -rshifts );
81 }
82
83 CAb[ 0 ] = CAf[ 0 ] = C0 + silk_SMMUL( SILK_FIX_CONST( FIND_LPC_COND_FAC, 32 ), C0 ) + 1; /* Q(-rshifts) */
84 silk_memset( C_first_row, 0, SILK_MAX_ORDER_LPC * sizeof( opus_int32 ) );
85 if( rshifts > 0 ) {
86 for( s = 0; s < nb_subfr; s++ ) {
87 x_ptr = x + s * subfr_length;
88 for( n = 1; n < D + 1; n++ ) {
89 C_first_row[ n - 1 ] += (opus_int32)silk_RSHIFT64(
90 silk_inner_prod16_aligned_64( x_ptr, x_ptr + n, subfr_length - n, arch ), rshifts );
91 }
92 }
93 } else {
94 for( s = 0; s < nb_subfr; s++ ) {
95 int i;
96 opus_int32 d;
97 x_ptr = x + s * subfr_length;
98 celt_pitch_xcorr(x_ptr, x_ptr + 1, xcorr, subfr_length - D, D, arch );
99 for( n = 1; n < D + 1; n++ ) {
100 for ( i = n + subfr_length - D, d = 0; i < subfr_length; i++ )
101 d = MAC16_16( d, x_ptr[ i ], x_ptr[ i - n ] );
102 xcorr[ n - 1 ] += d;
103 }
104 for( n = 1; n < D + 1; n++ ) {
105 C_first_row[ n - 1 ] += silk_LSHIFT32( xcorr[ n - 1 ], -rshifts );
106 }
107 }
108 }
109 silk_memcpy( C_last_row, C_first_row, SILK_MAX_ORDER_LPC * sizeof( opus_int32 ) );
110
111 /* Initialize */
112 CAb[ 0 ] = CAf[ 0 ] = C0 + silk_SMMUL( SILK_FIX_CONST( FIND_LPC_COND_FAC, 32 ), C0 ) + 1; /* Q(-rshifts) */
113
114 invGain_Q30 = (opus_int32)1 << 30;
115 reached_max_gain = 0;
116 for( n = 0; n < D; n++ ) {
117 /* Update first row of correlation matrix (without first element) */
118 /* Update last row of correlation matrix (without last element, stored in reversed order) */
119 /* Update C * Af */
120 /* Update C * flipud(Af) (stored in reversed order) */
121 if( rshifts > -2 ) {
122 for( s = 0; s < nb_subfr; s++ ) {
123 x_ptr = x + s * subfr_length;
124 x1 = -silk_LSHIFT32( (opus_int32)x_ptr[ n ], 16 - rshifts ); /* Q(16-rshifts) */
125 x2 = -silk_LSHIFT32( (opus_int32)x_ptr[ subfr_length - n - 1 ], 16 - rshifts ); /* Q(16-rshifts) */
126 tmp1 = silk_LSHIFT32( (opus_int32)x_ptr[ n ], QA - 16 ); /* Q(QA-16) */
127 tmp2 = silk_LSHIFT32( (opus_int32)x_ptr[ subfr_length - n - 1 ], QA - 16 ); /* Q(QA-16) */
128 for( k = 0; k < n; k++ ) {
129 C_first_row[ k ] = silk_SMLAWB( C_first_row[ k ], x1, x_ptr[ n - k - 1 ] ); /* Q( -rshifts ) */
130 C_last_row[ k ] = silk_SMLAWB( C_last_row[ k ], x2, x_ptr[ subfr_length - n + k ] ); /* Q( -rshifts ) */
131 Atmp_QA = Af_QA[ k ];
132 tmp1 = silk_SMLAWB( tmp1, Atmp_QA, x_ptr[ n - k - 1 ] ); /* Q(QA-16) */
133 tmp2 = silk_SMLAWB( tmp2, Atmp_QA, x_ptr[ subfr_length - n + k ] ); /* Q(QA-16) */
134 }
135 tmp1 = silk_LSHIFT32( -tmp1, 32 - QA - rshifts ); /* Q(16-rshifts) */
136 tmp2 = silk_LSHIFT32( -tmp2, 32 - QA - rshifts ); /* Q(16-rshifts) */
137 for( k = 0; k <= n; k++ ) {
138 CAf[ k ] = silk_SMLAWB( CAf[ k ], tmp1, x_ptr[ n - k ] ); /* Q( -rshift ) */
139 CAb[ k ] = silk_SMLAWB( CAb[ k ], tmp2, x_ptr[ subfr_length - n + k - 1 ] ); /* Q( -rshift ) */
140 }
141 }
142 } else {
143 for( s = 0; s < nb_subfr; s++ ) {
144 x_ptr = x + s * subfr_length;
145 x1 = -silk_LSHIFT32( (opus_int32)x_ptr[ n ], -rshifts ); /* Q( -rshifts ) */
