Diff: TransformFunctions/arm_rfft_q31.c

Revision:

0:3d9c67d97d6f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/TransformFunctions/arm_rfft_q31.c	Mon Jul 28 15:03:15 2014 +0000
@@ -0,0 +1,355 @@
+/* ----------------------------------------------------------------------    
+* Copyright (C) 2010-2014 ARM Limited. All rights reserved.    
+*    
+* $Date:        12. March 2014  
+* $Revision: 	V1.4.3  
+*    
+* Project: 	    CMSIS DSP Library    
+* Title:	    arm_rfft_q31.c    
+*    
+* Description:	RFFT & RIFFT Q31 process function    
+*    
+*    
+* 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"
+
+void arm_radix4_butterfly_inverse_q31(
+q31_t * pSrc,
+uint32_t fftLen,
+q31_t * pCoef,
+uint32_t twidCoefModifier);
+
+void arm_radix4_butterfly_q31(
+q31_t * pSrc,
+uint32_t fftLen,
+q31_t * pCoef,
+uint32_t twidCoefModifier);
+
+void arm_bitreversal_q31(
+q31_t * pSrc,
+uint32_t fftLen,
+uint16_t bitRevFactor,
+uint16_t * pBitRevTab);
+
+/*--------------------------------------------------------------------    
+*		Internal functions prototypes    
+--------------------------------------------------------------------*/
+
+void arm_split_rfft_q31(
+  q31_t * pSrc,
+  uint32_t fftLen,
+  q31_t * pATable,
+  q31_t * pBTable,
+  q31_t * pDst,
+  uint32_t modifier);
+
+void arm_split_rifft_q31(
+  q31_t * pSrc,
+  uint32_t fftLen,
+  q31_t * pATable,
+  q31_t * pBTable,
+  q31_t * pDst,
+  uint32_t modifier);
+
+/**    
+ * @addtogroup RealFFT    
+ * @{    
+ */
+
+/**    
+ * @brief Processing function for the Q31 RFFT/RIFFT.   
+ * @param[in]  *S    points to an instance of the Q31 RFFT/RIFFT structure.   
+ * @param[in]  *pSrc points to the input buffer.   
+ * @param[out] *pDst points to the output buffer.   
+ * @return none.   
+ *    
+ * \par Input an output formats:   
+ * \par    
+ * Internally input is downscaled by 2 for every stage to avoid saturations inside CFFT/CIFFT process.   
+ * Hence the output format is different for different RFFT sizes.    
+ * The input and output formats for different RFFT sizes and number of bits to upscale are mentioned in the tables below for RFFT and RIFFT:   
+ * \par    
+ * \image html RFFTQ31.gif "Input and Output Formats for Q31 RFFT"    
+ *    
+ * \par    
+ * \image html RIFFTQ31.gif "Input and Output Formats for Q31 RIFFT"    
+ */
+
+void arm_rfft_q31(
+  const arm_rfft_instance_q31 * S,
+  q31_t * pSrc,
+  q31_t * pDst)
+{
+  const arm_cfft_radix4_instance_q31 *S_CFFT = S->pCfft;
+  uint32_t i;
+
+  /* Calculation of RIFFT of input */
+  if(S->ifftFlagR == 1u)
+  {
+    /*  Real IFFT core process */
+    arm_split_rifft_q31(pSrc, S->fftLenBy2, S->pTwiddleAReal,
+                        S->pTwiddleBReal, pDst, S->twidCoefRModifier);
+
+    /* Complex readix-4 IFFT process */
+    arm_radix4_butterfly_inverse_q31(pDst, S_CFFT->fftLen,
+                                     S_CFFT->pTwiddle,
+                                     S_CFFT->twidCoefModifier);
+    /* Bit reversal process */
+    if(S->bitReverseFlagR == 1u)
+    {
+      arm_bitreversal_q31(pDst, S_CFFT->fftLen,
+                          S_CFFT->bitRevFactor, S_CFFT->pBitRevTable);
+    }
+    
+    for(i=0;i<S->fftLenReal;i++)
+    {
+      pDst[i] = pDst[i] << 1;
+    }
+  }
+  else
+  {
+    /* Calculation of RFFT of input */
+
+    /* Complex readix-4 FFT process */
+    arm_radix4_butterfly_q31(pSrc, S_CFFT->fftLen,
+                             S_CFFT->pTwiddle, S_CFFT->twidCoefModifier);
+
+    /* Bit reversal process */
+    if(S->bitReverseFlagR == 1u)
+    {
+      arm_bitreversal_q31(pSrc, S_CFFT->fftLen,
+                          S_CFFT->bitRevFactor, S_CFFT->pBitRevTable);
+    }
+
+    /*  Real FFT core process */
+    arm_split_rfft_q31(pSrc, S->fftLenBy2, S->pTwiddleAReal,
+                       S->pTwiddleBReal, pDst, S->twidCoefRModifier);
+  }
+
+}
+
+
+  /**    
+   * @} end of RealFFT group    
+   */
+
+/**    
+ * @brief  Core Real FFT process    
+ * @param[in]   *pSrc 				points to the input buffer.    
