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Diffstat (limited to 'Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_iir_lattice_f32.c')
| -rw-r--r-- | Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_iir_lattice_f32.c | 354 |
1 files changed, 354 insertions, 0 deletions
diff --git a/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_iir_lattice_f32.c b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_iir_lattice_f32.c new file mode 100644 index 0000000..cc8bff6 --- /dev/null +++ b/Drivers/CMSIS/DSP/Source/FilteringFunctions/arm_iir_lattice_f32.c @@ -0,0 +1,354 @@ +/* ----------------------------------------------------------------------
+ * Project: CMSIS DSP Library
+ * Title: arm_iir_lattice_f32.c
+ * Description: Floating-point 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
+ */
+
+/**
+ @defgroup IIR_Lattice Infinite Impulse Response (IIR) Lattice Filters
+
+ This set of functions implements lattice filters
+ for Q15, Q31 and floating-point data types. Lattice filters are used in a
+ variety of adaptive filter applications. The filter structure has feedforward and
+ feedback components and the net impulse response is infinite length.
+ The functions operate on blocks
+ of input and output data and each call to the function processes
+ <code>blockSize</code> samples through the filter. <code>pSrc</code> and
+ <code>pDst</code> point to input and output arrays containing <code>blockSize</code> values.
+
+ @par Algorithm
+ \image html IIRLattice.gif "Infinite Impulse Response Lattice filter"
+ @par
+ <pre>
+ fN(n) = x(n)
+ fm-1(n) = fm(n) - km * gm-1(n-1) for m = N, N-1, ..., 1
+ gm(n) = km * fm-1(n) + gm-1(n-1) for m = N, N-1, ..., 1
+ y(n) = vN * gN(n) + vN-1 * gN-1(n) + ...+ v0 * g0(n)
+ </pre>
+ @par
+ <code>pkCoeffs</code> points to array of reflection coefficients of size <code>numStages</code>.
+ Reflection Coefficients are stored in time-reversed order.
+ @par
+ <pre>
+ {kN, kN-1, ..., k1}
+ </pre>
+ @par
+ <code>pvCoeffs</code> points to the array of ladder coefficients of size <code>(numStages+1)</code>.
+ Ladder coefficients are stored in time-reversed order.
+ <pre>
+ {vN, vN-1, ..., v0}
+ </pre>
+ @par
+ <code>pState</code> points to a state array of size <code>numStages + blockSize</code>.
+ The state variables shown in the figure above (the g values) are stored in the <code>pState</code> array.
+ The state variables are updated after each block of data is processed; the coefficients are untouched.
+
+ @par Instance Structure
+ The coefficients and state variables for a filter are stored together in an instance data structure.
+ A separate instance structure must be defined for each filter.
+ Coefficient arrays may be shared among several instances while state variable arrays cannot be shared.
+ There are separate instance structure declarations for each of the 3 supported data types.
+
+ @par Initialization Functions
+ There is also an associated initialization function for each data type.
+ The initialization function performs the following operations:
+ - Sets the values of the internal structure fields.
+ - Zeros out the values in the state buffer.
+ To do this manually without calling the init function, assign the follow subfields of the instance structure:
+ numStages, pkCoeffs, pvCoeffs, pState. Also set all of the values in pState to zero.
+ @par
+ Use of the initialization function is optional.
+ However, if the initialization function is used, then the instance structure cannot be placed into a const data section.
+ To place an instance structure into a const data section, the instance structure must be manually initialized.
+ Set the values in the state buffer to zeros and then manually initialize the instance structure as follows:
+ <pre>
+ arm_iir_lattice_instance_f32 S = {numStages, pState, pkCoeffs, pvCoeffs};
+ arm_iir_lattice_instance_q31 S = {numStages, pState, pkCoeffs, pvCoeffs};
+ arm_iir_lattice_instance_q15 S = {numStages, pState, pkCoeffs, pvCoeffs};
+ </pre>
+ @par
+ where <code>numStages</code> is the number of stages in the filter; <code>pState</code> points to the state buffer array;
+ <code>pkCoeffs</code> points to array of the reflection coefficients; <code>pvCoeffs</code> points to the array of ladder coefficients.
+
+ @par Fixed-Point Behavior
+ Care must be taken when using the fixed-point versions of the IIR lattice filter functions.
+ In particular, the overflow and saturation behavior of the accumulator used in each function must be considered.
+ Refer to the function specific documentation below for usage guidelines.
+ */
+
+/**
+ @addtogroup IIR_Lattice
+ @{
+ */
+
+/**
+ @brief Processing function for the floating-point IIR lattice filter.
