diff options
Diffstat (limited to 'fw/hid-dials/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_q15.c')
| -rw-r--r-- | fw/hid-dials/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_q15.c | 679 |
1 files changed, 679 insertions, 0 deletions
diff --git a/fw/hid-dials/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_q15.c b/fw/hid-dials/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_q15.c new file mode 100644 index 0000000..a979783 --- /dev/null +++ b/fw/hid-dials/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_fir_q15.c @@ -0,0 +1,679 @@ +/* ----------------------------------------------------------------------
+ * Project: CMSIS DSP Library
+ * Title: arm_fir_q15.c
+ * Description: Q15 FIR filter processing function
+ *
+ * $Date: 27. January 2017
+ * $Revision: V.1.5.1
+ *
+ * Target Processor: Cortex-M cores
+ * -------------------------------------------------------------------- */
+/*
+ * Copyright (C) 2010-2017 ARM Limited or its affiliates. All rights reserved.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the License); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an AS IS BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "arm_math.h"
+
+/**
+ * @ingroup groupFilters
+ */
+
+/**
+ * @addtogroup FIR
+ * @{
+ */
+
+/**
+ * @brief Processing function for the Q15 FIR filter.
+ * @param[in] *S points to an instance of the Q15 FIR structure.
+ * @param[in] *pSrc points to the block of input data.
+ * @param[out] *pDst points to the block of output data.
+ * @param[in] blockSize number of samples to process per call.
+ * @return none.
+ *
+ *
+ * \par Restrictions
+ * If the silicon does not support unaligned memory access enable the macro UNALIGNED_SUPPORT_DISABLE
+ * In this case input, output, state buffers should be aligned by 32-bit
+ *
+ * <b>Scaling and Overflow Behavior:</b>
+ * \par
+ * The function is implemented using a 64-bit internal accumulator.
+ * Both coefficients and state variables are represented in 1.15 format and multiplications yield a 2.30 result.
+ * The 2.30 intermediate results are accumulated in a 64-bit accumulator in 34.30 format.
+ * There is no risk of internal overflow with this approach and the full precision of intermediate multiplications is preserved.
+ * After all additions have been performed, the accumulator is truncated to 34.15 format by discarding low 15 bits.
+ * Lastly, the accumulator is saturated to yield a result in 1.15 format.
+ *
+ * \par
+ * Refer to the function <code>arm_fir_fast_q15()</code> for a faster but less precise implementation of this function.
+ */
+
+#if defined (ARM_MATH_DSP)
+
+/* Run the below code for Cortex-M4 and Cortex-M3 */
+
+#ifndef UNALIGNED_SUPPORT_DISABLE
+
+
+void arm_fir_q15(
+ const arm_fir_instance_q15 * S,
+ q15_t * pSrc,
+ q15_t * pDst,
+ uint32_t blockSize)
+{
+ q15_t *pState = S->pState; /* State pointer */
+ q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
+ q15_t *pStateCurnt; /* Points to the current sample of the state */
+ q15_t *px1; /* Temporary q15 pointer for state buffer */
+ q15_t *pb; /* Temporary pointer for coefficient buffer */
+ q31_t x0, x1, x2, x3, c0; /* Temporary variables to hold SIMD state and coefficient values */
+ q63_t acc0, acc1, acc2, acc3; /* Accumulators */
+ uint32_t numTaps = S->numTaps; /* Number of taps in the filter */
+ uint32_t tapCnt, blkCnt; /* Loop counters */
+
+
+ /* S->pState points to state array which contains previous frame (numTaps - 1) samples */
+ /* pStateCurnt points to the location where the new input data should be written */
+ pStateCurnt = &(S->pState[(numTaps - 1U)]);
+
+ /* Apply loop unrolling and compute 4 output values simultaneously.
+ * The variables acc0 ... acc3 hold output values that are being computed:
+ *
+ * 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]
+ * 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]
+ * 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]
+ * 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]
+ */
+
+ blkCnt = blockSize >> 2;
+
+ /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
+ ** a second loop below computes the remaining 1 to 3 samples. */
+ while (blkCnt > 0U)
+ {
+ /* Copy four new input samples into the state buffer.
