Complex FFT Tables

Variables
const uint16_t	armBitRevTable [1024]
const float32_t	twiddleCoef_16 [32]
const float32_t	twiddleCoef_32 [64]
const float32_t	twiddleCoef_64 [128]
const float32_t	twiddleCoef_128 [256]
const float32_t	twiddleCoef_256 [512]
const float32_t	twiddleCoef_512 [1024]
const float32_t	twiddleCoef_1024 [2048]
const float32_t	twiddleCoef_2048 [4096]
const float32_t	twiddleCoef_4096 [8192]
const q31_t	twiddleCoef_16_q31 [24]
const q31_t	twiddleCoef_32_q31 [48]
const q31_t	twiddleCoef_64_q31 [96]
const q31_t	twiddleCoef_128_q31 [192]
const q31_t	twiddleCoef_256_q31 [384]
const q31_t	twiddleCoef_512_q31 [768]
const q31_t	twiddleCoef_1024_q31 [1536]
const q31_t	twiddleCoef_2048_q31 [3072]
const q31_t	twiddleCoef_4096_q31 [6144]
const q15_t	twiddleCoef_16_q15 [24]
const q15_t	twiddleCoef_32_q15 [48]
const q15_t	twiddleCoef_64_q15 [96]
const q15_t	twiddleCoef_128_q15 [192]
const q15_t	twiddleCoef_256_q15 [384]
const q15_t	twiddleCoef_512_q15 [768]
const q15_t	twiddleCoef_1024_q15 [1536]
const q15_t	twiddleCoef_2048_q15 [3072]
const q15_t	twiddleCoef_4096_q15 [6144]

Description

Variable Documentation

const uint16_t armBitRevTable[1024]

Pseudo code for Generation of Bit reversal Table is

for(l=1;l <= N/4;l++)
{
  for(i=0;i<logN2;i++)
  {
    a[i]=l&(1<<i);
  }
  for(j=0; j<logN2; j++)
  {
    if (a[j]!=0)
    y[l]+=(1<<((logN2-1)-j));
  }
  y[l] = y[l] >> 1;
 } 

where N = 4096 logN2 = 12

N is the maximum FFT Size supported

Referenced by arm_cfft_radix2_init_f32(), arm_cfft_radix2_init_q15(), arm_cfft_radix2_init_q31(), arm_cfft_radix4_init_f32(), arm_cfft_radix4_init_q15(), and arm_cfft_radix4_init_q31().

const float32_t twiddleCoef_1024[2048]

Example code for Floating-point Twiddle factors Generation:

for(i = 0; i< N/; i++)
{
      twiddleCoef[2*i]= cos(i * 2*PI/(float)N);
      twiddleCoef[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 1024 and PI = 3.14159265358979

Cos and Sin values are in interleaved fashion

Referenced by arm_rfft_fast_init_f32().

const q15_t twiddleCoef_1024_q15[1536]

Example code for q15 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefq15[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefq15[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 1024 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to q15(Fixed point 1.15): round(twiddleCoefq15(i) * pow(2, 15))

const q31_t twiddleCoef_1024_q31[1536]

Example code for Q31 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefQ31[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefQ31[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 1024 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to Q31(Fixed point 1.31): round(twiddleCoefQ31(i) * pow(2, 31))

const float32_t twiddleCoef_128[256]

Example code for Floating-point Twiddle factors Generation:

for(i = 0; i< N/; i++)
{
      twiddleCoef[2*i]= cos(i * 2*PI/(float)N);
      twiddleCoef[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 128 and PI = 3.14159265358979

Cos and Sin values are in interleaved fashion

Referenced by arm_rfft_fast_init_f32().

const q15_t twiddleCoef_128_q15[192]

Example code for q15 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefq15[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefq15[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 128 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to q15(Fixed point 1.15): round(twiddleCoefq15(i) * pow(2, 15))

const q31_t twiddleCoef_128_q31[192]

Example code for Q31 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefQ31[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefQ31[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 128 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to Q31(Fixed point 1.31): round(twiddleCoefQ31(i) * pow(2, 31))

const float32_t twiddleCoef_16[32]

Example code for Floating-point Twiddle factors Generation:

for(i = 0; i< N/; i++)
{
      twiddleCoef[2*i]= cos(i * 2*PI/(float)N);
      twiddleCoef[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 16 and PI = 3.14159265358979

Cos and Sin values are in interleaved fashion

Referenced by arm_rfft_fast_init_f32().

const q15_t twiddleCoef_16_q15[24]

Example code for q15 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefq15[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefq15[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 16 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to q15(Fixed point 1.15): round(twiddleCoefq15(i) * pow(2, 15))

const q31_t twiddleCoef_16_q31[24]

Example code for Q31 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefQ31[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefQ31[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 16 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to Q31(Fixed point 1.31): round(twiddleCoefQ31(i) * pow(2, 31))

const float32_t twiddleCoef_2048[4096]

Example code for Floating-point Twiddle factors Generation:

for(i = 0; i< N/; i++)
{
      twiddleCoef[2*i]= cos(i * 2*PI/(float)N);
      twiddleCoef[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 2048 and PI = 3.14159265358979

