mbed-os 6.10 versione
cmsis_dsp/TransformFunctions/arm_cfft_radix2_init_q31.c
- Committer:
- emilmont
- Date:
- 2013-05-30
- Revision:
- 2:da51fb522205
- Parent:
- 1:fdd22bb7aa52
- Child:
- 3:7a284390b0ce
File content as of revision 2:da51fb522205:
/* ---------------------------------------------------------------------- * 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 */