arm_cfft_radix4_q15.c
934 lines
| 28.3 KiB
| text/x-c
|
CLexer
|
r16 | /* ---------------------------------------------------------------------- | ||
* Copyright (C) 2010 ARM Limited. All rights reserved. | ||||
* | ||||
* $Date: 29. November 2010 | ||||
* $Revision: V1.0.3 | ||||
* | ||||
* Project: CMSIS DSP Library | ||||
* Title: arm_cfft_radix4_q15.c | ||||
* | ||||
* Description: This file has function definition of Radix-4 FFT & IFFT function and | ||||
* In-place bit reversal using bit reversal table | ||||
* | ||||
* Target Processor: Cortex-M4/Cortex-M3 | ||||
* | ||||
* Version 1.0.3 2010/11/29 | ||||
* Re-organized the CMSIS folders and updated documentation. | ||||
* | ||||
* Version 1.0.2 2010/11/11 | ||||
* Documentation updated. | ||||
* | ||||
* Version 1.0.1 2010/10/05 | ||||
* Production release and review comments incorporated. | ||||
* | ||||
* Version 1.0.0 2010/09/20 | ||||
* Production release and review comments incorporated. | ||||
* | ||||
* Version 0.0.5 2010/04/26 | ||||
* incorporated review comments and updated with latest CMSIS layer | ||||
* | ||||
* Version 0.0.3 2010/03/10 | ||||
* Initial version | ||||
* -------------------------------------------------------------------- */ | ||||
#include "arm_math.h" | ||||
/** | ||||
* @ingroup groupTransforms | ||||
*/ | ||||
/** | ||||
* @addtogroup CFFT_CIFFT | ||||
* @{ | ||||
*/ | ||||
/** | ||||
* @details | ||||
* @brief Processing function for the Q15 CFFT/CIFFT. | ||||
* @param[in] *S points to an instance of the Q15 CFFT/CIFFT structure. | ||||
* @param[in, out] *pSrc points to the complex data buffer. Processing occurs in-place. | ||||
* @return none. | ||||
* | ||||
* \par Input and output formats: | ||||
* \par | ||||
* Internally input is downscaled by 2 for every stage to avoid saturations inside CFFT/CIFFT process. | ||||
* Hence the output format is different for different FFT sizes. | ||||
* The input and output formats for different FFT sizes and number of bits to upscale are mentioned in the tables below for CFFT and CIFFT: | ||||
* \par | ||||
* \image html CFFTQ15.gif "Input and Output Formats for Q15 CFFT" | ||||
* \image html CIFFTQ15.gif "Input and Output Formats for Q15 CIFFT" | ||||
*/ | ||||
void arm_cfft_radix4_q15( | ||||
const arm_cfft_radix4_instance_q15 * S, | ||||
q15_t * pSrc) | ||||
{ | ||||
if(S->ifftFlag == 1u) | ||||
{ | ||||
/* Complex IFFT radix-4 */ | ||||
arm_radix4_butterfly_inverse_q15(pSrc, S->fftLen, S->pTwiddle, | ||||
S->twidCoefModifier); | ||||
} | ||||
else | ||||
{ | ||||
/* Complex FFT radix-4 */ | ||||
arm_radix4_butterfly_q15(pSrc, S->fftLen, S->pTwiddle, | ||||
S->twidCoefModifier); | ||||
} | ||||
if(S->bitReverseFlag == 1u) | ||||
{ | ||||
/* Bit Reversal */ | ||||
arm_bitreversal_q15(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable); | ||||
} | ||||
} | ||||
/** | ||||
* @} end of CFFT_CIFFT group | ||||
*/ | ||||
/* | ||||
* Radix-4 FFT algorithm used is : | ||||
* | ||||
* Input real and imaginary data: | ||||
* x(n) = xa + j * ya | ||||
* x(n+N/4 ) = xb + j * yb | ||||
* x(n+N/2 ) = xc + j * yc | ||||
* x(n+3N 4) = xd + j * yd | ||||
* | ||||
* | ||||
* Output real and imaginary data: | ||||
* x(4r) = xa'+ j * ya' | ||||
* x(4r+1) = xb'+ j * yb' | ||||
* x(4r+2) = xc'+ j * yc' | ||||
* x(4r+3) = xd'+ j * yd' | ||||
* | ||||
* | ||||
* Twiddle factors for radix-4 FFT: | ||||
* Wn = co1 + j * (- si1) | ||||
* W2n = co2 + j * (- si2) | ||||
* W3n = co3 + j * (- si3) | ||||
* The real and imaginary output values for the radix-4 butterfly are | ||||
* xa' = xa + xb + xc + xd | ||||
* ya' = ya + yb + yc + yd | ||||
