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CMSIS DSP library

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cmsis_dsp/FilteringFunctions/arm_iir_lattice_f32.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_f32.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 2:da51fb522205 10 * Description: Floating-point 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 * @defgroup IIR_Lattice Infinite Impulse Response (IIR) Lattice Filters
emilmont 1:fdd22bb7aa52 44 *
emilmont 1:fdd22bb7aa52 45 * This set of functions implements lattice filters
emilmont 1:fdd22bb7aa52 46 * for Q15, Q31 and floating-point data types. Lattice filters are used in a
emilmont 1:fdd22bb7aa52 47 * variety of adaptive filter applications. The filter structure has feedforward and
emilmont 1:fdd22bb7aa52 48 * feedback components and the net impulse response is infinite length.
emilmont 1:fdd22bb7aa52 49 * The functions operate on blocks
emilmont 1:fdd22bb7aa52 50 * of input and output data and each call to the function processes
emilmont 1:fdd22bb7aa52 51 * <code>blockSize</code> samples through the filter. <code>pSrc</code> and
emilmont 1:fdd22bb7aa52 52 * <code>pDst</code> point to input and output arrays containing <code>blockSize</code> values.
emilmont 1:fdd22bb7aa52 53
emilmont 1:fdd22bb7aa52 54 * \par Algorithm:
emilmont 1:fdd22bb7aa52 55 * \image html IIRLattice.gif "Infinite Impulse Response Lattice filter"
emilmont 1:fdd22bb7aa52 56 * <pre>
emilmont 1:fdd22bb7aa52 57 * fN(n) = x(n)
emilmont 1:fdd22bb7aa52 58 * fm-1(n) = fm(n) - km * gm-1(n-1) for m = N, N-1, ...1
emilmont 1:fdd22bb7aa52 59 * gm(n) = km * fm-1(n) + gm-1(n-1) for m = N, N-1, ...1
emilmont 1:fdd22bb7aa52 60 * y(n) = vN * gN(n) + vN-1 * gN-1(n) + ...+ v0 * g0(n)
emilmont 1:fdd22bb7aa52 61 * </pre>
emilmont 1:fdd22bb7aa52 62 * \par
emilmont 1:fdd22bb7aa52 63 * <code>pkCoeffs</code> points to array of reflection coefficients of size <code>numStages</code>.
emilmont 1:fdd22bb7aa52 64 * Reflection coefficients are stored in time-reversed order.
emilmont 1:fdd22bb7aa52 65 * \par
emilmont 1:fdd22bb7aa52 66 * <pre>
emilmont 1:fdd22bb7aa52 67 * {kN, kN-1, ....k1}
emilmont 1:fdd22bb7aa52 68 * </pre>
emilmont 1:fdd22bb7aa52 69 * <code>pvCoeffs</code> points to the array of ladder coefficients of size <code>(numStages+1)</code>.
emilmont 1:fdd22bb7aa52 70 * Ladder coefficients are stored in time-reversed order.
emilmont 1:fdd22bb7aa52 71 * \par
emilmont 1:fdd22bb7aa52 72 * <pre>
emilmont 1:fdd22bb7aa52 73 * {vN, vN-1, ...v0}
emilmont 1:fdd22bb7aa52 74 * </pre>
emilmont 1:fdd22bb7aa52 75 * <code>pState</code> points to a state array of size <code>numStages + blockSize</code>.
emilmont 1:fdd22bb7aa52 76 * The state variables shown in the figure above (the g values) are stored in the <code>pState</code> array.
emilmont 1:fdd22bb7aa52 77 * The state variables are updated after each block of data is processed; the coefficients are untouched.
emilmont 1:fdd22bb7aa52 78 * \par Instance Structure
emilmont 1:fdd22bb7aa52 79 * The coefficients and state variables for a filter are stored together in an instance data structure.
emilmont 1:fdd22bb7aa52 80 * A separate instance structure must be defined for each filter.
