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CMSIS DSP library

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cmsis_dsp/FilteringFunctions/arm_iir_lattice_q31.c@2:da51fb522205, 2013-05-30 (annotated)

Committer:
emilmont
Date:
Thu May 30 17:10:11 2013 +0100
Revision:
2:da51fb522205
Parent:
1:fdd22bb7aa52
Child:
3:7a284390b0ce
Keep "cmsis-dsp" module in synch with its source

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 1:fdd22bb7aa52 1 /* ----------------------------------------------------------------------
emilmont 1:fdd22bb7aa52 2 * Copyright (C) 2010 ARM Limited. All rights reserved.
emilmont 1:fdd22bb7aa52 3 *
emilmont 1:fdd22bb7aa52 4 * $Date: 15. February 2012
emilmont 2:da51fb522205 5 * $Revision: V1.1.0
emilmont 1:fdd22bb7aa52 6 *
emilmont 2:da51fb522205 7 * Project: CMSIS DSP Library
emilmont 2:da51fb522205 8 * Title: arm_iir_lattice_q31.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 2:da51fb522205 10 * Description: Q31 IIR lattice filter processing function.
emilmont 1:fdd22bb7aa52 11 *
emilmont 1:fdd22bb7aa52 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
emilmont 1:fdd22bb7aa52 13 *
emilmont 1:fdd22bb7aa52 14 * Version 1.1.0 2012/02/15
emilmont 1:fdd22bb7aa52 15 * Updated with more optimizations, bug fixes and minor API changes.
emilmont 1:fdd22bb7aa52 16 *
emilmont 1:fdd22bb7aa52 17 * Version 1.0.10 2011/7/15
emilmont 1:fdd22bb7aa52 18 * Big Endian support added and Merged M0 and M3/M4 Source code.
emilmont 1:fdd22bb7aa52 19 *
emilmont 1:fdd22bb7aa52 20 * Version 1.0.3 2010/11/29
emilmont 1:fdd22bb7aa52 21 * Re-organized the CMSIS folders and updated documentation.
emilmont 1:fdd22bb7aa52 22 *
emilmont 1:fdd22bb7aa52 23 * Version 1.0.2 2010/11/11
emilmont 1:fdd22bb7aa52 24 * Documentation updated.
emilmont 1:fdd22bb7aa52 25 *
emilmont 1:fdd22bb7aa52 26 * Version 1.0.1 2010/10/05
emilmont 1:fdd22bb7aa52 27 * Production release and review comments incorporated.
emilmont 1:fdd22bb7aa52 28 *
emilmont 1:fdd22bb7aa52 29 * Version 1.0.0 2010/09/20
emilmont 1:fdd22bb7aa52 30 * Production release and review comments incorporated
emilmont 1:fdd22bb7aa52 31 *
emilmont 1:fdd22bb7aa52 32 * Version 0.0.7 2010/06/10
emilmont 1:fdd22bb7aa52 33 * Misra-C changes done
emilmont 1:fdd22bb7aa52 34 * -------------------------------------------------------------------- */
emilmont 1:fdd22bb7aa52 35
emilmont 1:fdd22bb7aa52 36 #include "arm_math.h"
emilmont 1:fdd22bb7aa52 37
emilmont 1:fdd22bb7aa52 38 /**
emilmont 1:fdd22bb7aa52 39 * @ingroup groupFilters
emilmont 1:fdd22bb7aa52 40 */
emilmont 1:fdd22bb7aa52 41
emilmont 1:fdd22bb7aa52 42 /**
emilmont 1:fdd22bb7aa52 43 * @addtogroup IIR_Lattice
emilmont 1:fdd22bb7aa52 44 * @{
emilmont 1:fdd22bb7aa52 45 */
emilmont 1:fdd22bb7aa52 46
emilmont 1:fdd22bb7aa52 47 /**
emilmont 1:fdd22bb7aa52 48 * @brief Processing function for the Q31 IIR lattice filter.
