| /* ---------------------------------------------------------------------- |
| * Copyright (C) 2010 ARM Limited. All rights reserved. |
| * |
| * $Date: 15. July 2011 |
| * $Revision: V1.0.10 |
| * |
| * 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/Cortex-M0 |
| * |
| * Version 1.0.10 2011/7/15 |
| * Big Endian support added and Merged M0 and M3/M4 Source code. |
| * |
| * 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) |
| { |
| |
| #ifndef ARM_MATH_CM0 |
| |
| /* Run the below code for Cortex-M4 and Cortex-M3 */ |
| |
| 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]; |
| |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* 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); |
| |
| #else |
| |
| /* xc' = (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) */ |
| out1 = __SMUSDX(R, C2) >> 16u; |
| /* yc' = (xa-xb+xc-xd)* co2 + (ya-yb+yc-yd)* (si2) */ |
| out2 = __SMUAD(C2, R); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* 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); |
| |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* 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); |
| |
| #else |
| |
| /* 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); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* co1 & si1 are read from SIMD Coefficient pointer */ |
| C1 = pCoeff[ic]; |
| /* Butterfly process for the i0+fftLen/2 sample */ |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* 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); |
| |
| #else |
| |
| /* xb' = (ya-xb-yc+xd)* co1 - (xa+yb-xc-yd)* (si1) */ |
| out1 = __SMUSDX(S, C1) >> 16u; |
| /* yb' = (xa+yb-xc-yd)* co1 + (ya-xb-yc+xd)* (si1) */ |
| out2 = __SMUAD(C1, S); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* 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 */ |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* 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); |
| |
| #else |
| |
| /* xd' = (ya+xb-yc-xd)* co3 - (xa-yb-xc+yd)* (si3) */ |
| out1 = __SMUSDX(R, C3) >> 16u; |
| /* yd' = (xa-yb-xc+yd)* co3 + (ya+xb-yc-xd)* (si3) */ |
| out2 = __SMUAD(C3, R); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* 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); |
| |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* (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); |
| |
| #else |
| |
| /* (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) */ |
| out1 = __SMUSDX(R, C2) >> 16u; |
| |
| /* (ya-yb+yc-yd)* (si2) + (xa-xb+xc-xd)* co2 */ |
| out2 = __SMUAD(C2, R); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* 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); |
| |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* 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); |
| |
| #else |
| |
| /* 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 = __SMUSDX(S, C1) >> 16u; |
| out2 = __SMUAD(C1, S); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* 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 */ |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| out1 = __SMUAD(C3, R) >> 16u; |
| out2 = __SMUSDX(C3, R); |
| |
| #else |
| |
| out1 = __SMUSDX(R, C3) >> 16u; |
| out2 = __SMUAD(C3, R); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* 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); |
| |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* 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); |
| |
| #else |
| |
| /* 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); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| } |
| |
| /* 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 */ |
| |
| |
| #else |
| |