Cos and Sin values are in interleaved fashion

Referenced by arm_rfft_fast_init_f32().

const q15_t twiddleCoef_2048_q15[3072]

Example code for q15 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefq15[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefq15[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 2048 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to q15(Fixed point 1.15): round(twiddleCoefq15(i) * pow(2, 15))

const q31_t twiddleCoef_2048_q31[3072]

Example code for Q31 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefQ31[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefQ31[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 2048 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to Q31(Fixed point 1.31): round(twiddleCoefQ31(i) * pow(2, 31))

const float32_t twiddleCoef_256[512]

Example code for Floating-point Twiddle factors Generation:

for(i = 0; i< N/; i++)
{
      twiddleCoef[2*i]= cos(i * 2*PI/(float)N);
      twiddleCoef[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 256 and PI = 3.14159265358979

Cos and Sin values are in interleaved fashion

Referenced by arm_rfft_fast_init_f32().

const q15_t twiddleCoef_256_q15[384]

Example code for q15 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefq15[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefq15[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 256 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to q15(Fixed point 1.15): round(twiddleCoefq15(i) * pow(2, 15))

const q31_t twiddleCoef_256_q31[384]

Example code for Q31 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefQ31[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefQ31[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 256 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to Q31(Fixed point 1.31): round(twiddleCoefQ31(i) * pow(2, 31))

const float32_t twiddleCoef_32[64]

Example code for Floating-point Twiddle factors Generation:

for(i = 0; i< N/; i++)
{
      twiddleCoef[2*i]= cos(i * 2*PI/(float)N);
      twiddleCoef[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 32 and PI = 3.14159265358979

Cos and Sin values are in interleaved fashion

Referenced by arm_rfft_fast_init_f32().

const q15_t twiddleCoef_32_q15[48]

Example code for q15 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefq15[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefq15[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 32 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to q15(Fixed point 1.15): round(twiddleCoefq15(i) * pow(2, 15))

const q31_t twiddleCoef_32_q31[48]

Example code for Q31 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefQ31[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefQ31[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 32 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to Q31(Fixed point 1.31): round(twiddleCoefQ31(i) * pow(2, 31))

const float32_t twiddleCoef_4096[8192]

Example code for Floating-point Twiddle factors Generation:

for(i = 0; i< N/; i++)
{
      twiddleCoef[2*i]= cos(i * 2*PI/(float)N);
      twiddleCoef[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 4096 and PI = 3.14159265358979

Cos and Sin values are in interleaved fashion

const q15_t twiddleCoef_4096_q15[6144]

Example code for q15 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefq15[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefq15[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 4096 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to q15(Fixed point 1.15): round(twiddleCoefq15(i) * pow(2, 15))

Referenced by arm_cfft_radix2_init_q15(), and arm_cfft_radix4_init_q15().

const q31_t twiddleCoef_4096_q31[6144]

Example code for Q31 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefQ31[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefQ31[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 4096 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to Q31(Fixed point 1.31): round(twiddleCoefQ31(i) * pow(2, 31))

Referenced by arm_cfft_radix2_init_q31(), and arm_cfft_radix4_init_q31().

const float32_t twiddleCoef_512[1024]

Example code for Floating-point Twiddle factors Generation:

for(i = 0; i< N/; i++)
{
      twiddleCoef[2*i]= cos(i * 2*PI/(float)N);
      twiddleCoef[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 512 and PI = 3.14159265358979

Cos and Sin values are in interleaved fashion

Referenced by arm_rfft_fast_init_f32().

const q15_t twiddleCoef_512_q15[768]

Example code for q15 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefq15[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefq15[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 512 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to q15(Fixed point 1.15): round(twiddleCoefq15(i) * pow(2, 15))

const q31_t twiddleCoef_512_q31[768]

Example code for Q31 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefQ31[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefQ31[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 512 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to Q31(Fixed point 1.31): round(twiddleCoefQ31(i) * pow(2, 31))

const float32_t twiddleCoef_64[128]

Example code for Floating-point Twiddle factors Generation:

for(i = 0; i< N/; i++)
{
      twiddleCoef[2*i]= cos(i * 2*PI/(float)N);
      twiddleCoef[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 64 and PI = 3.14159265358979

Cos and Sin values are in interleaved fashion

Referenced by arm_rfft_fast_init_f32().

const q15_t twiddleCoef_64_q15[96]

Example code for q15 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefq15[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefq15[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 64 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to q15(Fixed point 1.15): round(twiddleCoefq15(i) * pow(2, 15))

const q31_t twiddleCoef_64_q31[96]

Example code for Q31 Twiddle factors Generation::

for(i = 0; i< 3N/4; i++)
{
   twiddleCoefQ31[2*i]= cos(i * 2*PI/(float)N);
   twiddleCoefQ31[2*i+1]= sin(i * 2*PI/(float)N);
} 

where N = 64 and PI = 3.14159265358979

Cos and Sin values are interleaved fashion

Convert Floating point to Q31(Fixed point 1.31): round(twiddleCoefQ31(i) * pow(2, 31))