1 /*
2 * Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 /*
12 * lattice.c
13 *
14 * Contains the normalized lattice filter routines (MA and AR) for iSAC codec
15 *
16 */
17
18 #include "codec.h"
19 #include "settings.h"
20
21 #define LATTICE_MUL_32_32_RSFT16(a32a, a32b, b32) \
22 ((int32_t)(WEBRTC_SPL_MUL(a32a, b32) + (WEBRTC_SPL_MUL_16_32_RSFT16(a32b, b32))))
23 /* This macro is FORBIDDEN to use elsewhere than in a function in this file and
24 its corresponding neon version. It might give unpredictable results, since a
25 general int32_t*int32_t multiplication results in a 64 bit value.
26 The result is then shifted just 16 steps to the right, giving need for 48
27 bits, i.e. in the generel case, it will NOT fit in a int32_t. In the
28 cases used in here, the int32_t will be enough, since (for a good
29 reason) the involved multiplicands aren't big enough to overflow a
30 int32_t after shifting right 16 bits. I have compared the result of a
31 multiplication between t32 and tmp32, done in two ways:
32 1) Using (int32_t) (((float)(tmp32))*((float)(tmp32b))/65536.0);
33 2) Using LATTICE_MUL_32_32_RSFT16(t16a, t16b, tmp32b);
34 By running 25 files, I haven't found any bigger diff than 64 - this was in the
35 case when method 1) gave 650235648 and 2) gave 650235712.
36 */
37
38 /* Function prototype: filtering ar_g_Q0[] and ar_f_Q0[] through an AR filter
39 with coefficients cth_Q15[] and sth_Q15[].
40 Implemented for both generic and ARMv7 platforms.
41 */
42 void WebRtcIsacfix_FilterArLoop(int16_t* ar_g_Q0,
43 int16_t* ar_f_Q0,
44 int16_t* cth_Q15,
45 int16_t* sth_Q15,
46 size_t order_coef);
47
48 /* Inner loop used for function WebRtcIsacfix_NormLatticeFilterMa(). It does:
49 for 0 <= n < HALF_SUBFRAMELEN - 1:
50 *ptr2 = input2 * (*ptr2) + input0 * (*ptr0));
51 *ptr1 = input1 * (*ptr0) + input0 * (*ptr2);
52 Note, function WebRtcIsacfix_FilterMaLoopNeon and WebRtcIsacfix_FilterMaLoopC
53 are not bit-exact. The accuracy by the ARM Neon function is same or better.
54 */
WebRtcIsacfix_FilterMaLoopC(int16_t input0,int16_t input1,int32_t input2,int32_t * ptr0,int32_t * ptr1,int32_t * ptr2)55 void WebRtcIsacfix_FilterMaLoopC(int16_t input0, // Filter coefficient
56 int16_t input1, // Filter coefficient
57 int32_t input2, // Inverse coeff. (1/input1)
58 int32_t* ptr0, // Sample buffer
59 int32_t* ptr1, // Sample buffer
60 int32_t* ptr2) { // Sample buffer
61 int n = 0;
62
63 // Separate the 32-bit variable input2 into two 16-bit integers (high 16 and
64 // low 16 bits), for using LATTICE_MUL_32_32_RSFT16 in the loop.
65 int16_t t16a = (int16_t)(input2 >> 16);
66 int16_t t16b = (int16_t)input2;
67 if (t16b < 0) t16a++;
68
69 // The loop filtering the samples *ptr0, *ptr1, *ptr2 with filter coefficients
70 // input0, input1, and input2.