emilmont 1:fdd22bb7aa52 81 * Coefficient arrays may be shared among several instances while state variable arrays cannot be shared.
emilmont 1:fdd22bb7aa52 82 * There are separate instance structure declarations for each of the 3 supported data types.
emilmont 1:fdd22bb7aa52 83 *
emilmont 1:fdd22bb7aa52 84 * \par Initialization Functions
emilmont 1:fdd22bb7aa52 85 * There is also an associated initialization function for each data type.
emilmont 1:fdd22bb7aa52 86 * The initialization function performs the following operations:
emilmont 1:fdd22bb7aa52 87 * - Sets the values of the internal structure fields.
emilmont 1:fdd22bb7aa52 88 * - Zeros out the values in the state buffer.
emilmont 1:fdd22bb7aa52 89 *
emilmont 1:fdd22bb7aa52 90 * \par
emilmont 1:fdd22bb7aa52 91 * Use of the initialization function is optional.
emilmont 1:fdd22bb7aa52 92 * However, if the initialization function is used, then the instance structure cannot be placed into a const data section.
emilmont 1:fdd22bb7aa52 93 * To place an instance structure into a const data section, the instance structure must be manually initialized.
emilmont 1:fdd22bb7aa52 94 * Set the values in the state buffer to zeros and then manually initialize the instance structure as follows:
emilmont 1:fdd22bb7aa52 95 * <pre>
emilmont 1:fdd22bb7aa52 96 *arm_iir_lattice_instance_f32 S = {numStages, pState, pkCoeffs, pvCoeffs};
emilmont 1:fdd22bb7aa52 97 *arm_iir_lattice_instance_q31 S = {numStages, pState, pkCoeffs, pvCoeffs};
emilmont 1:fdd22bb7aa52 98 *arm_iir_lattice_instance_q15 S = {numStages, pState, pkCoeffs, pvCoeffs};
emilmont 1:fdd22bb7aa52 99 * </pre>
emilmont 1:fdd22bb7aa52 100 * \par
emilmont 1:fdd22bb7aa52 101 * where <code>numStages</code> is the number of stages in the filter; <code>pState</code> points to the state buffer array;
emilmont 1:fdd22bb7aa52 102 * <code>pkCoeffs</code> points to array of the reflection coefficients; <code>pvCoeffs</code> points to the array of ladder coefficients.
emilmont 1:fdd22bb7aa52 103 * \par Fixed-Point Behavior
emilmont 1:fdd22bb7aa52 104 * Care must be taken when using the fixed-point versions of the IIR lattice filter functions.
emilmont 1:fdd22bb7aa52 105 * In particular, the overflow and saturation behavior of the accumulator used in each function must be considered.
emilmont 1:fdd22bb7aa52 106 * Refer to the function specific documentation below for usage guidelines.
emilmont 1:fdd22bb7aa52 107 */
emilmont 1:fdd22bb7aa52 108
emilmont 1:fdd22bb7aa52 109 /**
emilmont 1:fdd22bb7aa52 110 * @addtogroup IIR_Lattice
emilmont 1:fdd22bb7aa52 111 * @{
emilmont 1:fdd22bb7aa52 112 */
emilmont 1:fdd22bb7aa52 113
emilmont 1:fdd22bb7aa52 114 /**
emilmont 1:fdd22bb7aa52 115 * @brief Processing function for the floating-point IIR lattice filter.
emilmont 1:fdd22bb7aa52 116 * @param[in] *S points to an instance of the floating-point IIR lattice structure.
emilmont 1:fdd22bb7aa52 117 * @param[in] *pSrc points to the block of input data.
emilmont 1:fdd22bb7aa52 118 * @param[out] *pDst points to the block of output data.
emilmont 1:fdd22bb7aa52 119 * @param[in] blockSize number of samples to process.
emilmont 1:fdd22bb7aa52 120 * @return none.