+ ** Use 32-bit SIMD to move the 16-bit data. Only requires two copies. */
+ *__SIMD32(pStateCurnt)++ = *__SIMD32(pSrc)++;
+ *__SIMD32(pStateCurnt)++ = *__SIMD32(pSrc)++;
+
+ /* Set all accumulators to zero */
+ acc0 = 0;
+ acc1 = 0;
+ acc2 = 0;
+ acc3 = 0;
+
+ /* Initialize state pointer of type q15 */
+ px1 = pState;
+
+ /* Initialize coeff pointer of type q31 */
+ pb = pCoeffs;
+
+ /* Read the first two samples from the state buffer: x[n-N], x[n-N-1] */
+ x0 = _SIMD32_OFFSET(px1);
+
+ /* Read the third and forth samples from the state buffer: x[n-N-1], x[n-N-2] */
+ x1 = _SIMD32_OFFSET(px1 + 1U);
+
+ px1 += 2U;
+
+ /* Loop over the number of taps. Unroll by a factor of 4.
+ ** Repeat until we've computed numTaps-4 coefficients. */
+ tapCnt = numTaps >> 2;
+
+ while (tapCnt > 0U)
+ {
+ /* Read the first two coefficients using SIMD: b[N] and b[N-1] coefficients */
+ c0 = *__SIMD32(pb)++;
+
+ /* acc0 += b[N] * x[n-N] + b[N-1] * x[n-N-1] */
+ acc0 = __SMLALD(x0, c0, acc0);
+
+ /* acc1 += b[N] * x[n-N-1] + b[N-1] * x[n-N-2] */
+ acc1 = __SMLALD(x1, c0, acc1);
+
+ /* Read state x[n-N-2], x[n-N-3] */
+ x2 = _SIMD32_OFFSET(px1);
+
+ /* Read state x[n-N-3], x[n-N-4] */
+ x3 = _SIMD32_OFFSET(px1 + 1U);
+
+ /* acc2 += b[N] * x[n-N-2] + b[N-1] * x[n-N-3] */
+ acc2 = __SMLALD(x2, c0, acc2);
+
+ /* acc3 += b[N] * x[n-N-3] + b[N-1] * x[n-N-4] */
+ acc3 = __SMLALD(x3, c0, acc3);
+
+ /* Read coefficients b[N-2], b[N-3] */
+ c0 = *__SIMD32(pb)++;
+
+ /* acc0 += b[N-2] * x[n-N-2] + b[N-3] * x[n-N-3] */
+ acc0 = __SMLALD(x2, c0, acc0);
+
+ /* acc1 += b[N-2] * x[n-N-3] + b[N-3] * x[n-N-4] */
+ acc1 = __SMLALD(x3, c0, acc1);
+
+ /* Read state x[n-N-4], x[n-N-5] */
+ x0 = _SIMD32_OFFSET(px1 + 2U);
+
+ /* Read state x[n-N-5], x[n-N-6] */
+ x1 = _SIMD32_OFFSET(px1 + 3U);
+
+ /* acc2 += b[N-2] * x[n-N-4] + b[N-3] * x[n-N-5] */
+ acc2 = __SMLALD(x0, c0, acc2);
+
+ /* acc3 += b[N-2] * x[n-N-5] + b[N-3] * x[n-N-6] */
+ acc3 = __SMLALD(x1, c0, acc3);
+
+ px1 += 4U;
+
+ tapCnt--;
+
+ }
+
+
+ /* If the filter length is not a multiple of 4, compute the remaining filter taps.
+ ** This is always be 2 taps since the filter length is even. */
+ if ((numTaps & 0x3U) != 0U)
+ {
+ /* Read 2 coefficients */
+ c0 = *__SIMD32(pb)++;
+
+ /* Fetch 4 state variables */
+ x2 = _SIMD32_OFFSET(px1);
+
+ x3 = _SIMD32_OFFSET(px1 + 1U);
+
+ /* Perform the multiply-accumulates */
+ acc0 = __SMLALD(x0, c0, acc0);
+
+ px1 += 2U;
+
+ acc1 = __SMLALD(x1, c0, acc1);
+ acc2 = __SMLALD(x2, c0, acc2);
+ acc3 = __SMLALD(x3, c0, acc3);
+ }
+
+ /* The results in the 4 accumulators are in 2.30 format. Convert to 1.15 with saturation.
