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CMSIS DSP library

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cmsis_dsp/FilteringFunctions/arm_fir_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_fir_lattice_q31.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 2:da51fb522205 10 * Description: Q31 FIR 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 FIR_Lattice
emilmont 1:fdd22bb7aa52 44 * @{
emilmont 1:fdd22bb7aa52 45 */
emilmont 1:fdd22bb7aa52 46
emilmont 1:fdd22bb7aa52 47
emilmont 1:fdd22bb7aa52 48 /**
emilmont 1:fdd22bb7aa52 49 * @brief Processing function for the Q31 FIR lattice filter.
emilmont 1:fdd22bb7aa52 50 * @param[in] *S points to an instance of the Q31 FIR lattice structure.
emilmont 1:fdd22bb7aa52 51 * @param[in] *pSrc points to the block of input data.
emilmont 1:fdd22bb7aa52 52 * @param[out] *pDst points to the block of output data
emilmont 1:fdd22bb7aa52 53 * @param[in] blockSize number of samples to process.
emilmont 1:fdd22bb7aa52 54 * @return none.
emilmont 1:fdd22bb7aa52 55 *
emilmont 1:fdd22bb7aa52 56 * @details
emilmont 1:fdd22bb7aa52 57 * <b>Scaling and Overflow Behavior:</b>
emilmont 1:fdd22bb7aa52 58 * In order to avoid overflows the input signal must be scaled down by 2*log2(numStages) bits.
emilmont 1:fdd22bb7aa52 59 */
emilmont 1:fdd22bb7aa52 60
emilmont 1:fdd22bb7aa52 61 #ifndef ARM_MATH_CM0
emilmont 1:fdd22bb7aa52 62
emilmont 1:fdd22bb7aa52 63 /* Run the below code for Cortex-M4 and Cortex-M3 */
emilmont 1:fdd22bb7aa52 64
emilmont 1:fdd22bb7aa52 65 void arm_fir_lattice_q31(
emilmont 1:fdd22bb7aa52 66 const arm_fir_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 *pState; /* State pointer */
emilmont 1:fdd22bb7aa52 72 q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
emilmont 1:fdd22bb7aa52 73 q31_t *px; /* temporary state pointer */
emilmont 1:fdd22bb7aa52 74 q31_t *pk; /* temporary coefficient pointer */
emilmont 1:fdd22bb7aa52 75 q31_t fcurr1, fnext1, gcurr1 = 0, gnext1; /* temporary variables for first sample in loop unrolling */
emilmont 1:fdd22bb7aa52 76 q31_t fcurr2, fnext2, gnext2; /* temporary variables for second sample in loop unrolling */
emilmont 1:fdd22bb7aa52 77 uint32_t numStages = S->numStages; /* Length of the filter */
emilmont 1:fdd22bb7aa52 78 uint32_t blkCnt, stageCnt; /* temporary variables for counts */
emilmont 1:fdd22bb7aa52 79 q31_t k;
emilmont 1:fdd22bb7aa52 80
emilmont 1:fdd22bb7aa52 81 pState = &S->pState[0];
emilmont 1:fdd22bb7aa52 82
emilmont 1:fdd22bb7aa52 83 blkCnt = blockSize >> 1u;
emilmont 1:fdd22bb7aa52 84
emilmont 1:fdd22bb7aa52 85 /* First part of the processing with loop unrolling. Compute 2 outputs at a time.
