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Diffstat (limited to 'src/modules/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_biquad_cascade_df1_fast_q31.c')
| -rw-r--r-- | src/modules/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_biquad_cascade_df1_fast_q31.c | 275 |
1 files changed, 275 insertions, 0 deletions
diff --git a/src/modules/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_biquad_cascade_df1_fast_q31.c b/src/modules/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_biquad_cascade_df1_fast_q31.c new file mode 100644 index 000000000..0a479fe6b --- /dev/null +++ b/src/modules/mathlib/CMSIS/DSP_Lib/Source/FilteringFunctions/arm_biquad_cascade_df1_fast_q31.c @@ -0,0 +1,275 @@ +/* ----------------------------------------------------------------------
+* Copyright (C) 2010 ARM Limited. All rights reserved.
+*
+* $Date: 15. February 2012
+* $Revision: V1.1.0
+*
+* Project: CMSIS DSP Library
+* Title: arm_biquad_cascade_df1_fast_q31.c
+*
+* Description: Processing function for the
+* Q31 Fast Biquad cascade DirectFormI(DF1) 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 BiquadCascadeDF1
+ * @{
+ */
+
+/**
+ * @details
+ *
+ * @param[in] *S points to an instance of the Q31 Biquad cascade 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.
+ *
+ * <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 two bits and lie in the range [-0.25 +0.25). Use the intialization function
+ * arm_biquad_cascade_df1_init_q31() to initialize filter structure.
+ *
+ * \par
+ * Refer to the function <code>arm_biquad_cascade_df1_q31()</code> for a slower implementation of this function which uses 64-bit accumulation to provide higher precision. Both the slow and the fast versions use the same instance structure.
+ * Use the function <code>arm_biquad_cascade_df1_init_q31()</code> to initialize the filter structure.
+ */
+
+void arm_biquad_cascade_df1_fast_q31(
+ const arm_biquad_casd_df1_inst_q31 * S,
+ q31_t * pSrc,
+ q31_t * pDst,
+ uint32_t blockSize)
+{
+ q31_t acc; /* accumulator */
+ q31_t Xn1, Xn2, Yn1, Yn2; /* Filter state variables */
+ q31_t b0, b1, b2, a1, a2; /* Filter coefficients */
+ q31_t *pIn = pSrc; /* input pointer initialization */
+ q31_t *pOut = pDst; /* output pointer initialization */
+ q31_t *pState = S->pState; /* pState pointer initialization */
+ q31_t *pCoeffs = S->pCoeffs; /* coeff pointer initialization */
+ q31_t Xn; /* temporary input */
+ int32_t shift = (int32_t) S->postShift + 1; /* Shift to be applied to the output */
+ uint32_t sample, stage = S->numStages; /* loop counters */
+
+
+ do
+ {
+ /* Reading the coefficients */
+ b0 = *pCoeffs++;
+ b1 = *pCoeffs++;
+ b2 = *pCoeffs++;
+ a1 = *pCoeffs++;
+ a2 = *pCoeffs++;
+
+ /* Reading the state values */
+ Xn1 = pState[0];
+ Xn2 = pState[1];
+ Yn1 = pState[2];
+ Yn2 = pState[3];
+
+ /* Apply loop unrolling and compute 4 output values simultaneously. */
+ /* The variables acc ... acc3 hold output values that are being computed:
+ *
+ * acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2]
+ */
+
+ sample = blockSize >> 2u;
+
+ /* 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(sample > 0u)
+ {
+ /* Read the input */
+ Xn = *pIn;
+
+ /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */
+ /* acc = b0 * x[n] */
+ acc = (q31_t) (((q63_t) b1 * Xn1) >> 32);
+ /* acc += b1 * x[n-1] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b0 * (Xn))) >> 32);
+ /* acc += b[2] * x[n-2] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn2))) >> 32);
+ /* acc += a1 * y[n-1] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn1))) >> 32);
+ /* acc += a2 * y[n-2] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn2))) >> 32);
+
+ /* The result is converted to 1.31 , Yn2 variable is reused */
+ Yn2 = acc << shift;
+
+ /* Read the second input */
+ Xn2 = *(pIn + 1u);
+
+ /* Store the output in the destination buffer. */
+ *pOut = Yn2;
+
+ /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */
