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CMSIS DSP library

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cmsis_dsp/FilteringFunctions/arm_fir_fast_q15.c@5:3762170b6d4d, 2015-11-20 (annotated)

Committer:
mbed_official
Date:
Fri Nov 20 08:45:18 2015 +0000
Revision:
5:3762170b6d4d
Parent:
3:7a284390b0ce 
Synchronized with git revision 2eb940b9a73af188d3004a2575fdfbb05febe62b



Full URL: https://github.com/mbedmicro/mbed/commit/2eb940b9a73af188d3004a2575fdfbb05febe62b/



Added option to build rpc library. closes #1426

Who changed what in which revision?

UserRevisionLine numberNew contents of line
emilmont 1:fdd22bb7aa52 1 /* ----------------------------------------------------------------------
mbed_official 5:3762170b6d4d 2 * Copyright (C) 2010-2014 ARM Limited. All rights reserved.
emilmont 1:fdd22bb7aa52 3 *
mbed_official 5:3762170b6d4d 4 * $Date: 19. March 2015
mbed_official 5:3762170b6d4d 5 * $Revision: V.1.4.5
emilmont 1:fdd22bb7aa52 6 *
emilmont 2:da51fb522205 7 * Project: CMSIS DSP Library
emilmont 1:fdd22bb7aa52 8 * Title: arm_fir_fast_q15.c
emilmont 1:fdd22bb7aa52 9 *
emilmont 1:fdd22bb7aa52 10 * Description: Q15 Fast FIR filter processing function.
emilmont 1:fdd22bb7aa52 11 *
emilmont 1:fdd22bb7aa52 12 * Target Processor: Cortex-M4/Cortex-M3
emilmont 1:fdd22bb7aa52 13 *
mbed_official 3:7a284390b0ce 14 * Redistribution and use in source and binary forms, with or without
mbed_official 3:7a284390b0ce 15 * modification, are permitted provided that the following conditions
mbed_official 3:7a284390b0ce 16 * are met:
mbed_official 3:7a284390b0ce 17 * - Redistributions of source code must retain the above copyright
mbed_official 3:7a284390b0ce 18 * notice, this list of conditions and the following disclaimer.
mbed_official 3:7a284390b0ce 19 * - Redistributions in binary form must reproduce the above copyright
mbed_official 3:7a284390b0ce 20 * notice, this list of conditions and the following disclaimer in
mbed_official 3:7a284390b0ce 21 * the documentation and/or other materials provided with the
mbed_official 3:7a284390b0ce 22 * distribution.
mbed_official 3:7a284390b0ce 23 * - Neither the name of ARM LIMITED nor the names of its contributors
mbed_official 3:7a284390b0ce 24 * may be used to endorse or promote products derived from this
mbed_official 3:7a284390b0ce 25 * software without specific prior written permission.
mbed_official 3:7a284390b0ce 26 *
mbed_official 3:7a284390b0ce 27 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
mbed_official 3:7a284390b0ce 28 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
mbed_official 3:7a284390b0ce 29 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
mbed_official 3:7a284390b0ce 30 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
mbed_official 3:7a284390b0ce 31 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
mbed_official 3:7a284390b0ce 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
mbed_official 3:7a284390b0ce 33 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
mbed_official 3:7a284390b0ce 34 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
mbed_official 3:7a284390b0ce 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
mbed_official 3:7a284390b0ce 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
mbed_official 3:7a284390b0ce 37 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
mbed_official 3:7a284390b0ce 38 * POSSIBILITY OF SUCH DAMAGE.