* xb' = (xa+yb-xc-yd)* co1 + (ya-xb-yc+xd)* (si1) | ||||
* yb' = (ya-xb-yc+xd)* co1 - (xa+yb-xc-yd)* (si1) | ||||
* xc' = (xa-xb+xc-xd)* co2 + (ya-yb+yc-yd)* (si2) | ||||
* yc' = (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) | ||||
* xd' = (xa-yb-xc+yd)* co3 + (ya+xb-yc-xd)* (si3) | ||||
* yd' = (ya+xb-yc-xd)* co3 - (xa-yb-xc+yd)* (si3) | ||||
* | ||||
*/ | ||||
/** | ||||
* @brief Core function for the Q15 CFFT butterfly process. | ||||
* @param[in, out] *pSrc16 points to the in-place buffer of Q15 data type. | ||||
* @param[in] fftLen length of the FFT. | ||||
* @param[in] *pCoef16 points to twiddle coefficient buffer. | ||||
* @param[in] twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table. | ||||
* @return none. | ||||
*/ | ||||
void arm_radix4_butterfly_q15( | ||||
q15_t * pSrc16, | ||||
uint32_t fftLen, | ||||
q15_t * pCoef16, | ||||
uint32_t twidCoefModifier) | ||||
{ | ||||
q31_t R, S, T, U; | ||||
q31_t C1, C2, C3, out1, out2; | ||||
q31_t *pSrc, *pCoeff; | ||||
uint32_t n1, n2, ic, i0, i1, i2, i3, j, k; | ||||
q15_t in; | ||||
/* Total process is divided into three stages */ | ||||
/* process first stage, middle stages, & last stage */ | ||||
/* pointer initializations for SIMD calculations */ | ||||
pSrc = (q31_t *) pSrc16; | ||||
pCoeff = (q31_t *) pCoef16; | ||||
/* Initializations for the first stage */ | ||||
n2 = fftLen; | ||||
n1 = n2; | ||||
/* n2 = fftLen/4 */ | ||||
n2 >>= 2u; | ||||
/* Index for twiddle coefficient */ | ||||
ic = 0u; | ||||
/* Index for input read and output write */ | ||||
i0 = 0u; | ||||
j = n2; | ||||
/* Input is in 1.15(q15) format */ | ||||
/* start of first stage process */ | ||||
do | ||||
{ | ||||
/* Butterfly implementation */ | ||||
/* index calculation for the input as, */ | ||||
/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */ | ||||
i1 = i0 + n2; | ||||
i2 = i1 + n2; | ||||
i3 = i2 + n2; | ||||
/* Reading i0, i0+fftLen/2 inputs */ | ||||
/* Read ya (real), xa(imag) input */ | ||||
T = pSrc[i0]; | ||||
in = ((int16_t) (T & 0xFFFF)) >> 2; | ||||
T = ((T >> 2) & 0xFFFF0000) | (in & 0xFFFF); | ||||
/* Read yc (real), xc(imag) input */ | ||||
S = pSrc[i2]; | ||||
in = ((int16_t) (S & 0xFFFF)) >> 2; | ||||
S = ((S >> 2) & 0xFFFF0000) | (in & 0xFFFF); | ||||
/* R = packed((ya + yc), (xa + xc) ) */ | ||||
R = __QADD16(T, S); | ||||
/* S = packed((ya - yc), (xa - xc) ) */ | ||||
S = __QSUB16(T, S); | ||||
/* Reading i0+fftLen/4 , i0+3fftLen/4 inputs */ | ||||
/* Read yb (real), xb(imag) input */ | ||||
T = pSrc[i1]; | ||||
in = ((int16_t) (T & 0xFFFF)) >> 2; | ||||
T = ((T >> 2) & 0xFFFF0000) | (in & 0xFFFF); | ||||
/* Read yd (real), xd(imag) input */ | ||||
U = pSrc[i3]; | ||||
in = ((int16_t) (U & 0xFFFF)) >> 2; | ||||
U = ((U >> 2) & 0xFFFF0000) | (in & 0xFFFF); | ||||
/* T = packed((yb + yd), (xb + xd) ) */ | ||||
T = __QADD16(T, U); | ||||
/* writing the butterfly processed i0 sample */ | ||||
/* xa' = xa + xb + xc + xd */ | ||||
/* ya' = ya + yb + yc + yd */ | ||||
pSrc[i0] = __SHADD16(R, T); | ||||
/* R = packed((ya + yc) - (yb + yd), (xa + xc)- (xb + xd)) */ | ||||
R = __QSUB16(R, T); | ||||
/* co2 & si2 are read from SIMD Coefficient pointer */ | ||||
C2 = pCoeff[2u * ic]; | ||||
/* xc' = (xa-xb+xc-xd)* co2 + (ya-yb+yc-yd)* (si2) */ | ||||
out1 = __SMUAD(C2, R) >> 16u; | ||||
/* yc' = (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) */ | ||||
out2 = __SMUSDX(C2, R); | ||||
/* Reading i0+fftLen/4 */ | ||||
/* T = packed(yb, xb) */ | ||||
T = pSrc[i1]; | ||||
in = ((int16_t) (T & 0xFFFF)) >> 2; | ||||
T = ((T >> 2) & 0xFFFF0000) | (in & 0xFFFF); | ||||
/* writing the butterfly processed i0 + fftLen/4 sample */ | ||||