emilmont 1:fdd22bb7aa52 49 * @param[in] *S points to an instance of the Q31 IIR lattice structure.
emilmont 1:fdd22bb7aa52 50 * @param[in] *pSrc points to the block of input data.
emilmont 1:fdd22bb7aa52 51 * @param[out] *pDst points to the block of output data.
emilmont 1:fdd22bb7aa52 52 * @param[in] blockSize number of samples to process.
emilmont 1:fdd22bb7aa52 53 * @return none.
emilmont 1:fdd22bb7aa52 54 *
emilmont 1:fdd22bb7aa52 55 * @details
emilmont 1:fdd22bb7aa52 56 * <b>Scaling and Overflow Behavior:</b>
emilmont 1:fdd22bb7aa52 57 * \par
emilmont 1:fdd22bb7aa52 58 * The function is implemented using an internal 64-bit accumulator.
emilmont 1:fdd22bb7aa52 59 * The accumulator has a 2.62 format and maintains full precision of the intermediate multiplication results but provides only a single guard bit.
emilmont 1:fdd22bb7aa52 60 * Thus, if the accumulator result overflows it wraps around rather than clip.
emilmont 1:fdd22bb7aa52 61 * In order to avoid overflows completely the input signal must be scaled down by 2*log2(numStages) bits.
emilmont 1:fdd22bb7aa52 62 * After all multiply-accumulates are performed, the 2.62 accumulator is saturated to 1.32 format and then truncated to 1.31 format.
emilmont 1:fdd22bb7aa52 63 */
emilmont 1:fdd22bb7aa52 64
emilmont 1:fdd22bb7aa52 65 void arm_iir_lattice_q31(
emilmont 1:fdd22bb7aa52 66 const arm_iir_lattice_instance_q31 * S,
emilmont 1:fdd22bb7aa52 67 q31_t * pSrc,
emilmont 1:fdd22bb7aa52 68 q31_t * pDst,
emilmont 1:fdd22bb7aa52 69 uint32_t blockSize)
emilmont 1:fdd22bb7aa52 70 {
emilmont 1:fdd22bb7aa52 71 q31_t fcurr, fnext = 0, gcurr = 0, gnext; /* Temporary variables for lattice stages */
emilmont 1:fdd22bb7aa52 72 q63_t acc; /* Accumlator */
emilmont 1:fdd22bb7aa52 73 uint32_t blkCnt, tapCnt; /* Temporary variables for counts */
emilmont 1:fdd22bb7aa52 74 q31_t *px1, *px2, *pk, *pv; /* Temporary pointers for state and coef */
emilmont 1:fdd22bb7aa52 75 uint32_t numStages = S->numStages; /* number of stages */
emilmont 1:fdd22bb7aa52 76 q31_t *pState; /* State pointer */
emilmont 1:fdd22bb7aa52 77 q31_t *pStateCurnt; /* State current pointer */
emilmont 1:fdd22bb7aa52 78
emilmont 1:fdd22bb7aa52 79 blkCnt = blockSize;
emilmont 1:fdd22bb7aa52 80
emilmont 1:fdd22bb7aa52 81 pState = &S->pState[0];
emilmont 1:fdd22bb7aa52 82
emilmont 1:fdd22bb7aa52 83
emilmont 1:fdd22bb7aa52 84 #ifndef ARM_MATH_CM0
emilmont 1:fdd22bb7aa52 85
emilmont 1:fdd22bb7aa52 86 /* Run the below code for Cortex-M4 and Cortex-M3 */
emilmont 1:fdd22bb7aa52 87
emilmont 1:fdd22bb7aa52 88 /* Sample processing */
emilmont 1:fdd22bb7aa52 89 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 90 {