emilmont 1:fdd22bb7aa52 39 * -------------------------------------------------------------------- */
emilmont 1:fdd22bb7aa52 40
emilmont 1:fdd22bb7aa52 41 #include "arm_math.h"
emilmont 1:fdd22bb7aa52 42
emilmont 1:fdd22bb7aa52 43 /**
emilmont 1:fdd22bb7aa52 44 * @ingroup groupFilters
emilmont 1:fdd22bb7aa52 45 */
emilmont 1:fdd22bb7aa52 46
emilmont 1:fdd22bb7aa52 47 /**
emilmont 1:fdd22bb7aa52 48 * @addtogroup FIR
emilmont 1:fdd22bb7aa52 49 * @{
emilmont 1:fdd22bb7aa52 50 */
emilmont 1:fdd22bb7aa52 51
emilmont 1:fdd22bb7aa52 52 /**
emilmont 1:fdd22bb7aa52 53 * @param[in] *S points to an instance of the Q15 FIR filter structure.
emilmont 1:fdd22bb7aa52 54 * @param[in] *pSrc points to the block of input data.
emilmont 1:fdd22bb7aa52 55 * @param[out] *pDst points to the block of output data.
emilmont 1:fdd22bb7aa52 56 * @param[in] blockSize number of samples to process per call.
emilmont 1:fdd22bb7aa52 57 * @return none.
emilmont 1:fdd22bb7aa52 58 *
emilmont 1:fdd22bb7aa52 59 * <b>Scaling and Overflow Behavior:</b>
emilmont 1:fdd22bb7aa52 60 * \par
emilmont 1:fdd22bb7aa52 61 * This fast version uses a 32-bit accumulator with 2.30 format.
emilmont 1:fdd22bb7aa52 62 * The accumulator maintains full precision of the intermediate multiplication results but provides only a single guard bit.
emilmont 1:fdd22bb7aa52 63 * Thus, if the accumulator result overflows it wraps around and distorts the result.
emilmont 1:fdd22bb7aa52 64 * In order to avoid overflows completely the input signal must be scaled down by log2(numTaps) bits.
emilmont 1:fdd22bb7aa52 65 * The 2.30 accumulator is then truncated to 2.15 format and saturated to yield the 1.15 result.
emilmont 1:fdd22bb7aa52 66 *
emilmont 1:fdd22bb7aa52 67 * \par
emilmont 1:fdd22bb7aa52 68 * Refer to the function <code>arm_fir_q15()</code> for a slower implementation of this function which uses 64-bit accumulation to avoid wrap around distortion. Both the slow and the fast versions use the same instance structure.
emilmont 1:fdd22bb7aa52 69 * Use the function <code>arm_fir_init_q15()</code> to initialize the filter structure.
emilmont 1:fdd22bb7aa52 70 */
emilmont 1:fdd22bb7aa52 71
emilmont 1:fdd22bb7aa52 72 void arm_fir_fast_q15(
emilmont 1:fdd22bb7aa52 73 const arm_fir_instance_q15 * S,
emilmont 1:fdd22bb7aa52 74 q15_t * pSrc,
emilmont 1:fdd22bb7aa52 75 q15_t * pDst,
emilmont 1:fdd22bb7aa52 76 uint32_t blockSize)
emilmont 1:fdd22bb7aa52 77 {
emilmont 1:fdd22bb7aa52 78 q15_t *pState = S->pState; /* State pointer */
emilmont 1:fdd22bb7aa52 79 q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
emilmont 1:fdd22bb7aa52 80 q15_t *pStateCurnt; /* Points to the current sample of the state */
emilmont 1:fdd22bb7aa52 81 q31_t acc0, acc1, acc2, acc3; /* Accumulators */
emilmont 1:fdd22bb7aa52 82 q15_t *pb; /* Temporary pointer for coefficient buffer */
emilmont 1:fdd22bb7aa52 83 q15_t *px; /* Temporary q31 pointer for SIMD state buffer accesses */
emilmont 1:fdd22bb7aa52 84 q31_t x0, x1, x2, c0; /* Temporary variables to hold SIMD state and coefficient values */
emilmont 1:fdd22bb7aa52 85 uint32_t numTaps = S->numTaps; /* Number of taps in the filter */
emilmont 1:fdd22bb7aa52 86 uint32_t tapCnt, blkCnt; /* Loop counters */
emilmont 1:fdd22bb7aa52 87
emilmont 1:fdd22bb7aa52 88
emilmont 1:fdd22bb7aa52 89 /* S->pState points to state array which contains previous frame (numTaps - 1) samples */
emilmont 1:fdd22bb7aa52 90 /* pStateCurnt points to the location where the new input data should be written */
emilmont 1:fdd22bb7aa52 91 pStateCurnt = &(S->pState[(numTaps - 1u)]);
emilmont 1:fdd22bb7aa52 92
emilmont 1:fdd22bb7aa52 93 /* Apply loop unrolling and compute 4 output values simultaneously.
