diff options
Diffstat (limited to 'Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_iir_lattice_q31.c')
| -rw-r--r-- | Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_iir_lattice_q31.c | 356 |
1 files changed, 356 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_iir_lattice_q31.c b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_iir_lattice_q31.c new file mode 100644 index 0000000..d0348fe --- /dev/null +++ b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_iir_lattice_q31.c @@ -0,0 +1,356 @@ +/* ----------------------------------------------------------------------
+ * Project: CMSIS DSP Library
+ * Title: arm_iir_lattice_q31.c
+ * Description: Q31 IIR Lattice filter processing function
+ *
+ * $Date: 18. March 2019
+ * $Revision: V1.6.0
+ *
+ * Target Processor: Cortex-M cores
+ * -------------------------------------------------------------------- */
+/*
+ * Copyright (C) 2010-2019 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 IIR_Lattice
+ @{
+ */
+
+/**
+ @brief Processing function for the Q31 IIR lattice filter.
+ @param[in] S points to an instance of the Q31 IIR lattice 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
+ @return none
+
+ @par Scaling and Overflow Behavior
+ The function is implemented using an internal 64-bit accumulator.
+ The accumulator has a 2.62 format and maintains full precision of the intermediate multiplication results but provides only a single guard bit.
+ Thus, if the accumulator result overflows it wraps around rather than clip.
+ In order to avoid overflows completely the input signal must be scaled down by 2*log2(numStages) bits.
+ After all multiply-accumulates are performed, the 2.62 accumulator is saturated to 1.32 format and then truncated to 1.31 format.
+ */
+
+void arm_iir_lattice_q31(
+ const arm_iir_lattice_instance_q31 * S,
+ const q31_t * pSrc,
+ q31_t * pDst,
+ uint32_t blockSize)
+{
+ q31_t *pState = S->pState; /* State pointer */
+ q31_t *pStateCur; /* State current pointer */
+ q31_t fcurr, fnext = 0, gcurr = 0, gnext; /* Temporary variables for lattice stages */
+ q63_t acc; /* Accumlator */
+ q31_t *px1, *px2, *pk, *pv; /* Temporary pointers for state and coef */
+ uint32_t numStages = S->numStages; /* Number of stages */
+ uint32_t blkCnt, tapCnt; /* Temporary variables for counts */
+
+
+ /* initialise loop count */
+ blkCnt = blockSize;
+
+#if defined (ARM_MATH_DSP)
+
+ /* Sample processing */
+ while (blkCnt > 0U)
+ {
+ /* Read Sample from input buffer */
+ /* fN(n) = x(n) */
+ fcurr = *pSrc++;
+
+ /* Initialize Ladder coeff pointer */
+ pv = &S->pvCoeffs[0];
+
+ /* Initialize Reflection coeff pointer */
+ pk = &S->pkCoeffs[0];
+
+ /* Initialize state read pointer */
+ px1 = pState;
+
+ /* Initialize state write pointer */
+ px2 = pState;
+
+ /* Set accumulator to zero */
+ acc = 0;
+
+ /* Process sample for first tap */
+ gcurr = *px1++;
+ /* fN-1(n) = fN(n) - kN * gN-1(n-1) */
+ fnext = __QSUB(fcurr, (q31_t) (((q63_t) gcurr * (*pk )) >> 31));
+
+ /* gN(n) = kN * fN-1(n) + gN-1(n-1) */
+ gnext = __QADD(gcurr, (q31_t) (((q63_t) fnext * (*pk++)) >> 31));
+
+ /* write gN-1(n-1) into state for next sample processing */
+ *px2++ = gnext;