+ @param[in] S points to an instance of the floating-point 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
+ */
+
+void arm_iir_lattice_f32(
+ const arm_iir_lattice_instance_f32 * S,
+ const float32_t * pSrc,
+ float32_t * pDst,
+ uint32_t blockSize)
+{
+ float32_t *pState = S->pState; /* State pointer */
+ float32_t *pStateCur; /* State current pointer */
+ float32_t acc; /* Accumlator */
+ float32_t fnext1, fnext2, gcurr1, gnext; /* Temporary variables for lattice stages */
+ float32_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 */
+
+#if defined (ARM_MATH_LOOPUNROLL)
+ float32_t gcurr2; /* Temporary variables for lattice stages */
+ float32_t k1, k2;
+ float32_t v1, v2, v3, v4;
+#endif
+
+ /* initialise loop count */
+ blkCnt = blockSize;
+
+ /* Sample processing */
+ while (blkCnt > 0U)
+ {
+ /* Read Sample from input buffer */
+ /* fN(n) = x(n) */
+ fnext2 = *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 = 0.0;
+
+#if defined (ARM_MATH_LOOPUNROLL)
+
+ /* Loop unrolling: Compute 4 taps at a time. */
+ tapCnt = (numStages) >> 2U;
+
+ while (tapCnt > 0U)
+ {
+ /* Read gN-1(n-1) from state buffer */
+ gcurr1 = *px1;
+
+ /* read reflection coefficient kN */
+ k1 = *pk;
+
+ /* fN-1(n) = fN(n) - kN * gN-1(n-1) */
+ fnext1 = fnext2 - (k1 * gcurr1);
+
+ /* read ladder coefficient vN */
+ v1 = *pv;
+
+ /* read next reflection coefficient kN-1 */
+ k2 = *(pk + 1U);
+
+ /* Read gN-2(n-1) from state buffer */
+ gcurr2 = *(px1 + 1U);
+
+ /* read next ladder coefficient vN-1 */
+ v2 = *(pv + 1U);
+
+ /* fN-2(n) = fN-1(n) - kN-1 * gN-2(n-1) */
+ fnext2 = fnext1 - (k2 * gcurr2);
+
+ /* gN(n) = kN * fN-1(n) + gN-1(n-1) */
+ gnext = gcurr1 + (k1 * fnext1);
+
+ /* read reflection coefficient kN-2 */
+ k1 = *(pk + 2U);
+
+ /* write gN(n) into state for next sample processing */
+ *px2++ = gnext;
+
+ /* Read gN-3(n-1) from state buffer */
+ gcurr1 = *(px1 + 2U);
+
+ /* y(n) += gN(n) * vN */
+ acc += (gnext * v1);
+
+ /* fN-3(n) = fN-2(n) - kN-2 * gN-3(n-1) */
+ fnext1 = fnext2 - (k1 * gcurr1);
+
+ /* gN-1(n) = kN-1 * fN-2(n) + gN-2(n-1) */
+ gnext = gcurr2 + (k2 * fnext2);
+
+ /* Read gN-4(n-1) from state buffer */
+ gcurr2 = *(px1 + 3U);
+
+ /* y(n) += gN-1(n) * vN-1 */
+ acc += (gnext * v2);
+
+ /* read reflection coefficient kN-3 */
+ k2 = *(pk + 3U);
+
+ /* write gN-1(n) into state for next sample processing */
+ *px2++ = gnext;
+
+ /* fN-4(n) = fN-3(n) - kN-3 * gN-4(n-1) */
+ fnext2 = fnext1 - (k2 * gcurr2);
+
+ /* gN-2(n) = kN-2 * fN-3(n) + gN-3(n-1) */
+ gnext = gcurr1 + (k1 * fnext1);
+
+ /* read ladder coefficient vN-2 */
+ v3 = *(pv + 2U);
+
+ /* y(n) += gN-2(n) * vN-2 */
+ acc += (gnext * v3);
+
+ /* write gN-2(n) into state for next sample processing */
+ *px2++ = gnext;
+
+ /* update pointer */
+ pk += 4U;
+
+ /* gN-3(n) = kN-3 * fN-4(n) + gN-4(n-1) */
+ gnext = (fnext2 * k2) + gcurr2;
+
+ /* read next ladder coefficient vN-3 */
+ v4 = *(pv + 3U);
+
+ /* y(n) += gN-4(n) * vN-4 */
+ acc += (gnext * v4);
+
+ /* write gN-3(n) into state for next sample processing */
+ *px2++ = gnext;
+
+ /* update pointers */
+ px1 += 4U;
+ pv += 4U;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+ /* Loop unrolling: Compute remaining taps */
+ tapCnt = numStages % 0x4U;
+
+#else
+
+ /* Initialize tapCnt with number of samples */
+ tapCnt = numStages;
+
+#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
+
+ while (tapCnt > 0U)
+ {
+ gcurr1 = *px1++;
+ /* Process sample for last taps */
+ fnext1 = fnext2 - ((*pk) * gcurr1);
+ gnext = (fnext1 * (*pk++)) + gcurr1;
+ /* Output samples for last taps */
+ acc += (gnext * (*pv++));
+ *px2++ = gnext;
+ fnext2 = fnext1;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+ /* y(n) += g0(n) * v0 */
+ acc += (fnext2 * (*pv));
+
+ *px2++ = fnext2;
+
+ /* write out into pDst */
+ *pDst++ = acc;
+
+ /* 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;
+
+#endif /* #if defined (ARM_MATH_LOOPUNROLL) */
+
+ while (tapCnt > 0U)
+ {
+ *pStateCur++ = *pState++;
+
+ /* Decrement loop counter */
+ tapCnt--;
+ }
+
+}
+
+/**
+ @} end of IIR_Lattice group
+ */
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