emilmont 1:fdd22bb7aa52 94 * The variables acc0 ... acc3 hold output values that are being computed:
emilmont 1:fdd22bb7aa52 95 *
emilmont 1:fdd22bb7aa52 96 * 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]
emilmont 1:fdd22bb7aa52 97 * 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]
emilmont 1:fdd22bb7aa52 98 * 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]
emilmont 1:fdd22bb7aa52 99 * 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]
emilmont 1:fdd22bb7aa52 100 */
emilmont 1:fdd22bb7aa52 101
emilmont 1:fdd22bb7aa52 102 blkCnt = blockSize >> 2;
emilmont 1:fdd22bb7aa52 103
emilmont 1:fdd22bb7aa52 104 /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
emilmont 1:fdd22bb7aa52 105 ** a second loop below computes the remaining 1 to 3 samples. */
emilmont 1:fdd22bb7aa52 106 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 107 {
emilmont 1:fdd22bb7aa52 108 /* Copy four new input samples into the state buffer.
emilmont 1:fdd22bb7aa52 109 ** Use 32-bit SIMD to move the 16-bit data. Only requires two copies. */
emilmont 1:fdd22bb7aa52 110 *pStateCurnt++ = *pSrc++;
emilmont 1:fdd22bb7aa52 111 *pStateCurnt++ = *pSrc++;
emilmont 1:fdd22bb7aa52 112 *pStateCurnt++ = *pSrc++;
emilmont 1:fdd22bb7aa52 113 *pStateCurnt++ = *pSrc++;
emilmont 1:fdd22bb7aa52 114
emilmont 1:fdd22bb7aa52 115
emilmont 1:fdd22bb7aa52 116 /* Set all accumulators to zero */
emilmont 1:fdd22bb7aa52 117 acc0 = 0;
emilmont 1:fdd22bb7aa52 118 acc1 = 0;
emilmont 1:fdd22bb7aa52 119 acc2 = 0;
emilmont 1:fdd22bb7aa52 120 acc3 = 0;
emilmont 1:fdd22bb7aa52 121
emilmont 1:fdd22bb7aa52 122 /* Typecast q15_t pointer to q31_t pointer for state reading in q31_t */
emilmont 1:fdd22bb7aa52 123 px = pState;
emilmont 1:fdd22bb7aa52 124
emilmont 1:fdd22bb7aa52 125 /* Typecast q15_t pointer to q31_t pointer for coefficient reading in q31_t */
emilmont 1:fdd22bb7aa52 126 pb = pCoeffs;
emilmont 1:fdd22bb7aa52 127
emilmont 1:fdd22bb7aa52 128 /* Read the first two samples from the state buffer: x[n-N], x[n-N-1] */
emilmont 1:fdd22bb7aa52 129 x0 = *__SIMD32(px)++;
emilmont 1:fdd22bb7aa52 130
emilmont 1:fdd22bb7aa52 131 /* Read the third and forth samples from the state buffer: x[n-N-2], x[n-N-3] */
emilmont 1:fdd22bb7aa52 132 x2 = *__SIMD32(px)++;
emilmont 1:fdd22bb7aa52 133
emilmont 1:fdd22bb7aa52 134 /* Loop over the number of taps. Unroll by a factor of 4.