+ /* acc = b0 * x[n] */
+ acc = (q31_t) (((q63_t) b0 * (Xn2)) >> 32);
+ /* acc += b1 * x[n-1] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b1 * (Xn))) >> 32);
+ /* acc += b[2] * x[n-2] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn1))) >> 32);
+ /* acc += a1 * y[n-1] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn2))) >> 32);
+ /* acc += a2 * y[n-2] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn1))) >> 32);
+
+ /* The result is converted to 1.31, Yn1 variable is reused */
+ Yn1 = acc << shift;
+
+ /* Read the third input */
+ Xn1 = *(pIn + 2u);
+
+ /* Store the output in the destination buffer. */
+ *(pOut + 1u) = Yn1;
+
+ /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */
+ /* acc = b0 * x[n] */
+ acc = (q31_t) (((q63_t) b0 * (Xn1)) >> 32);
+ /* acc += b1 * x[n-1] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b1 * (Xn2))) >> 32);
+ /* acc += b[2] * x[n-2] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn))) >> 32);
+ /* acc += a1 * y[n-1] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn1))) >> 32);
+ /* acc += a2 * y[n-2] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn2))) >> 32);
+
+ /* The result is converted to 1.31, Yn2 variable is reused */
+ Yn2 = acc << shift;
+
+ /* Read the forth input */
+ Xn = *(pIn + 3u);
+
+ /* Store the output in the destination buffer. */
+ *(pOut + 2u) = Yn2;
+ pIn += 4u;
+
+ /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */
+ /* acc = b0 * x[n] */
+ acc = (q31_t) (((q63_t) b0 * (Xn)) >> 32);
+ /* acc += b1 * x[n-1] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b1 * (Xn1))) >> 32);
+ /* acc += b[2] * x[n-2] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn2))) >> 32);
+ /* acc += a1 * y[n-1] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn2))) >> 32);
+ /* acc += a2 * y[n-2] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn1))) >> 32);
+
+ /* Every time after the output is computed state should be updated. */
+ /* The states should be updated as: */
+ /* Xn2 = Xn1 */
+ Xn2 = Xn1;
+
+ /* The result is converted to 1.31, Yn1 variable is reused */
+ Yn1 = acc << shift;
+
+ /* Xn1 = Xn */
+ Xn1 = Xn;
+
+ /* Store the output in the destination buffer. */
+ *(pOut + 3u) = Yn1;
+ pOut += 4u;
+
+ /* decrement the loop counter */
+ sample--;
+ }
+
+ /* If the blockSize is not a multiple of 4, compute any remaining output samples here.
+ ** No loop unrolling is used. */
+ sample = (blockSize & 0x3u);
+
+ while(sample > 0u)
+ {
+ /* Read the input */
+ Xn = *pIn++;
+
+ /* acc = b0 * x[n] + b1 * x[n-1] + b2 * x[n-2] + a1 * y[n-1] + a2 * y[n-2] */
+ /* acc = b0 * x[n] */
+ acc = (q31_t) (((q63_t) b0 * (Xn)) >> 32);
+ /* acc += b1 * x[n-1] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b1 * (Xn1))) >> 32);
+ /* acc += b[2] * x[n-2] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) b2 * (Xn2))) >> 32);
+ /* acc += a1 * y[n-1] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a1 * (Yn1))) >> 32);
+ /* acc += a2 * y[n-2] */
+ acc = (q31_t) ((((q63_t) acc << 32) + ((q63_t) a2 * (Yn2))) >> 32);
+ /* The result is converted to 1.31 */
+ acc = acc << shift;
+
+ /* Every time after the output is computed state should be updated. */
+ /* The states should be updated as: */
+ /* Xn2 = Xn1 */
+ /* Xn1 = Xn */
+ /* Yn2 = Yn1 */
+ /* Yn1 = acc */
+ Xn2 = Xn1;
+ Xn1 = Xn;
+ Yn2 = Yn1;
+ Yn1 = acc;
+
+ /* Store the output in the destination buffer. */
+ *pOut++ = acc;
+
+ /* decrement the loop counter */
+ sample--;
+ }
+
+ /* The first stage goes from the input buffer to the output buffer. */
+ /* Subsequent stages occur in-place in the output buffer */
+ pIn = pDst;
+
+ /* Reset to destination pointer */
+ pOut = pDst;
+
+ /* Store the updated state variables back into the pState array */
+ *pState++ = Xn1;
+ *pState++ = Xn2;
+ *pState++ = Yn1;
+ *pState++ = Yn2;
+
+ } while(--stage);
+}
+
+/**
+ * @} end of BiquadCascadeDF1 group
+ */
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