From 76177aa280494bb36d7a0bcbda1078d4db717020 Mon Sep 17 00:00:00 2001 From: Ali Labbene Date: Mon, 9 Dec 2019 11:25:19 +0100 Subject: Official ARM version: v4.5 --- Documentation/DSP/html/group___real_f_f_t.html | 773 +++++++++++++++++++++++++ 1 file changed, 773 insertions(+) create mode 100644 Documentation/DSP/html/group___real_f_f_t.html (limited to 'Documentation/DSP/html/group___real_f_f_t.html') diff --git a/Documentation/DSP/html/group___real_f_f_t.html b/Documentation/DSP/html/group___real_f_f_t.html new file mode 100644 index 0000000..15611b2 --- /dev/null +++ b/Documentation/DSP/html/group___real_f_f_t.html @@ -0,0 +1,773 @@ + + + + + +RealFFT +CMSIS-DSP: RealFFT + + + + + + + + + + + + + + + +
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CMSIS-DSP +  Version 1.4.7 +
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CMSIS DSP Software Library
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+Functions | +Variables
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RealFFT
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Transform Functions
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+Functions

void arm_rfft_f32 (const arm_rfft_instance_f32 *S, float32_t *pSrc, float32_t *pDst)
 Processing function for the floating-point RFFT/RIFFT.
 
void arm_rfft_fast_f32 (arm_rfft_fast_instance_f32 *S, float32_t *p, float32_t *pOut, uint8_t ifftFlag)
 Processing function for the floating-point real FFT.
 
arm_status arm_rfft_fast_init_f32 (arm_rfft_fast_instance_f32 *S, uint16_t fftLen)
 Initialization function for the floating-point real FFT.
 
arm_status arm_rfft_init_f32 (arm_rfft_instance_f32 *S, arm_cfft_radix4_instance_f32 *S_CFFT, uint32_t fftLenReal, uint32_t ifftFlagR, uint32_t bitReverseFlag)
 Initialization function for the floating-point RFFT/RIFFT.
 
arm_status arm_rfft_init_q15 (arm_rfft_instance_q15 *S, uint32_t fftLenReal, uint32_t ifftFlagR, uint32_t bitReverseFlag)
 Initialization function for the Q15 RFFT/RIFFT.
 
arm_status arm_rfft_init_q31 (arm_rfft_instance_q31 *S, uint32_t fftLenReal, uint32_t ifftFlagR, uint32_t bitReverseFlag)
 Initialization function for the Q31 RFFT/RIFFT.
 
void arm_rfft_q15 (const arm_rfft_instance_q15 *S, q15_t *pSrc, q15_t *pDst)
 Processing function for the Q15 RFFT/RIFFT.
 
void arm_rfft_q31 (const arm_rfft_instance_q31 *S, q31_t *pSrc, q31_t *pDst)
 Processing function for the Q31 RFFT/RIFFT.
 
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+Variables

static const float32_t realCoefA [8192]
 
static const float32_t realCoefB [8192]
 
static const q15_t ALIGN4 realCoefAQ15 [8192]
 
static const q15_t ALIGN4 realCoefBQ15 [8192]
 
static const q31_t realCoefAQ31 [8192]
 
static const q31_t realCoefBQ31 [8192]
 
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Description

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Function Documentation

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void arm_rfft_f32 (const arm_rfft_instance_f32 * S,
float32_t * pSrc,
float32_t * pDst 
)
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+
Deprecated:
Do not use this function. It has been superceded by arm_rfft_fast_f32 and will be removed in the future.
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Parameters
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[in]*Spoints to an instance of the floating-point RFFT/RIFFT structure.
[in]*pSrcpoints to the input buffer.
[out]*pDstpoints to the output buffer.
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Returns
none.
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References arm_bitreversal_f32(), arm_radix4_butterfly_f32(), arm_radix4_butterfly_inverse_f32(), arm_split_rfft_f32(), arm_split_rifft_f32(), arm_rfft_instance_f32::bitReverseFlagR, arm_cfft_radix4_instance_f32::bitRevFactor, arm_cfft_radix4_instance_f32::fftLen, arm_rfft_instance_f32::fftLenBy2, arm_rfft_instance_f32::ifftFlagR, arm_cfft_radix4_instance_f32::onebyfftLen, arm_cfft_radix4_instance_f32::pBitRevTable, arm_rfft_instance_f32::pCfft, arm_cfft_radix4_instance_f32::pTwiddle, arm_rfft_instance_f32::pTwiddleAReal, arm_rfft_instance_f32::pTwiddleBReal, arm_cfft_radix4_instance_f32::twidCoefModifier, and arm_rfft_instance_f32::twidCoefRModifier.