emilmont 1:fdd22bb7aa52 135 ** Repeat until we've computed numTaps-(numTaps%4) coefficients. */
emilmont 1:fdd22bb7aa52 136 tapCnt = numTaps >> 2;
emilmont 1:fdd22bb7aa52 137
emilmont 1:fdd22bb7aa52 138 while(tapCnt > 0)
emilmont 1:fdd22bb7aa52 139 {
emilmont 1:fdd22bb7aa52 140 /* Read the first two coefficients using SIMD: b[N] and b[N-1] coefficients */
emilmont 1:fdd22bb7aa52 141 c0 = *__SIMD32(pb)++;
emilmont 1:fdd22bb7aa52 142
emilmont 1:fdd22bb7aa52 143 /* acc0 += b[N] * x[n-N] + b[N-1] * x[n-N-1] */
emilmont 1:fdd22bb7aa52 144 acc0 = __SMLAD(x0, c0, acc0);
emilmont 1:fdd22bb7aa52 145
emilmont 1:fdd22bb7aa52 146 /* acc2 += b[N] * x[n-N-2] + b[N-1] * x[n-N-3] */
emilmont 1:fdd22bb7aa52 147 acc2 = __SMLAD(x2, c0, acc2);
emilmont 1:fdd22bb7aa52 148
emilmont 1:fdd22bb7aa52 149 /* pack x[n-N-1] and x[n-N-2] */
emilmont 1:fdd22bb7aa52 150 #ifndef ARM_MATH_BIG_ENDIAN
emilmont 1:fdd22bb7aa52 151 x1 = __PKHBT(x2, x0, 0);
emilmont 1:fdd22bb7aa52 152 #else
emilmont 1:fdd22bb7aa52 153 x1 = __PKHBT(x0, x2, 0);
emilmont 1:fdd22bb7aa52 154 #endif
emilmont 1:fdd22bb7aa52 155
emilmont 1:fdd22bb7aa52 156 /* Read state x[n-N-4], x[n-N-5] */
emilmont 1:fdd22bb7aa52 157 x0 = _SIMD32_OFFSET(px);
emilmont 1:fdd22bb7aa52 158
emilmont 1:fdd22bb7aa52 159 /* acc1 += b[N] * x[n-N-1] + b[N-1] * x[n-N-2] */
emilmont 1:fdd22bb7aa52 160 acc1 = __SMLADX(x1, c0, acc1);
emilmont 1:fdd22bb7aa52 161
emilmont 1:fdd22bb7aa52 162 /* pack x[n-N-3] and x[n-N-4] */
emilmont 1:fdd22bb7aa52 163 #ifndef ARM_MATH_BIG_ENDIAN
emilmont 1:fdd22bb7aa52 164 x1 = __PKHBT(x0, x2, 0);
emilmont 1:fdd22bb7aa52 165 #else
emilmont 1:fdd22bb7aa52 166 x1 = __PKHBT(x2, x0, 0);
emilmont 1:fdd22bb7aa52 167 #endif
emilmont 1:fdd22bb7aa52 168
emilmont 1:fdd22bb7aa52 169 /* acc3 += b[N] * x[n-N-3] + b[N-1] * x[n-N-4] */
emilmont 1:fdd22bb7aa52 170 acc3 = __SMLADX(x1, c0, acc3);
emilmont 1:fdd22bb7aa52 171
emilmont 1:fdd22bb7aa52 172 /* Read coefficients b[N-2], b[N-3] */
emilmont 1:fdd22bb7aa52 173 c0 = *__SIMD32(pb)++;
emilmont 1:fdd22bb7aa52 174
emilmont 1:fdd22bb7aa52 175 /* acc0 += b[N-2] * x[n-N-2] + b[N-3] * x[n-N-3] */
emilmont 1:fdd22bb7aa52 176 acc0 = __SMLAD(x2, c0, acc0);
emilmont 1:fdd22bb7aa52 177
emilmont 1:fdd22bb7aa52 178 /* Read state x[n-N-6], x[n-N-7] with offset */
emilmont 1:fdd22bb7aa52 179 x2 = _SIMD32_OFFSET(px + 2u);
emilmont 1:fdd22bb7aa52 180
emilmont 1:fdd22bb7aa52 181 /* acc2 += b[N-2] * x[n-N-4] + b[N-3] * x[n-N-5] */
emilmont 1:fdd22bb7aa52 182 acc2 = __SMLAD(x0, c0, acc2);
emilmont 1:fdd22bb7aa52 183
emilmont 1:fdd22bb7aa52 184 /* acc1 += b[N-2] * x[n-N-3] + b[N-3] * x[n-N-4] */
emilmont 1:fdd22bb7aa52 185 acc1 = __SMLADX(x1, c0, acc1);
emilmont 1:fdd22bb7aa52 186
