Diff: TransformFunctions/arm_bitreversal.c

Revision:

0:3d9c67d97d6f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/TransformFunctions/arm_bitreversal.c	Mon Jul 28 15:03:15 2014 +0000
@@ -0,0 +1,242 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
+*    
+* $Date:        12. March 2014  
+* $Revision: 	V1.4.3  
+*    
+* 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
+*  
+* Redistribution and use in source and binary forms, with or without 
+* modification, are permitted provided that the following conditions
+* are met:
+*   - Redistributions of source code must retain the above copyright
+*     notice, this list of conditions and the following disclaimer.
+*   - Redistributions in binary form must reproduce the above copyright
+*     notice, this list of conditions and the following disclaimer in
+*     the documentation and/or other materials provided with the 
+*     distribution.
+*   - Neither the name of ARM LIMITED nor the names of its contributors
+*     may be used to endorse or promote products derived from this
+*     software without specific prior written permission.
+*
+* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
+* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+* POSSIBILITY OF SUCH DAMAGE.  
+* -------------------------------------------------------------------- */
+
+#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;
+   }
+}