emilmont 1:fdd22bb7aa52 91 /* Read Sample from input buffer */
emilmont 1:fdd22bb7aa52 92 /* fN(n) = x(n) */
emilmont 1:fdd22bb7aa52 93 fcurr = *pSrc++;
emilmont 1:fdd22bb7aa52 94
emilmont 1:fdd22bb7aa52 95 /* Initialize state read pointer */
emilmont 1:fdd22bb7aa52 96 px1 = pState;
emilmont 1:fdd22bb7aa52 97 /* Initialize state write pointer */
emilmont 1:fdd22bb7aa52 98 px2 = pState;
emilmont 1:fdd22bb7aa52 99 /* Set accumulator to zero */
emilmont 1:fdd22bb7aa52 100 acc = 0;
emilmont 1:fdd22bb7aa52 101 /* Initialize Ladder coeff pointer */
emilmont 1:fdd22bb7aa52 102 pv = &S->pvCoeffs[0];
emilmont 1:fdd22bb7aa52 103 /* Initialize Reflection coeff pointer */
emilmont 1:fdd22bb7aa52 104 pk = &S->pkCoeffs[0];
emilmont 1:fdd22bb7aa52 105
emilmont 1:fdd22bb7aa52 106
emilmont 1:fdd22bb7aa52 107 /* Process sample for first tap */
emilmont 1:fdd22bb7aa52 108 gcurr = *px1++;
emilmont 1:fdd22bb7aa52 109 /* fN-1(n) = fN(n) - kN * gN-1(n-1) */
emilmont 1:fdd22bb7aa52 110 fnext = __QSUB(fcurr, (q31_t) (((q63_t) gcurr * (*pk)) >> 31));
emilmont 1:fdd22bb7aa52 111 /* gN(n) = kN * fN-1(n) + gN-1(n-1) */
emilmont 1:fdd22bb7aa52 112 gnext = __QADD(gcurr, (q31_t) (((q63_t) fnext * (*pk++)) >> 31));
emilmont 1:fdd22bb7aa52 113 /* write gN-1(n-1) into state for next sample processing */
emilmont 1:fdd22bb7aa52 114 *px2++ = gnext;
emilmont 1:fdd22bb7aa52 115 /* y(n) += gN(n) * vN */
emilmont 1:fdd22bb7aa52 116 acc += ((q63_t) gnext * *pv++);
emilmont 1:fdd22bb7aa52 117
emilmont 1:fdd22bb7aa52 118 /* Update f values for next coefficient processing */
emilmont 1:fdd22bb7aa52 119 fcurr = fnext;
emilmont 1:fdd22bb7aa52 120
emilmont 1:fdd22bb7aa52 121 /* Loop unrolling. Process 4 taps at a time. */
emilmont 1:fdd22bb7aa52 122 tapCnt = (numStages - 1u) >> 2;
emilmont 1:fdd22bb7aa52 123
emilmont 1:fdd22bb7aa52 124 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 125 {
emilmont 1:fdd22bb7aa52 126
emilmont 1:fdd22bb7aa52 127 /* Process sample for 2nd, 6th .. taps */
emilmont 1:fdd22bb7aa52 128 /* Read gN-2(n-1) from state buffer */
emilmont 1:fdd22bb7aa52 129 gcurr = *px1++;
emilmont 1:fdd22bb7aa52 130 /* fN-2(n) = fN-1(n) - kN-1 * gN-2(n-1) */
emilmont 1:fdd22bb7aa52 131 fnext = __QSUB(fcurr, (q31_t) (((q63_t) gcurr * (*pk)) >> 31));
emilmont 1:fdd22bb7aa52 132 /* gN-1(n) = kN-1 * fN-2(n) + gN-2(n-1) */
emilmont 1:fdd22bb7aa52 133 gnext = __QADD(gcurr, (q31_t) (((q63_t) fnext * (*pk++)) >> 31));
emilmont 1:fdd22bb7aa52 134 /* y(n) += gN-1(n) * vN-1 */
emilmont 1:fdd22bb7aa52 135 /* process for gN-5(n) * vN-5, gN-9(n) * vN-9 ... */
emilmont 1:fdd22bb7aa52 136 acc += ((q63_t) gnext * *pv++);
emilmont 1:fdd22bb7aa52 137 /* write gN-1(n) into state for next sample processing */