emilmont 1:fdd22bb7aa52 187 /* pack x[n-N-5] and x[n-N-6] */
emilmont 1:fdd22bb7aa52 188 #ifndef ARM_MATH_BIG_ENDIAN
emilmont 1:fdd22bb7aa52 189 x1 = __PKHBT(x2, x0, 0);
emilmont 1:fdd22bb7aa52 190 #else
emilmont 1:fdd22bb7aa52 191 x1 = __PKHBT(x0, x2, 0);
emilmont 1:fdd22bb7aa52 192 #endif
emilmont 1:fdd22bb7aa52 193
emilmont 1:fdd22bb7aa52 194 /* acc3 += b[N-2] * x[n-N-5] + b[N-3] * x[n-N-6] */
emilmont 1:fdd22bb7aa52 195 acc3 = __SMLADX(x1, c0, acc3);
emilmont 1:fdd22bb7aa52 196
emilmont 1:fdd22bb7aa52 197 /* Update state pointer for next state reading */
emilmont 1:fdd22bb7aa52 198 px += 4u;
emilmont 1:fdd22bb7aa52 199
emilmont 1:fdd22bb7aa52 200 /* Decrement tap count */
emilmont 1:fdd22bb7aa52 201 tapCnt--;
emilmont 1:fdd22bb7aa52 202
emilmont 1:fdd22bb7aa52 203 }
emilmont 1:fdd22bb7aa52 204
emilmont 1:fdd22bb7aa52 205 /* If the filter length is not a multiple of 4, compute the remaining filter taps.
emilmont 1:fdd22bb7aa52 206 ** This is always be 2 taps since the filter length is even. */
emilmont 1:fdd22bb7aa52 207 if((numTaps & 0x3u) != 0u)
emilmont 1:fdd22bb7aa52 208 {
emilmont 1:fdd22bb7aa52 209
emilmont 1:fdd22bb7aa52 210 /* Read last two coefficients */
emilmont 1:fdd22bb7aa52 211 c0 = *__SIMD32(pb)++;
emilmont 1:fdd22bb7aa52 212
emilmont 1:fdd22bb7aa52 213 /* Perform the multiply-accumulates */
emilmont 1:fdd22bb7aa52 214 acc0 = __SMLAD(x0, c0, acc0);
emilmont 1:fdd22bb7aa52 215 acc2 = __SMLAD(x2, c0, acc2);
emilmont 1:fdd22bb7aa52 216
emilmont 1:fdd22bb7aa52 217 /* pack state variables */
emilmont 1:fdd22bb7aa52 218 #ifndef ARM_MATH_BIG_ENDIAN
emilmont 1:fdd22bb7aa52 219 x1 = __PKHBT(x2, x0, 0);
emilmont 1:fdd22bb7aa52 220 #else
emilmont 1:fdd22bb7aa52 221 x1 = __PKHBT(x0, x2, 0);
emilmont 1:fdd22bb7aa52 222 #endif
emilmont 1:fdd22bb7aa52 223
emilmont 1:fdd22bb7aa52 224 /* Read last state variables */
emilmont 1:fdd22bb7aa52 225 x0 = *__SIMD32(px);
emilmont 1:fdd22bb7aa52 226
emilmont 1:fdd22bb7aa52 227 /* Perform the multiply-accumulates */
emilmont 1:fdd22bb7aa52 228 acc1 = __SMLADX(x1, c0, acc1);
emilmont 1:fdd22bb7aa52 229
emilmont 1:fdd22bb7aa52 230 /* pack state variables */
emilmont 1:fdd22bb7aa52 231 #ifndef ARM_MATH_BIG_ENDIAN
emilmont 1:fdd22bb7aa52 232 x1 = __PKHBT(x0, x2, 0);
emilmont 1:fdd22bb7aa52 233 #else
emilmont 1:fdd22bb7aa52 234 x1 = __PKHBT(x2, x0, 0);
emilmont 1:fdd22bb7aa52 235 #endif
emilmont 1:fdd22bb7aa52 236
emilmont 1:fdd22bb7aa52 237 /* Perform the multiply-accumulates */
emilmont 1:fdd22bb7aa52 238 acc3 = __SMLADX(x1, c0, acc3);
emilmont 1:fdd22bb7aa52 239 }
emilmont 1:fdd22bb7aa52 240
emilmont 1:fdd22bb7aa52 241 /* The results in the 4 accumulators are in 2.30 format. Convert to 1.15 with saturation.