emilmont 1:fdd22bb7aa52 121 */
emilmont 1:fdd22bb7aa52 122
emilmont 1:fdd22bb7aa52 123 #ifndef ARM_MATH_CM0
emilmont 1:fdd22bb7aa52 124
emilmont 1:fdd22bb7aa52 125 /* Run the below code for Cortex-M4 and Cortex-M3 */
emilmont 1:fdd22bb7aa52 126
emilmont 1:fdd22bb7aa52 127 void arm_iir_lattice_f32(
emilmont 1:fdd22bb7aa52 128 const arm_iir_lattice_instance_f32 * S,
emilmont 1:fdd22bb7aa52 129 float32_t * pSrc,
emilmont 1:fdd22bb7aa52 130 float32_t * pDst,
emilmont 1:fdd22bb7aa52 131 uint32_t blockSize)
emilmont 1:fdd22bb7aa52 132 {
emilmont 1:fdd22bb7aa52 133 float32_t fnext1, gcurr1, gnext; /* Temporary variables for lattice stages */
emilmont 1:fdd22bb7aa52 134 float32_t acc; /* Accumlator */
emilmont 1:fdd22bb7aa52 135 uint32_t blkCnt, tapCnt; /* temporary variables for counts */
emilmont 1:fdd22bb7aa52 136 float32_t *px1, *px2, *pk, *pv; /* temporary pointers for state and coef */
emilmont 1:fdd22bb7aa52 137 uint32_t numStages = S->numStages; /* number of stages */
emilmont 1:fdd22bb7aa52 138 float32_t *pState; /* State pointer */
emilmont 1:fdd22bb7aa52 139 float32_t *pStateCurnt; /* State current pointer */
emilmont 1:fdd22bb7aa52 140 float32_t k1, k2;
emilmont 1:fdd22bb7aa52 141 float32_t v1, v2, v3, v4;
emilmont 1:fdd22bb7aa52 142 float32_t gcurr2;
emilmont 1:fdd22bb7aa52 143 float32_t fnext2;
emilmont 1:fdd22bb7aa52 144
emilmont 1:fdd22bb7aa52 145 /* initialise loop count */
emilmont 1:fdd22bb7aa52 146 blkCnt = blockSize;
emilmont 1:fdd22bb7aa52 147
emilmont 1:fdd22bb7aa52 148 /* initialise state pointer */
emilmont 1:fdd22bb7aa52 149 pState = &S->pState[0];
emilmont 1:fdd22bb7aa52 150
emilmont 1:fdd22bb7aa52 151 /* Sample processing */
emilmont 1:fdd22bb7aa52 152 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 153 {
emilmont 1:fdd22bb7aa52 154 /* Read Sample from input buffer */
emilmont 1:fdd22bb7aa52 155 /* fN(n) = x(n) */
emilmont 1:fdd22bb7aa52 156 fnext2 = *pSrc++;
emilmont 1:fdd22bb7aa52 157
emilmont 1:fdd22bb7aa52 158 /* Initialize Ladder coeff pointer */
emilmont 1:fdd22bb7aa52 159 pv = &S->pvCoeffs[0];
emilmont 1:fdd22bb7aa52 160 /* Initialize Reflection coeff pointer */
emilmont 1:fdd22bb7aa52 161 pk = &S->pkCoeffs[0];
emilmont 1:fdd22bb7aa52 162
emilmont 1:fdd22bb7aa52 163 /* Initialize state read pointer */
emilmont 1:fdd22bb7aa52 164 px1 = pState;
emilmont 1:fdd22bb7aa52 165 /* Initialize state write pointer */
emilmont 1:fdd22bb7aa52 166 px2 = pState;
emilmont 1:fdd22bb7aa52 167
emilmont 1:fdd22bb7aa52 168 /* Set accumulator to zero */
emilmont 1:fdd22bb7aa52 169 acc = 0.0;
emilmont 1:fdd22bb7aa52 170