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void arm_rfft_fast_f32 (arm_rfft_fast_instance_f32 * S,
float32_t * p,
float32_t * pOut,
uint8_t ifftFlag 
)
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Parameters
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[in]*Spoints to an arm_rfft_fast_instance_f32 structure.
[in]*ppoints to the input buffer.
[in]*pOutpoints to the output buffer.
[in]ifftFlagRFFT if flag is 0, RIFFT if flag is 1
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Returns
none.
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References arm_cfft_f32(), arm_cfft_instance_f32::fftLen, arm_rfft_fast_instance_f32::fftLenRFFT, merge_rfft_f32(), arm_rfft_fast_instance_f32::Sint, and stage_rfft_f32().

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arm_status arm_rfft_fast_init_f32 (arm_rfft_fast_instance_f32 * S,
uint16_t fftLen 
)
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Parameters
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[in,out]*Spoints to an arm_rfft_fast_instance_f32 structure.
[in]fftLenlength of the Real Sequence.
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Returns
The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if fftLen is not a supported value.
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Description:
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The parameter fftLen Specifies length of RFFT/CIFFT process. Supported FFT Lengths are 32, 64, 128, 256, 512, 1024, 2048, 4096.
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This Function also initializes Twiddle factor table pointer and Bit reversal table pointer.
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References ARM_MATH_ARGUMENT_ERROR, ARM_MATH_SUCCESS, armBitRevIndexTable1024, ARMBITREVINDEXTABLE1024_TABLE_LENGTH, armBitRevIndexTable128, armBitRevIndexTable16, armBitRevIndexTable2048, ARMBITREVINDEXTABLE2048_TABLE_LENGTH, armBitRevIndexTable256, armBitRevIndexTable32, armBitRevIndexTable512, armBitRevIndexTable64, ARMBITREVINDEXTABLE_128_TABLE_LENGTH, ARMBITREVINDEXTABLE_256_TABLE_LENGTH, ARMBITREVINDEXTABLE_512_TABLE_LENGTH, ARMBITREVINDEXTABLE__16_TABLE_LENGTH, ARMBITREVINDEXTABLE__32_TABLE_LENGTH, ARMBITREVINDEXTABLE__64_TABLE_LENGTH, arm_cfft_instance_f32::bitRevLength, arm_cfft_instance_f32::fftLen, arm_rfft_fast_instance_f32::fftLenRFFT, arm_cfft_instance_f32::pBitRevTable, arm_cfft_instance_f32::pTwiddle, arm_rfft_fast_instance_f32::pTwiddleRFFT, arm_rfft_fast_instance_f32::Sint, status, twiddleCoef_1024, twiddleCoef_128, twiddleCoef_16, twiddleCoef_2048, twiddleCoef_256, twiddleCoef_32, twiddleCoef_512, twiddleCoef_64, twiddleCoef_rfft_1024, twiddleCoef_rfft_128, twiddleCoef_rfft_2048, twiddleCoef_rfft_256, twiddleCoef_rfft_32, twiddleCoef_rfft_4096, twiddleCoef_rfft_512, and twiddleCoef_rfft_64.

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arm_status arm_rfft_init_f32 (arm_rfft_instance_f32 * S,
arm_cfft_radix4_instance_f32 * S_CFFT,
uint32_t fftLenReal,
uint32_t ifftFlagR,
uint32_t bitReverseFlag 
)
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+
Deprecated:
Do not use this function. It has been superceded by arm_rfft_fast_init_f32 and will be removed in the future.
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Parameters
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[in,out]*Spoints to an instance of the floating-point RFFT/RIFFT structure.
[in,out]*S_CFFTpoints to an instance of the floating-point CFFT/CIFFT structure.
[in]fftLenReallength of the FFT.
[in]ifftFlagRflag that selects forward (ifftFlagR=0) or inverse (ifftFlagR=1) transform.
[in]bitReverseFlagflag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
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Returns
The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if fftLenReal is not a supported value.
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Description:
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The parameter fftLenReal Specifies length of RFFT/RIFFT Process. Supported FFT Lengths are 128, 512, 2048.
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The parameter ifftFlagR controls whether a forward or inverse transform is computed. Set(=1) ifftFlagR to calculate RIFFT, otherwise RFFT is calculated.
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The parameter bitReverseFlag 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.
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This function also initializes Twiddle factor table.
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References arm_cfft_radix4_init_f32(), ARM_MATH_ARGUMENT_ERROR, ARM_MATH_SUCCESS, arm_rfft_instance_f32::bitReverseFlagR, arm_rfft_instance_f32::fftLenBy2, arm_rfft_instance_f32::fftLenReal, arm_rfft_instance_f32::ifftFlagR, arm_rfft_instance_f32::pCfft, arm_rfft_instance_f32::pTwiddleAReal, arm_rfft_instance_f32::pTwiddleBReal, realCoefA, realCoefB, status, and arm_rfft_instance_f32::twidCoefRModifier.

