Diff: cmsis_dsp/TransformFunctions/arm_cfft_radix2_q31.c

Revision:

1:fdd22bb7aa52

Child:

2:da51fb522205

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cmsis_dsp/TransformFunctions/arm_cfft_radix2_q31.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,310 @@
+/* ----------------------------------------------------------------------   
+* Copyright (C) 2010 ARM Limited. All rights reserved.   
+*   
+* $Date:        15. February 2012  
+* $Revision:     V1.1.0  
+*   
+* Project:         CMSIS DSP Library   
+* Title:        arm_cfft_radix2_q31.c   
+*   
+* Description:    Radix-2 Decimation in Frequency CFFT & CIFFT Fixed point 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 0.0.3  2010/03/10    
+*    Initial version   
+* -------------------------------------------------------------------- */
+
+#include "arm_math.h"
+
+/**   
+ * @ingroup groupTransforms   
+ */
+
+/**   
+ * @defgroup Radix2_CFFT_CIFFT Radix-2 Complex FFT Functions   
+ *   
+ * \par   
+ * Complex Fast Fourier Transform(CFFT) and Complex Inverse Fast Fourier Transform(CIFFT) is an efficient algorithm to compute Discrete Fourier Transform(DFT) and Inverse Discrete Fourier Transform(IDFT).   
+ * Computational complexity of CFFT reduces drastically when compared to DFT.    
+ */
+
+
+/**   
+ * @addtogroup Radix2_CFFT_CIFFT   
+ * @{   
+ */
+
+/**   
+ * @details   
+ * @brief Processing function for the fixed-point CFFT/CIFFT.  
+ * @param[in]      *S    points to an instance of the fixed-point CFFT/CIFFT structure.  
+ * @param[in, out] *pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place.  
+ * @return none.  
+ */
+
+void arm_cfft_radix2_q31(
+  const arm_cfft_radix2_instance_q31 * S,
+  q31_t * pSrc)
+{
+
+  if(S->ifftFlag == 1u)
+  {
+    arm_radix2_butterfly_inverse_q31(pSrc, S->fftLen,
+                                     S->pTwiddle, S->twidCoefModifier);
+  }
+  else
+  {
+    arm_radix2_butterfly_q31(pSrc, S->fftLen,
+                             S->pTwiddle, S->twidCoefModifier);
+  }
+
+  arm_bitreversal_q31(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable);
+}
+
+/**   
+ * @} end of Radix2_CFFT_CIFFT group   
+ */
+
+void arm_radix2_butterfly_q31(
+  q31_t * pSrc,
+  uint32_t fftLen,
+  q31_t * pCoef,
+  uint16_t twidCoefModifier)
+{
+
+  int i, j, k, l;
+  int n1, n2, ia;
+  q31_t xt, yt, cosVal, sinVal;
+
+  //N = fftLen; 
+  n2 = fftLen;
+
+  n1 = n2;
+  n2 = n2 >> 1;
+  ia = 0;
+
+  // loop for groups 
+  for (i = 0; i < n2; i++)
+  {
+    cosVal = pCoef[ia * 2];
+    sinVal = pCoef[(ia * 2) + 1];
+    ia = ia + twidCoefModifier;
+
+    l = i + n2;
+    xt = (pSrc[2 * i] >> 2u) - (pSrc[2 * l] >> 2u);
+    pSrc[2 * i] = ((pSrc[2 * i] >> 2u) + (pSrc[2 * l] >> 2u)) >> 1u;
+
+    yt = (pSrc[2 * i + 1] >> 2u) - (pSrc[2 * l + 1] >> 2u);
+    pSrc[2 * i + 1] =
+      ((pSrc[2 * l + 1] >> 2u) + (pSrc[2 * i + 1] >> 2u)) >> 1u;
+
+    pSrc[2u * l] = (((int32_t) (((q63_t) xt * cosVal) >> 32)) +
+                    ((int32_t) (((q63_t) yt * sinVal) >> 32)));
+
+    pSrc[2u * l + 1u] = (((int32_t) (((q63_t) yt * cosVal) >> 32)) -
+                         ((int32_t) (((q63_t) xt * sinVal) >> 32)));
+
+  }                             // groups loop end 
+
+  twidCoefModifier = twidCoefModifier << 1u;
+
+  // loop for stage 
+  for (k = fftLen / 2; k > 2; k = k >> 1)
+  {
+    n1 = n2;
+    n2 = n2 >> 1;
+    ia = 0;
+
+    // loop for groups 
+    for (j = 0; j < n2; j++)
+    {
+      cosVal = pCoef[ia * 2];
+      sinVal = pCoef[(ia * 2) + 1];
+      ia = ia + twidCoefModifier;
+
+      // loop for butterfly 
+      for (i = j; i < fftLen; i += n1)
+      {
+        l = i + n2;
+        xt = pSrc[2 * i] - pSrc[2 * l];
+        pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1u;
+
+        yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
+        pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1u;
+
+        pSrc[2u * l] = (((int32_t) (((q63_t) xt * cosVal) >> 32)) +
+                        ((int32_t) (((q63_t) yt * sinVal) >> 32)));
+
+        pSrc[2u * l + 1u] = (((int32_t) (((q63_t) yt * cosVal) >> 32)) -
+                             ((int32_t) (((q63_t) xt * sinVal) >> 32)));
