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Diffstat (limited to 'src/modules/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_fir_fast_q31.c')
| -rw-r--r-- | src/modules/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_fir_fast_q31.c | 309 |
1 files changed, 309 insertions, 0 deletions
diff --git a/src/modules/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_fir_fast_q31.c b/src/modules/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_fir_fast_q31.c new file mode 100644 index 000000000..e384ff973 --- /dev/null +++ b/src/modules/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_fir_fast_q31.c @@ -0,0 +1,309 @@ +/* ----------------------------------------------------------------------
+* Copyright (C) 2010 ARM Limited. All rights reserved.
+*
+* $Date: 15. February 2012
+* $Revision: V1.1.0
+*
+* Project: CMSIS DSP Library
+* Title: arm_fir_fast_q31.c
+*
+* Description: Processing function for the Q31 Fast FIR filter.
+*
+* Target Processor: Cortex-M4/Cortex-M3
+*
+* Version 1.1.0 2012/02/15
+* Updated with more optimizations, bug fixes and minor API changes.
+*
+* Version 1.0.10 2011/7/15
+* Big Endian support added and Merged M0 and M3/M4 Source code.
+*
+* Version 1.0.3 2010/11/29
+* Re-organized the CMSIS folders and updated documentation.
+*
+* Version 1.0.2 2010/11/11
+* Documentation updated.
+*
+* Version 1.0.1 2010/10/05
+* Production release and review comments incorporated.
+*
+* Version 1.0.0 2010/09/20
+* Production release and review comments incorporated.
+*
+* Version 0.0.9 2010/08/27
+* Initial version
+* -------------------------------------------------------------------- */
+
+#include "arm_math.h"
+
+/**
+ * @ingroup groupFilters
+ */
+
+/**
+ * @addtogroup FIR
+ * @{
+ */
+
+/**
+ * @param[in] *S points to an instance of the Q31 structure.
+ * @param[in] *pSrc points to the block of input data.
+ * @param[out] *pDst points to the block output data.
+ * @param[in] blockSize number of samples to process per call.
+ * @return none.
+ *
+ * <b>Scaling and Overflow Behavior:</b>
+ *
+ * \par
+ * This function is optimized for speed at the expense of fixed-point precision and overflow protection.
+ * The result of each 1.31 x 1.31 multiplication is truncated to 2.30 format.
+ * These intermediate results are added to a 2.30 accumulator.
+ * Finally, the accumulator is saturated and converted to a 1.31 result.
+ * The fast version has the same overflow behavior as the standard version and provides less precision since it discards the low 32 bits of each multiplication result.
+ * In order to avoid overflows completely the input signal must be scaled down by log2(numTaps) bits.
+ *
+ * \par
+ * Refer to the function <code>arm_fir_q31()</code> for a slower implementation of this function which uses a 64-bit accumulator to provide higher precision. Both the slow and the fast versions use the same instance structure.
+ * Use the function <code>arm_fir_init_q31()</code> to initialize the filter structure.
+ */
+
+void arm_fir_fast_q31(
+ const arm_fir_instance_q31 * S,
+ q31_t * pSrc,
+ q31_t * pDst,
+ uint32_t blockSize)
+{
+ q31_t *pState = S->pState; /* State pointer */
+ q31_t *pCoeffs = S->pCoeffs; /* Coefficient pointer */
+ q31_t *pStateCurnt; /* Points to the current sample of the state */
+ q31_t x0, x1, x2, x3; /* Temporary variables to hold state */
+ q31_t c0; /* Temporary variable to hold coefficient value */
+ q31_t *px; /* Temporary pointer for state */
+ q31_t *pb; /* Temporary pointer for coefficient buffer */
+ q31_t acc0, acc1, acc2, acc3; /* Accumulators */
+ uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
+ uint32_t i, tapCnt, blkCnt; /* Loop counters */
+
+ /* S->pState points to buffer 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 */
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+
+ /* Set all accumulators to zero */
+ acc0 = 0;
+ acc1 = 0;
+ acc2 = 0;
+ acc3 = 0;
+
+ /* Initialize state pointer */
+ px = pState;
+
+ /* Initialize coefficient pointer */
+ pb = pCoeffs;
+
+ /* Read the first three samples from the state buffer:
+ * x[n-numTaps], x[n-numTaps-1], x[n-numTaps-2] */
+ x0 = *(px++);
+ x1 = *(px++);
+ x2 = *(px++);
+
+ /* Loop unrolling. Process 4 taps at a time. */
+ tapCnt = numTaps >> 2;
+ i = tapCnt;
+
+ while(i > 0u)
+ {