emilmont 1:fdd22bb7aa52 242 ** Then store the 4 outputs in the destination buffer. */
emilmont 1:fdd22bb7aa52 243
emilmont 1:fdd22bb7aa52 244 #ifndef ARM_MATH_BIG_ENDIAN
emilmont 1:fdd22bb7aa52 245
emilmont 1:fdd22bb7aa52 246 *__SIMD32(pDst)++ =
emilmont 1:fdd22bb7aa52 247 __PKHBT(__SSAT((acc0 >> 15), 16), __SSAT((acc1 >> 15), 16), 16);
emilmont 1:fdd22bb7aa52 248
emilmont 1:fdd22bb7aa52 249 *__SIMD32(pDst)++ =
emilmont 1:fdd22bb7aa52 250 __PKHBT(__SSAT((acc2 >> 15), 16), __SSAT((acc3 >> 15), 16), 16);
emilmont 1:fdd22bb7aa52 251
emilmont 1:fdd22bb7aa52 252 #else
emilmont 1:fdd22bb7aa52 253
emilmont 1:fdd22bb7aa52 254 *__SIMD32(pDst)++ =
emilmont 1:fdd22bb7aa52 255 __PKHBT(__SSAT((acc1 >> 15), 16), __SSAT((acc0 >> 15), 16), 16);
emilmont 1:fdd22bb7aa52 256
emilmont 1:fdd22bb7aa52 257 *__SIMD32(pDst)++ =
emilmont 1:fdd22bb7aa52 258 __PKHBT(__SSAT((acc3 >> 15), 16), __SSAT((acc2 >> 15), 16), 16);
emilmont 1:fdd22bb7aa52 259
emilmont 1:fdd22bb7aa52 260
emilmont 1:fdd22bb7aa52 261 #endif /* #ifndef ARM_MATH_BIG_ENDIAN */
emilmont 1:fdd22bb7aa52 262
emilmont 1:fdd22bb7aa52 263 /* Advance the state pointer by 4 to process the next group of 4 samples */
emilmont 1:fdd22bb7aa52 264 pState = pState + 4u;
emilmont 1:fdd22bb7aa52 265
emilmont 1:fdd22bb7aa52 266 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 267 blkCnt--;
emilmont 1:fdd22bb7aa52 268 }
emilmont 1:fdd22bb7aa52 269
emilmont 1:fdd22bb7aa52 270 /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
emilmont 1:fdd22bb7aa52 271 ** No loop unrolling is used. */
emilmont 1:fdd22bb7aa52 272 blkCnt = blockSize % 0x4u;
emilmont 1:fdd22bb7aa52 273 while(blkCnt > 0u)
emilmont 1:fdd22bb7aa52 274 {
emilmont 1:fdd22bb7aa52 275 /* Copy two samples into state buffer */
emilmont 1:fdd22bb7aa52 276 *pStateCurnt++ = *pSrc++;
emilmont 1:fdd22bb7aa52 277
emilmont 1:fdd22bb7aa52 278 /* Set the accumulator to zero */
emilmont 1:fdd22bb7aa52 279 acc0 = 0;
emilmont 1:fdd22bb7aa52 280
emilmont 1:fdd22bb7aa52 281 /* Use SIMD to hold states and coefficients */
emilmont 1:fdd22bb7aa52 282 px = pState;
emilmont 1:fdd22bb7aa52 283 pb = pCoeffs;
emilmont 1:fdd22bb7aa52 284
emilmont 1:fdd22bb7aa52 285 tapCnt = numTaps >> 1u;
emilmont 1:fdd22bb7aa52 286
emilmont 1:fdd22bb7aa52 287 do
emilmont 1:fdd22bb7aa52 288 {
emilmont 1:fdd22bb7aa52 289
emilmont 1:fdd22bb7aa52 290 acc0 += (q31_t) * px++ * *pb++;
emilmont 2:da51fb522205 291 acc0 += (q31_t) * px++ * *pb++;