+
+      }                         // butterfly loop end 
+
+    }                           // groups loop end 
+
+    twidCoefModifier = twidCoefModifier << 1u;
+  }                             // stages loop end 
+
+  n1 = n2;
+  n2 = n2 >> 1;
+  ia = 0;
+
+  cosVal = pCoef[ia * 2];
+  sinVal = pCoef[(ia * 2) + 1];
+  ia = ia + twidCoefModifier;
+
+  // loop for butterfly 
+  for (i = 0; i < fftLen; i += n1)
+  {
+    l = i + n2;
+    xt = pSrc[2 * i] - pSrc[2 * l];
+    pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
+
+    yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
+    pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
+
+    pSrc[2u * l] = xt;
+
+    pSrc[2u * l + 1u] = yt;
+
+    i += n1;
+    l = i + n2;
+
+    xt = pSrc[2 * i] - pSrc[2 * l];
+    pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
+
+    yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
+    pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
+
+    pSrc[2u * l] = xt;
+
+    pSrc[2u * l + 1u] = yt;
+
+  }                             // butterfly loop end 
+
+}
+
+
+void arm_radix2_butterfly_inverse_q31(
+  q31_t * pSrc,
+  uint32_t fftLen,
+  q31_t * pCoef,
+  uint16_t twidCoefModifier)
+{
+
+  int i, j, k, l;
+  int n1, n2, ia;
+  q31_t xt, yt, cosVal, sinVal;
+
+  //N = fftLen; 
+  n2 = fftLen;
+
+  n1 = n2;
+  n2 = n2 >> 1;
+  ia = 0;
+
+  // loop for groups 
+  for (i = 0; i < n2; i++)
+  {
+    cosVal = pCoef[ia * 2];
+    sinVal = pCoef[(ia * 2) + 1];
+    ia = ia + twidCoefModifier;
+
+    l = i + n2;
+    xt = (pSrc[2 * i] >> 2u) - (pSrc[2 * l] >> 2u);
+    pSrc[2 * i] = ((pSrc[2 * i] >> 2u) + (pSrc[2 * l] >> 2u)) >> 1u;
+
+    yt = (pSrc[2 * i + 1] >> 2u) - (pSrc[2 * l + 1] >> 2u);
+    pSrc[2 * i + 1] =
+      ((pSrc[2 * l + 1] >> 2u) + (pSrc[2 * i + 1] >> 2u)) >> 1u;
+
+    pSrc[2u * l] = (((int32_t) (((q63_t) xt * cosVal) >> 32)) -
+                    ((int32_t) (((q63_t) yt * sinVal) >> 32)));
+
+    pSrc[2u * l + 1u] = (((int32_t) (((q63_t) yt * cosVal) >> 32)) +
+                         ((int32_t) (((q63_t) xt * sinVal) >> 32)));
+
+  }                             // groups loop end 
+
+  twidCoefModifier = twidCoefModifier << 1u;
+
+  // loop for stage 
+  for (k = fftLen / 2; k > 2; k = k >> 1)
+  {
+    n1 = n2;
+    n2 = n2 >> 1;
+    ia = 0;
+
+    // loop for groups 
+    for (j = 0; j < n2; j++)
+    {
+      cosVal = pCoef[ia * 2];
+      sinVal = pCoef[(ia * 2) + 1];
+      ia = ia + twidCoefModifier;
+
+      // loop for butterfly 
+      for (i = j; i < fftLen; i += n1)
+      {
+        l = i + n2;
+        xt = pSrc[2 * i] - pSrc[2 * l];
+        pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1u;
+
+        yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
+        pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1u;
+
+        pSrc[2u * l] = (((int32_t) (((q63_t) xt * cosVal) >> 32)) -
+                        ((int32_t) (((q63_t) yt * sinVal) >> 32)));
+
+        pSrc[2u * l + 1u] = (((int32_t) (((q63_t) yt * cosVal) >> 32)) +
+                             ((int32_t) (((q63_t) xt * sinVal) >> 32)));
+
+      }                         // butterfly loop end 
+
+    }                           // groups loop end 
+
+    twidCoefModifier = twidCoefModifier << 1u;
+  }                             // stages loop end 
+
+  n1 = n2;
+  n2 = n2 >> 1;
+  ia = 0;
+
+  cosVal = pCoef[ia * 2];
+  sinVal = pCoef[(ia * 2) + 1];
+  ia = ia + twidCoefModifier;
+
+  // loop for butterfly 
+  for (i = 0; i < fftLen; i += n1)
+  {
+    l = i + n2;
+    xt = pSrc[2 * i] - pSrc[2 * l];
+    pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
+
+    yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
+    pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
+
+    pSrc[2u * l] = xt;
+
+    pSrc[2u * l + 1u] = yt;
+
+    i += n1;
+    l = i + n2;
+
+    xt = pSrc[2 * i] - pSrc[2 * l];
+    pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]);
+
+    yt = pSrc[2 * i + 1] - pSrc[2 * l + 1];
+    pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]);
+
+    pSrc[2u * l] = xt;
+
+    pSrc[2u * l + 1u] = yt;
+
+  }                             // butterfly loop end 
+
+}