+ ** Then store the 4 outputs in the destination buffer. */
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+ *__SIMD32(pDst)++ =
+ __PKHBT(__SSAT((acc0 >> 15), 16), __SSAT((acc1 >> 15), 16), 16);
+ *__SIMD32(pDst)++ =
+ __PKHBT(__SSAT((acc2 >> 15), 16), __SSAT((acc3 >> 15), 16), 16);
+
+#else
+
+ *__SIMD32(pDst)++ =
+ __PKHBT(__SSAT((acc1 >> 15), 16), __SSAT((acc0 >> 15), 16), 16);
+ *__SIMD32(pDst)++ =
+ __PKHBT(__SSAT((acc3 >> 15), 16), __SSAT((acc2 >> 15), 16), 16);
+
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+
+
+ /* Advance the state pointer by 4 to process the next group of 4 samples */
+ pState = pState + 4;
+
+ /* Decrement the loop counter */
+ blkCnt--;
+ }
+
+ /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
+ ** No loop unrolling is used. */
+ blkCnt = blockSize % 0x4U;
+ while (blkCnt > 0U)
+ {
+ /* Copy two samples into state buffer */
+ *pStateCurnt++ = *pSrc++;
+
+ /* Set the accumulator to zero */
+ acc0 = 0;
+
+ /* Initialize state pointer of type q15 */
+ px1 = pState;
+
+ /* Initialize coeff pointer of type q31 */
+ pb = pCoeffs;
+
+ tapCnt = numTaps >> 1;
+
+ do
+ {
+
+ c0 = *__SIMD32(pb)++;
+ x0 = *__SIMD32(px1)++;
+
+ acc0 = __SMLALD(x0, c0, acc0);
+ tapCnt--;
+ }
+ while (tapCnt > 0U);
+
+ /* The result is in 2.30 format. Convert to 1.15 with saturation.
+ ** Then store the output in the destination buffer. */
+ *pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16));
+
+ /* Advance state pointer by 1 for the next sample */
+ pState = pState + 1;
+
+ /* Decrement the loop counter */
+ blkCnt--;
+ }
+
+ /* Processing is complete.
+ ** Now copy the last numTaps - 1 samples to the satrt of the state buffer.
+ ** This prepares the state buffer for the next function call. */
+
+ /* Points to the start of the state buffer */
+ pStateCurnt = S->pState;
+
+ /* Calculation of count for copying integer writes */
+ tapCnt = (numTaps - 1U) >> 2;
+
+ while (tapCnt > 0U)
+ {
+
+ /* Copy state values to start of state buffer */
+ *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
+ *__SIMD32(pStateCurnt)++ = *__SIMD32(pState)++;
+
+ tapCnt--;
+
+ }
+
+ /* Calculation of count for remaining q15_t data */
+ tapCnt = (numTaps - 1U) % 0x4U;
+
+ /* copy remaining data */
+ while (tapCnt > 0U)
+ {
+ *pStateCurnt++ = *pState++;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+}
+
+#else /* UNALIGNED_SUPPORT_DISABLE */
+
+void arm_fir_q15(
+ const arm_fir_instance_q15 * S,
+ q15_t * pSrc,
+ q15_t * pDst,
+ uint32_t blockSize)
+{
+ q15_t *pState = S->pState; /* State pointer */
+ q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
+ q15_t *pStateCurnt; /* Points to the current sample of the state */
+ q63_t acc0, acc1, acc2, acc3; /* Accumulators */
+ q15_t *pb; /* Temporary pointer for coefficient buffer */
+ q15_t *px; /* Temporary q31 pointer for SIMD state buffer accesses */
+ q31_t x0, x1, x2, c0; /* Temporary variables to hold SIMD state and coefficient values */
+ uint32_t numTaps = S->numTaps; /* Number of taps in the filter */
+ uint32_t tapCnt, blkCnt; /* Loop counters */
+
+
+ /* S->pState points to state array which contains previous frame (numTaps - 1) samples */
+ /* pStateCurnt points to the location where the new input data should be written */
+ pStateCurnt = &(S->pState[(numTaps - 1U)]);
+
+ /* Apply loop unrolling and compute 4 output values simultaneously.