| /* Run the below code for Cortex-M0 */ |
| |
| q15_t R0, R1, S0, S1, T0, T1, U0, U1; |
| q15_t Co1, Si1, Co2, Si2, Co3, Si3, out1, out2; |
| uint32_t n1, n2, ic, i0, i1, i2, i3, j, k; |
| |
| /* Total process is divided into three stages */ |
| |
| /* process first stage, middle stages, & last stage */ |
| |
| /* 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, */ |
| /* pSrc16[i0 + 0], pSrc16[i0 + fftLen/4], pSrc16[i0 + fftLen/2], pSrc16[i0 + 3fftLen/4] */ |
| i1 = i0 + n2; |
| i2 = i1 + n2; |
| i3 = i2 + n2; |
| |
| /* Reading i0, i0+fftLen/2 inputs */ |
| |
| /* input is down scale by 4 to avoid overflow */ |
| /* Read ya (real), xa(imag) input */ |
| T0 = pSrc16[i0 * 2u] >> 2u; |
| T1 = pSrc16[(i0 * 2u) + 1u] >> 2u; |
| |
| /* input is down scale by 4 to avoid overflow */ |
| /* Read yc (real), xc(imag) input */ |
| S0 = pSrc16[i2 * 2u] >> 2u; |
| S1 = pSrc16[(i2 * 2u) + 1u] >> 2u; |
| |
| /* R0 = (ya + yc) */ |
| R0 = __SSAT(T0 + S0, 16u); |
| /* R1 = (xa + xc) */ |
| R1 = __SSAT(T1 + S1, 16u); |
| |
| /* S0 = (ya - yc) */ |
| S0 = __SSAT(T0 - S0, 16); |
| /* S1 = (xa - xc) */ |
| S1 = __SSAT(T1 - S1, 16); |
| |
| /* Reading i0+fftLen/4 , i0+3fftLen/4 inputs */ |
| /* input is down scale by 4 to avoid overflow */ |
| /* Read yb (real), xb(imag) input */ |
| T0 = pSrc16[i1 * 2u] >> 2u; |
| T1 = pSrc16[(i1 * 2u) + 1u] >> 2u; |
| |
| /* input is down scale by 4 to avoid overflow */ |
| /* Read yd (real), xd(imag) input */ |
| U0 = pSrc16[i3 * 2u] >> 2u; |
| U1 = pSrc16[(i3 * 2u) + 1] >> 2u; |
| |
| /* T0 = (yb + yd) */ |
| T0 = __SSAT(T0 + U0, 16u); |
| /* T1 = (xb + xd) */ |
| T1 = __SSAT(T1 + U1, 16u); |
| |
| /* writing the butterfly processed i0 sample */ |
| /* ya' = ya + yb + yc + yd */ |
| /* xa' = xa + xb + xc + xd */ |
| pSrc16[i0 * 2u] = (R0 >> 1u) + (T0 >> 1u); |
| pSrc16[(i0 * 2u) + 1u] = (R1 >> 1u) + (T1 >> 1u); |
| |
| /* R0 = (ya + yc) - (yb + yd) */ |
| /* R1 = (xa + xc) - (xb + xd) */ |
| R0 = __SSAT(R0 - T0, 16u); |
| R1 = __SSAT(R1 - T1, 16u); |
| |
| /* co2 & si2 are read from Coefficient pointer */ |
| Co2 = pCoef16[2u * ic * 2u]; |
| Si2 = pCoef16[(2u * ic * 2u) + 1]; |
| |
| /* xc' = (xa-xb+xc-xd)* co2 + (ya-yb+yc-yd)* (si2) */ |
| out1 = (short) ((Co2 * R0 + Si2 * R1) >> 16u); |
| /* yc' = (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) */ |
| out2 = (short) ((-Si2 * R0 + Co2 * R1) >> 16u); |
| |
| /* Reading i0+fftLen/4 */ |
| /* input is down scale by 4 to avoid overflow */ |
| /* T0 = yb, T1 = xb */ |
| T0 = pSrc16[i1 * 2u] >> 2; |
| T1 = pSrc16[(i1 * 2u) + 1] >> 2; |
| |
| /* writing the butterfly processed i0 + fftLen/4 sample */ |
| /* writing output(xc', yc') in little endian format */ |
| pSrc16[i1 * 2u] = out1; |
| pSrc16[(i1 * 2u) + 1] = out2; |
| |
| /* Butterfly calculations */ |
| /* input is down scale by 4 to avoid overflow */ |
| /* U0 = yd, U1 = xd */ |
| U0 = pSrc16[i3 * 2u] >> 2; |
| U1 = pSrc16[(i3 * 2u) + 1] >> 2; |
| /* T0 = yb-yd */ |
| T0 = __SSAT(T0 - U0, 16); |
| /* T1 = xb-xd */ |
| T1 = __SSAT(T1 - U1, 16); |
| |
| /* R1 = (ya-yc) + (xb- xd), R0 = (xa-xc) - (yb-yd)) */ |
| R0 = (short) __SSAT((q31_t) (S0 - T1), 16); |
| R1 = (short) __SSAT((q31_t) (S1 + T0), 16); |
| |
| /* S1 = (ya-yc) - (xb- xd), S0 = (xa-xc) + (yb-yd)) */ |
| S0 = (short) __SSAT(((q31_t) S0 + T1), 16u); |
| S1 = (short) __SSAT(((q31_t) S1 - T0), 16u); |
| |
| /* co1 & si1 are read from Coefficient pointer */ |
| Co1 = pCoef16[ic * 2u]; |
| Si1 = pCoef16[(ic * 2u) + 1]; |
| /* Butterfly process for the i0+fftLen/2 sample */ |
| /* xb' = (xa+yb-xc-yd)* co1 + (ya-xb-yc+xd)* (si1) */ |
| out1 = (short) ((Si1 * S1 + Co1 * S0) >> 16); |
| /* yb' = (ya-xb-yc+xd)* co1 - (xa+yb-xc-yd)* (si1) */ |
