Laxmi Kant Tiwari
CMSIS DSP Lib
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Diff: cmsis_dsp/TransformFunctions/arm_bitreversal.c
- Revision:
- 1:fdd22bb7aa52
- Child:
- 2:da51fb522205
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/TransformFunctions/arm_bitreversal.c Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,222 @@
+/* ----------------------------------------------------------------------
+* Copyright (C) 2010 ARM Limited. All rights reserved.
+*
+* $Date: 15. February 2012
+* $Revision: V1.1.0
+*
+* Project: CMSIS DSP Library
+* Title: arm_bitreversal.c
+*
+* Description: This file has common tables like Bitreverse, reciprocal etc which are used across different functions
+*
+* 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
+* Initial Version
+* -------------------------------------------------------------------- */
+
+#include "arm_math.h"
+#include "arm_common_tables.h"
+
+/*
+ * @brief In-place bit reversal function.
+ * @param[in, out] *pSrc points to the in-place buffer of floating-point data type.
+ * @param[in] fftSize length of the FFT.
+ * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table.
+ * @param[in] *pBitRevTab points to the bit reversal table.
+ * @return none.
+ */
+
+void arm_bitreversal_f32(
+ float32_t * pSrc,
+ uint16_t fftSize,
+ uint16_t bitRevFactor,
+ uint16_t * pBitRevTab)
+{
+ uint16_t fftLenBy2, fftLenBy2p1;
+ uint16_t i, j;
+ float32_t in;
+
+ /* Initializations */
+ j = 0u;
+ fftLenBy2 = fftSize >> 1u;
+ fftLenBy2p1 = (fftSize >> 1u) + 1u;
+
+ /* Bit Reversal Implementation */
+ for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
+ {
+ if(i < j)
+ {
+ /* pSrc[i] <-> pSrc[j]; */
+ in = pSrc[2u * i];
+ pSrc[2u * i] = pSrc[2u * j];
+ pSrc[2u * j] = in;
+
+ /* pSrc[i+1u] <-> pSrc[j+1u] */
+ in = pSrc[(2u * i) + 1u];
+ pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u];
+ pSrc[(2u * j) + 1u] = in;
+
+ /* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
+ in = pSrc[2u * (i + fftLenBy2p1)];
+ pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)];
+ pSrc[2u * (j + fftLenBy2p1)] = in;
+
+ /* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */
+ in = pSrc[(2u * (i + fftLenBy2p1)) + 1u];
+ pSrc[(2u * (i + fftLenBy2p1)) + 1u] =
+ pSrc[(2u * (j + fftLenBy2p1)) + 1u];
+ pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in;
+
+ }
+
+ /* pSrc[i+1u] <-> pSrc[j+1u] */
+ in = pSrc[2u * (i + 1u)];
+ pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)];
+ pSrc[2u * (j + fftLenBy2)] = in;
+
+ /* pSrc[i+2u] <-> pSrc[j+2u] */
+ in = pSrc[(2u * (i + 1u)) + 1u];
+ pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u];
+ pSrc[(2u * (j + fftLenBy2)) + 1u] = in;
+
+ /* Reading the index for the bit reversal */
+ j = *pBitRevTab;
+
+ /* Updating the bit reversal index depending on the fft length */
+ pBitRevTab += bitRevFactor;
+ }
+}
+
+
+
+/*
+ * @brief In-place bit reversal function.
+ * @param[in, out] *pSrc points to the in-place buffer of Q31 data type.
+ * @param[in] fftLen length of the FFT.
+ * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
+ * @param[in] *pBitRevTab points to bit reversal table.
+ * @return none.
