Diff: cmsis_dsp/TransformFunctions/arm_cfft_radix2_init_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_init_q31.c	Wed Nov 28 12:30:09 2012 +0000
@@ -0,0 +1,164 @@
+/* ----------------------------------------------------------------------   
+* Copyright (C) 2010 ARM Limited. All rights reserved.   
+*   
+* $Date:        15. February 2012  
+* $Revision:     V1.1.0  
+*   
+* Project:         CMSIS DSP Library   
+* Title:        arm_cfft_radix2_init_q31.c   
+*   
+* Description:    Radix-2 Decimation in Frequency Fixed-point CFFT & CIFFT Initialization 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.  
+*   
+* -------------------------------------------------------------------- */
+
+
+#include "arm_math.h"
+#include "arm_common_tables.h"
+
+/**   
+ * @ingroup groupTransforms   
+ */
+
+/**   
+ * @addtogroup Radix2_CFFT_CIFFT   
+ * @{   
+ */
+
+
+/**    
+*    
+* @brief  Initialization function for the Q31 CFFT/CIFFT.   
+* @param[in,out] *S             points to an instance of the Q31 CFFT/CIFFT structure.   
+* @param[in]     fftLen         length of the FFT.  
+* @param[in]     ifftFlag       flag that selects forward (ifftFlag=0) or inverse (ifftFlag=1) transform.  
+* @param[in]     bitReverseFlag flag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.  
+* @return        The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if <code>fftLen</code> is not a supported value.  
+*   
+* \par Description:  
+* \par   
+* The parameter <code>ifftFlag</code> controls whether a forward or inverse transform is computed.   
+* Set(=1) ifftFlag for calculation of CIFFT otherwise  CFFT is calculated  
+* \par   
+* The parameter <code>bitReverseFlag</code> controls whether output is in normal order or bit reversed order.   
+* Set(=1) bitReverseFlag for output to be in normal order otherwise output is in bit reversed order.   
+* \par   
+* The parameter <code>fftLen</code>    Specifies length of CFFT/CIFFT process. Supported FFT Lengths are 16, 64, 256, 1024.   
+* \par   
+* This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.   
+*/
+
+arm_status arm_cfft_radix2_init_q31(
+  arm_cfft_radix2_instance_q31 * S,
+  uint16_t fftLen,
+  uint8_t ifftFlag,
+  uint8_t bitReverseFlag)
+{
+  /*  Initialise the default arm status */
+  arm_status status = ARM_MATH_SUCCESS;
+
+  /*  Initialise the FFT length */
+  S->fftLen = fftLen;
+
+  /*  Initialise the Twiddle coefficient pointer */
+  S->pTwiddle = (q31_t *) twiddleCoefQ31;
+  /*  Initialise the Flag for selection of CFFT or CIFFT */
+  S->ifftFlag = ifftFlag;
+  /*  Initialise the Flag for calculation Bit reversal or not */
+  S->bitReverseFlag = bitReverseFlag;
+
+  /*  Initializations of Instance structure depending on the FFT length */
+  switch (S->fftLen)
+  {
+    /*  Initializations of structure parameters for 4096 point FFT */
+  case 4096u:
+    /*  Initialise the twiddle coef modifier value */
+    S->twidCoefModifier = 1u;
+    /*  Initialise the bit reversal table modifier */
+    S->bitRevFactor = 1u;
+    /*  Initialise the bit reversal table pointer */
+    S->pBitRevTable = (uint16_t *) armBitRevTable;
+    break;
+
+    /*  Initializations of structure parameters for 2048 point FFT */
+  case 2048u:
+    /*  Initialise the twiddle coef modifier value */
+    S->twidCoefModifier = 2u;
+    /*  Initialise the bit reversal table modifier */
+    S->bitRevFactor = 2u;
+    /*  Initialise the bit reversal table pointer */
+    S->pBitRevTable = (uint16_t *) & armBitRevTable[1];
+    break;
+
+    /*  Initializations of structure parameters for 1024 point FFT */
+  case 1024u:
+    /*  Initialise the twiddle coef modifier value */
+    S->twidCoefModifier = 4u;
+    /*  Initialise the bit reversal table modifier */
+    S->bitRevFactor = 4u;
+    /*  Initialise the bit reversal table pointer */
+    S->pBitRevTable = (uint16_t *) & armBitRevTable[3];
+    break;
+
+    /*  Initializations of structure parameters for 512 point FFT */
+  case 512u:
+    /*  Initialise the twiddle coef modifier value */
+    S->twidCoefModifier = 8u;
+    /*  Initialise the bit reversal table modifier */
+    S->bitRevFactor = 8u;
+    /*  Initialise the bit reversal table pointer */
+    S->pBitRevTable = (uint16_t *) & armBitRevTable[7];
+    break;
+
+  case 256u:
+    /*  Initializations of structure parameters for 256 point FFT */
+    S->twidCoefModifier = 16u;
+    S->bitRevFactor = 16u;
+    S->pBitRevTable = (uint16_t *) & armBitRevTable[15];
+    break;
+
+  case 128u:
+    /*  Initializations of structure parameters for 128 point FFT */
+    S->twidCoefModifier = 32u;
+    S->bitRevFactor = 32u;
+    S->pBitRevTable = (uint16_t *) & armBitRevTable[31];
+    break;
+
+  case 64u:
+    /*  Initializations of structure parameters for 64 point FFT */
+    S->twidCoefModifier = 64u;
+    S->bitRevFactor = 64u;
+    S->pBitRevTable = (uint16_t *) & armBitRevTable[63];
+    break;
+
+  case 32u:
+    /*  Initializations of structure parameters for 32 point FFT */
+    S->twidCoefModifier = 128u;
+    S->bitRevFactor = 128u;
+    S->pBitRevTable = (uint16_t *) & armBitRevTable[127];
+    break;
+
+  case 16u:
+    /*  Initializations of structure parameters for 16 point FFT */
+    S->twidCoefModifier = 256u;
+    S->bitRevFactor = 256u;
+    S->pBitRevTable = (uint16_t *) & armBitRevTable[255];
+    break;
+
+
+  default:
+    /*  Reporting argument error if fftSize is not valid value */
+    status = ARM_MATH_ARGUMENT_ERROR;
+    break;
+  }
+
+  return (status);
+}
+
+/**   
+ * @} end of Radix2_CFFT_CIFFT group   
+ */