emilmont 1:fdd22bb7aa52 138 *px2++ = gnext;
emilmont 1:fdd22bb7aa52 139
emilmont 1:fdd22bb7aa52 140 /* Process sample for 3nd, 7th ...taps */
emilmont 1:fdd22bb7aa52 141 /* Read gN-3(n-1) from state buffer */
emilmont 1:fdd22bb7aa52 142 gcurr = *px1++;
emilmont 1:fdd22bb7aa52 143 /* Process sample for 3rd, 7th .. taps */
emilmont 1:fdd22bb7aa52 144 /* fN-3(n) = fN-2(n) - kN-2 * gN-3(n-1) */
emilmont 1:fdd22bb7aa52 145 fcurr = __QSUB(fnext, (q31_t) (((q63_t) gcurr * (*pk)) >> 31));
emilmont 1:fdd22bb7aa52 146 /* gN-2(n) = kN-2 * fN-3(n) + gN-3(n-1) */
emilmont 1:fdd22bb7aa52 147 gnext = __QADD(gcurr, (q31_t) (((q63_t) fcurr * (*pk++)) >> 31));
emilmont 1:fdd22bb7aa52 148 /* y(n) += gN-2(n) * vN-2 */
emilmont 1:fdd22bb7aa52 149 /* process for gN-6(n) * vN-6, gN-10(n) * vN-10 ... */
emilmont 1:fdd22bb7aa52 150 acc += ((q63_t) gnext * *pv++);
emilmont 1:fdd22bb7aa52 151 /* write gN-2(n) into state for next sample processing */
emilmont 1:fdd22bb7aa52 152 *px2++ = gnext;
emilmont 1:fdd22bb7aa52 153
emilmont 1:fdd22bb7aa52 154
emilmont 1:fdd22bb7aa52 155 /* Process sample for 4th, 8th ...taps */
emilmont 1:fdd22bb7aa52 156 /* Read gN-4(n-1) from state buffer */
emilmont 1:fdd22bb7aa52 157 gcurr = *px1++;
emilmont 1:fdd22bb7aa52 158 /* Process sample for 4th, 8th .. taps */
emilmont 1:fdd22bb7aa52 159 /* fN-4(n) = fN-3(n) - kN-3 * gN-4(n-1) */
emilmont 1:fdd22bb7aa52 160 fnext = __QSUB(fcurr, (q31_t) (((q63_t) gcurr * (*pk)) >> 31));
emilmont 1:fdd22bb7aa52 161 /* gN-3(n) = kN-3 * fN-4(n) + gN-4(n-1) */
emilmont 1:fdd22bb7aa52 162 gnext = __QADD(gcurr, (q31_t) (((q63_t) fnext * (*pk++)) >> 31));
emilmont 1:fdd22bb7aa52 163 /* y(n) += gN-3(n) * vN-3 */
emilmont 1:fdd22bb7aa52 164 /* process for gN-7(n) * vN-7, gN-11(n) * vN-11 ... */
emilmont 1:fdd22bb7aa52 165 acc += ((q63_t) gnext * *pv++);
emilmont 1:fdd22bb7aa52 166 /* write gN-3(n) into state for next sample processing */
emilmont 1:fdd22bb7aa52 167 *px2++ = gnext;
emilmont 1:fdd22bb7aa52 168
emilmont 1:fdd22bb7aa52 169
emilmont 1:fdd22bb7aa52 170 /* Process sample for 5th, 9th ...taps */
emilmont 1:fdd22bb7aa52 171 /* Read gN-5(n-1) from state buffer */
emilmont 1:fdd22bb7aa52 172 gcurr = *px1++;
emilmont 1:fdd22bb7aa52 173 /* Process sample for 5th, 9th .. taps */
emilmont 1:fdd22bb7aa52 174 /* fN-5(n) = fN-4(n) - kN-4 * gN-1(n-1) */
emilmont 1:fdd22bb7aa52 175 fcurr = __QSUB(fnext, (q31_t) (((q63_t) gcurr * (*pk)) >> 31));
emilmont 1:fdd22bb7aa52 176 /* gN-4(n) = kN-4 * fN-5(n) + gN-5(n-1) */
emilmont 1:fdd22bb7aa52 177 gnext = __QADD(gcurr, (q31_t) (((q63_t) fcurr * (*pk++)) >> 31));
emilmont 1:fdd22bb7aa52 178 /* y(n) += gN-4(n) * vN-4 */
