Eli Hughes / CMSIS_DSP_401

V4.0.1 of the ARM CMSIS DSP libraries. Note that arm_bitreversal2.s, arm_cfft_f32.c and arm_rfft_fast_f32.c had to be removed. arm_bitreversal2.s will not assemble with the online tools. So, the fast f32 FFT functions are not yet available. All the other FFT functions are available.

Dependents:   MPU9150_Example fir_f32 fir_f32 MPU9150_nucleo_noni2cdev ... more

FilteringFunctions/arm_fir_q31.c@0:3d9c67d97d6f, 2014-07-28 (annotated)

Committer:
emh203
Date:
Mon Jul 28 15:03:15 2014 +0000
Revision:
0:3d9c67d97d6f
1st working commit.   Had to remove arm_bitreversal2.s     arm_cfft_f32.c and arm_rfft_fast_f32.c.    The .s will not assemble.      For now I removed these functions so we could at least have a library for the other functions.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emh203 0:3d9c67d97d6f 1 /* ----------------------------------------------------------------------
emh203 0:3d9c67d97d6f 2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
emh203 0:3d9c67d97d6f 3 *
emh203 0:3d9c67d97d6f 4 * $Date: 12. March 2014
emh203 0:3d9c67d97d6f 5 * $Revision: V1.4.3
emh203 0:3d9c67d97d6f 6 *
emh203 0:3d9c67d97d6f 7 * Project: CMSIS DSP Library
emh203 0:3d9c67d97d6f 8 * Title: arm_fir_q31.c
emh203 0:3d9c67d97d6f 9 *
emh203 0:3d9c67d97d6f 10 * Description: Q31 FIR filter processing function.
emh203 0:3d9c67d97d6f 11 *
emh203 0:3d9c67d97d6f 12 * Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
emh203 0:3d9c67d97d6f 13 *
emh203 0:3d9c67d97d6f 14 * Redistribution and use in source and binary forms, with or without
emh203 0:3d9c67d97d6f 15 * modification, are permitted provided that the following conditions
emh203 0:3d9c67d97d6f 16 * are met:
emh203 0:3d9c67d97d6f 17 * - Redistributions of source code must retain the above copyright
emh203 0:3d9c67d97d6f 18 * notice, this list of conditions and the following disclaimer.
emh203 0:3d9c67d97d6f 19 * - Redistributions in binary form must reproduce the above copyright
emh203 0:3d9c67d97d6f 20 * notice, this list of conditions and the following disclaimer in
emh203 0:3d9c67d97d6f 21 * the documentation and/or other materials provided with the
emh203 0:3d9c67d97d6f 22 * distribution.
emh203 0:3d9c67d97d6f 23 * - Neither the name of ARM LIMITED nor the names of its contributors
emh203 0:3d9c67d97d6f 24 * may be used to endorse or promote products derived from this
emh203 0:3d9c67d97d6f 25 * software without specific prior written permission.
emh203 0:3d9c67d97d6f 26 *
emh203 0:3d9c67d97d6f 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
emh203 0:3d9c67d97d6f 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
emh203 0:3d9c67d97d6f 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
emh203 0:3d9c67d97d6f 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
emh203 0:3d9c67d97d6f 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
emh203 0:3d9c67d97d6f 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
emh203 0:3d9c67d97d6f 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
emh203 0:3d9c67d97d6f 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
emh203 0:3d9c67d97d6f 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
emh203 0:3d9c67d97d6f 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
emh203 0:3d9c67d97d6f 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
emh203 0:3d9c67d97d6f 38 * POSSIBILITY OF SUCH DAMAGE.
emh203 0:3d9c67d97d6f 39 * -------------------------------------------------------------------- */
emh203 0:3d9c67d97d6f 40
emh203 0:3d9c67d97d6f 41 #include "arm_math.h"
emh203 0:3d9c67d97d6f 42
emh203 0:3d9c67d97d6f 43 /**
emh203 0:3d9c67d97d6f 44 * @ingroup groupFilters
emh203 0:3d9c67d97d6f 45 */
emh203 0:3d9c67d97d6f 46
emh203 0:3d9c67d97d6f 47 /**
emh203 0:3d9c67d97d6f 48 * @addtogroup FIR
emh203 0:3d9c67d97d6f 49 * @{
emh203 0:3d9c67d97d6f 50 */
emh203 0:3d9c67d97d6f 51
emh203 0:3d9c67d97d6f 52 /**
emh203 0:3d9c67d97d6f 53 * @param[in] *S points to an instance of the Q31 FIR filter structure.