/* writing output(xc', yc') in little endian format */ | ||||
pSrc[i1] = (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF); | ||||
/* Butterfly calculations */ | ||||
/* U = packed(yd, xd) */ | ||||
U = pSrc[i3]; | ||||
in = ((int16_t) (U & 0xFFFF)) >> 2; | ||||
U = ((U >> 2) & 0xFFFF0000) | (in & 0xFFFF); | ||||
/* T = packed(yb-yd, xb-xd) */ | ||||
T = __QSUB16(T, U); | ||||
/* R = packed((ya-yc) + (xb- xd) , (xa-xc) - (yb-yd)) */ | ||||
R = __QASX(S, T); | ||||
/* S = packed((ya-yc) - (xb- xd), (xa-xc) + (yb-yd)) */ | ||||
S = __QSAX(S, T); | ||||
/* co1 & si1 are read from SIMD Coefficient pointer */ | ||||
C1 = pCoeff[ic]; | ||||
/* Butterfly process for the i0+fftLen/2 sample */ | ||||
/* xb' = (xa+yb-xc-yd)* co1 + (ya-xb-yc+xd)* (si1) */ | ||||
out1 = __SMUAD(C1, S) >> 16u; | ||||
/* yb' = (ya-xb-yc+xd)* co1 - (xa+yb-xc-yd)* (si1) */ | ||||
out2 = __SMUSDX(C1, S); | ||||
/* writing output(xb', yb') in little endian format */ | ||||
pSrc[i2] = ((out2) & 0xFFFF0000) | ((out1) & 0x0000FFFF); | ||||
/* co3 & si3 are read from SIMD Coefficient pointer */ | ||||
C3 = pCoeff[3u * ic]; | ||||
/* Butterfly process for the i0+3fftLen/4 sample */ | ||||
/* xd' = (xa-yb-xc+yd)* co3 + (ya+xb-yc-xd)* (si3) */ | ||||
out1 = __SMUAD(C3, R) >> 16u; | ||||
/* yd' = (ya+xb-yc-xd)* co3 - (xa-yb-xc+yd)* (si3) */ | ||||
out2 = __SMUSDX(C3, R); | ||||
/* writing output(xd', yd') in little endian format */ | ||||
pSrc[i3] = ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF); | ||||
/* Twiddle coefficients index modifier */ | ||||
ic = ic + twidCoefModifier; | ||||
/* Updating input index */ | ||||
i0 = i0 + 1u; | ||||
} while(--j); | ||||
/* data is in 4.11(q11) format */ | ||||
/* end of first stage process */ | ||||
/* start of middle stage process */ | ||||
/* Twiddle coefficients index modifier */ | ||||
twidCoefModifier <<= 2u; | ||||
/* Calculation of Middle stage */ | ||||
for (k = fftLen / 4u; k > 4u; k >>= 2u) | ||||
{ | ||||
/* Initializations for the middle stage */ | ||||
n1 = n2; | ||||
n2 >>= 2u; | ||||
ic = 0u; | ||||
for (j = 0u; j <= (n2 - 1u); j++) | ||||
{ | ||||
/* index calculation for the coefficients */ | ||||
C1 = pCoeff[ic]; | ||||
C2 = pCoeff[2u * ic]; | ||||
C3 = pCoeff[3u * ic]; | ||||
/* Twiddle coefficients index modifier */ | ||||
ic = ic + twidCoefModifier; | ||||
/* Butterfly implementation */ | ||||
for (i0 = j; i0 < fftLen; i0 += n1) | ||||
{ | ||||
/* index calculation for the input as, */ | ||||
/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */ | ||||
i1 = i0 + n2; | ||||
i2 = i1 + n2; | ||||
i3 = i2 + n2; | ||||
/* Reading i0, i0+fftLen/2 inputs */ | ||||
/* Read ya (real), xa(imag) input */ | ||||
T = pSrc[i0]; | ||||
/* Read yc (real), xc(imag) input */ | ||||
S = pSrc[i2]; | ||||
/* R = packed( (ya + yc), (xa + xc)) */ | ||||
R = __QADD16(T, S); | ||||
/* S = packed((ya - yc), (xa - xc)) */ | ||||
S = __QSUB16(T, S); | ||||
/* Reading i0+fftLen/4 , i0+3fftLen/4 inputs */ | ||||
/* Read yb (real), xb(imag) input */ | ||||
T = pSrc[i1]; | ||||
/* Read yd (real), xd(imag) input */ | ||||
U = pSrc[i3]; | ||||
/* T = packed( (yb + yd), (xb + xd)) */ | ||||
T = __QADD16(T, U); | ||||
/* writing the butterfly processed i0 sample */ | ||||
/* xa' = xa + xb + xc + xd */ | ||||
/* ya' = ya + yb + yc + yd */ | ||||
out1 = __SHADD16(R, T); | ||||
in = ((int16_t) (out1 & 0xFFFF)) >> 1; | ||||
out1 = ((out1 >> 1) & 0xFFFF0000) | (in & 0xFFFF); | ||||
pSrc[i0] = out1; | ||||
/* R = packed( (ya + yc) - (yb + yd), (xa + xc) - (xb + xd)) */ | ||||
R = __SHSUB16(R, T); | ||||
/* (ya-yb+yc-yd)* (si2) + (xa-xb+xc-xd)* co2 */ | ||||