emilmont 1:fdd22bb7aa52 86 a second loop below computes the remaining 1 sample. */
emilmont 1:fdd22bb7aa52 87 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 88 {
emilmont 1:fdd22bb7aa52 89 /* f0(n) = x(n) */
emilmont 1:fdd22bb7aa52 90 fcurr1 = *pSrc++;
emilmont 1:fdd22bb7aa52 91
emilmont 1:fdd22bb7aa52 92 /* f0(n) = x(n) */
emilmont 1:fdd22bb7aa52 93 fcurr2 = *pSrc++;
emilmont 1:fdd22bb7aa52 94
emilmont 1:fdd22bb7aa52 95 /* Initialize coeff pointer */
emilmont 1:fdd22bb7aa52 96 pk = (pCoeffs);
emilmont 1:fdd22bb7aa52 97
emilmont 1:fdd22bb7aa52 98 /* Initialize state pointer */
emilmont 1:fdd22bb7aa52 99 px = pState;
emilmont 1:fdd22bb7aa52 100
emilmont 1:fdd22bb7aa52 101 /* read g0(n - 1) from state buffer */
emilmont 1:fdd22bb7aa52 102 gcurr1 = *px;
emilmont 1:fdd22bb7aa52 103
emilmont 1:fdd22bb7aa52 104 /* Read the reflection coefficient */
emilmont 1:fdd22bb7aa52 105 k = *pk++;
emilmont 1:fdd22bb7aa52 106
emilmont 1:fdd22bb7aa52 107 /* for sample 1 processing */
emilmont 1:fdd22bb7aa52 108 /* f1(n) = f0(n) + K1 * g0(n-1) */
emilmont 1:fdd22bb7aa52 109 fnext1 = (q31_t) (((q63_t) gcurr1 * k) >> 32);
emilmont 1:fdd22bb7aa52 110
emilmont 1:fdd22bb7aa52 111 /* g1(n) = f0(n) * K1 + g0(n-1) */
emilmont 1:fdd22bb7aa52 112 gnext1 = (q31_t) (((q63_t) fcurr1 * (k)) >> 32);
emilmont 1:fdd22bb7aa52 113 fnext1 = fcurr1 + (fnext1 << 1u);
emilmont 1:fdd22bb7aa52 114 gnext1 = gcurr1 + (gnext1 << 1u);
emilmont 1:fdd22bb7aa52 115
emilmont 1:fdd22bb7aa52 116 /* for sample 1 processing */
emilmont 1:fdd22bb7aa52 117 /* f1(n) = f0(n) + K1 * g0(n-1) */
emilmont 1:fdd22bb7aa52 118 fnext2 = (q31_t) (((q63_t) fcurr1 * k) >> 32);
emilmont 1:fdd22bb7aa52 119
emilmont 1:fdd22bb7aa52 120 /* g1(n) = f0(n) * K1 + g0(n-1) */
emilmont 1:fdd22bb7aa52 121 gnext2 = (q31_t) (((q63_t) fcurr2 * (k)) >> 32);
emilmont 1:fdd22bb7aa52 122 fnext2 = fcurr2 + (fnext2 << 1u);
emilmont 1:fdd22bb7aa52 123 gnext2 = fcurr1 + (gnext2 << 1u);
emilmont 1:fdd22bb7aa52 124
emilmont 1:fdd22bb7aa52 125 /* save g1(n) in state buffer */
emilmont 1:fdd22bb7aa52 126 *px++ = fcurr2;
emilmont 1:fdd22bb7aa52 127
emilmont 1:fdd22bb7aa52 128 /* f1(n) is saved in fcurr1
emilmont 1:fdd22bb7aa52 129 for next stage processing */
emilmont 1:fdd22bb7aa52 130 fcurr1 = fnext1;
emilmont 1:fdd22bb7aa52 131 fcurr2 = fnext2;
emilmont 1:fdd22bb7aa52 132
emilmont 1:fdd22bb7aa52 133 stageCnt = (numStages - 1u);
emilmont 1:fdd22bb7aa52 134
emilmont 1:fdd22bb7aa52 135 /* stage loop */
