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author | px4dev <px4@purgatory.org> | 2013-01-06 12:52:05 -0800 |
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committer | px4dev <px4@purgatory.org> | 2013-01-06 12:52:05 -0800 |
commit | 4447282260be0780eb6e36f5e953bf56888a5688 (patch) | |
tree | 3ba1e976d998d433397343b79a0612af52075aef /apps/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_fir_q31.c | |
parent | 659543f852d18197f68fafee5db5671567b74f4b (diff) | |
download | px4-firmware-4447282260be0780eb6e36f5e953bf56888a5688.tar.gz px4-firmware-4447282260be0780eb6e36f5e953bf56888a5688.tar.bz2 px4-firmware-4447282260be0780eb6e36f5e953bf56888a5688.zip |
Integrate the interesting parts of the CMSIS 3.01 (r3p1) DSP library
Diffstat (limited to 'apps/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_fir_q31.c')
-rw-r--r-- | apps/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_fir_q31.c | 363 |
1 files changed, 363 insertions, 0 deletions
diff --git a/apps/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_fir_q31.c b/apps/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_fir_q31.c new file mode 100644 index 000000000..b3b84ec51 --- /dev/null +++ b/apps/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_fir_q31.c @@ -0,0 +1,363 @@ +/* ----------------------------------------------------------------------
+* Copyright (C) 2010 ARM Limited. All rights reserved.
+*
+* $Date: 15. February 2012
+* $Revision: V1.1.0
+*
+* Project: CMSIS DSP Library
+* Title: arm_fir_q31.c
+*
+* Description: Q31 FIR filter processing function.
+*
+* Target Processor: Cortex-M4/Cortex-M3/Cortex-M0
+*
+* 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 0.0.5 2010/04/26
+* incorporated review comments and updated with latest CMSIS layer
+*
+* Version 0.0.3 2010/03/10
+* Initial version
+* -------------------------------------------------------------------- */
+
+#include "arm_math.h"
+
+/**
+ * @ingroup groupFilters
+ */
+
+/**
+ * @addtogroup FIR
+ * @{
+ */
+
+/**
+ * @param[in] *S points to an instance of the Q31 FIR filter 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.
+ *
+ * @details
+ * <b>Scaling and Overflow Behavior:</b>
+ * \par
+ * 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 log2(numTaps) bits.
+ * After all multiply-accumulates are performed, the 2.62 accumulator is right shifted by 31 bits and saturated to 1.31 format to yield the final result.
+ *
+ * \par
+ * Refer to the function <code>arm_fir_fast_q31()</code> for a faster but less precise implementation of this filter for Cortex-M3 and Cortex-M4.
+ */
+
+void arm_fir_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 */
+
+
+#ifndef ARM_MATH_CM0
+
+ /* Run the below code for Cortex-M4 and Cortex-M3 */
+
+ q31_t x0, x1, x2; /* 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 */
+ q63_t acc0, acc1, acc2; /* Accumulators */
+ uint32_t numTaps = S->numTaps; /* Number of filter coefficients in the filter */
+ uint32_t i, tapCnt, blkCnt, tapCntN3; /* 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 / 3;
+ blockSize = blockSize - (3 * blkCnt);
+
+ tapCnt = numTaps / 3;
+ tapCntN3 = numTaps - (3 * tapCnt);
+
+ /* 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 three new input samples into the state buffer */
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+ *pStateCurnt++ = *pSrc++;
+
+ /* Set all accumulators to zero */
+ acc0 = 0;
+ acc1 = 0;
+ acc2 = 0;
+
+ /* Initialize state pointer */
+ px = pState;