out1 = __SMUAD(C2, R) >> 16u; | ||||
/* (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) */ | ||||
out2 = __SMUSDX(C2, R); | ||||
/* Reading i0+3fftLen/4 */ | ||||
/* Read yb (real), xb(imag) input */ | ||||
T = pSrc[i1]; | ||||
/* writing the butterfly processed i0 + fftLen/4 sample */ | ||||
/* xc' = (xa-xb+xc-xd)* co2 + (ya-yb+yc-yd)* (si2) */ | ||||
/* yc' = (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) */ | ||||
pSrc[i1] = ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF); | ||||
/* Butterfly calculations */ | ||||
/* Read yd (real), xd(imag) input */ | ||||
U = pSrc[i3]; | ||||
/* T = packed(yb-yd, xb-xd) */ | ||||
T = __QSUB16(T, U); | ||||
/* R = packed((ya-yc) + (xb- xd) , (xa-xc) - (yb-yd)) */ | ||||
R = __SHASX(S, T); | ||||
/* S = packed((ya-yc) - (xb- xd), (xa-xc) + (yb-yd)) */ | ||||
S = __SHSAX(S, T); | ||||
/* Butterfly process for the i0+fftLen/2 sample */ | ||||
out1 = __SMUAD(C1, S) >> 16u; | ||||
out2 = __SMUSDX(C1, S); | ||||
/* xb' = (xa+yb-xc-yd)* co1 + (ya-xb-yc+xd)* (si1) */ | ||||
/* yb' = (ya-xb-yc+xd)* co1 - (xa+yb-xc-yd)* (si1) */ | ||||
pSrc[i2] = ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF); | ||||
/* Butterfly process for the i0+3fftLen/4 sample */ | ||||
out1 = __SMUAD(C3, R) >> 16u; | ||||
out2 = __SMUSDX(C3, R); | ||||
/* xd' = (xa-yb-xc+yd)* co3 + (ya+xb-yc-xd)* (si3) */ | ||||
/* yd' = (ya+xb-yc-xd)* co3 - (xa-yb-xc+yd)* (si3) */ | ||||
pSrc[i3] = ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF); | ||||
} | ||||
} | ||||
/* Twiddle coefficients index modifier */ | ||||
twidCoefModifier <<= 2u; | ||||
} | ||||
/* end of middle stage process */ | ||||
/* data is in 10.6(q6) format for the 1024 point */ | ||||
/* data is in 8.8(q8) format for the 256 point */ | ||||
/* data is in 6.10(q10) format for the 64 point */ | ||||
/* data is in 4.12(q12) format for the 16 point */ | ||||
/* Initializations for the last stage */ | ||||
n1 = n2; | ||||
n2 >>= 2u; | ||||
/* start of last stage process */ | ||||
/* Butterfly implementation */ | ||||
for (i0 = 0u; i0 <= (fftLen - n1); i0 += n1) | ||||
{ | ||||
/* index calculation for the input as, */ | ||||
/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */ | ||||
i1 = i0 + n2; | ||||
i2 = i1 + n2; | ||||
i3 = i2 + n2; | ||||
/* Reading i0, i0+fftLen/2 inputs */ | ||||
/* Read ya (real), xa(imag) input */ | ||||
T = pSrc[i0]; | ||||
/* Read yc (real), xc(imag) input */ | ||||
S = pSrc[i2]; | ||||
/* R = packed((ya + yc), (xa + xc)) */ | ||||
R = __QADD16(T, S); | ||||
/* S = packed((ya - yc), (xa - xc)) */ | ||||
S = __QSUB16(T, S); | ||||
/* Reading i0+fftLen/4 , i0+3fftLen/4 inputs */ | ||||
/* Read yb (real), xb(imag) input */ | ||||
T = pSrc[i1]; | ||||
/* Read yd (real), xd(imag) input */ | ||||
U = pSrc[i3]; | ||||
/* T = packed((yb + yd), (xb + xd)) */ | ||||
T = __QADD16(T, U); | ||||
/* writing the butterfly processed i0 sample */ | ||||
/* xa' = xa + xb + xc + xd */ | ||||
/* ya' = ya + yb + yc + yd */ | ||||
pSrc[i0] = __SHADD16(R, T); | ||||
/* R = packed((ya + yc) - (yb + yd), (xa + xc) - (xb + xd)) */ | ||||
R = __SHSUB16(R, T); | ||||
/* Read yb (real), xb(imag) input */ | ||||
T = pSrc[i1]; | ||||
/* writing the butterfly processed i0 + fftLen/4 sample */ | ||||
/* xc' = (xa-xb+xc-xd) */ | ||||
/* yc' = (ya-yb+yc-yd) */ | ||||
pSrc[i1] = R; | ||||
/* Read yd (real), xd(imag) input */ | ||||
U = pSrc[i3]; | ||||
/* T = packed( (yb - yd), (xb - xd)) */ | ||||
T = __QSUB16(T, U); | ||||
/* writing the butterfly processed i0 + fftLen/2 sample */ | ||||
/* xb' = (xa+yb-xc-yd) */ | ||||
/* yb' = (ya-xb-yc+xd) */ | ||||
pSrc[i2] = __SHSAX(S, T); | ||||