emilmont 1:fdd22bb7aa52 136 while(stageCnt > 0u)
emilmont 1:fdd22bb7aa52 137 {
emilmont 1:fdd22bb7aa52 138
emilmont 1:fdd22bb7aa52 139 /* Read the reflection coefficient */
emilmont 1:fdd22bb7aa52 140 k = *pk++;
emilmont 1:fdd22bb7aa52 141
emilmont 1:fdd22bb7aa52 142 /* read g2(n) from state buffer */
emilmont 1:fdd22bb7aa52 143 gcurr1 = *px;
emilmont 1:fdd22bb7aa52 144
emilmont 1:fdd22bb7aa52 145 /* save g1(n) in state buffer */
emilmont 1:fdd22bb7aa52 146 *px++ = gnext2;
emilmont 1:fdd22bb7aa52 147
emilmont 1:fdd22bb7aa52 148 /* Sample processing for K2, K3.... */
emilmont 1:fdd22bb7aa52 149 /* f2(n) = f1(n) + K2 * g1(n-1) */
emilmont 1:fdd22bb7aa52 150 fnext1 = (q31_t) (((q63_t) gcurr1 * k) >> 32);
emilmont 1:fdd22bb7aa52 151 fnext2 = (q31_t) (((q63_t) gnext1 * k) >> 32);
emilmont 1:fdd22bb7aa52 152
emilmont 1:fdd22bb7aa52 153 fnext1 = fcurr1 + (fnext1 << 1u);
emilmont 1:fdd22bb7aa52 154 fnext2 = fcurr2 + (fnext2 << 1u);
emilmont 1:fdd22bb7aa52 155
emilmont 1:fdd22bb7aa52 156 /* g2(n) = f1(n) * K2 + g1(n-1) */
emilmont 1:fdd22bb7aa52 157 gnext2 = (q31_t) (((q63_t) fcurr2 * (k)) >> 32);
emilmont 1:fdd22bb7aa52 158 gnext2 = gnext1 + (gnext2 << 1u);
emilmont 1:fdd22bb7aa52 159
emilmont 1:fdd22bb7aa52 160 /* g2(n) = f1(n) * K2 + g1(n-1) */
emilmont 1:fdd22bb7aa52 161 gnext1 = (q31_t) (((q63_t) fcurr1 * (k)) >> 32);
emilmont 1:fdd22bb7aa52 162 gnext1 = gcurr1 + (gnext1 << 1u);
emilmont 1:fdd22bb7aa52 163
emilmont 1:fdd22bb7aa52 164 /* f1(n) is saved in fcurr1
emilmont 1:fdd22bb7aa52 165 for next stage processing */
emilmont 1:fdd22bb7aa52 166 fcurr1 = fnext1;
emilmont 1:fdd22bb7aa52 167 fcurr2 = fnext2;
emilmont 1:fdd22bb7aa52 168
emilmont 1:fdd22bb7aa52 169 stageCnt--;
emilmont 1:fdd22bb7aa52 170
emilmont 1:fdd22bb7aa52 171 }
emilmont 1:fdd22bb7aa52 172
emilmont 1:fdd22bb7aa52 173 /* y(n) = fN(n) */
emilmont 1:fdd22bb7aa52 174 *pDst++ = fcurr1;
emilmont 1:fdd22bb7aa52 175 *pDst++ = fcurr2;
emilmont 1:fdd22bb7aa52 176
emilmont 1:fdd22bb7aa52 177 blkCnt--;
emilmont 1:fdd22bb7aa52 178
emilmont 1:fdd22bb7aa52 179 }
emilmont 1:fdd22bb7aa52 180
emilmont 1:fdd22bb7aa52 181 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
emilmont 1:fdd22bb7aa52 182 ** No loop unrolling is used. */
emilmont 1:fdd22bb7aa52 183 blkCnt = blockSize % 0x2u;
emilmont 1:fdd22bb7aa52 184
emilmont 1:fdd22bb7aa52 185 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 186 {
emilmont 1:fdd22bb7aa52 187 /* f0(n) = x(n) */
emilmont 1:fdd22bb7aa52 188 fcurr1 = *pSrc++;