+ */
+
+void arm_bitreversal_q31(
+ q31_t * pSrc,
+ uint32_t fftLen,
+ uint16_t bitRevFactor,
+ uint16_t * pBitRevTable)
+{
+ uint32_t fftLenBy2, fftLenBy2p1, i, j;
+ q31_t in;
+
+ /* Initializations */
+ j = 0u;
+ fftLenBy2 = fftLen / 2u;
+ fftLenBy2p1 = (fftLen / 2u) + 1u;
+
+ /* Bit Reversal Implementation */
+ for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
+ {
+ if(i < j)
+ {
+ /* pSrc[i] <-> pSrc[j]; */
+ in = pSrc[2u * i];
+ pSrc[2u * i] = pSrc[2u * j];
+ pSrc[2u * j] = in;
+
+ /* pSrc[i+1u] <-> pSrc[j+1u] */
+ in = pSrc[(2u * i) + 1u];
+ pSrc[(2u * i) + 1u] = pSrc[(2u * j) + 1u];
+ pSrc[(2u * j) + 1u] = in;
+
+ /* pSrc[i+fftLenBy2p1] <-> pSrc[j+fftLenBy2p1] */
+ in = pSrc[2u * (i + fftLenBy2p1)];
+ pSrc[2u * (i + fftLenBy2p1)] = pSrc[2u * (j + fftLenBy2p1)];
+ pSrc[2u * (j + fftLenBy2p1)] = in;
+
+ /* pSrc[i+fftLenBy2p1+1u] <-> pSrc[j+fftLenBy2p1+1u] */
+ in = pSrc[(2u * (i + fftLenBy2p1)) + 1u];
+ pSrc[(2u * (i + fftLenBy2p1)) + 1u] =
+ pSrc[(2u * (j + fftLenBy2p1)) + 1u];
+ pSrc[(2u * (j + fftLenBy2p1)) + 1u] = in;
+
+ }
+
+ /* pSrc[i+1u] <-> pSrc[j+1u] */
+ in = pSrc[2u * (i + 1u)];
+ pSrc[2u * (i + 1u)] = pSrc[2u * (j + fftLenBy2)];
+ pSrc[2u * (j + fftLenBy2)] = in;
+
+ /* pSrc[i+2u] <-> pSrc[j+2u] */
+ in = pSrc[(2u * (i + 1u)) + 1u];
+ pSrc[(2u * (i + 1u)) + 1u] = pSrc[(2u * (j + fftLenBy2)) + 1u];
+ pSrc[(2u * (j + fftLenBy2)) + 1u] = in;
+
+ /* Reading the index for the bit reversal */
+ j = *pBitRevTable;
+
+ /* Updating the bit reversal index depending on the fft length */
+ pBitRevTable += bitRevFactor;
+ }
+}
+
+
+
+/*
+ * @brief In-place bit reversal function.
+ * @param[in, out] *pSrc points to the in-place buffer of Q15 data type.
+ * @param[in] fftLen length of the FFT.
+ * @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table
+ * @param[in] *pBitRevTab points to bit reversal table.
+ * @return none.
+ */
+
+void arm_bitreversal_q15(
+ q15_t * pSrc16,
+ uint32_t fftLen,
+ uint16_t bitRevFactor,
+ uint16_t * pBitRevTab)
+{
+ q31_t *pSrc = (q31_t *) pSrc16;
+ q31_t in;
+ uint32_t fftLenBy2, fftLenBy2p1;
+ uint32_t i, j;
+
+ /* Initializations */
+ j = 0u;
+ fftLenBy2 = fftLen / 2u;
+ fftLenBy2p1 = (fftLen / 2u) + 1u;
+
+ /* Bit Reversal Implementation */
+ for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u)
+ {
+ if(i < j)
+ {
+ /* pSrc[i] <-> pSrc[j]; */
+ /* pSrc[i+1u] <-> pSrc[j+1u] */
+ in = pSrc[i];
+ pSrc[i] = pSrc[j];
+ pSrc[j] = in;
+
+ /* pSrc[i + fftLenBy2p1] <-> pSrc[j + fftLenBy2p1]; */
+ /* pSrc[i + fftLenBy2p1+1u] <-> pSrc[j + fftLenBy2p1+1u] */
+ in = pSrc[i + fftLenBy2p1];
+ pSrc[i + fftLenBy2p1] = pSrc[j + fftLenBy2p1];
+ pSrc[j + fftLenBy2p1] = in;
+ }
+
+ /* pSrc[i+1u] <-> pSrc[j+fftLenBy2]; */
+ /* pSrc[i+2] <-> pSrc[j+fftLenBy2+1u] */
+ in = pSrc[i + 1u];
+ pSrc[i + 1u] = pSrc[j + fftLenBy2];
+ pSrc[j + fftLenBy2] = in;
+
+ /* Reading the index for the bit reversal */
+ j = *pBitRevTab;
+
+ /* Updating the bit reversal index depending on the fft length */
+ pBitRevTab += bitRevFactor;
+ }
+}