+ * @param[in]   fftLen  			length of FFT.   
+ * @param[in]   *pATable 			points to the twiddle Coef A buffer.    
+ * @param[in]   *pBTable 			points to the twiddle Coef B buffer.    
+ * @param[out]  *pDst 				points to the output buffer.    
+ * @param[in]   modifier 	        twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.   
+ * @return none.    
+ */
+
+void arm_split_rfft_q31(
+  q31_t * pSrc,
+  uint32_t fftLen,
+  q31_t * pATable,
+  q31_t * pBTable,
+  q31_t * pDst,
+  uint32_t modifier)
+{
+  uint32_t i;                                    /* Loop Counter */
+  q31_t outR, outI;                              /* Temporary variables for output */
+  q31_t *pCoefA, *pCoefB;                        /* Temporary pointers for twiddle factors */
+  q31_t CoefA1, CoefA2, CoefB1;                  /* Temporary variables for twiddle coefficients */
+  q31_t *pOut1 = &pDst[2], *pOut2 = &pDst[(4u * fftLen) - 1u];
+  q31_t *pIn1 = &pSrc[2], *pIn2 = &pSrc[(2u * fftLen) - 1u];
+
+  /* Init coefficient pointers */
+  pCoefA = &pATable[modifier * 2u];
+  pCoefB = &pBTable[modifier * 2u];
+
+  i = fftLen - 1u;
+
+  while(i > 0u)
+  {
+    /*    
+       outR = (pSrc[2 * i] * pATable[2 * i] - pSrc[2 * i + 1] * pATable[2 * i + 1]    
+       + pSrc[2 * n - 2 * i] * pBTable[2 * i] +    
+       pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);    
+     */
+
+    /* outI = (pIn[2 * i + 1] * pATable[2 * i] + pIn[2 * i] * pATable[2 * i + 1] +    
+       pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -    
+       pIn[2 * n - 2 * i + 1] * pBTable[2 * i]); */
+
+    CoefA1 = *pCoefA++;
+    CoefA2 = *pCoefA;
+
+    /* outR = (pSrc[2 * i] * pATable[2 * i] */
+    outR = ((int32_t) (((q63_t) * pIn1 * CoefA1) >> 32));
+
+    /* outI = pIn[2 * i] * pATable[2 * i + 1] */
+    outI = ((int32_t) (((q63_t) * pIn1++ * CoefA2) >> 32));
+
+    /* - pSrc[2 * i + 1] * pATable[2 * i + 1] */
+    outR =
+      (q31_t) ((((q63_t) outR << 32) + ((q63_t) * pIn1 * (-CoefA2))) >> 32);
+
+    /* (pIn[2 * i + 1] * pATable[2 * i] */
+    outI =
+      (q31_t) ((((q63_t) outI << 32) + ((q63_t) * pIn1++ * (CoefA1))) >> 32);
+
+    /* pSrc[2 * n - 2 * i] * pBTable[2 * i]  */
+    outR =
+      (q31_t) ((((q63_t) outR << 32) + ((q63_t) * pIn2 * (-CoefA2))) >> 32);
+    CoefB1 = *pCoefB;
+
+    /* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] */
+    outI =
+      (q31_t) ((((q63_t) outI << 32) + ((q63_t) * pIn2-- * (-CoefB1))) >> 32);
+
+    /* pSrc[2 * n - 2 * i + 1] * pBTable[2 * i + 1] */
+    outR =
+      (q31_t) ((((q63_t) outR << 32) + ((q63_t) * pIn2 * (CoefB1))) >> 32);
+
+    /* pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */
+    outI =
+      (q31_t) ((((q63_t) outI << 32) + ((q63_t) * pIn2-- * (-CoefA2))) >> 32);
+
+    /* write output */
+    *pOut1++ = outR;
+    *pOut1++ = outI;
+
+    /* write complex conjugate output */
+    *pOut2-- = -outI;
+    *pOut2-- = outR;
+
+    /* update coefficient pointer */
+    pCoefB = pCoefB + (modifier * 2u);
+    pCoefA = pCoefA + ((modifier * 2u) - 1u);
+
+    i--;
+
+  }
+
+  pDst[2u * fftLen] = (pSrc[0] - pSrc[1]) >> 1;
+  pDst[(2u * fftLen) + 1u] = 0;
+
+  pDst[0] = (pSrc[0] + pSrc[1]) >> 1;
+  pDst[1] = 0;
+
+}
+
+
+/**    
+ * @brief  Core Real IFFT process    
+ * @param[in]   *pSrc 				points to the input buffer.   