emilmont 1:fdd22bb7aa52 171 /* Loop unrolling. Process 4 taps at a time. */
emilmont 1:fdd22bb7aa52 172 tapCnt = (numStages) >> 2;
emilmont 1:fdd22bb7aa52 173
emilmont 1:fdd22bb7aa52 174 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 175 {
emilmont 1:fdd22bb7aa52 176 /* Read gN-1(n-1) from state buffer */
emilmont 1:fdd22bb7aa52 177 gcurr1 = *px1;
emilmont 1:fdd22bb7aa52 178
emilmont 1:fdd22bb7aa52 179 /* read reflection coefficient kN */
emilmont 1:fdd22bb7aa52 180 k1 = *pk;
emilmont 1:fdd22bb7aa52 181
emilmont 1:fdd22bb7aa52 182 /* fN-1(n) = fN(n) - kN * gN-1(n-1) */
emilmont 1:fdd22bb7aa52 183 fnext1 = fnext2 - (k1 * gcurr1);
emilmont 1:fdd22bb7aa52 184
emilmont 1:fdd22bb7aa52 185 /* read ladder coefficient vN */
emilmont 1:fdd22bb7aa52 186 v1 = *pv;
emilmont 1:fdd22bb7aa52 187
emilmont 1:fdd22bb7aa52 188 /* read next reflection coefficient kN-1 */
emilmont 1:fdd22bb7aa52 189 k2 = *(pk + 1u);
emilmont 1:fdd22bb7aa52 190
emilmont 1:fdd22bb7aa52 191 /* Read gN-2(n-1) from state buffer */
emilmont 1:fdd22bb7aa52 192 gcurr2 = *(px1 + 1u);
emilmont 1:fdd22bb7aa52 193
emilmont 1:fdd22bb7aa52 194 /* read next ladder coefficient vN-1 */
emilmont 1:fdd22bb7aa52 195 v2 = *(pv + 1u);
emilmont 1:fdd22bb7aa52 196
emilmont 1:fdd22bb7aa52 197 /* fN-2(n) = fN-1(n) - kN-1 * gN-2(n-1) */
emilmont 1:fdd22bb7aa52 198 fnext2 = fnext1 - (k2 * gcurr2);
emilmont 1:fdd22bb7aa52 199
emilmont 1:fdd22bb7aa52 200 /* gN(n) = kN * fN-1(n) + gN-1(n-1) */
emilmont 1:fdd22bb7aa52 201 gnext = gcurr1 + (k1 * fnext1);
emilmont 1:fdd22bb7aa52 202
emilmont 1:fdd22bb7aa52 203 /* read reflection coefficient kN-2 */
emilmont 1:fdd22bb7aa52 204 k1 = *(pk + 2u);
emilmont 1:fdd22bb7aa52 205
emilmont 1:fdd22bb7aa52 206 /* write gN(n) into state for next sample processing */
emilmont 1:fdd22bb7aa52 207 *px2++ = gnext;
emilmont 1:fdd22bb7aa52 208
emilmont 1:fdd22bb7aa52 209 /* Read gN-3(n-1) from state buffer */
emilmont 1:fdd22bb7aa52 210 gcurr1 = *(px1 + 2u);
emilmont 1:fdd22bb7aa52 211
emilmont 1:fdd22bb7aa52 212 /* y(n) += gN(n) * vN */
emilmont 1:fdd22bb7aa52 213 acc += (gnext * v1);
emilmont 1:fdd22bb7aa52 214
emilmont 1:fdd22bb7aa52 215 /* fN-3(n) = fN-2(n) - kN-2 * gN-3(n-1) */
emilmont 1:fdd22bb7aa52 216 fnext1 = fnext2 - (k1 * gcurr1);
emilmont 1:fdd22bb7aa52 217
emilmont 1:fdd22bb7aa52 218 /* gN-1(n) = kN-1 * fN-2(n) + gN-2(n-1) */
emilmont 1:fdd22bb7aa52 219 gnext = gcurr2 + (k2 * fnext2);
emilmont 1:fdd22bb7aa52 220
emilmont 1:fdd22bb7aa52 221 /* Read gN-4(n-1) from state buffer */
emilmont 1:fdd22bb7aa52 222 gcurr2 = *(px1 + 3u);