+ * The variables acc0 ... acc3 hold output values that are being computed:
+ *
+ * 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]
+ * 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]
+ * 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]
+ * 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]
+ */
+
+ blkCnt = blockSize >> 2;
+
+ /* First part of the processing with loop unrolling. Compute 4 outputs at a time.
+ ** a second loop below computes the remaining 1 to 3 samples. */
+ while (blkCnt > 0U)
+ {
+ /* Copy four new input samples into the state buffer.
+ ** Use 32-bit SIMD to move the 16-bit data. Only requires two copies. */
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+
+
+ /* Set all accumulators to zero */
+ acc0 = 0;
+ acc1 = 0;
+ acc2 = 0;
+ acc3 = 0;
+
+ /* Typecast q15_t pointer to q31_t pointer for state reading in q31_t */
+ px = pState;
+
+ /* Typecast q15_t pointer to q31_t pointer for coefficient reading in q31_t */
+ pb = pCoeffs;
+
+ /* Read the first two samples from the state buffer: x[n-N], x[n-N-1] */
+ x0 = *__SIMD32(px)++;
+
+ /* Read the third and forth samples from the state buffer: x[n-N-2], x[n-N-3] */
+ x2 = *__SIMD32(px)++;
+
+ /* Loop over the number of taps. Unroll by a factor of 4.
+ ** Repeat until we've computed numTaps-(numTaps%4) coefficients. */
+ tapCnt = numTaps >> 2;
+
+ while (tapCnt > 0)
+ {
+ /* Read the first two coefficients using SIMD: b[N] and b[N-1] coefficients */
+ c0 = *__SIMD32(pb)++;
+
+ /* acc0 += b[N] * x[n-N] + b[N-1] * x[n-N-1] */
+ acc0 = __SMLALD(x0, c0, acc0);
+
+ /* acc2 += b[N] * x[n-N-2] + b[N-1] * x[n-N-3] */
+ acc2 = __SMLALD(x2, c0, acc2);
+
+ /* pack x[n-N-1] and x[n-N-2] */
+#ifndef ARM_MATH_BIG_ENDIAN
+ x1 = __PKHBT(x2, x0, 0);
+#else
+ x1 = __PKHBT(x0, x2, 0);
+#endif
+
+ /* Read state x[n-N-4], x[n-N-5] */
+ x0 = _SIMD32_OFFSET(px);
+
+ /* acc1 += b[N] * x[n-N-1] + b[N-1] * x[n-N-2] */
+ acc1 = __SMLALDX(x1, c0, acc1);
+
+ /* pack x[n-N-3] and x[n-N-4] */
+#ifndef ARM_MATH_BIG_ENDIAN
+ x1 = __PKHBT(x0, x2, 0);
+#else
+ x1 = __PKHBT(x2, x0, 0);
+#endif
+
+ /* acc3 += b[N] * x[n-N-3] + b[N-1] * x[n-N-4] */
+ acc3 = __SMLALDX(x1, c0, acc3);
+
+ /* Read coefficients b[N-2], b[N-3] */
+ c0 = *__SIMD32(pb)++;
+
+ /* acc0 += b[N-2] * x[n-N-2] + b[N-3] * x[n-N-3] */
+ acc0 = __SMLALD(x2, c0, acc0);
+
+ /* Read state x[n-N-6], x[n-N-7] with offset */
+ x2 = _SIMD32_OFFSET(px + 2U);
+
+ /* acc2 += b[N-2] * x[n-N-4] + b[N-3] * x[n-N-5] */
+ acc2 = __SMLALD(x0, c0, acc2);
+
+ /* acc1 += b[N-2] * x[n-N-3] + b[N-3] * x[n-N-4] */
+ acc1 = __SMLALDX(x1, c0, acc1);
+
+ /* pack x[n-N-5] and x[n-N-6] */
+#ifndef ARM_MATH_BIG_ENDIAN
+ x1 = __PKHBT(x2, x0, 0);
+#else
+ x1 = __PKHBT(x0, x2, 0);
+#endif
+
+ /* acc3 += b[N-2] * x[n-N-5] + b[N-3] * x[n-N-6] */
+ acc3 = __SMLALDX(x1, c0, acc3);
+
+ /* Update state pointer for next state reading */
+ px += 4U;
+
+ /* Decrement tap count */
+ tapCnt--;
+
+ }
+
+ /* If the filter length is not a multiple of 4, compute the remaining filter taps.