emilmont 1:fdd22bb7aa52 179 /* process for gN-8(n) * vN-8, gN-12(n) * vN-12 ... */
emilmont 1:fdd22bb7aa52 180 acc += ((q63_t) gnext * *pv++);
emilmont 1:fdd22bb7aa52 181 /* write gN-4(n) into state for next sample processing */
emilmont 1:fdd22bb7aa52 182 *px2++ = gnext;
emilmont 1:fdd22bb7aa52 183
emilmont 1:fdd22bb7aa52 184 tapCnt--;
emilmont 1:fdd22bb7aa52 185
emilmont 1:fdd22bb7aa52 186 }
emilmont 1:fdd22bb7aa52 187
emilmont 1:fdd22bb7aa52 188 fnext = fcurr;
emilmont 1:fdd22bb7aa52 189
emilmont 1:fdd22bb7aa52 190 /* If the filter length is not a multiple of 4, compute the remaining filter taps */
emilmont 1:fdd22bb7aa52 191 tapCnt = (numStages - 1u) % 0x4u;
emilmont 1:fdd22bb7aa52 192
emilmont 1:fdd22bb7aa52 193 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 194 {
emilmont 1:fdd22bb7aa52 195 gcurr = *px1++;
emilmont 1:fdd22bb7aa52 196 /* Process sample for last taps */
emilmont 1:fdd22bb7aa52 197 fnext = __QSUB(fcurr, (q31_t) (((q63_t) gcurr * (*pk)) >> 31));
emilmont 1:fdd22bb7aa52 198 gnext = __QADD(gcurr, (q31_t) (((q63_t) fnext * (*pk++)) >> 31));
emilmont 1:fdd22bb7aa52 199 /* Output samples for last taps */
emilmont 1:fdd22bb7aa52 200 acc += ((q63_t) gnext * *pv++);
emilmont 1:fdd22bb7aa52 201 *px2++ = gnext;
emilmont 1:fdd22bb7aa52 202 fcurr = fnext;
emilmont 1:fdd22bb7aa52 203
emilmont 1:fdd22bb7aa52 204 tapCnt--;
emilmont 1:fdd22bb7aa52 205
emilmont 1:fdd22bb7aa52 206 }
emilmont 1:fdd22bb7aa52 207
emilmont 1:fdd22bb7aa52 208 /* y(n) += g0(n) * v0 */
emilmont 1:fdd22bb7aa52 209 acc += (q63_t) fnext *(
emilmont 1:fdd22bb7aa52 210 *pv++);
emilmont 1:fdd22bb7aa52 211
emilmont 1:fdd22bb7aa52 212 *px2++ = fnext;
emilmont 1:fdd22bb7aa52 213
emilmont 1:fdd22bb7aa52 214 /* write out into pDst */
emilmont 1:fdd22bb7aa52 215 *pDst++ = (q31_t) (acc >> 31u);
emilmont 1:fdd22bb7aa52 216
emilmont 1:fdd22bb7aa52 217 /* Advance the state pointer by 4 to process the next group of 4 samples */
emilmont 1:fdd22bb7aa52 218 pState = pState + 1u;
emilmont 1:fdd22bb7aa52 219 blkCnt--;
emilmont 1:fdd22bb7aa52 220
emilmont 1:fdd22bb7aa52 221 }
emilmont 1:fdd22bb7aa52 222
emilmont 1:fdd22bb7aa52 223 /* Processing is complete. Now copy last S->numStages samples to start of the buffer
emilmont 1:fdd22bb7aa52 224 for the preperation of next frame process */
emilmont 1:fdd22bb7aa52 225
emilmont 1:fdd22bb7aa52 226 /* Points to the start of the state buffer */
emilmont 1:fdd22bb7aa52 227 pStateCurnt = &S->pState[0];
emilmont 1:fdd22bb7aa52 228 pState = &S->pState[blockSize];
emilmont 1:fdd22bb7aa52 229
emilmont 1:fdd22bb7aa52 230 tapCnt = numStages >> 2u;
emilmont 1:fdd22bb7aa52 231