/* writing the butterfly processed i0 + 3fftLen/4 sample */ | ||||
/* xd' = (xa-yb-xc+yd) */ | ||||
/* yd' = (ya+xb-yc-xd) */ | ||||
pSrc[i3] = __SHASX(S, T); | ||||
} | ||||
/* end of last stage process */ | ||||
/* output is in 11.5(q5) format for the 1024 point */ | ||||
/* output is in 9.7(q7) format for the 256 point */ | ||||
/* output is in 7.9(q9) format for the 64 point */ | ||||
/* output is in 5.11(q11) format for the 16 point */ | ||||
} | ||||
/** | ||||
* @brief Core function for the Q15 CIFFT butterfly process. | ||||
* @param[in, out] *pSrc16 points to the in-place buffer of Q15 data type. | ||||
* @param[in] fftLen length of the FFT. | ||||
* @param[in] *pCoef16 points to twiddle coefficient buffer. | ||||
* @param[in] twidCoefModifier twiddle coefficient modifier that supports different size FFTs with the same twiddle factor table. | ||||
* @return none. | ||||
*/ | ||||
/* | ||||
* Radix-4 IFFT algorithm used is : | ||||
* | ||||
* CIFFT uses same twiddle coefficients as CFFT function | ||||
* x[k] = x[n] + (j)k * x[n + fftLen/4] + (-1)k * x[n+fftLen/2] + (-j)k * x[n+3*fftLen/4] | ||||
* | ||||
* | ||||
* IFFT is implemented with following changes in equations from FFT | ||||
* | ||||
* Input real and imaginary data: | ||||
* x(n) = xa + j * ya | ||||
* x(n+N/4 ) = xb + j * yb | ||||
* x(n+N/2 ) = xc + j * yc | ||||
* x(n+3N 4) = xd + j * yd | ||||
* | ||||
* | ||||
* Output real and imaginary data: | ||||
* x(4r) = xa'+ j * ya' | ||||
* x(4r+1) = xb'+ j * yb' | ||||
* x(4r+2) = xc'+ j * yc' | ||||
* x(4r+3) = xd'+ j * yd' | ||||
* | ||||
* | ||||
* Twiddle factors for radix-4 IFFT: | ||||
* Wn = co1 + j * (si1) | ||||
* W2n = co2 + j * (si2) | ||||
* W3n = co3 + j * (si3) | ||||
* The real and imaginary output values for the radix-4 butterfly are | ||||
* xa' = xa + xb + xc + xd | ||||
* ya' = ya + yb + yc + yd | ||||
* xb' = (xa-yb-xc+yd)* co1 - (ya+xb-yc-xd)* (si1) | ||||
* yb' = (ya+xb-yc-xd)* co1 + (xa-yb-xc+yd)* (si1) | ||||
* xc' = (xa-xb+xc-xd)* co2 - (ya-yb+yc-yd)* (si2) | ||||
* yc' = (ya-yb+yc-yd)* co2 + (xa-xb+xc-xd)* (si2) | ||||
* xd' = (xa+yb-xc-yd)* co3 - (ya-xb-yc+xd)* (si3) | ||||
* yd' = (ya-xb-yc+xd)* co3 + (xa+yb-xc-yd)* (si3) | ||||
* | ||||
*/ | ||||
void arm_radix4_butterfly_inverse_q15( | ||||
q15_t * pSrc16, | ||||
uint32_t fftLen, | ||||
q15_t * pCoef16, | ||||
uint32_t twidCoefModifier) | ||||
{ | ||||
q31_t R, S, T, U; | ||||
q31_t C1, C2, C3, out1, out2; | ||||
q31_t *pSrc, *pCoeff; | ||||
uint32_t n1, n2, ic, i0, i1, i2, i3, j, k; | ||||
q15_t in; | ||||
/* Total process is divided into three stages */ | ||||
/* process first stage, middle stages, & last stage */ | ||||
/* pointer initializations for SIMD calculations */ | ||||
pSrc = (q31_t *) pSrc16; | ||||
pCoeff = (q31_t *) pCoef16; | ||||
/* Initializations for the first stage */ | ||||
n2 = fftLen; | ||||
n1 = n2; | ||||
/* n2 = fftLen/4 */ | ||||
n2 >>= 2u; | ||||
/* Index for twiddle coefficient */ | ||||
ic = 0u; | ||||
/* Index for input read and output write */ | ||||
i0 = 0u; | ||||
j = n2; | ||||
/* Input is in 1.15(q15) format */ | ||||
/* Start of first stage process */ | ||||
do | ||||
{ | ||||
/* Butterfly implementation */ | ||||
/* index calculation for the input as, */ | ||||
/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */ | ||||
i1 = i0 + n2; | ||||
i2 = i1 + n2; | ||||
i3 = i2 + n2; | ||||
/* Reading i0, i0+fftLen/2 inputs */ | ||||
/* Read ya (real), xa(imag) input */ | ||||
T = pSrc[i0]; | ||||
in = ((int16_t) (T & 0xFFFF)) >> 2; | ||||
T = ((T >> 2) & 0xFFFF0000) | (in & 0xFFFF); | ||||
/* Read yc (real), xc(imag) input */ | ||||
S = pSrc[i2]; | ||||