71 for(n = 0; n < HALF_SUBFRAMELEN - 1; n++, ptr0++, ptr1++, ptr2++) {
72 int32_t tmp32a = 0;
73 int32_t tmp32b = 0;
74
75 // Calculate *ptr2 = input2 * (*ptr2 + input0 * (*ptr0));
76 tmp32a = WEBRTC_SPL_MUL_16_32_RSFT15(input0, *ptr0); // Q15 * Q15 >> 15 = Q15
77 tmp32b = *ptr2 + tmp32a; // Q15 + Q15 = Q15
78 *ptr2 = LATTICE_MUL_32_32_RSFT16(t16a, t16b, tmp32b);
79
80 // Calculate *ptr1 = input1 * (*ptr0) + input0 * (*ptr2);
81 tmp32a = WEBRTC_SPL_MUL_16_32_RSFT15(input1, *ptr0); // Q15*Q15>>15 = Q15
82 tmp32b = WEBRTC_SPL_MUL_16_32_RSFT15(input0, *ptr2); // Q15*Q15>>15 = Q15
83 *ptr1 = tmp32a + tmp32b; // Q15 + Q15 = Q15
84 }
85 }
86
87 /* filter the signal using normalized lattice filter */
88 /* MA filter */
WebRtcIsacfix_NormLatticeFilterMa(size_t orderCoef,int32_t * stateGQ15,int16_t * lat_inQ0,int16_t * filt_coefQ15,int32_t * gain_lo_hiQ17,int16_t lo_hi,int16_t * lat_outQ9)89 void WebRtcIsacfix_NormLatticeFilterMa(size_t orderCoef,
90 int32_t *stateGQ15,
91 int16_t *lat_inQ0,
92 int16_t *filt_coefQ15,
93 int32_t *gain_lo_hiQ17,
94 int16_t lo_hi,
95 int16_t *lat_outQ9)
96 {
97 int16_t sthQ15[MAX_AR_MODEL_ORDER];
98 int16_t cthQ15[MAX_AR_MODEL_ORDER];
99
100 int u, n;
101 size_t i, k;
102 int16_t temp2,temp3;
103 size_t ord_1 = orderCoef+1;
104 int32_t inv_cthQ16[MAX_AR_MODEL_ORDER];
105
106 int32_t gain32, fQtmp;
107 int16_t gain16;
108 int16_t gain_sh;
109
110 int32_t tmp32, tmp32b;
111 int32_t fQ15vec[HALF_SUBFRAMELEN];
112 int32_t gQ15[MAX_AR_MODEL_ORDER+1][HALF_SUBFRAMELEN];
113 int16_t sh;
114 int16_t t16a;
115 int16_t t16b;
116
117 for (u=0;u<SUBFRAMES;u++)
118 {
119 int32_t temp1 = u * HALF_SUBFRAMELEN;
120
121 /* set the Direct Form coefficients */
122 temp2 = (int16_t)(u * orderCoef);
123 temp3 = (int16_t)(2 * u + lo_hi);
124
125 /* compute lattice filter coefficients */
126 memcpy(sthQ15, &filt_coefQ15[temp2], orderCoef * sizeof(int16_t));
127
128 WebRtcSpl_SqrtOfOneMinusXSquared(sthQ15, orderCoef, cthQ15);
129
130 /* compute the gain */
131 gain32 = gain_lo_hiQ17[temp3];
132 gain_sh = WebRtcSpl_NormW32(gain32);
133 gain32 <<= gain_sh; // Q(17+gain_sh)
134
135 for (k=0;k<orderCoef;k++)
136 {
137 gain32 = WEBRTC_SPL_MUL_16_32_RSFT15(cthQ15[k], gain32); //Q15*Q(17+gain_sh)>>15 = Q(17+gain_sh)
138 inv_cthQ16[k] = WebRtcSpl_DivW32W16((int32_t)2147483647, cthQ15[k]); // 1/cth[k] in Q31/Q15 = Q16
139 }
140 gain16 = (int16_t)(gain32 >> 16); // Q(1+gain_sh).