emh203 0:3d9c67d97d6f 54 * @param[in] *pSrc points to the block of input data.
emh203 0:3d9c67d97d6f 55 * @param[out] *pDst points to the block of output data.
emh203 0:3d9c67d97d6f 56 * @param[in] blockSize number of samples to process per call.
emh203 0:3d9c67d97d6f 57 * @return none.
emh203 0:3d9c67d97d6f 58 *
emh203 0:3d9c67d97d6f 59 * @details
emh203 0:3d9c67d97d6f 60 * <b>Scaling and Overflow Behavior:</b>
emh203 0:3d9c67d97d6f 61 * \par
emh203 0:3d9c67d97d6f 62 * The function is implemented using an internal 64-bit accumulator.
emh203 0:3d9c67d97d6f 63 * The accumulator has a 2.62 format and maintains full precision of the intermediate multiplication results but provides only a single guard bit.
emh203 0:3d9c67d97d6f 64 * Thus, if the accumulator result overflows it wraps around rather than clip.
emh203 0:3d9c67d97d6f 65 * In order to avoid overflows completely the input signal must be scaled down by log2(numTaps) bits.
emh203 0:3d9c67d97d6f 66 * After all multiply-accumulates are performed, the 2.62 accumulator is right shifted by 31 bits and saturated to 1.31 format to yield the final result.
emh203 0:3d9c67d97d6f 67 *
emh203 0:3d9c67d97d6f 68 * \par
emh203 0:3d9c67d97d6f 69 * Refer to the function <code>arm_fir_fast_q31()</code> for a faster but less precise implementation of this filter for Cortex-M3 and Cortex-M4.
emh203 0:3d9c67d97d6f 70 */
emh203 0:3d9c67d97d6f 71
emh203 0:3d9c67d97d6f 72 void arm_fir_q31(
emh203 0:3d9c67d97d6f 73 const arm_fir_instance_q31 * S,
emh203 0:3d9c67d97d6f 74 q31_t * pSrc,
emh203 0:3d9c67d97d6f 75 q31_t * pDst,
emh203 0:3d9c67d97d6f 76 uint32_t blockSize)
emh203 0:3d9c67d97d6f 77 {
emh203 0:3d9c67d97d6f 78 q31_t *pState = S->pState; /* State pointer */
emh203 0:3d9c67d97d6f 79 q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
emh203 0:3d9c67d97d6f 80 q31_t *pStateCurnt; /* Points to the current sample of the state */
emh203 0:3d9c67d97d6f 81
emh203 0:3d9c67d97d6f 82
emh203 0:3d9c67d97d6f 83 #ifndef ARM_MATH_CM0_FAMILY
emh203 0:3d9c67d97d6f 84
emh203 0:3d9c67d97d6f 85 /* Run the below code for Cortex-M4 and Cortex-M3 */
emh203 0:3d9c67d97d6f 86
emh203 0:3d9c67d97d6f 87 q31_t x0, x1, x2; /* Temporary variables to hold state */
emh203 0:3d9c67d97d6f 88 q31_t c0; /* Temporary variable to hold coefficient value */
emh203 0:3d9c67d97d6f 89 q31_t *px; /* Temporary pointer for state */
emh203 0:3d9c67d97d6f 90 q31_t *pb; /* Temporary pointer for coefficient buffer */
emh203 0:3d9c67d97d6f 91 q63_t acc0, acc1, acc2; /* Accumulators */
emh203 0:3d9c67d97d6f 92 uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
emh203 0:3d9c67d97d6f 93 uint32_t i, tapCnt, blkCnt, tapCntN3; /* Loop counters */
emh203 0:3d9c67d97d6f 94
emh203 0:3d9c67d97d6f 95 /* S->pState points to state array which contains previous frame (numTaps - 1) samples */
emh203 0:3d9c67d97d6f 96 /* pStateCurnt points to the location where the new input data should be written */
emh203 0:3d9c67d97d6f 97 pStateCurnt = &(S->pState[(numTaps - 1u)]);
emh203 0:3d9c67d97d6f 98
emh203 0:3d9c67d97d6f 99 /* Apply loop unrolling and compute 4 output values simultaneously.