emilmont 1:fdd22bb7aa52 223
emilmont 1:fdd22bb7aa52 224 /* y(n) += gN-1(n) * vN-1 */
emilmont 1:fdd22bb7aa52 225 acc += (gnext * v2);
emilmont 1:fdd22bb7aa52 226
emilmont 1:fdd22bb7aa52 227 /* read reflection coefficient kN-3 */
emilmont 1:fdd22bb7aa52 228 k2 = *(pk + 3u);
emilmont 1:fdd22bb7aa52 229
emilmont 1:fdd22bb7aa52 230 /* write gN-1(n) into state for next sample processing */
emilmont 1:fdd22bb7aa52 231 *px2++ = gnext;
emilmont 1:fdd22bb7aa52 232
emilmont 1:fdd22bb7aa52 233 /* fN-4(n) = fN-3(n) - kN-3 * gN-4(n-1) */
emilmont 1:fdd22bb7aa52 234 fnext2 = fnext1 - (k2 * gcurr2);
emilmont 1:fdd22bb7aa52 235
emilmont 1:fdd22bb7aa52 236 /* gN-2(n) = kN-2 * fN-3(n) + gN-3(n-1) */
emilmont 1:fdd22bb7aa52 237 gnext = gcurr1 + (k1 * fnext1);
emilmont 1:fdd22bb7aa52 238
emilmont 1:fdd22bb7aa52 239 /* read ladder coefficient vN-2 */
emilmont 1:fdd22bb7aa52 240 v3 = *(pv + 2u);
emilmont 1:fdd22bb7aa52 241
emilmont 1:fdd22bb7aa52 242 /* y(n) += gN-2(n) * vN-2 */
emilmont 1:fdd22bb7aa52 243 acc += (gnext * v3);
emilmont 1:fdd22bb7aa52 244
emilmont 1:fdd22bb7aa52 245 /* write gN-2(n) into state for next sample processing */
emilmont 1:fdd22bb7aa52 246 *px2++ = gnext;
emilmont 1:fdd22bb7aa52 247
emilmont 1:fdd22bb7aa52 248 /* update pointer */
emilmont 1:fdd22bb7aa52 249 pk += 4u;
emilmont 1:fdd22bb7aa52 250
emilmont 1:fdd22bb7aa52 251 /* gN-3(n) = kN-3 * fN-4(n) + gN-4(n-1) */
emilmont 1:fdd22bb7aa52 252 gnext = (fnext2 * k2) + gcurr2;
emilmont 1:fdd22bb7aa52 253
emilmont 1:fdd22bb7aa52 254 /* read next ladder coefficient vN-3 */
emilmont 1:fdd22bb7aa52 255 v4 = *(pv + 3u);
emilmont 1:fdd22bb7aa52 256
emilmont 1:fdd22bb7aa52 257 /* y(n) += gN-4(n) * vN-4 */
emilmont 1:fdd22bb7aa52 258 acc += (gnext * v4);
emilmont 1:fdd22bb7aa52 259
emilmont 1:fdd22bb7aa52 260 /* write gN-3(n) into state for next sample processing */
emilmont 1:fdd22bb7aa52 261 *px2++ = gnext;
emilmont 1:fdd22bb7aa52 262
emilmont 1:fdd22bb7aa52 263 /* update pointers */
emilmont 1:fdd22bb7aa52 264 px1 += 4u;
emilmont 1:fdd22bb7aa52 265 pv += 4u;
emilmont 1:fdd22bb7aa52 266
emilmont 1:fdd22bb7aa52 267 tapCnt--;
emilmont 1:fdd22bb7aa52 268
emilmont 1:fdd22bb7aa52 269 }
emilmont 1:fdd22bb7aa52 270
emilmont 1:fdd22bb7aa52 271 /* If the filter length is not a multiple of 4, compute the remaining filter taps */
emilmont 1:fdd22bb7aa52 272 tapCnt = (numStages) % 0x4u;
emilmont 1:fdd22bb7aa52 273
emilmont 1:fdd22bb7aa52 274 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 275 {
emilmont 1:fdd22bb7aa52 276 gcurr1 = *px1++;
emilmont 1:fdd22bb7aa52 277 /* Process sample for last taps */