emilmont 1:fdd22bb7aa52 189
emilmont 1:fdd22bb7aa52 190 /* Initialize coeff pointer */
emilmont 1:fdd22bb7aa52 191 pk = (pCoeffs);
emilmont 1:fdd22bb7aa52 192
emilmont 1:fdd22bb7aa52 193 /* Initialize state pointer */
emilmont 1:fdd22bb7aa52 194 px = pState;
emilmont 1:fdd22bb7aa52 195
emilmont 1:fdd22bb7aa52 196 /* read g0(n - 1) from state buffer */
emilmont 1:fdd22bb7aa52 197 gcurr1 = *px;
emilmont 1:fdd22bb7aa52 198
emilmont 1:fdd22bb7aa52 199 /* Read the reflection coefficient */
emilmont 1:fdd22bb7aa52 200 k = *pk++;
emilmont 1:fdd22bb7aa52 201
emilmont 1:fdd22bb7aa52 202 /* for sample 1 processing */
emilmont 1:fdd22bb7aa52 203 /* f1(n) = f0(n) + K1 * g0(n-1) */
emilmont 1:fdd22bb7aa52 204 fnext1 = (q31_t) (((q63_t) gcurr1 * k) >> 32);
emilmont 1:fdd22bb7aa52 205 fnext1 = fcurr1 + (fnext1 << 1u);
emilmont 1:fdd22bb7aa52 206
emilmont 1:fdd22bb7aa52 207 /* g1(n) = f0(n) * K1 + g0(n-1) */
emilmont 1:fdd22bb7aa52 208 gnext1 = (q31_t) (((q63_t) fcurr1 * (k)) >> 32);
emilmont 1:fdd22bb7aa52 209 gnext1 = gcurr1 + (gnext1 << 1u);
emilmont 1:fdd22bb7aa52 210
emilmont 1:fdd22bb7aa52 211 /* save g1(n) in state buffer */
emilmont 1:fdd22bb7aa52 212 *px++ = fcurr1;
emilmont 1:fdd22bb7aa52 213
emilmont 1:fdd22bb7aa52 214 /* f1(n) is saved in fcurr1
emilmont 1:fdd22bb7aa52 215 for next stage processing */
emilmont 1:fdd22bb7aa52 216 fcurr1 = fnext1;
emilmont 1:fdd22bb7aa52 217
emilmont 1:fdd22bb7aa52 218 stageCnt = (numStages - 1u);
emilmont 1:fdd22bb7aa52 219
emilmont 1:fdd22bb7aa52 220 /* stage loop */
emilmont 1:fdd22bb7aa52 221 while(stageCnt > 0u)
emilmont 1:fdd22bb7aa52 222 {
emilmont 1:fdd22bb7aa52 223 /* Read the reflection coefficient */
emilmont 1:fdd22bb7aa52 224 k = *pk++;
emilmont 1:fdd22bb7aa52 225
emilmont 1:fdd22bb7aa52 226 /* read g2(n) from state buffer */
emilmont 1:fdd22bb7aa52 227 gcurr1 = *px;
emilmont 1:fdd22bb7aa52 228
emilmont 1:fdd22bb7aa52 229 /* save g1(n) in state buffer */
emilmont 1:fdd22bb7aa52 230 *px++ = gnext1;
emilmont 1:fdd22bb7aa52 231
emilmont 1:fdd22bb7aa52 232 /* Sample processing for K2, K3.... */
emilmont 1:fdd22bb7aa52 233 /* f2(n) = f1(n) + K2 * g1(n-1) */
emilmont 1:fdd22bb7aa52 234 fnext1 = (q31_t) (((q63_t) gcurr1 * k) >> 32);
emilmont 1:fdd22bb7aa52 235 fnext1 = fcurr1 + (fnext1 << 1u);
emilmont 1:fdd22bb7aa52 236
emilmont 1:fdd22bb7aa52 237 /* g2(n) = f1(n) * K2 + g1(n-1) */
emilmont 1:fdd22bb7aa52 238 gnext1 = (q31_t) (((q63_t) fcurr1 * (k)) >> 32);