146 x2 = -silk_LSHIFT32( (opus_int32)x_ptr[ subfr_length - n - 1 ], -rshifts ); /* Q( -rshifts ) */
147 tmp1 = silk_LSHIFT32( (opus_int32)x_ptr[ n ], 17 ); /* Q17 */
148 tmp2 = silk_LSHIFT32( (opus_int32)x_ptr[ subfr_length - n - 1 ], 17 ); /* Q17 */
149 for( k = 0; k < n; k++ ) {
150 C_first_row[ k ] = silk_MLA( C_first_row[ k ], x1, x_ptr[ n - k - 1 ] ); /* Q( -rshifts ) */
151 C_last_row[ k ] = silk_MLA( C_last_row[ k ], x2, x_ptr[ subfr_length - n + k ] ); /* Q( -rshifts ) */
152 Atmp1 = silk_RSHIFT_ROUND( Af_QA[ k ], QA - 17 ); /* Q17 */
153 /* We sometimes have get overflows in the multiplications (even beyond +/- 2^32),
154 but they cancel each other and the real result seems to always fit in a 32-bit
155 signed integer. This was determined experimentally, not theoretically (unfortunately). */
156 tmp1 = silk_MLA_ovflw( tmp1, x_ptr[ n - k - 1 ], Atmp1 ); /* Q17 */
157 tmp2 = silk_MLA_ovflw( tmp2, x_ptr[ subfr_length - n + k ], Atmp1 ); /* Q17 */
158 }
159 tmp1 = -tmp1; /* Q17 */
160 tmp2 = -tmp2; /* Q17 */
161 for( k = 0; k <= n; k++ ) {
162 CAf[ k ] = silk_SMLAWW( CAf[ k ], tmp1,
163 silk_LSHIFT32( (opus_int32)x_ptr[ n - k ], -rshifts - 1 ) ); /* Q( -rshift ) */
164 CAb[ k ] = silk_SMLAWW( CAb[ k ], tmp2,
165 silk_LSHIFT32( (opus_int32)x_ptr[ subfr_length - n + k - 1 ], -rshifts - 1 ) ); /* Q( -rshift ) */
166 }
167 }
168 }
169
170 /* Calculate nominator and denominator for the next order reflection (parcor) coefficient */
171 tmp1 = C_first_row[ n ]; /* Q( -rshifts ) */
172 tmp2 = C_last_row[ n ]; /* Q( -rshifts ) */
173 num = 0; /* Q( -rshifts ) */
174 nrg = silk_ADD32( CAb[ 0 ], CAf[ 0 ] ); /* Q( 1-rshifts ) */
175 for( k = 0; k < n; k++ ) {
176 Atmp_QA = Af_QA[ k ];
177 lz = silk_CLZ32( silk_abs( Atmp_QA ) ) - 1;
178 lz = silk_min( 32 - QA, lz );
179 Atmp1 = silk_LSHIFT32( Atmp_QA, lz ); /* Q( QA + lz ) */
180
181 tmp1 = silk_ADD_LSHIFT32( tmp1, silk_SMMUL( C_last_row[ n - k - 1 ], Atmp1 ), 32 - QA - lz ); /* Q( -rshifts ) */
182 tmp2 = silk_ADD_LSHIFT32( tmp2, silk_SMMUL( C_first_row[ n - k - 1 ], Atmp1 ), 32 - QA - lz ); /* Q( -rshifts ) */
183 num = silk_ADD_LSHIFT32( num, silk_SMMUL( CAb[ n - k ], Atmp1 ), 32 - QA - lz ); /* Q( -rshifts ) */
184 nrg = silk_ADD_LSHIFT32( nrg, silk_SMMUL( silk_ADD32( CAb[ k + 1 ], CAf[ k + 1 ] ),
185 Atmp1 ), 32 - QA - lz ); /* Q( 1-rshifts ) */
186 }
187 CAf[ n + 1 ] = tmp1; /* Q( -rshifts ) */
188 CAb[ n + 1 ] = tmp2; /* Q( -rshifts ) */
189 num = silk_ADD32( num, tmp2 ); /* Q( -rshifts ) */
190 num = silk_LSHIFT32( -num, 1 ); /* Q( 1-rshifts ) */
191
192 /* Calculate the next order reflection (parcor) coefficient */
193 if( silk_abs( num ) < nrg ) {
194 rc_Q31 = silk_DIV32_varQ( num, nrg, 31 );
195 } else {
196 rc_Q31 = ( num > 0 ) ? silk_int32_MAX : silk_int32_MIN;
197 }
198
199 /* Update inverse prediction gain */
200 tmp1 = ( (opus_int32)1 << 30 ) - silk_SMMUL( rc_Q31, rc_Q31 );
201 tmp1 = silk_LSHIFT( silk_SMMUL( invGain_Q30, tmp1 ), 2 );