emh203 0:3d9c67d97d6f 100 * The variables acc0 ... acc3 hold output values that are being computed:
emh203 0:3d9c67d97d6f 101 *
emh203 0:3d9c67d97d6f 102 * acc0 = b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0]
emh203 0:3d9c67d97d6f 103 * acc1 = b[numTaps-1] * x[n-numTaps] + b[numTaps-2] * x[n-numTaps-1] + b[numTaps-3] * x[n-numTaps-2] +...+ b[0] * x[1]
emh203 0:3d9c67d97d6f 104 * acc2 = b[numTaps-1] * x[n-numTaps+1] + b[numTaps-2] * x[n-numTaps] + b[numTaps-3] * x[n-numTaps-1] +...+ b[0] * x[2]
emh203 0:3d9c67d97d6f 105 * acc3 = b[numTaps-1] * x[n-numTaps+2] + b[numTaps-2] * x[n-numTaps+1] + b[numTaps-3] * x[n-numTaps] +...+ b[0] * x[3]
emh203 0:3d9c67d97d6f 106 */
emh203 0:3d9c67d97d6f 107 blkCnt = blockSize / 3;
emh203 0:3d9c67d97d6f 108 blockSize = blockSize - (3 * blkCnt);
emh203 0:3d9c67d97d6f 109
emh203 0:3d9c67d97d6f 110 tapCnt = numTaps / 3;
emh203 0:3d9c67d97d6f 111 tapCntN3 = numTaps - (3 * tapCnt);
emh203 0:3d9c67d97d6f 112
emh203 0:3d9c67d97d6f 113 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
emh203 0:3d9c67d97d6f 114 ** a second loop below computes the remaining 1 to 3 samples. */
emh203 0:3d9c67d97d6f 115 while(blkCnt > 0u)
emh203 0:3d9c67d97d6f 116 {
emh203 0:3d9c67d97d6f 117 /* Copy three new input samples into the state buffer */
emh203 0:3d9c67d97d6f 118 *pStateCurnt++ = *pSrc++;
emh203 0:3d9c67d97d6f 119 *pStateCurnt++ = *pSrc++;
emh203 0:3d9c67d97d6f 120 *pStateCurnt++ = *pSrc++;
emh203 0:3d9c67d97d6f 121
emh203 0:3d9c67d97d6f 122 /* Set all accumulators to zero */
emh203 0:3d9c67d97d6f 123 acc0 = 0;
emh203 0:3d9c67d97d6f 124 acc1 = 0;
emh203 0:3d9c67d97d6f 125 acc2 = 0;
emh203 0:3d9c67d97d6f 126
emh203 0:3d9c67d97d6f 127 /* Initialize state pointer */
emh203 0:3d9c67d97d6f 128 px = pState;
emh203 0:3d9c67d97d6f 129
emh203 0:3d9c67d97d6f 130 /* Initialize coefficient pointer */
emh203 0:3d9c67d97d6f 131 pb = pCoeffs;
emh203 0:3d9c67d97d6f 132
emh203 0:3d9c67d97d6f 133 /* Read the first two samples from the state buffer:
emh203 0:3d9c67d97d6f 134 * x[n-numTaps], x[n-numTaps-1] */
emh203 0:3d9c67d97d6f 135 x0 = *(px++);
emh203 0:3d9c67d97d6f 136 x1 = *(px++);
emh203 0:3d9c67d97d6f 137
emh203 0:3d9c67d97d6f 138 /* Loop unrolling. Process 3 taps at a time. */
emh203 0:3d9c67d97d6f 139 i = tapCnt;
emh203 0:3d9c67d97d6f 140
emh203 0:3d9c67d97d6f 141 while(i > 0u)
emh203 0:3d9c67d97d6f 142 {
emh203 0:3d9c67d97d6f 143 /* Read the b[numTaps] coefficient */
emh203 0:3d9c67d97d6f 144 c0 = *pb;
emh203 0:3d9c67d97d6f 145