+ * @param[in]   fftLen  			length of FFT.    
+ * @param[in]   *pATable 			points to the twiddle Coef A buffer.   
+ * @param[in]   *pBTable 			points to the twiddle Coef B buffer.    
+ * @param[out]  *pDst 				points to the output buffer.   
+ * @param[in]   modifier 	        twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table.   
+ * @return none.    
+ */
+
+void arm_split_rifft_q31(
+  q31_t * pSrc,
+  uint32_t fftLen,
+  q31_t * pATable,
+  q31_t * pBTable,
+  q31_t * pDst,
+  uint32_t modifier)
+{
+  q31_t outR, outI;                              /* Temporary variables for output */
+  q31_t *pCoefA, *pCoefB;                        /* Temporary pointers for twiddle factors */
+  q31_t CoefA1, CoefA2, CoefB1;                  /* Temporary variables for twiddle coefficients */
+  q31_t *pIn1 = &pSrc[0], *pIn2 = &pSrc[(2u * fftLen) + 1u];
+
+  pCoefA = &pATable[0];
+  pCoefB = &pBTable[0];
+
+  while(fftLen > 0u)
+  {
+    /*    
+       outR = (pIn[2 * i] * pATable[2 * i] + pIn[2 * i + 1] * pATable[2 * i + 1] +    
+       pIn[2 * n - 2 * i] * pBTable[2 * i] -    
+       pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1]);    
+
+       outI = (pIn[2 * i + 1] * pATable[2 * i] - pIn[2 * i] * pATable[2 * i + 1] -    
+       pIn[2 * n - 2 * i] * pBTable[2 * i + 1] -    
+       pIn[2 * n - 2 * i + 1] * pBTable[2 * i]);    
+
+     */
+    CoefA1 = *pCoefA++;
+    CoefA2 = *pCoefA;
+
+    /* outR = (pIn[2 * i] * pATable[2 * i] */
+    outR = ((int32_t) (((q63_t) * pIn1 * CoefA1) >> 32));
+
+    /* - pIn[2 * i] * pATable[2 * i + 1] */
+    outI = -((int32_t) (((q63_t) * pIn1++ * CoefA2) >> 32));
+
+    /* pIn[2 * i + 1] * pATable[2 * i + 1] */
+    outR =
+      (q31_t) ((((q63_t) outR << 32) + ((q63_t) * pIn1 * (CoefA2))) >> 32);
+
+    /* pIn[2 * i + 1] * pATable[2 * i] */
+    outI =
+      (q31_t) ((((q63_t) outI << 32) + ((q63_t) * pIn1++ * (CoefA1))) >> 32);
+
+    /* pIn[2 * n - 2 * i] * pBTable[2 * i] */
+    outR =
+      (q31_t) ((((q63_t) outR << 32) + ((q63_t) * pIn2 * (CoefA2))) >> 32);
+
+    CoefB1 = *pCoefB;
+
+    /* pIn[2 * n - 2 * i] * pBTable[2 * i + 1] */
+    outI =
+      (q31_t) ((((q63_t) outI << 32) - ((q63_t) * pIn2-- * (CoefB1))) >> 32);
+
+    /* pIn[2 * n - 2 * i + 1] * pBTable[2 * i + 1] */
+    outR =
+      (q31_t) ((((q63_t) outR << 32) + ((q63_t) * pIn2 * (CoefB1))) >> 32);
+
+    /* pIn[2 * n - 2 * i + 1] * pBTable[2 * i] */
+    outI =
+      (q31_t) ((((q63_t) outI << 32) + ((q63_t) * pIn2-- * (CoefA2))) >> 32);
+
+    /* write output */
+    *pDst++ = outR;
+    *pDst++ = outI;
+
+    /* update coefficient pointer */
+    pCoefB = pCoefB + (modifier * 2u);
+    pCoefA = pCoefA + ((modifier * 2u) - 1u);
+
+    /* Decrement loop count */
+    fftLen--;
+
+  }
+
+
+}