202 if( tmp1 <= minInvGain_Q30 ) {
203 /* Max prediction gain exceeded; set reflection coefficient such that max prediction gain is exactly hit */
204 tmp2 = ( (opus_int32)1 << 30 ) - silk_DIV32_varQ( minInvGain_Q30, invGain_Q30, 30 ); /* Q30 */
205 rc_Q31 = silk_SQRT_APPROX( tmp2 ); /* Q15 */
206 if( rc_Q31 > 0 ) {
207 /* Newton-Raphson iteration */
208 rc_Q31 = silk_RSHIFT32( rc_Q31 + silk_DIV32( tmp2, rc_Q31 ), 1 ); /* Q15 */
209 rc_Q31 = silk_LSHIFT32( rc_Q31, 16 ); /* Q31 */
210 if( num < 0 ) {
211 /* Ensure adjusted reflection coefficients has the original sign */
212 rc_Q31 = -rc_Q31;
213 }
214 }
215 invGain_Q30 = minInvGain_Q30;
216 reached_max_gain = 1;
217 } else {
218 invGain_Q30 = tmp1;
219 }
220
221 /* Update the AR coefficients */
222 for( k = 0; k < (n + 1) >> 1; k++ ) {
223 tmp1 = Af_QA[ k ]; /* QA */
224 tmp2 = Af_QA[ n - k - 1 ]; /* QA */
225 Af_QA[ k ] = silk_ADD_LSHIFT32( tmp1, silk_SMMUL( tmp2, rc_Q31 ), 1 ); /* QA */
226 Af_QA[ n - k - 1 ] = silk_ADD_LSHIFT32( tmp2, silk_SMMUL( tmp1, rc_Q31 ), 1 ); /* QA */
227 }
228 Af_QA[ n ] = silk_RSHIFT32( rc_Q31, 31 - QA ); /* QA */
229
230 if( reached_max_gain ) {
231 /* Reached max prediction gain; set remaining coefficients to zero and exit loop */
232 for( k = n + 1; k < D; k++ ) {
233 Af_QA[ k ] = 0;
234 }
235 break;
236 }
237
238 /* Update C * Af and C * Ab */
239 for( k = 0; k <= n + 1; k++ ) {
240 tmp1 = CAf[ k ]; /* Q( -rshifts ) */
241 tmp2 = CAb[ n - k + 1 ]; /* Q( -rshifts ) */
242 CAf[ k ] = silk_ADD_LSHIFT32( tmp1, silk_SMMUL( tmp2, rc_Q31 ), 1 ); /* Q( -rshifts ) */
243 CAb[ n - k + 1 ] = silk_ADD_LSHIFT32( tmp2, silk_SMMUL( tmp1, rc_Q31 ), 1 ); /* Q( -rshifts ) */
244 }
245 }
246
247 if( reached_max_gain ) {
248 for( k = 0; k < D; k++ ) {
249 /* Scale coefficients */
250 A_Q16[ k ] = -silk_RSHIFT_ROUND( Af_QA[ k ], QA - 16 );
251 }
252 /* Subtract energy of preceding samples from C0 */
253 if( rshifts > 0 ) {
254 for( s = 0; s < nb_subfr; s++ ) {
255 x_ptr = x + s * subfr_length;
256 C0 -= (opus_int32)silk_RSHIFT64( silk_inner_prod16_aligned_64( x_ptr, x_ptr, D, arch ), rshifts );
257 }
258 } else {
259 for( s = 0; s < nb_subfr; s++ ) {
260 x_ptr = x + s * subfr_length;
261 C0 -= silk_LSHIFT32( silk_inner_prod_aligned( x_ptr, x_ptr, D, arch), -rshifts);
262 }
263 }
264 /* Approximate residual energy */
265 *res_nrg = silk_LSHIFT( silk_SMMUL( invGain_Q30, C0 ), 2 );
266 *res_nrg_Q = -rshifts;
267 } else {
268 /* Return residual energy */
269 nrg = CAf[ 0 ]; /* Q( -rshifts ) */
270 tmp1 = (opus_int32)1 << 16; /* Q16 */
271 for( k = 0; k < D; k++ ) {
272 Atmp1 = silk_RSHIFT_ROUND( Af_QA[ k ], QA - 16 ); /* Q16 */
273 nrg = silk_SMLAWW( nrg, CAf[ k + 1 ], Atmp1 ); /* Q( -rshifts ) */
274 tmp1 = silk_SMLAWW( tmp1, Atmp1, Atmp1 ); /* Q16 */
275 A_Q16[ k ] = -Atmp1;
276 }
277 *res_nrg = silk_SMLAWW( nrg, silk_SMMUL( SILK_FIX_CONST( FIND_LPC_COND_FAC, 32 ), C0 ), -tmp1 );/* Q( -rshifts ) */
278 *res_nrg_Q = -rshifts;
279 }
280 }
281