in = ((int16_t) (S & 0xFFFF)) >> 2; | ||||
S = ((S >> 2) & 0xFFFF0000) | (in & 0xFFFF); | ||||
/* R = packed((ya + yc), (xa + xc) ) */ | ||||
R = __QADD16(T, S); | ||||
/* S = packed((ya - yc), (xa - xc) ) */ | ||||
S = __QSUB16(T, S); | ||||
/* Reading i0+fftLen/4 , i0+3fftLen/4 inputs */ | ||||
/* Read yb (real), xb(imag) input */ | ||||
T = pSrc[i1]; | ||||
in = ((int16_t) (T & 0xFFFF)) >> 2; | ||||
T = ((T >> 2) & 0xFFFF0000) | (in & 0xFFFF); | ||||
/* Read yd (real), xd(imag) input */ | ||||
U = pSrc[i3]; | ||||
in = ((int16_t) (U & 0xFFFF)) >> 2; | ||||
U = ((U >> 2) & 0xFFFF0000) | (in & 0xFFFF); | ||||
/* T = packed((yb + yd), (xb + xd) ) */ | ||||
T = __QADD16(T, U); | ||||
/* writing the butterfly processed i0 sample */ | ||||
/* xa' = xa + xb + xc + xd */ | ||||
/* ya' = ya + yb + yc + yd */ | ||||
pSrc[i0] = __SHADD16(R, T); | ||||
/* R = packed((ya + yc) - (yb + yd), (xa + xc)- (xb + xd)) */ | ||||
R = __QSUB16(R, T); | ||||
/* co2 & si2 are read from SIMD Coefficient pointer */ | ||||
C2 = pCoeff[2u * ic]; | ||||
/* xc' = (xa-xb+xc-xd)* co2 - (ya-yb+yc-yd)* (si2) */ | ||||
out1 = __SMUSD(C2, R) >> 16u; | ||||
/* yc' = (ya-yb+yc-yd)* co2 + (xa-xb+xc-xd)* (si2) */ | ||||
out2 = __SMUADX(C2, R); | ||||
/* Reading i0+fftLen/4 */ | ||||
/* T = packed(yb, xb) */ | ||||
T = pSrc[i1]; | ||||
in = ((int16_t) (T & 0xFFFF)) >> 2; | ||||
T = ((T >> 2) & 0xFFFF0000) | (in & 0xFFFF); | ||||
/* writing the butterfly processed i0 + fftLen/4 sample */ | ||||
/* writing output(xc', yc') in little endian format */ | ||||
pSrc[i1] = (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF); | ||||
/* Butterfly calculations */ | ||||
/* U = packed(yd, xd) */ | ||||
U = pSrc[i3]; | ||||
in = ((int16_t) (U & 0xFFFF)) >> 2; | ||||
U = ((U >> 2) & 0xFFFF0000) | (in & 0xFFFF); | ||||
/* T = packed(yb-yd, xb-xd) */ | ||||
T = __QSUB16(T, U); | ||||
/* R = packed((ya-yc) - (xb- xd) , (xa-xc) + (yb-yd)) */ | ||||
R = __QSAX(S, T); | ||||
/* S = packed((ya-yc) + (xb- xd), (xa-xc) - (yb-yd)) */ | ||||
S = __QASX(S, T); | ||||
/* co1 & si1 are read from SIMD Coefficient pointer */ | ||||
C1 = pCoeff[ic]; | ||||
/* Butterfly process for the i0+fftLen/2 sample */ | ||||
/* xb' = (xa-yb-xc+yd)* co1 - (ya+xb-yc-xd)* (si1) */ | ||||
out1 = __SMUSD(C1, S) >> 16u; | ||||
/* yb' = (ya+xb-yc-xd)* co1 + (xa-yb-xc+yd)* (si1) */ | ||||
out2 = __SMUADX(C1, S); | ||||
/* writing output(xb', yb') in little endian format */ | ||||
pSrc[i2] = ((out2) & 0xFFFF0000) | ((out1) & 0x0000FFFF); | ||||
/* co3 & si3 are read from SIMD Coefficient pointer */ | ||||
C3 = pCoeff[3u * ic]; | ||||
/* Butterfly process for the i0+3fftLen/4 sample */ | ||||
/* xd' = (xa+yb-xc-yd)* co3 - (ya-xb-yc+xd)* (si3) */ | ||||
out1 = __SMUSD(C3, R) >> 16u; | ||||
/* yd' = (ya-xb-yc+xd)* co3 + (xa+yb-xc-yd)* (si3) */ | ||||
out2 = __SMUADX(C3, R); | ||||
/* writing output(xd', yd') in little endian format */ | ||||
pSrc[i3] = ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF); | ||||
/* Twiddle coefficients index modifier */ | ||||
ic = ic + twidCoefModifier; | ||||
/* Updating input index */ | ||||
i0 = i0 + 1u; | ||||
} while(--j); | ||||
/* End of first stage process */ | ||||
/* data is in 4.11(q11) format */ | ||||
/* Start of Middle stage process */ | ||||
/* Twiddle coefficients index modifier */ | ||||
twidCoefModifier <<= 2u; | ||||
/* Calculation of Middle stage */ | ||||
for (k = fftLen / 4u; k > 4u; k >>= 2u) | ||||
{ | ||||
/* Initializations for the middle stage */ | ||||
n1 = n2; | ||||
n2 >>= 2u; | ||||
ic = 0u; | ||||
for (j = 0u; j <= (n2 - 1u); j++) | ||||
{ | ||||
/* index calculation for the coefficients */ | ||||