+
+ /* y(n) += gN(n) * vN */
+ acc += ((q63_t) gnext * *pv++);
+
+ /* Update f values for next coefficient processing */
+ fcurr = fnext;
+
+
+#if defined (ARM_MATH_LOOPUNROLL)
+
+ /* Loop unrolling: Compute 4 taps at a time. */
+ tapCnt = (numStages - 1U) >> 2U;
+
+ while (tapCnt > 0U)
+ {
+ /* Process sample for 2nd, 6th ...taps */
+ /* Read gN-2(n-1) from state buffer */
+ gcurr = *px1++;
+ /* fN-2(n) = fN-1(n) - kN-1 * gN-2(n-1) */
+ fnext = __QSUB(fcurr, (q31_t) (((q63_t) gcurr * (*pk )) >> 31));
+ /* gN-1(n) = kN-1 * fN-2(n) + gN-2(n-1) */
+ gnext = __QADD(gcurr, (q31_t) (((q63_t) fnext * (*pk++)) >> 31));
+ /* y(n) += gN-1(n) * vN-1 */
+ /* process for gN-5(n) * vN-5, gN-9(n) * vN-9 ... */
+ acc += ((q63_t) gnext * *pv++);
+ /* write gN-1(n) into state for next sample processing */
+ *px2++ = gnext;
+
+ /* Process sample for 3nd, 7th ...taps */
+ /* Read gN-3(n-1) from state buffer */
+ gcurr = *px1++;
+ /* Process sample for 3rd, 7th .. taps */
+ /* fN-3(n) = fN-2(n) - kN-2 * gN-3(n-1) */
+ fcurr = __QSUB(fnext, (q31_t) (((q63_t) gcurr * (*pk )) >> 31));
+ /* gN-2(n) = kN-2 * fN-3(n) + gN-3(n-1) */
+ gnext = __QADD(gcurr, (q31_t) (((q63_t) fcurr * (*pk++)) >> 31));
+ /* y(n) += gN-2(n) * vN-2 */
+ /* process for gN-6(n) * vN-6, gN-10(n) * vN-10 ... */
+ acc += ((q63_t) gnext * *pv++);
+ /* write gN-2(n) into state for next sample processing */
+ *px2++ = gnext;
+
+ /* Process sample for 4th, 8th ...taps */
+ /* Read gN-4(n-1) from state buffer */
+ gcurr = *px1++;
+ /* Process sample for 4th, 8th .. taps */
+ /* fN-4(n) = fN-3(n) - kN-3 * gN-4(n-1) */
+ fnext = __QSUB(fcurr, (q31_t) (((q63_t) gcurr * (*pk )) >> 31));
+ /* gN-3(n) = kN-3 * fN-4(n) + gN-4(n-1) */
+ gnext = __QADD(gcurr, (q31_t) (((q63_t) fnext * (*pk++)) >> 31));
+ /* y(n) += gN-3(n) * vN-3 */
+ /* process for gN-7(n) * vN-7, gN-11(n) * vN-11 ... */
+ acc += ((q63_t) gnext * *pv++);
+ /* write gN-3(n) into state for next sample processing */
+ *px2++ = gnext;
+
+ /* Process sample for 5th, 9th ...taps */
+ /* Read gN-5(n-1) from state buffer */
+ gcurr = *px1++;
+ /* Process sample for 5th, 9th .. taps */
+ /* fN-5(n) = fN-4(n) - kN-4 * gN-1(n-1) */
+ fcurr = __QSUB(fnext, (q31_t) (((q63_t) gcurr * (*pk )) >> 31));
+ /* gN-4(n) = kN-4 * fN-5(n) + gN-5(n-1) */
+ gnext = __QADD(gcurr, (q31_t) (((q63_t) fcurr * (*pk++)) >> 31));
+ /* y(n) += gN-4(n) * vN-4 */
+ /* process for gN-8(n) * vN-8, gN-12(n) * vN-12 ... */
+ acc += ((q63_t) gnext * *pv++);
+
+ /* write gN-4(n) into state for next sample processing */
+ *px2++ = gnext;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+ fnext = fcurr;
+
+ /* Loop unrolling: Compute remaining taps */
+ tapCnt = (numStages - 1U) % 0x4U;
+
+#else
+
+ /* Initialize blkCnt with number of samples */
+ tapCnt = (numStages - 1U);
+
+#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
+
+ while (tapCnt > 0U)
+ {
+ gcurr = *px1++;
+ /* Process sample for last taps */
+ fnext = __QSUB(fcurr, (q31_t) (((q63_t) gcurr * (*pk )) >> 31));
+ gnext = __QADD(gcurr, (q31_t) (((q63_t) fnext * (*pk++)) >> 31));
+
+ /* Output samples for last taps */
+ acc += ((q63_t) gnext * *pv++);
+ *px2++ = gnext;