141
142 /* normalized lattice filter */
143 /*****************************/
144
145 /* initial conditions */
146 for (i=0;i<HALF_SUBFRAMELEN;i++)
147 {
148 fQ15vec[i] = lat_inQ0[i + temp1] << 15; // Q15
149 gQ15[0][i] = lat_inQ0[i + temp1] << 15; // Q15
150 }
151
152
153 fQtmp = fQ15vec[0];
154
155 /* get the state of f&g for the first input, for all orders */
156 for (i=1;i<ord_1;i++)
157 {
158 // Calculate f[i][0] = inv_cth[i-1]*(f[i-1][0] + sth[i-1]*stateG[i-1]);
159 tmp32 = WEBRTC_SPL_MUL_16_32_RSFT15(sthQ15[i-1], stateGQ15[i-1]);//Q15*Q15>>15 = Q15
160 tmp32b= fQtmp + tmp32; //Q15+Q15=Q15
161 tmp32 = inv_cthQ16[i-1]; //Q16
162 t16a = (int16_t)(tmp32 >> 16);
163 t16b = (int16_t)(tmp32 - (t16a << 16));
164 if (t16b<0) t16a++;
165 tmp32 = LATTICE_MUL_32_32_RSFT16(t16a, t16b, tmp32b);
166 fQtmp = tmp32; // Q15
167
168 // Calculate g[i][0] = cth[i-1]*stateG[i-1] + sth[i-1]* f[i][0];
169 tmp32 = WEBRTC_SPL_MUL_16_32_RSFT15(cthQ15[i-1], stateGQ15[i-1]); //Q15*Q15>>15 = Q15
170 tmp32b = WEBRTC_SPL_MUL_16_32_RSFT15(sthQ15[i-1], fQtmp); //Q15*Q15>>15 = Q15
171 tmp32 = tmp32 + tmp32b;//Q15+Q15 = Q15
172 gQ15[i][0] = tmp32; // Q15
173 }
174
175 /* filtering */
176 /* save the states */
177 for(k=0;k<orderCoef;k++)
178 {
179 // for 0 <= n < HALF_SUBFRAMELEN - 1:
180 // f[k+1][n+1] = inv_cth[k]*(f[k][n+1] + sth[k]*g[k][n]);
181 // g[k+1][n+1] = cth[k]*g[k][n] + sth[k]* f[k+1][n+1];
182 WebRtcIsacfix_FilterMaLoopFix(sthQ15[k], cthQ15[k], inv_cthQ16[k],
183 &gQ15[k][0], &gQ15[k+1][1], &fQ15vec[1]);
184 }
185
186 fQ15vec[0] = fQtmp;
187
188 for(n=0;n<HALF_SUBFRAMELEN;n++)
189 {
190 //gain32 >>= gain_sh; // Q(17+gain_sh) -> Q17
191 tmp32 = WEBRTC_SPL_MUL_16_32_RSFT16(gain16, fQ15vec[n]); //Q(1+gain_sh)*Q15>>16 = Q(gain_sh)
192 sh = 9-gain_sh; //number of needed shifts to reach Q9
193 t16a = (int16_t) WEBRTC_SPL_SHIFT_W32(tmp32, sh);
194 lat_outQ9[n + temp1] = t16a;
195 }
196
197 /* save the states */
198 for (i=0;i<ord_1;i++)
199 {
200 stateGQ15[i] = gQ15[i][HALF_SUBFRAMELEN-1];
201 }
202 //process next frame
203 }
204
205 return;
206 }
207
208
209
210
211
212 /* ----------------AR filter-------------------------*/
213 /* filter the signal using normalized lattice filter */
WebRtcIsacfix_NormLatticeFilterAr(size_t orderCoef,int16_t * stateGQ0,int32_t * lat_inQ25,int16_t * filt_coefQ15,int32_t * gain_lo_hiQ17,int16_t lo_hi,int16_t * lat_outQ0)214 void WebRtcIsacfix_NormLatticeFilterAr(size_t orderCoef,
215 int16_t *stateGQ0,
216 int32_t *lat_inQ25,
217 int16_t *filt_coefQ15,
218 int32_t *gain_lo_hiQ17,
219 int16_t lo_hi,
220 int16_t *lat_outQ0)
221 {
222 size_t ii, k, i;
223 int n, u;
224 int16_t sthQ15[MAX_AR_MODEL_ORDER];
225 int16_t cthQ15[MAX_AR_MODEL_ORDER];
226 int32_t tmp32;
227