C1 = pCoeff[ic]; | ||||
C2 = pCoeff[2u * ic]; | ||||
C3 = pCoeff[3u * ic]; | ||||
/* Twiddle coefficients index modifier */ | ||||
ic = ic + twidCoefModifier; | ||||
/* Butterfly implementation */ | ||||
for (i0 = j; i0 < fftLen; i0 += n1) | ||||
{ | ||||
/* index calculation for the input as, */ | ||||
/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */ | ||||
i1 = i0 + n2; | ||||
i2 = i1 + n2; | ||||
i3 = i2 + n2; | ||||
/* Reading i0, i0+fftLen/2 inputs */ | ||||
/* Read ya (real), xa(imag) input */ | ||||
T = pSrc[i0]; | ||||
/* Read yc (real), xc(imag) input */ | ||||
S = pSrc[i2]; | ||||
/* R = packed( (ya + yc), (xa + xc)) */ | ||||
R = __QADD16(T, S); | ||||
/* S = packed((ya - yc), (xa - xc)) */ | ||||
S = __QSUB16(T, S); | ||||
/* Reading i0+fftLen/4 , i0+3fftLen/4 inputs */ | ||||
/* Read yb (real), xb(imag) input */ | ||||
T = pSrc[i1]; | ||||
/* Read yd (real), xd(imag) input */ | ||||
U = pSrc[i3]; | ||||
/* T = packed( (yb + yd), (xb + xd)) */ | ||||
T = __QADD16(T, U); | ||||
/* writing the butterfly processed i0 sample */ | ||||
/* xa' = xa + xb + xc + xd */ | ||||
/* ya' = ya + yb + yc + yd */ | ||||
out1 = __SHADD16(R, T); | ||||
in = ((int16_t) (out1 & 0xFFFF)) >> 1; | ||||
out1 = ((out1 >> 1) & 0xFFFF0000) | (in & 0xFFFF); | ||||
pSrc[i0] = out1; | ||||
/* R = packed( (ya + yc) - (yb + yd), (xa + xc) - (xb + xd)) */ | ||||
R = __SHSUB16(R, T); | ||||
/* (ya-yb+yc-yd)* (si2) - (xa-xb+xc-xd)* co2 */ | ||||
out1 = __SMUSD(C2, R) >> 16u; | ||||
/* (ya-yb+yc-yd)* co2 + (xa-xb+xc-xd)* (si2) */ | ||||
out2 = __SMUADX(C2, R); | ||||
/* Reading i0+3fftLen/4 */ | ||||
/* Read yb (real), xb(imag) input */ | ||||
T = pSrc[i1]; | ||||
/* writing the butterfly processed i0 + fftLen/4 sample */ | ||||
/* xc' = (xa-xb+xc-xd)* co2 - (ya-yb+yc-yd)* (si2) */ | ||||
/* yc' = (ya-yb+yc-yd)* co2 + (xa-xb+xc-xd)* (si2) */ | ||||
pSrc[i1] = ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF); | ||||
/* Butterfly calculations */ | ||||
/* Read yd (real), xd(imag) input */ | ||||
U = pSrc[i3]; | ||||
/* T = packed(yb-yd, xb-xd) */ | ||||
T = __QSUB16(T, U); | ||||
/* R = packed((ya-yc) - (xb- xd) , (xa-xc) + (yb-yd)) */ | ||||
R = __SHSAX(S, T); | ||||
/* S = packed((ya-yc) + (xb- xd), (xa-xc) - (yb-yd)) */ | ||||
S = __SHASX(S, T); | ||||
/* Butterfly process for the i0+fftLen/2 sample */ | ||||
out1 = __SMUSD(C1, S) >> 16u; | ||||
out2 = __SMUADX(C1, S); | ||||
/* xb' = (xa-yb-xc+yd)* co1 - (ya+xb-yc-xd)* (si1) */ | ||||
/* yb' = (ya+xb-yc-xd)* co1 + (xa-yb-xc+yd)* (si1) */ | ||||
pSrc[i2] = ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF); | ||||
/* Butterfly process for the i0+3fftLen/4 sample */ | ||||
out1 = __SMUSD(C3, R) >> 16u; | ||||
out2 = __SMUADX(C3, R); | ||||
/* xd' = (xa+yb-xc-yd)* co3 - (ya-xb-yc+xd)* (si3) */ | ||||
/* yd' = (ya-xb-yc+xd)* co3 + (xa+yb-xc-yd)* (si3) */ | ||||
pSrc[i3] = ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF); | ||||
} | ||||
} | ||||
/* Twiddle coefficients index modifier */ | ||||
twidCoefModifier <<= 2u; | ||||
} | ||||
/* End of Middle stages process */ | ||||
/* data is in 10.6(q6) format for the 1024 point */ | ||||
/* data is in 8.8(q8) format for the 256 point */ | ||||
/* data is in 6.10(q10) format for the 64 point */ | ||||
/* data is in 4.12(q12) format for the 16 point */ | ||||
/* start of last stage process */ | ||||
/* Initializations for the last stage */ | ||||
n1 = n2; | ||||
n2 >>= 2u; | ||||
/* Butterfly implementation */ | ||||
for (i0 = 0u; i0 <= (fftLen - n1); i0 += n1) | ||||
{ | ||||
/* index calculation for the input as, */ | ||||
/* pSrc[i0 + 0], pSrc[i0 + fftLen/4], pSrc[i0 + fftLen/2], pSrc[i0 + 3fftLen/4] */ | ||||