+ ** This is always be 2 taps since the filter length is even. */
+ if ((numTaps & 0x3U) != 0U)
+ {
+
+ /* Read last two coefficients */
+ c0 = *__SIMD32(pb)++;
+
+ /* Perform the multiply-accumulates */
+ acc0 = __SMLALD(x0, c0, acc0);
+ acc2 = __SMLALD(x2, c0, acc2);
+
+ /* pack state variables */
+#ifndef ARM_MATH_BIG_ENDIAN
+ x1 = __PKHBT(x2, x0, 0);
+#else
+ x1 = __PKHBT(x0, x2, 0);
+#endif
+
+ /* Read last state variables */
+ x0 = *__SIMD32(px);
+
+ /* Perform the multiply-accumulates */
+ acc1 = __SMLALDX(x1, c0, acc1);
+
+ /* pack state variables */
+#ifndef ARM_MATH_BIG_ENDIAN
+ x1 = __PKHBT(x0, x2, 0);
+#else
+ x1 = __PKHBT(x2, x0, 0);
+#endif
+
+ /* Perform the multiply-accumulates */
+ acc3 = __SMLALDX(x1, c0, acc3);
+ }
+
+ /* The results in the 4 accumulators are in 2.30 format. Convert to 1.15 with saturation.
+ ** Then store the 4 outputs in the destination buffer. */
+
+#ifndef ARM_MATH_BIG_ENDIAN
+
+ *__SIMD32(pDst)++ =
+ __PKHBT(__SSAT((acc0 >> 15), 16), __SSAT((acc1 >> 15), 16), 16);
+
+ *__SIMD32(pDst)++ =
+ __PKHBT(__SSAT((acc2 >> 15), 16), __SSAT((acc3 >> 15), 16), 16);
+
+#else
+
+ *__SIMD32(pDst)++ =
+ __PKHBT(__SSAT((acc1 >> 15), 16), __SSAT((acc0 >> 15), 16), 16);
+
+ *__SIMD32(pDst)++ =
+ __PKHBT(__SSAT((acc3 >> 15), 16), __SSAT((acc2 >> 15), 16), 16);
+
+#endif /* #ifndef ARM_MATH_BIG_ENDIAN */
+
+ /* Advance the state pointer by 4 to process the next group of 4 samples */
+ pState = pState + 4;
+
+ /* Decrement the loop counter */
+ blkCnt--;
+ }
+
+ /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
+ ** No loop unrolling is used. */
+ blkCnt = blockSize % 0x4U;
+ while (blkCnt > 0U)
+ {
+ /* Copy two samples into state buffer */
+ *pStateCurnt++ = *pSrc++;
+
+ /* Set the accumulator to zero */
+ acc0 = 0;
+
+ /* Use SIMD to hold states and coefficients */
+ px = pState;
+ pb = pCoeffs;
+
+ tapCnt = numTaps >> 1U;
+
+ do
+ {
+ acc0 += (q31_t) * px++ * *pb++;
+ acc0 += (q31_t) * px++ * *pb++;
+ tapCnt--;
+ }
+ while (tapCnt > 0U);
+
+ /* The result is in 2.30 format. Convert to 1.15 with saturation.