emh203 0:3d9c67d97d6f 146 /* Read x[n-numTaps-2] sample */
emh203 0:3d9c67d97d6f 147 x2 = *(px++);
emh203 0:3d9c67d97d6f 148
emh203 0:3d9c67d97d6f 149 /* Perform the multiply-accumulates */
emh203 0:3d9c67d97d6f 150 acc0 += ((q63_t) x0 * c0);
emh203 0:3d9c67d97d6f 151 acc1 += ((q63_t) x1 * c0);
emh203 0:3d9c67d97d6f 152 acc2 += ((q63_t) x2 * c0);
emh203 0:3d9c67d97d6f 153
emh203 0:3d9c67d97d6f 154 /* Read the coefficient and state */
emh203 0:3d9c67d97d6f 155 c0 = *(pb + 1u);
emh203 0:3d9c67d97d6f 156 x0 = *(px++);
emh203 0:3d9c67d97d6f 157
emh203 0:3d9c67d97d6f 158 /* Perform the multiply-accumulates */
emh203 0:3d9c67d97d6f 159 acc0 += ((q63_t) x1 * c0);
emh203 0:3d9c67d97d6f 160 acc1 += ((q63_t) x2 * c0);
emh203 0:3d9c67d97d6f 161 acc2 += ((q63_t) x0 * c0);
emh203 0:3d9c67d97d6f 162
emh203 0:3d9c67d97d6f 163 /* Read the coefficient and state */
emh203 0:3d9c67d97d6f 164 c0 = *(pb + 2u);
emh203 0:3d9c67d97d6f 165 x1 = *(px++);
emh203 0:3d9c67d97d6f 166
emh203 0:3d9c67d97d6f 167 /* update coefficient pointer */
emh203 0:3d9c67d97d6f 168 pb += 3u;
emh203 0:3d9c67d97d6f 169
emh203 0:3d9c67d97d6f 170 /* Perform the multiply-accumulates */
emh203 0:3d9c67d97d6f 171 acc0 += ((q63_t) x2 * c0);
emh203 0:3d9c67d97d6f 172 acc1 += ((q63_t) x0 * c0);
emh203 0:3d9c67d97d6f 173 acc2 += ((q63_t) x1 * c0);
emh203 0:3d9c67d97d6f 174
emh203 0:3d9c67d97d6f 175 /* Decrement the loop counter */
emh203 0:3d9c67d97d6f 176 i--;
emh203 0:3d9c67d97d6f 177 }
emh203 0:3d9c67d97d6f 178
emh203 0:3d9c67d97d6f 179 /* If the filter length is not a multiple of 3, compute the remaining filter taps */
emh203 0:3d9c67d97d6f 180
emh203 0:3d9c67d97d6f 181 i = tapCntN3;
emh203 0:3d9c67d97d6f 182
emh203 0:3d9c67d97d6f 183 while(i > 0u)
emh203 0:3d9c67d97d6f 184 {
emh203 0:3d9c67d97d6f 185 /* Read coefficients */
emh203 0:3d9c67d97d6f 186 c0 = *(pb++);
emh203 0:3d9c67d97d6f 187
emh203 0:3d9c67d97d6f 188 /* Fetch 1 state variable */
emh203 0:3d9c67d97d6f 189 x2 = *(px++);
emh203 0:3d9c67d97d6f 190
emh203 0:3d9c67d97d6f 191 /* Perform the multiply-accumulates */
emh203 0:3d9c67d97d6f 192 acc0 += ((q63_t) x0 * c0);
emh203 0:3d9c67d97d6f 193 acc1 += ((q63_t) x1 * c0);
emh203 0:3d9c67d97d6f 194 acc2 += ((q63_t) x2 * c0);
emh203 0:3d9c67d97d6f 195
emh203 0:3d9c67d97d6f 196 /* Reuse the present sample states for next sample */
emh203 0:3d9c67d97d6f 197 x0 = x1;
emh203 0:3d9c67d97d6f 198 x1 = x2;
emh203 0:3d9c67d97d6f 199
emh203 0:3d9c67d97d6f 200 /* Decrement the loop counter */
emh203 0:3d9c67d97d6f 201 i--;
emh203 0:3d9c67d97d6f 202 }
