Project Ne10
An Open Optimized Software Library Project for the ARM Architecture
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NE10_iir.c
1/*
2 * Copyright 2012-15 ARM Limited and Contributors.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 * * Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * * Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * * Neither the name of ARM Limited nor the
13 * names of its contributors may be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY ARM LIMITED AND CONTRIBUTORS "AS IS" AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
18 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
19 * DISCLAIMED. IN NO EVENT SHALL ARM LIMITED AND CONTRIBUTORS BE LIABLE FOR ANY
20 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
21 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
22 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
23 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28/*
29 * NE10 Library : dsp/NE10_iir.c
30 */
31
32#include "NE10_types.h"
33
119 ne10_float32_t * pSrc,
120 ne10_float32_t * pDst,
121 ne10_uint32_t blockSize)
122{
123 ne10_float32_t fcurr, fnext = 0, gcurr, gnext; /* Temporary variables for lattice stages */
124 ne10_float32_t acc; /* Accumlator */
125 ne10_uint32_t blkCnt, tapCnt; /* temporary variables for counts */
126 ne10_float32_t *px1, *px2, *pk, *pv; /* temporary pointers for state and coef */
127 ne10_uint32_t numStages = S->numStages; /* number of stages */
128 ne10_float32_t *pState; /* State pointer */
129 ne10_float32_t *pStateCurnt; /* State current pointer */
130
131
132 /* Run the below code for Cortex-M4 and Cortex-M3 */
133
134 gcurr = 0.0f;
135 blkCnt = blockSize;
136
137 pState = &S->pState[0];
138
139 /* Sample processing */
140 while (blkCnt > 0u)
141 {
142 /* Read Sample from input buffer */
143 /* fN(n) = x(n) */
144 fcurr = *pSrc++;
145
146 /* Initialize state read pointer */
147 px1 = pState;
148 /* Initialize state write pointer */
149 px2 = pState;
150 /* Set accumulator to zero */
151 acc = 0.0f;
152 /* Initialize Ladder coeff pointer */
153 pv = &S->pvCoeffs[S->numStages];
154 /* Initialize Reflection coeff pointer */
155 pk = &S->pkCoeffs[0];
156
157
158 /* Process sample for first tap */
159 gcurr = *px1++;
160 /* fN-1(n) = fN(n) - kN * gN-1(n-1) */
161 fnext = fcurr - ( (*pk) * gcurr);
162 /* gN(n) = kN * fN-1(n) + gN-1(n-1) */
163 gnext = (fnext * (*pk++)) + gcurr;
164 /* write gN(n) into state for next sample processing */
165 *px2++ = gnext;
166 /* y(n) += gN(n) * vN */
167 acc += (gnext * (*pv--));
168
169 /* Update f values for next coefficient processing */
170 fcurr = fnext;
171
172 /* Loop unrolling. Process 4 taps at a time. */
173 tapCnt = (numStages - 1u) >> 2;
174
175 while (tapCnt > 0u)
176 {
177 /* Process sample for 2nd, 6th ...taps */
178 /* Read gN-2(n-1) from state buffer */
179 gcurr = *px1++;
180 /* Process sample for 2nd, 6th .. taps */
181 /* fN-2(n) = fN-1(n) - kN-1 * gN-2(n-1) */
182 fnext = fcurr - ( (*pk) * gcurr);
183 /* gN-1(n) = kN-1 * fN-2(n) + gN-2(n-1) */
184 gnext = (fnext * (*pk++)) + gcurr;
185 /* y(n) += gN-1(n) * vN-1 */
186 /* process for gN-5(n) * vN-5, gN-9(n) * vN-9 ... */
187 acc += (gnext * (*pv--));
188 /* write gN-1(n) into state for next sample processing */
189 *px2++ = gnext;
190
191
192 /* Process sample for 3nd, 7th ...taps */
193 /* Read gN-3(n-1) from state buffer */
194 gcurr = *px1++;
195 /* Process sample for 3rd, 7th .. taps */
196 /* fN-3(n) = fN-2(n) - kN-2 * gN-3(n-1) */
197 fcurr = fnext - ( (*pk) * gcurr);
198 /* gN-2(n) = kN-2 * fN-3(n) + gN-3(n-1) */