+ fcurr = fnext;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+ /* y(n) += g0(n) * v0 */
+ acc += ((q63_t) fnext * *pv++);
+
+ *px2++ = fnext;
+
+ /* write out into pDst */
+ *pDst++ = (q31_t) (acc >> 31U);
+
+ /* Advance the state pointer by 4 to process the next group of 4 samples */
+ pState = pState + 1U;
+
+ /* Decrement loop counter */
+ blkCnt--;
+ }
+
+ /* Processing is complete. Now copy last S->numStages samples to start of the buffer
+ for the preperation of next frame process */
+
+ /* Points to the start of the state buffer */
+ pStateCur = &S->pState[0];
+ pState = &S->pState[blockSize];
+
+ /* Copy data */
+#if defined (ARM_MATH_LOOPUNROLL)
+
+ /* Loop unrolling: Compute 4 taps at a time. */
+ tapCnt = numStages >> 2U;
+
+ while (tapCnt > 0U)
+ {
+ *pStateCur++ = *pState++;
+ *pStateCur++ = *pState++;
+ *pStateCur++ = *pState++;
+ *pStateCur++ = *pState++;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+ /* Loop unrolling: Compute remaining taps */
+ tapCnt = numStages % 0x4U;
+
+#else
+
+ /* Initialize blkCnt with number of samples */
+ tapCnt = (numStages - 1U);
+
+#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
+
+ while (tapCnt > 0U)
+ {
+ *pStateCur++ = *pState++;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+#else /* #if defined (ARM_MATH_DSP) */
+
+ /* Sample processing */
+ while (blkCnt > 0U)
+ {
+ /* Read Sample from input buffer */
+ /* fN(n) = x(n) */
+ fcurr = *pSrc++;
+
+ /* Initialize Ladder coeff pointer */
+ pv = &S->pvCoeffs[0];
+
+ /* Initialize Reflection coeff pointer */
+ pk = &S->pkCoeffs[0];
+
+ /* Initialize state read pointer */
+ px1 = pState;
+
+ /* Initialize state write pointer */
+ px2 = pState;
+
+ /* Set accumulator to zero */
+ acc = 0;
+
+ tapCnt = numStages;
+
+ while (tapCnt > 0U)
+ {
+ gcurr = *px1++;
+ /* Process sample */
+ /* fN-1(n) = fN(n) - kN * gN-1(n-1) */
+ fnext = clip_q63_to_q31(((q63_t) fcurr - ((q31_t) (((q63_t) gcurr * (*pk )) >> 31))));
+
+ /* gN(n) = kN * fN-1(n) + gN-1(n-1) */
+ gnext = clip_q63_to_q31(((q63_t) gcurr + ((q31_t) (((q63_t) fnext * (*pk++)) >> 31))));
+
+ /* Output samples */
+ /* y(n) += gN(n) * vN */
+ acc += ((q63_t) gnext * *pv++);
+
+ /* write gN-1(n-1) into state for next sample processing */
+ *px2++ = gnext;
+
+ /* Update f values for next coefficient processing */
+ fcurr = fnext;
+
+ tapCnt--;
+ }
+
+ /* y(n) += g0(n) * v0 */
+ acc += ((q63_t) fnext * *pv++);
+
+ *px2++ = fnext;
+
+ /* write out into pDst */
+ *pDst++ = (q31_t) (acc >> 31U);
+
+ /* Advance the state pointer by 1 to process the next group of samples */
+ pState = pState + 1U;
+
+ /* Decrement loop counter */
+ blkCnt--;
+ }
+
+ /* Processing is complete. Now copy last S->numStages samples to start of the buffer
+ for the preperation of next frame process */
+
+ /* Points to the start of the state buffer */
+ pStateCur = &S->pState[0];
+ pState = &S->pState[blockSize];
+
+ tapCnt = numStages;
+
+ /* Copy data */
+ while (tapCnt > 0U)
+ {
+ *pStateCur++ = *pState++;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+#endif /* #if defined (ARM_MATH_DSP) */
+
+}
+
+/**
+ @} end of IIR_Lattice group
+ */
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