228
229 int16_t tmpAR;
230 int16_t ARfQ0vec[HALF_SUBFRAMELEN];
231 int16_t ARgQ0vec[MAX_AR_MODEL_ORDER+1];
232
233 int32_t inv_gain32;
234 int16_t inv_gain16;
235 int16_t den16;
236 int16_t sh;
237
238 int16_t temp2,temp3;
239 size_t ord_1 = orderCoef+1;
240
241 for (u=0;u<SUBFRAMES;u++)
242 {
243 int32_t temp1 = u * HALF_SUBFRAMELEN;
244
245 //set the denominator and numerator of the Direct Form
246 temp2 = (int16_t)(u * orderCoef);
247 temp3 = (int16_t)(2 * u + lo_hi);
248
249 for (ii=0; ii<orderCoef; ii++) {
250 sthQ15[ii] = filt_coefQ15[temp2+ii];
251 }
252
253 WebRtcSpl_SqrtOfOneMinusXSquared(sthQ15, orderCoef, cthQ15);
254
255 /* Simulation of the 25 files shows that maximum value in
256 the vector gain_lo_hiQ17[] is 441344, which means that
257 it is log2((2^31)/441344) = 12.2 shifting bits from
258 saturation. Therefore, it should be safe to use Q27 instead
259 of Q17. */
260
261 tmp32 = gain_lo_hiQ17[temp3] << 10; // Q27
262
263 for (k=0;k<orderCoef;k++) {
264 tmp32 = WEBRTC_SPL_MUL_16_32_RSFT15(cthQ15[k], tmp32); // Q15*Q27>>15 = Q27
265 }
266
267 sh = WebRtcSpl_NormW32(tmp32); // tmp32 is the gain
268 den16 = (int16_t) WEBRTC_SPL_SHIFT_W32(tmp32, sh-16); //Q(27+sh-16) = Q(sh+11) (all 16 bits are value bits)
269 inv_gain32 = WebRtcSpl_DivW32W16((int32_t)2147483647, den16); // 1/gain in Q31/Q(sh+11) = Q(20-sh)
270
271 //initial conditions
272 inv_gain16 = (int16_t)(inv_gain32 >> 2); // 1/gain in Q(20-sh-2) = Q(18-sh)
273
274 for (i=0;i<HALF_SUBFRAMELEN;i++)
275 {
276
277 tmp32 = lat_inQ25[i + temp1] << 1; // Q25->Q26
278 tmp32 = WEBRTC_SPL_MUL_16_32_RSFT16(inv_gain16, tmp32); //lat_in[]*inv_gain in (Q(18-sh)*Q26)>>16 = Q(28-sh)
279 tmp32 = WEBRTC_SPL_SHIFT_W32(tmp32, -(28-sh)); // lat_in[]*inv_gain in Q0
280
281 ARfQ0vec[i] = (int16_t)WebRtcSpl_SatW32ToW16(tmp32); // Q0
282 }
283
284 // Get the state of f & g for the first input, for all orders.
285 for (i = orderCoef; i > 0; i--)
286 {
287 tmp32 = (cthQ15[i - 1] * ARfQ0vec[0] - sthQ15[i - 1] * stateGQ0[i - 1] +
288 16384) >> 15;
289 tmpAR = (int16_t)WebRtcSpl_SatW32ToW16(tmp32); // Q0
290
291 tmp32 = (sthQ15[i - 1] * ARfQ0vec[0] + cthQ15[i - 1] * stateGQ0[i - 1] +
292 16384) >> 15;
293 ARgQ0vec[i] = (int16_t)WebRtcSpl_SatW32ToW16(tmp32); // Q0
294 ARfQ0vec[0] = tmpAR;
295 }
296 ARgQ0vec[0] = ARfQ0vec[0];
297
298 // Filter ARgQ0vec[] and ARfQ0vec[] through coefficients cthQ15[] and sthQ15[].
299 WebRtcIsacfix_FilterArLoop(ARgQ0vec, ARfQ0vec, cthQ15, sthQ15, orderCoef);
300
301 for(n=0;n<HALF_SUBFRAMELEN;n++)
302 {
303 lat_outQ0[n + temp1] = ARfQ0vec[n];
304 }
305
306
307 /* cannot use memcpy in the following */
308
309 for (i=0;i<ord_1;i++)
310 {
311 stateGQ0[i] = ARgQ0vec[i];
312 }
313 }
314
315 return;
316 }
317