Complex FFT Tables

Collaboration diagram for Complex FFT Tables:

Functions
const q15_t	__ALIGNED (4)
	Q15 table for reciprocal.

Variables
const q31_t	tptRecipTableQ31 [64]
	Q31 table for reciprocal.
const q31_t	sqrt_initial_lut_q31 [32]
const q15_t	sqrt_initial_lut_q15 [16]

Detailed Description

Function Documentation

__ALIGNED()

const q15_t __ALIGNED

(

4

)

Q15 table for reciprocal.

Pseudo code for Generation of Bit reversal Table is

pre>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

Variable Documentation

sqrt_initial_lut_q15

const q15_t sqrt_initial_lut_q15[16]

Initial value:

= {8192, 7327, 6689, 6193, 5793, 5461,
                                        5181, 4940, 4730, 4544, 4379, 4230,
                                        4096, 3974, 3862, 3759}

sqrt_initial_lut_q31

const q31_t sqrt_initial_lut_q31[32]

Initial value:

= {
    536870912, 506166750, 480191942, 457845052, 438353264, 421156193, 405836263,
    392075079, 379625062, 368290407, 357913941, 348367849, 339546978, 331363921,
    323745341, 316629190, 309962566, 303700050, 297802400, 292235509, 286969573,
    281978417, 277238947, 272730696, 268435456, 264336964, 260420644, 256673389,
    253083375, 249639903, 246333269, 243154642}

tptRecipTableQ31

const q31_t tptRecipTableQ31[64]

Initial value:

= {
    0x7F03F03F, 0x7D137420, 0x7B31E739, 0x795E9F94, 0x7798FD29, 0x75E06928,
    0x7434554D, 0x72943B4B, 0x70FF9C40, 0x6F760031, 0x6DF6F593, 0x6C8210E3,
    0x6B16EC3A, 0x69B526F6, 0x685C655F, 0x670C505D, 0x65C4952D, 0x6484E519,
    0x634CF53E, 0x621C7E4F, 0x60F33C61, 0x5FD0EEB3, 0x5EB55785, 0x5DA03BEB,
    0x5C9163A1, 0x5B8898E6, 0x5A85A85A, 0x598860DF, 0x58909373, 0x579E1318,
    0x56B0B4B8, 0x55C84F0B, 0x54E4BA80, 0x5405D124, 0x532B6E8F, 0x52556FD0,
    0x5183B35A, 0x50B618F3, 0x4FEC81A2, 0x4F26CFA2, 0x4E64E64E, 0x4DA6AA1D,
    0x4CEC008B, 0x4C34D010, 0x4B810016, 0x4AD078EF, 0x4A2323C4, 0x4978EA96,
    0x48D1B827, 0x482D77FE, 0x478C1657, 0x46ED801D, 0x4651A2E5, 0x45B86CE2,
    0x4521CCE1, 0x448DB244, 0x43FC0CFA, 0x436CCD78, 0x42DFE4B4, 0x42554426,
    0x41CCDDB6, 0x4146A3C6, 0x40C28923, 0x40408102}

Q31 table for reciprocal.