199 gnext = (fcurr * (*pk++)) + gcurr;
200 /* y(n) += gN-2(n) * vN-2 */
201 /* process for gN-6(n) * vN-6, gN-10(n) * vN-10 ... */
202 acc += (gnext * (*pv--));
203 /* write gN-2(n) into state for next sample processing */
204 *px2++ = gnext;
205
206
207 /* Process sample for 4th, 8th ...taps */
208 /* Read gN-4(n-1) from state buffer */
209 gcurr = *px1++;
210 /* Process sample for 4th, 8th .. taps */
211 /* fN-4(n) = fN-3(n) - kN-3 * gN-4(n-1) */
212 fnext = fcurr - ( (*pk) * gcurr);
213 /* gN-3(n) = kN-3 * fN-4(n) + gN-4(n-1) */
214 gnext = (fnext * (*pk++)) + gcurr;
215 /* y(n) += gN-3(n) * vN-3 */
216 /* process for gN-7(n) * vN-7, gN-11(n) * vN-11 ... */
217 acc += (gnext * (*pv--));
218 /* write gN-3(n) into state for next sample processing */
219 *px2++ = gnext;
220
221
222 /* Process sample for 5th, 9th ...taps */
223 /* Read gN-5(n-1) from state buffer */
224 gcurr = *px1++;
225 /* Process sample for 5th, 9th .. taps */
226 /* fN-5(n) = fN-4(n) - kN-4 * gN-1(n-1) */
227 fcurr = fnext - ( (*pk) * gcurr);
228 /* gN-4(n) = kN-4 * fN-5(n) + gN-5(n-1) */
229 gnext = (fcurr * (*pk++)) + gcurr;
230 /* y(n) += gN-4(n) * vN-4 */
231 /* process for gN-8(n) * vN-8, gN-12(n) * vN-12 ... */
232 acc += (gnext * (*pv--));
233 /* write gN-4(n) into state for next sample processing */
234 *px2++ = gnext;
235
236 tapCnt--;
237
238 }
239
240 fnext = fcurr;
241
242 /* If the filter length is not a multiple of 4, compute the remaining filter taps */
243 tapCnt = (numStages - 1u) % 0x4u;
244
245 while (tapCnt > 0u)
246 {
247 gcurr = *px1++;
248 /* Process sample for last taps */
249 fnext = fcurr - ( (*pk) * gcurr);
250 gnext = (fnext * (*pk++)) + gcurr;
251 /* Output samples for last taps */
252 acc += (gnext * (*pv--));
253 *px2++ = gnext;
254 fcurr = fnext;
255
256 tapCnt--;
257
258 }
259
260
261 /* y(n) += g0(n) * v0 */
262 acc += (fnext * (*pv));
263
264 *px2++ = fnext;
265
266 /* write out into pDst */
267 *pDst++ = acc;
268
269 /* Advance the state pointer by 4 to process the next group of 4 samples */
270 pState = pState + 1u;
271 blkCnt--;
272
273 }
274
275 /* Processing is complete. Now copy last S->numStages samples to start of the buffer
276 for the preperation of next frame process */
277
278 /* Points to the start of the state buffer */
279 pStateCurnt = &S->pState[0];
280 pState = &S->pState[blockSize];
281
282 tapCnt = numStages >> 2u;
283
284 /* copy data */
285 while (tapCnt > 0u)
286 {
287 *pStateCurnt++ = *pState++;
288 *pStateCurnt++ = *pState++;
289 *pStateCurnt++ = *pState++;
290 *pStateCurnt++ = *pState++;
291
292 /* Decrement the loop counter */
293 tapCnt--;
294
295 }
296
297 /* Calculate remaining number of copies */
298 tapCnt = (numStages) % 0x4u;
299
300 /* Copy the remaining q31_t data */
301 while (tapCnt > 0u)
302 {
303 *pStateCurnt++ = *pState++;
304
305 /* Decrement the loop counter */
306 tapCnt--;
307 }
308
309}
//end of IIR_Lattice group
void ne10_iir_lattice_float_c(const ne10_iir_lattice_instance_f32_t *S, ne10_float32_t *pSrc, ne10_float32_t *pDst, ne10_uint32_t blockSize)
Processing function for the floating-point IIR lattice filter.
Definition NE10_iir.c:118
Instance structure for the floating point IIR Lattice filter.
Definition NE10_types.h:420
ne10_float32_t * pState
Points to the state variable array.
Definition NE10_types.h:422
ne10_float32_t * pkCoeffs
Points to the reflection coefficient array.
Definition NE10_types.h:423
ne10_uint16_t numStages
numStages of the of lattice filter.
Definition NE10_types.h:421
ne10_float32_t * pvCoeffs
Points to the ladder coefficient array.
Definition NE10_types.h:424