emilmont 1:fdd22bb7aa52 232 /* copy data */
emilmont 1:fdd22bb7aa52 233 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 234 {
emilmont 1:fdd22bb7aa52 235 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 236 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 237 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 238 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 239
emilmont 1:fdd22bb7aa52 240 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 241 tapCnt--;
emilmont 1:fdd22bb7aa52 242
emilmont 1:fdd22bb7aa52 243 }
emilmont 1:fdd22bb7aa52 244
emilmont 1:fdd22bb7aa52 245 /* Calculate remaining number of copies */
emilmont 1:fdd22bb7aa52 246 tapCnt = (numStages) % 0x4u;
emilmont 1:fdd22bb7aa52 247
emilmont 1:fdd22bb7aa52 248 /* Copy the remaining q31_t data */
emilmont 1:fdd22bb7aa52 249 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 250 {
emilmont 1:fdd22bb7aa52 251 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 252
emilmont 1:fdd22bb7aa52 253 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 254 tapCnt--;
emilmont 1:fdd22bb7aa52 255 };
emilmont 1:fdd22bb7aa52 256
emilmont 1:fdd22bb7aa52 257 #else
emilmont 1:fdd22bb7aa52 258
emilmont 1:fdd22bb7aa52 259 /* Run the below code for Cortex-M0 */
emilmont 1:fdd22bb7aa52 260 /* Sample processing */
emilmont 1:fdd22bb7aa52 261 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 262 {
emilmont 1:fdd22bb7aa52 263 /* Read Sample from input buffer */
emilmont 1:fdd22bb7aa52 264 /* fN(n) = x(n) */
emilmont 1:fdd22bb7aa52 265 fcurr = *pSrc++;
emilmont 1:fdd22bb7aa52 266
emilmont 1:fdd22bb7aa52 267 /* Initialize state read pointer */
emilmont 1:fdd22bb7aa52 268 px1 = pState;
emilmont 1:fdd22bb7aa52 269 /* Initialize state write pointer */
emilmont 1:fdd22bb7aa52 270 px2 = pState;
emilmont 1:fdd22bb7aa52 271 /* Set accumulator to zero */
emilmont 1:fdd22bb7aa52 272 acc = 0;
emilmont 1:fdd22bb7aa52 273 /* Initialize Ladder coeff pointer */
emilmont 1:fdd22bb7aa52 274 pv = &S->pvCoeffs[0];
emilmont 1:fdd22bb7aa52 275 /* Initialize Reflection coeff pointer */
emilmont 1:fdd22bb7aa52 276 pk = &S->pkCoeffs[0];
emilmont 1:fdd22bb7aa52 277
emilmont 1:fdd22bb7aa52 278 tapCnt = numStages;
emilmont 1:fdd22bb7aa52 279
emilmont 1:fdd22bb7aa52 280 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 281 {
emilmont 1:fdd22bb7aa52 282 gcurr = *px1++;
emilmont 1:fdd22bb7aa52 283 /* Process sample */
emilmont 1:fdd22bb7aa52 284 /* fN-1(n) = fN(n) - kN * gN-1(n-1) */
emilmont 1:fdd22bb7aa52 285 fnext =
emilmont 1:fdd22bb7aa52 286 clip_q63_to_q31(((q63_t) fcurr -
emilmont 1:fdd22bb7aa52 287 ((q31_t) (((q63_t) gcurr * (*pk)) >> 31))));
emilmont 1:fdd22bb7aa52 288 /* gN(n) = kN * fN-1(n) + gN-1(n-1) */