emh203 0:3d9c67d97d6f 203
emh203 0:3d9c67d97d6f 204 /* Advance the state pointer by 3 to process the next group of 3 samples */
emh203 0:3d9c67d97d6f 205 pState = pState + 3;
emh203 0:3d9c67d97d6f 206
emh203 0:3d9c67d97d6f 207 /* The results in the 3 accumulators are in 2.30 format. Convert to 1.31
emh203 0:3d9c67d97d6f 208 ** Then store the 3 outputs in the destination buffer. */
emh203 0:3d9c67d97d6f 209 *pDst++ = (q31_t) (acc0 >> 31u);
emh203 0:3d9c67d97d6f 210 *pDst++ = (q31_t) (acc1 >> 31u);
emh203 0:3d9c67d97d6f 211 *pDst++ = (q31_t) (acc2 >> 31u);
emh203 0:3d9c67d97d6f 212
emh203 0:3d9c67d97d6f 213 /* Decrement the samples loop counter */
emh203 0:3d9c67d97d6f 214 blkCnt--;
emh203 0:3d9c67d97d6f 215 }
emh203 0:3d9c67d97d6f 216
emh203 0:3d9c67d97d6f 217 /* If the blockSize is not a multiple of 3, compute any remaining output samples here.
emh203 0:3d9c67d97d6f 218 ** No loop unrolling is used. */
emh203 0:3d9c67d97d6f 219
emh203 0:3d9c67d97d6f 220 while(blockSize > 0u)
emh203 0:3d9c67d97d6f 221 {
emh203 0:3d9c67d97d6f 222 /* Copy one sample at a time into state buffer */
emh203 0:3d9c67d97d6f 223 *pStateCurnt++ = *pSrc++;
emh203 0:3d9c67d97d6f 224
emh203 0:3d9c67d97d6f 225 /* Set the accumulator to zero */
emh203 0:3d9c67d97d6f 226 acc0 = 0;
emh203 0:3d9c67d97d6f 227
emh203 0:3d9c67d97d6f 228 /* Initialize state pointer */
emh203 0:3d9c67d97d6f 229 px = pState;
emh203 0:3d9c67d97d6f 230
emh203 0:3d9c67d97d6f 231 /* Initialize Coefficient pointer */
emh203 0:3d9c67d97d6f 232 pb = (pCoeffs);
emh203 0:3d9c67d97d6f 233
emh203 0:3d9c67d97d6f 234 i = numTaps;
emh203 0:3d9c67d97d6f 235
emh203 0:3d9c67d97d6f 236 /* Perform the multiply-accumulates */
emh203 0:3d9c67d97d6f 237 do
emh203 0:3d9c67d97d6f 238 {
emh203 0:3d9c67d97d6f 239 acc0 += (q63_t) * (px++) * (*(pb++));
emh203 0:3d9c67d97d6f 240 i--;
emh203 0:3d9c67d97d6f 241 } while(i > 0u);
emh203 0:3d9c67d97d6f 242
emh203 0:3d9c67d97d6f 243 /* The result is in 2.62 format. Convert to 1.31
emh203 0:3d9c67d97d6f 244 ** Then store the output in the destination buffer. */
emh203 0:3d9c67d97d6f 245 *pDst++ = (q31_t) (acc0 >> 31u);
emh203 0:3d9c67d97d6f 246
emh203 0:3d9c67d97d6f 247 /* Advance state pointer by 1 for the next sample */
emh203 0:3d9c67d97d6f 248 pState = pState + 1;
emh203 0:3d9c67d97d6f 249
emh203 0:3d9c67d97d6f 250 /* Decrement the samples loop counter */
emh203 0:3d9c67d97d6f 251 blockSize--;
emh203 0:3d9c67d97d6f 252 }
emh203 0:3d9c67d97d6f 253
emh203 0:3d9c67d97d6f 254 /* Processing is complete.