emilmont 1:fdd22bb7aa52 278 fnext1 = fnext2 - ((*pk) * gcurr1);
emilmont 1:fdd22bb7aa52 279 gnext = (fnext1 * (*pk++)) + gcurr1;
emilmont 1:fdd22bb7aa52 280 /* Output samples for last taps */
emilmont 1:fdd22bb7aa52 281 acc += (gnext * (*pv++));
emilmont 1:fdd22bb7aa52 282 *px2++ = gnext;
emilmont 1:fdd22bb7aa52 283 fnext2 = fnext1;
emilmont 1:fdd22bb7aa52 284
emilmont 1:fdd22bb7aa52 285 tapCnt--;
emilmont 1:fdd22bb7aa52 286
emilmont 1:fdd22bb7aa52 287 }
emilmont 1:fdd22bb7aa52 288
emilmont 1:fdd22bb7aa52 289 /* y(n) += g0(n) * v0 */
emilmont 1:fdd22bb7aa52 290 acc += (fnext2 * (*pv));
emilmont 1:fdd22bb7aa52 291
emilmont 1:fdd22bb7aa52 292 *px2++ = fnext2;
emilmont 1:fdd22bb7aa52 293
emilmont 1:fdd22bb7aa52 294 /* write out into pDst */
emilmont 1:fdd22bb7aa52 295 *pDst++ = acc;
emilmont 1:fdd22bb7aa52 296
emilmont 1:fdd22bb7aa52 297 /* Advance the state pointer by 4 to process the next group of 4 samples */
emilmont 1:fdd22bb7aa52 298 pState = pState + 1u;
emilmont 1:fdd22bb7aa52 299
emilmont 1:fdd22bb7aa52 300 blkCnt--;
emilmont 1:fdd22bb7aa52 301
emilmont 1:fdd22bb7aa52 302 }
emilmont 1:fdd22bb7aa52 303
emilmont 1:fdd22bb7aa52 304 /* Processing is complete. Now copy last S->numStages samples to start of the buffer
emilmont 1:fdd22bb7aa52 305 for the preperation of next frame process */
emilmont 1:fdd22bb7aa52 306
emilmont 1:fdd22bb7aa52 307 /* Points to the start of the state buffer */
emilmont 1:fdd22bb7aa52 308 pStateCurnt = &S->pState[0];
emilmont 1:fdd22bb7aa52 309 pState = &S->pState[blockSize];
emilmont 1:fdd22bb7aa52 310
emilmont 1:fdd22bb7aa52 311 tapCnt = numStages >> 2u;
emilmont 1:fdd22bb7aa52 312
emilmont 1:fdd22bb7aa52 313 /* copy data */
emilmont 1:fdd22bb7aa52 314 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 315 {
emilmont 1:fdd22bb7aa52 316 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 317 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 318 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 319 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 320
emilmont 1:fdd22bb7aa52 321 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 322 tapCnt--;
emilmont 1:fdd22bb7aa52 323
emilmont 1:fdd22bb7aa52 324 }
emilmont 1:fdd22bb7aa52 325
emilmont 1:fdd22bb7aa52 326 /* Calculate remaining number of copies */
emilmont 1:fdd22bb7aa52 327 tapCnt = (numStages) % 0x4u;
emilmont 1:fdd22bb7aa52 328
emilmont 1:fdd22bb7aa52 329 /* Copy the remaining q31_t data */
emilmont 1:fdd22bb7aa52 330 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 331 {