emilmont 1:fdd22bb7aa52 289 gnext =
emilmont 1:fdd22bb7aa52 290 clip_q63_to_q31(((q63_t) gcurr +
emilmont 1:fdd22bb7aa52 291 ((q31_t) (((q63_t) fnext * (*pk++)) >> 31))));
emilmont 1:fdd22bb7aa52 292 /* Output samples */
emilmont 1:fdd22bb7aa52 293 /* y(n) += gN(n) * vN */
emilmont 1:fdd22bb7aa52 294 acc += ((q63_t) gnext * *pv++);
emilmont 1:fdd22bb7aa52 295 /* write gN-1(n-1) into state for next sample processing */
emilmont 1:fdd22bb7aa52 296 *px2++ = gnext;
emilmont 1:fdd22bb7aa52 297 /* Update f values for next coefficient processing */
emilmont 1:fdd22bb7aa52 298 fcurr = fnext;
emilmont 1:fdd22bb7aa52 299
emilmont 1:fdd22bb7aa52 300 tapCnt--;
emilmont 1:fdd22bb7aa52 301 }
emilmont 1:fdd22bb7aa52 302
emilmont 1:fdd22bb7aa52 303 /* y(n) += g0(n) * v0 */
emilmont 1:fdd22bb7aa52 304 acc += (q63_t) fnext *(
emilmont 1:fdd22bb7aa52 305 *pv++);
emilmont 1:fdd22bb7aa52 306
emilmont 1:fdd22bb7aa52 307 *px2++ = fnext;
emilmont 1:fdd22bb7aa52 308
emilmont 1:fdd22bb7aa52 309 /* write out into pDst */
emilmont 1:fdd22bb7aa52 310 *pDst++ = (q31_t) (acc >> 31u);
emilmont 1:fdd22bb7aa52 311
emilmont 1:fdd22bb7aa52 312 /* Advance the state pointer by 1 to process the next group of samples */
emilmont 1:fdd22bb7aa52 313 pState = pState + 1u;
emilmont 1:fdd22bb7aa52 314 blkCnt--;
emilmont 1:fdd22bb7aa52 315
emilmont 1:fdd22bb7aa52 316 }
emilmont 1:fdd22bb7aa52 317
emilmont 1:fdd22bb7aa52 318 /* Processing is complete. Now copy last S->numStages samples to start of the buffer
emilmont 1:fdd22bb7aa52 319 for the preperation of next frame process */
emilmont 1:fdd22bb7aa52 320
emilmont 1:fdd22bb7aa52 321 /* Points to the start of the state buffer */
emilmont 1:fdd22bb7aa52 322 pStateCurnt = &S->pState[0];
emilmont 1:fdd22bb7aa52 323 pState = &S->pState[blockSize];
emilmont 1:fdd22bb7aa52 324
emilmont 1:fdd22bb7aa52 325 tapCnt = numStages;
emilmont 1:fdd22bb7aa52 326
emilmont 1:fdd22bb7aa52 327 /* Copy the remaining q31_t data */
emilmont 1:fdd22bb7aa52 328 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 329 {
emilmont 1:fdd22bb7aa52 330 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 331
emilmont 1:fdd22bb7aa52 332 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 333 tapCnt--;
emilmont 1:fdd22bb7aa52 334 }
emilmont 1:fdd22bb7aa52 335
emilmont 1:fdd22bb7aa52 336 #endif /* #ifndef ARM_MATH_CM0 */
emilmont 1:fdd22bb7aa52 337
emilmont 1:fdd22bb7aa52 338 }
emilmont 1:fdd22bb7aa52 339
emilmont 1:fdd22bb7aa52 340
emilmont 1:fdd22bb7aa52 341
emilmont 1:fdd22bb7aa52 342
emilmont 1:fdd22bb7aa52 343 /**
emilmont 1:fdd22bb7aa52 344 * @} end of IIR_Lattice group
emilmont 1:fdd22bb7aa52 345 */