emh203 0:3d9c67d97d6f 255 ** Now copy the last numTaps - 1 samples to the satrt of the state buffer.
emh203 0:3d9c67d97d6f 256 ** This prepares the state buffer for the next function call. */
emh203 0:3d9c67d97d6f 257
emh203 0:3d9c67d97d6f 258 /* Points to the start of the state buffer */
emh203 0:3d9c67d97d6f 259 pStateCurnt = S->pState;
emh203 0:3d9c67d97d6f 260
emh203 0:3d9c67d97d6f 261 tapCnt = (numTaps - 1u) >> 2u;
emh203 0:3d9c67d97d6f 262
emh203 0:3d9c67d97d6f 263 /* copy data */
emh203 0:3d9c67d97d6f 264 while(tapCnt > 0u)
emh203 0:3d9c67d97d6f 265 {
emh203 0:3d9c67d97d6f 266 *pStateCurnt++ = *pState++;
emh203 0:3d9c67d97d6f 267 *pStateCurnt++ = *pState++;
emh203 0:3d9c67d97d6f 268 *pStateCurnt++ = *pState++;
emh203 0:3d9c67d97d6f 269 *pStateCurnt++ = *pState++;
emh203 0:3d9c67d97d6f 270
emh203 0:3d9c67d97d6f 271 /* Decrement the loop counter */
emh203 0:3d9c67d97d6f 272 tapCnt--;
emh203 0:3d9c67d97d6f 273 }
emh203 0:3d9c67d97d6f 274
emh203 0:3d9c67d97d6f 275 /* Calculate remaining number of copies */
emh203 0:3d9c67d97d6f 276 tapCnt = (numTaps - 1u) % 0x4u;
emh203 0:3d9c67d97d6f 277
emh203 0:3d9c67d97d6f 278 /* Copy the remaining q31_t data */
emh203 0:3d9c67d97d6f 279 while(tapCnt > 0u)
emh203 0:3d9c67d97d6f 280 {
emh203 0:3d9c67d97d6f 281 *pStateCurnt++ = *pState++;
emh203 0:3d9c67d97d6f 282
emh203 0:3d9c67d97d6f 283 /* Decrement the loop counter */
emh203 0:3d9c67d97d6f 284 tapCnt--;
emh203 0:3d9c67d97d6f 285 }
emh203 0:3d9c67d97d6f 286
emh203 0:3d9c67d97d6f 287 #else
emh203 0:3d9c67d97d6f 288
emh203 0:3d9c67d97d6f 289 /* Run the below code for Cortex-M0 */
emh203 0:3d9c67d97d6f 290
emh203 0:3d9c67d97d6f 291 q31_t *px; /* Temporary pointer for state */
emh203 0:3d9c67d97d6f 292 q31_t *pb; /* Temporary pointer for coefficient buffer */
emh203 0:3d9c67d97d6f 293 q63_t acc; /* Accumulator */
emh203 0:3d9c67d97d6f 294 uint32_t numTaps = S->numTaps; /* Length of the filter */
emh203 0:3d9c67d97d6f 295 uint32_t i, tapCnt, blkCnt; /* Loop counters */
emh203 0:3d9c67d97d6f 296
emh203 0:3d9c67d97d6f 297 /* S->pState buffer contains previous frame (numTaps - 1) samples */
emh203 0:3d9c67d97d6f 298 /* pStateCurnt points to the location where the new input data should be written */
emh203 0:3d9c67d97d6f 299 pStateCurnt = &(S->pState[(numTaps - 1u)]);
emh203 0:3d9c67d97d6f 300
emh203 0:3d9c67d97d6f 301 /* Initialize blkCnt with blockSize */
emh203 0:3d9c67d97d6f 302 blkCnt = blockSize;
emh203 0:3d9c67d97d6f 303
emh203 0:3d9c67d97d6f 304 while(blkCnt > 0u)
emh203 0:3d9c67d97d6f 305 {
emh203 0:3d9c67d97d6f 306 /* Copy one sample at a time into state buffer */
emh203 0:3d9c67d97d6f 307 *pStateCurnt++ = *pSrc++;