emilmont 1:fdd22bb7aa52 332 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 333
emilmont 1:fdd22bb7aa52 334 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 335 tapCnt--;
emilmont 1:fdd22bb7aa52 336 }
emilmont 1:fdd22bb7aa52 337 }
emilmont 1:fdd22bb7aa52 338
emilmont 1:fdd22bb7aa52 339 #else
emilmont 1:fdd22bb7aa52 340
emilmont 1:fdd22bb7aa52 341 void arm_iir_lattice_f32(
emilmont 1:fdd22bb7aa52 342 const arm_iir_lattice_instance_f32 * S,
emilmont 1:fdd22bb7aa52 343 float32_t * pSrc,
emilmont 1:fdd22bb7aa52 344 float32_t * pDst,
emilmont 1:fdd22bb7aa52 345 uint32_t blockSize)
emilmont 1:fdd22bb7aa52 346 {
emilmont 1:fdd22bb7aa52 347 float32_t fcurr, fnext = 0, gcurr, gnext; /* Temporary variables for lattice stages */
emilmont 1:fdd22bb7aa52 348 float32_t acc; /* Accumlator */
emilmont 1:fdd22bb7aa52 349 uint32_t blkCnt, tapCnt; /* temporary variables for counts */
emilmont 1:fdd22bb7aa52 350 float32_t *px1, *px2, *pk, *pv; /* temporary pointers for state and coef */
emilmont 1:fdd22bb7aa52 351 uint32_t numStages = S->numStages; /* number of stages */
emilmont 1:fdd22bb7aa52 352 float32_t *pState; /* State pointer */
emilmont 1:fdd22bb7aa52 353 float32_t *pStateCurnt; /* State current pointer */
emilmont 1:fdd22bb7aa52 354
emilmont 1:fdd22bb7aa52 355
emilmont 1:fdd22bb7aa52 356 /* Run the below code for Cortex-M0 */
emilmont 1:fdd22bb7aa52 357
emilmont 1:fdd22bb7aa52 358 blkCnt = blockSize;
emilmont 1:fdd22bb7aa52 359
emilmont 1:fdd22bb7aa52 360 pState = &S->pState[0];
emilmont 1:fdd22bb7aa52 361
emilmont 1:fdd22bb7aa52 362 /* Sample processing */
emilmont 1:fdd22bb7aa52 363 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 364 {
emilmont 1:fdd22bb7aa52 365 /* Read Sample from input buffer */
emilmont 1:fdd22bb7aa52 366 /* fN(n) = x(n) */
emilmont 1:fdd22bb7aa52 367 fcurr = *pSrc++;
emilmont 1:fdd22bb7aa52 368
emilmont 1:fdd22bb7aa52 369 /* Initialize state read pointer */
emilmont 1:fdd22bb7aa52 370 px1 = pState;
emilmont 1:fdd22bb7aa52 371 /* Initialize state write pointer */
emilmont 1:fdd22bb7aa52 372 px2 = pState;
emilmont 1:fdd22bb7aa52 373 /* Set accumulator to zero */
emilmont 1:fdd22bb7aa52 374 acc = 0.0f;
emilmont 1:fdd22bb7aa52 375 /* Initialize Ladder coeff pointer */
emilmont 1:fdd22bb7aa52 376 pv = &S->pvCoeffs[0];
emilmont 1:fdd22bb7aa52 377 /* Initialize Reflection coeff pointer */
emilmont 1:fdd22bb7aa52 378 pk = &S->pkCoeffs[0];
emilmont 1:fdd22bb7aa52 379
emilmont 1:fdd22bb7aa52 380
emilmont 1:fdd22bb7aa52 381 /* Process sample for numStages */
emilmont 1:fdd22bb7aa52 382 tapCnt = numStages;