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Referenced by arm_dct4_init_f32().

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arm_status arm_rfft_init_q15 (arm_rfft_instance_q15 * S,
uint32_t fftLenReal,
uint32_t ifftFlagR,
uint32_t bitReverseFlag 
)
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Parameters
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[in,out]*Spoints to an instance of the Q15 RFFT/RIFFT structure.
[in]fftLenReallength of the FFT.
[in]ifftFlagRflag that selects forward (ifftFlagR=0) or inverse (ifftFlagR=1) transform.
[in]bitReverseFlagflag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
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Returns
The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if fftLenReal is not a supported value.
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Description:
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The parameter fftLenReal Specifies length of RFFT/RIFFT Process. Supported FFT Lengths are 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192.
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The parameter ifftFlagR controls whether a forward or inverse transform is computed. Set(=1) ifftFlagR to calculate RIFFT, otherwise RFFT is calculated.
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The parameter bitReverseFlag 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.
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This function also initializes Twiddle factor table.
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References arm_cfft_sR_q15_len1024, arm_cfft_sR_q15_len128, arm_cfft_sR_q15_len16, arm_cfft_sR_q15_len2048, arm_cfft_sR_q15_len256, arm_cfft_sR_q15_len32, arm_cfft_sR_q15_len4096, arm_cfft_sR_q15_len512, arm_cfft_sR_q15_len64, ARM_MATH_ARGUMENT_ERROR, ARM_MATH_SUCCESS, arm_rfft_instance_q15::bitReverseFlagR, arm_rfft_instance_q15::fftLenReal, arm_rfft_instance_q15::ifftFlagR, arm_rfft_instance_q15::pCfft, arm_rfft_instance_q15::pTwiddleAReal, arm_rfft_instance_q15::pTwiddleBReal, realCoefAQ15, realCoefBQ15, status, and arm_rfft_instance_q15::twidCoefRModifier.

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Referenced by arm_dct4_init_q15().

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arm_status arm_rfft_init_q31 (arm_rfft_instance_q31 * S,
uint32_t fftLenReal,
uint32_t ifftFlagR,
uint32_t bitReverseFlag 
)
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Parameters
+ + + + + +
[in,out]*Spoints to an instance of the Q31 RFFT/RIFFT structure.
[in]fftLenReallength of the FFT.
[in]ifftFlagRflag that selects forward (ifftFlagR=0) or inverse (ifftFlagR=1) transform.
[in]bitReverseFlagflag that enables (bitReverseFlag=1) or disables (bitReverseFlag=0) bit reversal of output.
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Returns
The function returns ARM_MATH_SUCCESS if initialization is successful or ARM_MATH_ARGUMENT_ERROR if fftLenReal is not a supported value.
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Description:
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The parameter fftLenReal Specifies length of RFFT/RIFFT Process. Supported FFT Lengths are 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192.
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The parameter ifftFlagR controls whether a forward or inverse transform is computed. Set(=1) ifftFlagR to calculate RIFFT, otherwise RFFT is calculated.
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The parameter bitReverseFlag 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.
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This function also initializes Twiddle factor table.
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References arm_cfft_sR_q31_len1024, arm_cfft_sR_q31_len128, arm_cfft_sR_q31_len16, arm_cfft_sR_q31_len2048, arm_cfft_sR_q31_len256, arm_cfft_sR_q31_len32, arm_cfft_sR_q31_len4096, arm_cfft_sR_q31_len512, arm_cfft_sR_q31_len64, ARM_MATH_ARGUMENT_ERROR, ARM_MATH_SUCCESS, arm_rfft_instance_q31::bitReverseFlagR, arm_rfft_instance_q31::fftLenReal, arm_rfft_instance_q31::ifftFlagR, arm_rfft_instance_q31::pCfft, arm_rfft_instance_q31::pTwiddleAReal, arm_rfft_instance_q31::pTwiddleBReal, realCoefAQ31, realCoefBQ31, status, and arm_rfft_instance_q31::twidCoefRModifier.

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Referenced by arm_dct4_init_q31().

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void arm_rfft_q15 (const arm_rfft_instance_q15 * S,
q15_t * pSrc,
q15_t * pDst 
)
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Parameters
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[in]*Spoints to an instance of the Q15 RFFT/RIFFT structure.
[in]*pSrcpoints to the input buffer.
[out]*pDstpoints to the output buffer.
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Returns
none.
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Input an output formats:
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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:
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+RFFTQ15.gif +
+Input and Output Formats for Q15 RFFT
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+RIFFTQ15.gif +
+Input and Output Formats for Q15 RIFFT
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References arm_cfft_q15(), arm_split_rfft_q15(), arm_split_rifft_q15(), arm_rfft_instance_q15::bitReverseFlagR, arm_rfft_instance_q15::fftLenReal, arm_rfft_instance_q15::ifftFlagR, arm_rfft_instance_q15::pCfft, arm_rfft_instance_q15::pTwiddleAReal, arm_rfft_instance_q15::pTwiddleBReal, and arm_rfft_instance_q15::twidCoefRModifier.