emh203 0:3d9c67d97d6f 308
emh203 0:3d9c67d97d6f 309 /* Set the accumulator to zero */
emh203 0:3d9c67d97d6f 310 acc = 0;
emh203 0:3d9c67d97d6f 311
emh203 0:3d9c67d97d6f 312 /* Initialize state pointer */
emh203 0:3d9c67d97d6f 313 px = pState;
emh203 0:3d9c67d97d6f 314
emh203 0:3d9c67d97d6f 315 /* Initialize Coefficient pointer */
emh203 0:3d9c67d97d6f 316 pb = pCoeffs;
emh203 0:3d9c67d97d6f 317
emh203 0:3d9c67d97d6f 318 i = numTaps;
emh203 0:3d9c67d97d6f 319
emh203 0:3d9c67d97d6f 320 /* Perform the multiply-accumulates */
emh203 0:3d9c67d97d6f 321 do
emh203 0:3d9c67d97d6f 322 {
emh203 0:3d9c67d97d6f 323 /* acc = b[numTaps-1] * x[n-numTaps-1] + b[numTaps-2] * x[n-numTaps-2] + b[numTaps-3] * x[n-numTaps-3] +...+ b[0] * x[0] */
emh203 0:3d9c67d97d6f 324 acc += (q63_t) * px++ * *pb++;
emh203 0:3d9c67d97d6f 325 i--;
emh203 0:3d9c67d97d6f 326 } while(i > 0u);
emh203 0:3d9c67d97d6f 327
emh203 0:3d9c67d97d6f 328 /* The result is in 2.62 format. Convert to 1.31
emh203 0:3d9c67d97d6f 329 ** Then store the output in the destination buffer. */
emh203 0:3d9c67d97d6f 330 *pDst++ = (q31_t) (acc >> 31u);
emh203 0:3d9c67d97d6f 331
emh203 0:3d9c67d97d6f 332 /* Advance state pointer by 1 for the next sample */
emh203 0:3d9c67d97d6f 333 pState = pState + 1;
emh203 0:3d9c67d97d6f 334
emh203 0:3d9c67d97d6f 335 /* Decrement the samples loop counter */
emh203 0:3d9c67d97d6f 336 blkCnt--;
emh203 0:3d9c67d97d6f 337 }
emh203 0:3d9c67d97d6f 338
emh203 0:3d9c67d97d6f 339 /* Processing is complete.
emh203 0:3d9c67d97d6f 340 ** Now copy the last numTaps - 1 samples to the starting of the state buffer.
emh203 0:3d9c67d97d6f 341 ** This prepares the state buffer for the next function call. */
emh203 0:3d9c67d97d6f 342
emh203 0:3d9c67d97d6f 343 /* Points to the start of the state buffer */
emh203 0:3d9c67d97d6f 344 pStateCurnt = S->pState;
emh203 0:3d9c67d97d6f 345
emh203 0:3d9c67d97d6f 346 /* Copy numTaps number of values */
emh203 0:3d9c67d97d6f 347 tapCnt = numTaps - 1u;
emh203 0:3d9c67d97d6f 348
emh203 0:3d9c67d97d6f 349 /* Copy the data */
emh203 0:3d9c67d97d6f 350 while(tapCnt > 0u)
emh203 0:3d9c67d97d6f 351 {
emh203 0:3d9c67d97d6f 352 *pStateCurnt++ = *pState++;
emh203 0:3d9c67d97d6f 353
emh203 0:3d9c67d97d6f 354 /* Decrement the loop counter */
emh203 0:3d9c67d97d6f 355 tapCnt--;
emh203 0:3d9c67d97d6f 356 }
emh203 0:3d9c67d97d6f 357
emh203 0:3d9c67d97d6f 358
emh203 0:3d9c67d97d6f 359 #endif /* #ifndef ARM_MATH_CM0_FAMILY */
emh203 0:3d9c67d97d6f 360
emh203 0:3d9c67d97d6f 361 }
emh203 0:3d9c67d97d6f 362
emh203 0:3d9c67d97d6f 363 /**
emh203 0:3d9c67d97d6f 364 * @} end of FIR group
emh203 0:3d9c67d97d6f 365 */