emilmont 1:fdd22bb7aa52 239 gnext1 = gcurr1 + (gnext1 << 1u);
emilmont 1:fdd22bb7aa52 240
emilmont 1:fdd22bb7aa52 241 /* f1(n) is saved in fcurr1
emilmont 1:fdd22bb7aa52 242 for next stage processing */
emilmont 1:fdd22bb7aa52 243 fcurr1 = fnext1;
emilmont 1:fdd22bb7aa52 244
emilmont 1:fdd22bb7aa52 245 stageCnt--;
emilmont 1:fdd22bb7aa52 246
emilmont 1:fdd22bb7aa52 247 }
emilmont 1:fdd22bb7aa52 248
emilmont 1:fdd22bb7aa52 249
emilmont 1:fdd22bb7aa52 250 /* y(n) = fN(n) */
emilmont 1:fdd22bb7aa52 251 *pDst++ = fcurr1;
emilmont 1:fdd22bb7aa52 252
emilmont 1:fdd22bb7aa52 253 blkCnt--;
emilmont 1:fdd22bb7aa52 254
emilmont 1:fdd22bb7aa52 255 }
emilmont 1:fdd22bb7aa52 256
emilmont 1:fdd22bb7aa52 257
emilmont 1:fdd22bb7aa52 258 }
emilmont 1:fdd22bb7aa52 259
emilmont 1:fdd22bb7aa52 260
emilmont 1:fdd22bb7aa52 261 #else
emilmont 1:fdd22bb7aa52 262
emilmont 1:fdd22bb7aa52 263 /* Run the below code for Cortex-M0 */
emilmont 1:fdd22bb7aa52 264
emilmont 1:fdd22bb7aa52 265 void arm_fir_lattice_q31(
emilmont 1:fdd22bb7aa52 266 const arm_fir_lattice_instance_q31 * S,
emilmont 1:fdd22bb7aa52 267 q31_t * pSrc,
emilmont 1:fdd22bb7aa52 268 q31_t * pDst,
emilmont 1:fdd22bb7aa52 269 uint32_t blockSize)
emilmont 1:fdd22bb7aa52 270 {
emilmont 1:fdd22bb7aa52 271 q31_t *pState; /* State pointer */
emilmont 1:fdd22bb7aa52 272 q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
emilmont 1:fdd22bb7aa52 273 q31_t *px; /* temporary state pointer */
emilmont 1:fdd22bb7aa52 274 q31_t *pk; /* temporary coefficient pointer */
emilmont 1:fdd22bb7aa52 275 q31_t fcurr, fnext, gcurr, gnext; /* temporary variables */
emilmont 1:fdd22bb7aa52 276 uint32_t numStages = S->numStages; /* Length of the filter */
emilmont 1:fdd22bb7aa52 277 uint32_t blkCnt, stageCnt; /* temporary variables for counts */
emilmont 1:fdd22bb7aa52 278
emilmont 1:fdd22bb7aa52 279 pState = &S->pState[0];
emilmont 1:fdd22bb7aa52 280
emilmont 1:fdd22bb7aa52 281 blkCnt = blockSize;
emilmont 1:fdd22bb7aa52 282
emilmont 1:fdd22bb7aa52 283 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 284 {
emilmont 1:fdd22bb7aa52 285 /* f0(n) = x(n) */
emilmont 1:fdd22bb7aa52 286 fcurr = *pSrc++;
emilmont 1:fdd22bb7aa52 287
emilmont 1:fdd22bb7aa52 288 /* Initialize coeff pointer */
emilmont 1:fdd22bb7aa52 289 pk = (pCoeffs);
emilmont 1:fdd22bb7aa52 290
emilmont 1:fdd22bb7aa52 291 /* Initialize state pointer */
emilmont 1:fdd22bb7aa52 292 px = pState;
emilmont 1:fdd22bb7aa52 293
emilmont 1:fdd22bb7aa52 294 /* read g0(n-1) from state buffer */