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void arm_rfft_q31 (const arm_rfft_instance_q31 * S,
q31_t * pSrc,
q31_t * pDst 
)
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Parameters
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[in]*Spoints to an instance of the Q31 RFFT/RIFFT structure.
[in]*pSrcpoints to the input buffer.
[out]*pDstpoints to the output buffer.
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Returns
none.
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Input an output formats:
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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:
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+RFFTQ31.gif +
+Input and Output Formats for Q31 RFFT
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+RIFFTQ31.gif +
+Input and Output Formats for Q31 RIFFT
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References arm_cfft_q31(), arm_split_rfft_q31(), arm_split_rifft_q31(), arm_rfft_instance_q31::bitReverseFlagR, arm_rfft_instance_q31::fftLenReal, arm_rfft_instance_q31::ifftFlagR, arm_rfft_instance_q31::pCfft, arm_rfft_instance_q31::pTwiddleAReal, arm_rfft_instance_q31::pTwiddleBReal, and arm_rfft_instance_q31::twidCoefRModifier.

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Referenced by arm_dct4_q31().

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Variable Documentation

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const float32_t realCoefA[8192]
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Generation of realCoefA array:
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n = 4096 
for (i = 0; i < n; i++)    
+ {    
+   pATable[2 * i] = 0.5 * (1.0 - sin (2 * PI / (double) (2 * n) * (double) i));    
+   pATable[2 * i + 1] = 0.5 * (-1.0 * cos (2 * PI / (double) (2 * n) * (double) i));    
+ }
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Referenced by arm_rfft_init_f32().

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const q15_t ALIGN4 realCoefAQ15[8192]
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Generation fixed-point realCoefAQ15 array in Q15 format:
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n = 4096 
for (i = 0; i < n; i++)    
+ {    
+   pATable[2 * i] = 0.5 * (1.0 - sin (2 * PI / (double) (2 * n) * (double) i));    
+   pATable[2 * i + 1] = 0.5 * (-1.0 * cos (2 * PI / (double) (2 * n) * (double) i));    
+ }
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Convert to fixed point Q15 format round(pATable[i] * pow(2, 15))
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Referenced by arm_rfft_init_q15().

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const q31_t realCoefAQ31[8192]
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Generation fixed-point realCoefAQ31 array in Q31 format:
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n = 4096 
for (i = 0; i < n; i++)    
+{    
+   pATable[2 * i] = 0.5 * (1.0 - sin (2 * PI / (double) (2 * n) * (double) i));    
+   pATable[2 * i + 1] = 0.5 * (-1.0 * cos (2 * PI / (double) (2 * n) * (double) i));    
+}
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Convert to fixed point Q31 format round(pATable[i] * pow(2, 31))
+ +

Referenced by arm_rfft_init_q31().

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const float32_t realCoefB[8192]
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Generation of realCoefB array:
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n = 4096 
for (i = 0; i < n; i++)    
+{    
+   pBTable[2 * i] = 0.5 * (1.0 + sin (2 * PI / (double) (2 * n) * (double) i));    
+   pBTable[2 * i + 1] = 0.5 * (1.0 * cos (2 * PI / (double) (2 * n) * (double) i));    
+ }
+ +

Referenced by arm_rfft_init_f32().

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const q15_t ALIGN4 realCoefBQ15[8192]
+ 		+static
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+
Generation of real_CoefB array:
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n = 4096 
for (i = 0; i < n; i++)    
+ {    
+   pBTable[2 * i] = 0.5 * (1.0 + sin (2 * PI / (double) (2 * n) * (double) i));    
+   pBTable[2 * i + 1] = 0.5 * (1.0 * cos (2 * PI / (double) (2 * n) * (double) i));    
+ }
+
Convert to fixed point Q15 format round(pBTable[i] * pow(2, 15))
+ +

Referenced by arm_rfft_init_q15().

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const q31_t realCoefBQ31[8192]
+ 		+static
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+
Generation of realCoefBQ31 array:
+
n = 4096 
for (i = 0; i < n; i++)    
+{    
+   pBTable[2 * i] = 0.5 * (1.0 + sin (2 * PI / (double) (2 * n) * (double) i));    
+   pBTable[2 * i + 1] = 0.5 * (1.0 * cos (2 * PI / (double) (2 * n) * (double) i));    
+}
+
Convert to fixed point Q31 format round(pBTable[i] * pow(2, 31))
+ +

Referenced by arm_rfft_init_q31().

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+ + + + -- cgit