+ ** Then store the output in the destination buffer. */
+ *pDst++ = (q15_t) (__SSAT((acc0 >> 15), 16));
+
+ /* Advance state pointer by 1 for the next sample */
+ pState = pState + 1U;
+
+ /* Decrement the loop counter */
+ blkCnt--;
+ }
+
+ /* Processing is complete.
+ ** Now copy the last numTaps - 1 samples to the satrt of the state buffer.
+ ** This prepares the state buffer for the next function call. */
+
+ /* Points to the start of the state buffer */
+ pStateCurnt = S->pState;
+
+ /* Calculation of count for copying integer writes */
+ tapCnt = (numTaps - 1U) >> 2;
+
+ while (tapCnt > 0U)
+ {
+ *pStateCurnt++ = *pState++;
+ *pStateCurnt++ = *pState++;
+ *pStateCurnt++ = *pState++;
+ *pStateCurnt++ = *pState++;
+
+ tapCnt--;
+
+ }
+
+ /* Calculation of count for remaining q15_t data */
+ tapCnt = (numTaps - 1U) % 0x4U;
+
+ /* copy remaining data */
+ while (tapCnt > 0U)
+ {
+ *pStateCurnt++ = *pState++;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+}
+
+
+#endif /* #ifndef UNALIGNED_SUPPORT_DISABLE */
+
+#else /* ARM_MATH_CM0_FAMILY */
+
+
+/* Run the below code for Cortex-M0 */
+
+void arm_fir_q15(
+ const arm_fir_instance_q15 * S,
+ q15_t * pSrc,
+ q15_t * pDst,
+ uint32_t blockSize)
+{
+ q15_t *pState = S->pState; /* State pointer */
+ q15_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
+ q15_t *pStateCurnt; /* Points to the current sample of the state */
+
+
+
+ q15_t *px; /* Temporary pointer for state buffer */
+ q15_t *pb; /* Temporary pointer for coefficient buffer */
+ q63_t acc; /* Accumulator */
+ uint32_t numTaps = S->numTaps; /* Number of nTaps in the filter */
+ uint32_t tapCnt, blkCnt; /* Loop counters */
+
+ /* S->pState buffer contains previous frame (numTaps - 1) samples */
+ /* pStateCurnt points to the location where the new input data should be written */
+ pStateCurnt = &(S->pState[(numTaps - 1U)]);
+
+ /* Initialize blkCnt with blockSize */
+ blkCnt = blockSize;
+
+ while (blkCnt > 0U)
+ {
+ /* Copy one sample at a time into state buffer */
+ *pStateCurnt++ = *pSrc++;
+
+ /* Set the accumulator to zero */
+ acc = 0;
+
+ /* Initialize state pointer */
+ px = pState;
+
+ /* Initialize Coefficient pointer */
+ pb = pCoeffs;
+
+ tapCnt = numTaps;
+
+ /* Perform the multiply-accumulates */
+ do
+ {
+ /* 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] */
+ acc += (q31_t) * px++ * *pb++;
+ tapCnt--;
+ } while (tapCnt > 0U);
+
+ /* The result is in 2.30 format. Convert to 1.15
+ ** Then store the output in the destination buffer. */
+ *pDst++ = (q15_t) __SSAT((acc >> 15U), 16);
+
+ /* Advance state pointer by 1 for the next sample */
+ pState = pState + 1;
+
+ /* Decrement the samples loop counter */
+ blkCnt--;
+ }
+
+ /* Processing is complete.
+ ** Now copy the last numTaps - 1 samples to the satrt of the state buffer.
+ ** This prepares the state buffer for the next function call. */
+
+ /* Points to the start of the state buffer */
+ pStateCurnt = S->pState;
+
+ /* Copy numTaps number of values */
+ tapCnt = (numTaps - 1U);
+
+ /* copy data */
+ while (tapCnt > 0U)
+ {
+ *pStateCurnt++ = *pState++;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+}
+
+#endif /* #if defined (ARM_MATH_DSP) */
+
+
+
+
+/**
+ * @} end of FIR group
+ */
|