+
+ /* Initialize coefficient pointer */
+ pb = pCoeffs;
+
+ /* Read the first two samples from the state buffer:
+ * x[n-numTaps], x[n-numTaps-1] */
+ x0 = *(px++);
+ x1 = *(px++);
+
+ /* Loop unrolling. Process 3 taps at a time. */
+ i = tapCnt;
+
+ while(i > 0u)
+ {
+ /* Read the b[numTaps] coefficient */
+ c0 = *pb;
+
+ /* Read x[n-numTaps-2] sample */
+ x2 = *(px++);
+
+ /* Perform the multiply-accumulates */
+ acc0 += ((q63_t) x0 * c0);
+ acc1 += ((q63_t) x1 * c0);
+ acc2 += ((q63_t) x2 * c0);
+
+ /* Read the coefficient and state */
+ c0 = *(pb + 1u);
+ x0 = *(px++);
+
+ /* Perform the multiply-accumulates */
+ acc0 += ((q63_t) x1 * c0);
+ acc1 += ((q63_t) x2 * c0);
+ acc2 += ((q63_t) x0 * c0);
+
+ /* Read the coefficient and state */
+ c0 = *(pb + 2u);
+ x1 = *(px++);
+
+ /* update coefficient pointer */
+ pb += 3u;
+
+ /* Perform the multiply-accumulates */
+ acc0 += ((q63_t) x2 * c0);
+ acc1 += ((q63_t) x0 * c0);
+ acc2 += ((q63_t) x1 * c0);
+
+ /* Decrement the loop counter */
+ i--;
+ }
+
+ /* If the filter length is not a multiple of 3, compute the remaining filter taps */
+
+ i = tapCntN3;
+
+ while(i > 0u)
+ {
+ /* Read coefficients */
+ c0 = *(pb++);
+
+ /* Fetch 1 state variable */
+ x2 = *(px++);
+
+ /* Perform the multiply-accumulates */
+ acc0 += ((q63_t) x0 * c0);
+ acc1 += ((q63_t) x1 * c0);
+ acc2 += ((q63_t) x2 * c0);
+
+ /* Reuse the present sample states for next sample */
+ x0 = x1;
+ x1 = x2;
+
+ /* Decrement the loop counter */
+ i--;
+ }
+
+ /* Advance the state pointer by 3 to process the next group of 3 samples */
+ pState = pState + 3;
+
+ /* The results in the 3 accumulators are in 2.30 format. Convert to 1.31
+ ** Then store the 3 outputs in the destination buffer. */
+ *pDst++ = (q31_t) (acc0 >> 31u);
+ *pDst++ = (q31_t) (acc1 >> 31u);
+ *pDst++ = (q31_t) (acc2 >> 31u);
+
+ /* Decrement the samples loop counter */
+ blkCnt--;
+ }
+
+ /* If the blockSize is not a multiple of 3, compute any remaining output samples here.
+ ** No loop unrolling is used. */
+
+ while(blockSize > 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 += (q63_t) * (px++) * (*(pb++));
+ i--;
+ } while(i > 0u);
+
+ /* The result is in 2.62 format. Convert to 1.31
+ ** Then store the output in the destination buffer. */
+ *pDst++ = (q31_t) (acc0 >> 31u);
+
+ /* Advance state pointer by 1 for the next sample */
+ pState = pState + 1;
+
+ /* Decrement the samples loop counter */
+ blockSize--;
+ }
+
+ /* 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--;
+ }
+
+#else
+
+/* Run the below code for Cortex-M0 */
+
+ q31_t *px; /* Temporary pointer for state */
+ q31_t *pb; /* Temporary pointer for coefficient buffer */
+ q63_t acc; /* Accumulator */
+ uint32_t numTaps = S->numTaps; /* Length of the filter */
+ uint32_t i, 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;
+
+ i = 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 += (q63_t) * px++ * *pb++;
+ i--;
+ } while(i > 0u);
+
+ /* The result is in 2.62 format. Convert to 1.31
+ ** Then store the output in the destination buffer. */
+ *pDst++ = (q31_t) (acc >> 31u);
+
+ /* 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 starting 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 the data */
+ while(tapCnt > 0u)
+ {
+ *pStateCurnt++ = *pState++;
+
+ /* Decrement the loop counter */
+ tapCnt--;
+ }
+
+
+#endif /* #ifndef ARM_MATH_CM0 */
+
+}
+
+/**
+ * @} end of FIR group
+ */
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