i1 = i0 + n2; | ||||
i2 = i1 + n2; | ||||
i3 = i2 + n2; | ||||
/* Reading i0, i0+fftLen/2 inputs */ | ||||
/* Read ya (real), xa(imag) input */ | ||||
T = pSrc[i0]; | ||||
/* Read yc (real), xc(imag) input */ | ||||
S = pSrc[i2]; | ||||
/* R = packed((ya + yc), (xa + xc)) */ | ||||
R = __QADD16(T, S); | ||||
/* S = packed((ya - yc), (xa - xc)) */ | ||||
S = __QSUB16(T, S); | ||||
/* Reading i0+fftLen/4 , i0+3fftLen/4 inputs */ | ||||
/* Read yb (real), xb(imag) input */ | ||||
T = pSrc[i1]; | ||||
/* Read yd (real), xd(imag) input */ | ||||
U = pSrc[i3]; | ||||
/* T = packed((yb + yd), (xb + xd)) */ | ||||
T = __QADD16(T, U); | ||||
/* writing the butterfly processed i0 sample */ | ||||
/* xa' = xa + xb + xc + xd */ | ||||
/* ya' = ya + yb + yc + yd */ | ||||
pSrc[i0] = __SHADD16(R, T); | ||||
/* R = packed((ya + yc) - (yb + yd), (xa + xc) - (xb + xd)) */ | ||||
R = __SHSUB16(R, T); | ||||
/* Read yb (real), xb(imag) input */ | ||||
T = pSrc[i1]; | ||||
/* writing the butterfly processed i0 + fftLen/4 sample */ | ||||
/* xc' = (xa-xb+xc-xd) */ | ||||
/* yc' = (ya-yb+yc-yd) */ | ||||
pSrc[i1] = R; | ||||
/* Read yd (real), xd(imag) input */ | ||||
U = pSrc[i3]; | ||||
/* T = packed( (yb - yd), (xb - xd)) */ | ||||
T = __QSUB16(T, U); | ||||
/* writing the butterfly processed i0 + fftLen/2 sample */ | ||||
/* xb' = (xa-yb-xc+yd) */ | ||||
/* yb' = (ya+xb-yc-xd) */ | ||||
pSrc[i2] = __SHASX(S, T); | ||||
/* writing the butterfly processed i0 + 3fftLen/4 sample */ | ||||
/* xd' = (xa+yb-xc-yd) */ | ||||
/* yd' = (ya-xb-yc+xd) */ | ||||
pSrc[i3] = __SHSAX(S, T); | ||||
} | ||||
/* end of last stage process */ | ||||
/* output is in 11.5(q5) format for the 1024 point */ | ||||
/* output is in 9.7(q7) format for the 256 point */ | ||||
/* output is in 7.9(q9) format for the 64 point */ | ||||
/* output is in 5.11(q11) format for the 16 point */ | ||||
} | ||||
/* | ||||
* @brief In-place bit reversal function. | ||||
* @param[in, out] *pSrc points to the in-place buffer of Q15 data type. | ||||
* @param[in] fftLen length of the FFT. | ||||
* @param[in] bitRevFactor bit reversal modifier that supports different size FFTs with the same bit reversal table | ||||
* @param[in] *pBitRevTab points to bit reversal table. | ||||
* @return none. | ||||
*/ | ||||
void arm_bitreversal_q15( | ||||
q15_t * pSrc16, | ||||
uint32_t fftLen, | ||||
uint16_t bitRevFactor, | ||||
uint16_t * pBitRevTab) | ||||
{ | ||||
q31_t *pSrc = (q31_t *) pSrc16; | ||||
q31_t in; | ||||
uint32_t fftLenBy2, fftLenBy2p1; | ||||
uint32_t i, j; | ||||
/* Initializations */ | ||||
j = 0u; | ||||
fftLenBy2 = fftLen / 2u; | ||||
fftLenBy2p1 = (fftLen / 2u) + 1u; | ||||
/* Bit Reversal Implementation */ | ||||
for (i = 0u; i <= (fftLenBy2 - 2u); i += 2u) | ||||
{ | ||||
if(i < j) | ||||
{ | ||||
/* pSrc[i] <-> pSrc[j]; */ | ||||
/* pSrc[i+1u] <-> pSrc[j+1u] */ | ||||
in = pSrc[i]; | ||||
pSrc[i] = pSrc[j]; | ||||
pSrc[j] = in; | ||||
/* pSrc[i + fftLenBy2p1] <-> pSrc[j + fftLenBy2p1]; */ | ||||
/* pSrc[i + fftLenBy2p1+1u] <-> pSrc[j + fftLenBy2p1+1u] */ | ||||
in = pSrc[i + fftLenBy2p1]; | ||||
pSrc[i + fftLenBy2p1] = pSrc[j + fftLenBy2p1]; | ||||
pSrc[j + fftLenBy2p1] = in; | ||||
} | ||||
/* pSrc[i+1u] <-> pSrc[j+fftLenBy2]; */ | ||||
/* pSrc[i+2] <-> pSrc[j+fftLenBy2+1u] */ | ||||
in = pSrc[i + 1u]; | ||||
pSrc[i + 1u] = pSrc[j + fftLenBy2]; | ||||
pSrc[j + fftLenBy2] = in; | ||||
/* Reading the index for the bit reversal */ | ||||
j = *pBitRevTab; | ||||
/* Updating the bit reversal index depending on the fft length */ | ||||
pBitRevTab += bitRevFactor; | ||||
} | ||||
} | ||||