emilmont 1:fdd22bb7aa52 295 gcurr = *px;
emilmont 1:fdd22bb7aa52 296
emilmont 1:fdd22bb7aa52 297 /* for sample 1 processing */
emilmont 1:fdd22bb7aa52 298 /* f1(n) = f0(n) + K1 * g0(n-1) */
emilmont 1:fdd22bb7aa52 299 fnext = (q31_t) (((q63_t) gcurr * (*pk)) >> 31) + fcurr;
emilmont 1:fdd22bb7aa52 300 /* g1(n) = f0(n) * K1 + g0(n-1) */
emilmont 1:fdd22bb7aa52 301 gnext = (q31_t) (((q63_t) fcurr * (*pk++)) >> 31) + gcurr;
emilmont 1:fdd22bb7aa52 302 /* save g1(n) in state buffer */
emilmont 1:fdd22bb7aa52 303 *px++ = fcurr;
emilmont 1:fdd22bb7aa52 304
emilmont 1:fdd22bb7aa52 305 /* f1(n) is saved in fcurr1
emilmont 1:fdd22bb7aa52 306 for next stage processing */
emilmont 1:fdd22bb7aa52 307 fcurr = fnext;
emilmont 1:fdd22bb7aa52 308
emilmont 1:fdd22bb7aa52 309 stageCnt = (numStages - 1u);
emilmont 1:fdd22bb7aa52 310
emilmont 1:fdd22bb7aa52 311 /* stage loop */
emilmont 1:fdd22bb7aa52 312 while(stageCnt > 0u)
emilmont 1:fdd22bb7aa52 313 {
emilmont 1:fdd22bb7aa52 314 /* read g2(n) from state buffer */
emilmont 1:fdd22bb7aa52 315 gcurr = *px;
emilmont 1:fdd22bb7aa52 316
emilmont 1:fdd22bb7aa52 317 /* save g1(n) in state buffer */
emilmont 1:fdd22bb7aa52 318 *px++ = gnext;
emilmont 1:fdd22bb7aa52 319
emilmont 1:fdd22bb7aa52 320 /* Sample processing for K2, K3.... */
emilmont 1:fdd22bb7aa52 321 /* f2(n) = f1(n) + K2 * g1(n-1) */
emilmont 1:fdd22bb7aa52 322 fnext = (q31_t) (((q63_t) gcurr * (*pk)) >> 31) + fcurr;
emilmont 1:fdd22bb7aa52 323 /* g2(n) = f1(n) * K2 + g1(n-1) */
emilmont 1:fdd22bb7aa52 324 gnext = (q31_t) (((q63_t) fcurr * (*pk++)) >> 31) + gcurr;
emilmont 1:fdd22bb7aa52 325
emilmont 1:fdd22bb7aa52 326 /* f1(n) is saved in fcurr1
emilmont 1:fdd22bb7aa52 327 for next stage processing */
emilmont 1:fdd22bb7aa52 328 fcurr = fnext;
emilmont 1:fdd22bb7aa52 329
emilmont 1:fdd22bb7aa52 330 stageCnt--;
emilmont 1:fdd22bb7aa52 331
emilmont 1:fdd22bb7aa52 332 }
emilmont 1:fdd22bb7aa52 333
emilmont 1:fdd22bb7aa52 334 /* y(n) = fN(n) */
emilmont 1:fdd22bb7aa52 335 *pDst++ = fcurr;
emilmont 1:fdd22bb7aa52 336
emilmont 1:fdd22bb7aa52 337 blkCnt--;
emilmont 1:fdd22bb7aa52 338
emilmont 1:fdd22bb7aa52 339 }
emilmont 1:fdd22bb7aa52 340
emilmont 1:fdd22bb7aa52 341 }
emilmont 1:fdd22bb7aa52 342
emilmont 1:fdd22bb7aa52 343 #endif /* #ifndef ARM_MATH_CM0 */
emilmont 1:fdd22bb7aa52 344
emilmont 1:fdd22bb7aa52 345
emilmont 1:fdd22bb7aa52 346 /**
emilmont 1:fdd22bb7aa52 347 * @} end of FIR_Lattice group
emilmont 1:fdd22bb7aa52 348 */