+ /* Read the b[numTaps] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-3] sample */
+ x3 = *(px++);
+
+ /* acc0 += b[numTaps] * x[n-numTaps] */
+ acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32);
+
+ /* acc1 += b[numTaps] * x[n-numTaps-1] */
+ acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x1 * c0)) >> 32);
+
+ /* acc2 += b[numTaps] * x[n-numTaps-2] */
+ acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x2 * c0)) >> 32);
+
+ /* acc3 += b[numTaps] * x[n-numTaps-3] */
+ acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x3 * c0)) >> 32);
+
+ /* Read the b[numTaps-1] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-4] sample */
+ x0 = *(px++);
+
+ /* Perform the multiply-accumulates */
+ acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x1 * c0)) >> 32);
+ acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x2 * c0)) >> 32);
+ acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x3 * c0)) >> 32);
+ acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x0 * c0)) >> 32);
+
+ /* Read the b[numTaps-2] coefficient */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-5] sample */
+ x1 = *(px++);
+
+ /* Perform the multiply-accumulates */
+ acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x2 * c0)) >> 32);
+ acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x3 * c0)) >> 32);
+ acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x0 * c0)) >> 32);
+ acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x1 * c0)) >> 32);
+
+ /* Read the b[numTaps-3] coefficients */
+ c0 = *(pb++);
+
+ /* Read x[n-numTaps-6] sample */
+ x2 = *(px++);
+
+ /* Perform the multiply-accumulates */
+ acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x3 * c0)) >> 32);
+ acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x0 * c0)) >> 32);
+ acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x1 * c0)) >> 32);
+ acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x2 * c0)) >> 32);
+ i--;
+ }
+
+ /* If the filter length is not a multiple of 4, compute the remaining filter taps */
+
+ i = numTaps - (tapCnt * 4u);
+ while(i > 0u)
+ {
+ /* Read coefficients */
+ c0 = *(pb++);
+
+ /* Fetch 1 state variable */
+ x3 = *(px++);
+
+ /* Perform the multiply-accumulates */
+ acc0 = (q31_t) ((((q63_t) acc0 << 32) + ((q63_t) x0 * c0)) >> 32);
+ acc1 = (q31_t) ((((q63_t) acc1 << 32) + ((q63_t) x1 * c0)) >> 32);
+ acc2 = (q31_t) ((((q63_t) acc2 << 32) + ((q63_t) x2 * c0)) >> 32);
+ acc3 = (q31_t) ((((q63_t) acc3 << 32) + ((q63_t) x3 * c0)) >> 32);
+
+ /* Reuse the present sample states for next sample */
+ x0 = x1;
+ x1 = x2;
+ x2 = x3;
+
+ /* Decrement the loop counter */
+ i--;
+ }
+
+ /* Advance the state pointer by 4 to process the next group of 4 samples */
+ pState = pState + 4;
+
+ /* The results in the 4 accumulators are in 2.30 format. Convert to 1.31
+ ** Then store the 4 outputs in the destination buffer. */
+ *pDst++ = (q31_t) (acc0 << 1);
+ *pDst++ = (q31_t) (acc1 << 1);
+ *pDst++ = (q31_t) (acc2 << 1);
+ *pDst++ = (q31_t) (acc3 << 1);
+
+ /* Decrement the samples 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 % 4u;
+
+ while(blkCnt > 0u)
+ {
+ /* Copy one sample at a time into state buffer */
+ *pStateCurnt++ = *pSrc++;
+
+ /* Set the accumulator to zero */
+ acc0 = 0;
+
+ /* Initialize state pointer */
+ px = pState;
+
+ /* Initialize Coefficient pointer */
+ pb = (pCoeffs);
+
+ i = numTaps;
+
+ /* Perform the multiply-accumulates */
+ do
+ {
+ acc0 =
+ (q31_t) ((((q63_t) acc0 << 32) +
+ ((q63_t) (*px++) * (*(pb++)))) >> 32);
+ i--;
+ } while(i > 0u);
+
+ /* The result is in 2.30 format. Convert to 1.31
+ ** Then store the output in the destination buffer. */
+ *pDst++ = (q31_t) (acc0 << 1);
+
+ /* 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;
+
+ tapCnt = (numTaps - 1u) >> 2u;
+
+ /* copy data */
+ while(tapCnt > 0u)
+ {
+ *pStateCurnt++ = *pState++;
+ *pStateCurnt++ = *pState++;
+ *pStateCurnt++ = *pState++;
+ *pStateCurnt++ = *pState++;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+ /* Calculate remaining number of copies */
+ tapCnt = (numTaps - 1u) % 0x4u;
+
+ /* Copy the remaining q31_t data */
+ while(tapCnt > 0u)
+ {
+ *pStateCurnt++ = *pState++;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+
+}
+
+/**
+ * @} end of FIR group
+ */
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