emilmont 1:fdd22bb7aa52 383
emilmont 1:fdd22bb7aa52 384 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 385 {
emilmont 1:fdd22bb7aa52 386 gcurr = *px1++;
emilmont 1:fdd22bb7aa52 387 /* Process sample for last taps */
emilmont 1:fdd22bb7aa52 388 fnext = fcurr - ((*pk) * gcurr);
emilmont 1:fdd22bb7aa52 389 gnext = (fnext * (*pk++)) + gcurr;
emilmont 1:fdd22bb7aa52 390
emilmont 1:fdd22bb7aa52 391 /* Output samples for last taps */
emilmont 1:fdd22bb7aa52 392 acc += (gnext * (*pv++));
emilmont 1:fdd22bb7aa52 393 *px2++ = gnext;
emilmont 1:fdd22bb7aa52 394 fcurr = fnext;
emilmont 1:fdd22bb7aa52 395
emilmont 1:fdd22bb7aa52 396 /* Decrementing loop counter */
emilmont 1:fdd22bb7aa52 397 tapCnt--;
emilmont 1:fdd22bb7aa52 398
emilmont 1:fdd22bb7aa52 399 }
emilmont 1:fdd22bb7aa52 400
emilmont 1:fdd22bb7aa52 401 /* y(n) += g0(n) * v0 */
emilmont 1:fdd22bb7aa52 402 acc += (fnext * (*pv));
emilmont 1:fdd22bb7aa52 403
emilmont 1:fdd22bb7aa52 404 *px2++ = fnext;
emilmont 1:fdd22bb7aa52 405
emilmont 1:fdd22bb7aa52 406 /* write out into pDst */
emilmont 1:fdd22bb7aa52 407 *pDst++ = acc;
emilmont 1:fdd22bb7aa52 408
emilmont 1:fdd22bb7aa52 409 /* Advance the state pointer by 1 to process the next group of samples */
emilmont 1:fdd22bb7aa52 410 pState = pState + 1u;
emilmont 1:fdd22bb7aa52 411 blkCnt--;
emilmont 1:fdd22bb7aa52 412
emilmont 1:fdd22bb7aa52 413 }
emilmont 1:fdd22bb7aa52 414
emilmont 1:fdd22bb7aa52 415 /* Processing is complete. Now copy last S->numStages samples to start of the buffer
emilmont 1:fdd22bb7aa52 416 for the preperation of next frame process */
emilmont 1:fdd22bb7aa52 417
emilmont 1:fdd22bb7aa52 418 /* Points to the start of the state buffer */
emilmont 1:fdd22bb7aa52 419 pStateCurnt = &S->pState[0];
emilmont 1:fdd22bb7aa52 420 pState = &S->pState[blockSize];
emilmont 1:fdd22bb7aa52 421
emilmont 1:fdd22bb7aa52 422 tapCnt = numStages;
emilmont 1:fdd22bb7aa52 423
emilmont 1:fdd22bb7aa52 424 /* Copy the data */
emilmont 1:fdd22bb7aa52 425 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 426 {
emilmont 1:fdd22bb7aa52 427 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 428
emilmont 1:fdd22bb7aa52 429 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 430 tapCnt--;
emilmont 1:fdd22bb7aa52 431 }
emilmont 1:fdd22bb7aa52 432
emilmont 1:fdd22bb7aa52 433 }
emilmont 1:fdd22bb7aa52 434
emilmont 1:fdd22bb7aa52 435 #endif /* #ifndef ARM_MATH_CM0 */
emilmont 1:fdd22bb7aa52 436
emilmont 1:fdd22bb7aa52 437
emilmont 1:fdd22bb7aa52 438 /**
emilmont 1:fdd22bb7aa52 439 * @} end of IIR_Lattice group
emilmont 1:fdd22bb7aa52 440 */