emilmont 1:fdd22bb7aa52 292
emilmont 1:fdd22bb7aa52 293 tapCnt--;
emilmont 1:fdd22bb7aa52 294 }
emilmont 1:fdd22bb7aa52 295 while(tapCnt > 0u);
emilmont 1:fdd22bb7aa52 296
emilmont 1:fdd22bb7aa52 297 /* The result is in 2.30 format. Convert to 1.15 with saturation.
emilmont 1:fdd22bb7aa52 298 ** Then store the output in the destination buffer. */
emilmont 1:fdd22bb7aa52 299 *pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16));
emilmont 1:fdd22bb7aa52 300
emilmont 1:fdd22bb7aa52 301 /* Advance state pointer by 1 for the next sample */
emilmont 1:fdd22bb7aa52 302 pState = pState + 1u;
emilmont 1:fdd22bb7aa52 303
emilmont 1:fdd22bb7aa52 304 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 305 blkCnt--;
emilmont 1:fdd22bb7aa52 306 }
emilmont 1:fdd22bb7aa52 307
emilmont 1:fdd22bb7aa52 308 /* Processing is complete.
emilmont 1:fdd22bb7aa52 309 ** Now copy the last numTaps - 1 samples to the satrt of the state buffer.
emilmont 1:fdd22bb7aa52 310 ** This prepares the state buffer for the next function call. */
emilmont 1:fdd22bb7aa52 311
emilmont 1:fdd22bb7aa52 312 /* Points to the start of the state buffer */
emilmont 1:fdd22bb7aa52 313 pStateCurnt = S->pState;
emilmont 1:fdd22bb7aa52 314
emilmont 1:fdd22bb7aa52 315 /* Calculation of count for copying integer writes */
emilmont 1:fdd22bb7aa52 316 tapCnt = (numTaps - 1u) >> 2;
emilmont 1:fdd22bb7aa52 317
emilmont 1:fdd22bb7aa52 318 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 319 {
emilmont 1:fdd22bb7aa52 320 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 321 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 322 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 323 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 324
emilmont 1:fdd22bb7aa52 325 tapCnt--;
emilmont 1:fdd22bb7aa52 326
emilmont 1:fdd22bb7aa52 327 }
emilmont 1:fdd22bb7aa52 328
emilmont 1:fdd22bb7aa52 329 /* Calculation of count for remaining q15_t data */
emilmont 1:fdd22bb7aa52 330 tapCnt = (numTaps - 1u) % 0x4u;
emilmont 1:fdd22bb7aa52 331
emilmont 1:fdd22bb7aa52 332 /* copy remaining data */
emilmont 1:fdd22bb7aa52 333 while(tapCnt > 0u)
emilmont 1:fdd22bb7aa52 334 {
emilmont 1:fdd22bb7aa52 335 *pStateCurnt++ = *pState++;
emilmont 1:fdd22bb7aa52 336
emilmont 1:fdd22bb7aa52 337 /* Decrement the loop counter */
emilmont 1:fdd22bb7aa52 338 tapCnt--;
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 FIR group
emilmont 1:fdd22bb7aa52 345 */