| out2 = (short) ((-Si1 * S0 + Co1 * S1) >> 16); |
| |
| /* writing output(xb', yb') in little endian format */ |
| pSrc16[i2 * 2u] = out1; |
| pSrc16[(i2 * 2u) + 1] = out2; |
| |
| /* Co3 & si3 are read from Coefficient pointer */ |
| Co3 = pCoef16[3u * (ic * 2u)]; |
| Si3 = pCoef16[(3u * (ic * 2u)) + 1]; |
| /* Butterfly process for the i0+3fftLen/4 sample */ |
| /* xd' = (xa-yb-xc+yd)* Co3 + (ya+xb-yc-xd)* (si3) */ |
| out1 = (short) ((Si3 * R1 + Co3 * R0) >> 16u); |
| /* yd' = (ya+xb-yc-xd)* Co3 - (xa-yb-xc+yd)* (si3) */ |
| out2 = (short) ((-Si3 * R0 + Co3 * R1) >> 16u); |
| /* writing output(xd', yd') in little endian format */ |
| pSrc16[i3 * 2u] = out1; |
| pSrc16[(i3 * 2u) + 1] = out2; |
| |
| /* 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 */ |
| Co1 = pCoef16[ic * 2u]; |
| Si1 = pCoef16[(ic * 2u) + 1u]; |
| Co2 = pCoef16[2u * (ic * 2u)]; |
| Si2 = pCoef16[(2u * (ic * 2u)) + 1u]; |
| Co3 = pCoef16[3u * (ic * 2u)]; |
| Si3 = pCoef16[(3u * (ic * 2u)) + 1u]; |
| |
| /* Twiddle coefficients index modifier */ |
| ic = ic + twidCoefModifier; |
| |
| /* Butterfly implementation */ |
| for (i0 = j; i0 < fftLen; i0 += n1) |
| { |
| /* index calculation for the input as, */ |
| /* pSrc16[i0 + 0], pSrc16[i0 + fftLen/4], pSrc16[i0 + fftLen/2], pSrc16[i0 + 3fftLen/4] */ |
| i1 = i0 + n2; |
| i2 = i1 + n2; |
| i3 = i2 + n2; |
| |
| /* Reading i0, i0+fftLen/2 inputs */ |
| /* Read ya (real), xa(imag) input */ |
| T0 = pSrc16[i0 * 2u]; |
| T1 = pSrc16[(i0 * 2u) + 1u]; |
| |
| /* Read yc (real), xc(imag) input */ |
| S0 = pSrc16[i2 * 2u]; |
| S1 = pSrc16[(i2 * 2u) + 1u]; |
| |
| /* R0 = (ya + yc), R1 = (xa + xc) */ |
| R0 = __SSAT(T0 + S0, 16); |
| R1 = __SSAT(T1 + S1, 16); |
| |
| /* S0 = (ya - yc), S1 =(xa - xc) */ |
| S0 = __SSAT(T0 - S0, 16); |
| S1 = __SSAT(T1 - S1, 16); |
| |
| /* Reading i0+fftLen/4 , i0+3fftLen/4 inputs */ |
| /* Read yb (real), xb(imag) input */ |
| T0 = pSrc16[i1 * 2u]; |
| T1 = pSrc16[(i1 * 2u) + 1u]; |
| |
| /* Read yd (real), xd(imag) input */ |
| U0 = pSrc16[i3 * 2u]; |
| U1 = pSrc16[(i3 * 2u) + 1u]; |
| |
| |
| /* T0 = (yb + yd), T1 = (xb + xd) */ |
| T0 = __SSAT(T0 + U0, 16); |
| T1 = __SSAT(T1 + U1, 16); |
| |
| /* writing the butterfly processed i0 sample */ |
| |
| /* xa' = xa + xb + xc + xd */ |
| /* ya' = ya + yb + yc + yd */ |
| out1 = ((R0 >> 1u) + (T0 >> 1u)) >> 1u; |
| out2 = ((R1 >> 1u) + (T1 >> 1u)) >> 1u; |
| |
| pSrc16[i0 * 2u] = out1; |
| pSrc16[(2u * i0) + 1u] = out2; |
| |
| /* R0 = (ya + yc) - (yb + yd), R1 = (xa + xc) - (xb + xd) */ |
| R0 = (R0 >> 1u) - (T0 >> 1u); |
| R1 = (R1 >> 1u) - (T1 >> 1u); |
| |
| /* (ya-yb+yc-yd)* (si2) + (xa-xb+xc-xd)* co2 */ |
| out1 = (short) ((Co2 * R0 + Si2 * R1) >> 16u); |
| |
| /* (ya-yb+yc-yd)* co2 - (xa-xb+xc-xd)* (si2) */ |
| out2 = (short) ((-Si2 * R0 + Co2 * R1) >> 16u); |
| |
| /* Reading i0+3fftLen/4 */ |
| /* Read yb (real), xb(imag) input */ |
| T0 = pSrc16[i1 * 2u]; |
| T1 = pSrc16[(i1 * 2u) + 1u]; |
| |
| /* 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) */ |
| pSrc16[i1 * 2u] = out1; |
| pSrc16[(i1 * 2u) + 1u] = out2; |
| |
| /* Butterfly calculations */ |
| |
| /* Read yd (real), xd(imag) input */ |
| U0 = pSrc16[i3 * 2u]; |
| U1 = pSrc16[(i3 * 2u) + 1u]; |
| |
| /* T0 = yb-yd, T1 = xb-xd */ |
| T0 = __SSAT(T0 - U0, 16); |
| T1 = __SSAT(T1 - U1, 16); |
| |
| /* R0 = (ya-yc) + (xb- xd), R1 = (xa-xc) - (yb-yd)) */ |
| R0 = (S0 >> 1u) - (T1 >> 1u); |
| R1 = (S1 >> 1u) + (T0 >> 1u); |
| |
| /* S0 = (ya-yc) - (xb- xd), S1 = (xa-xc) + (yb-yd)) */ |
| S0 = (S0 >> 1u) + (T1 >> 1u); |
| S1 = (S1 >> 1u) - (T0 >> 1u); |
| |
| /* Butterfly process for the i0+fftLen/2 sample */ |
| out1 = (short) ((Co1 * S0 + Si1 * S1) >> 16u); |
| |
| out2 = (short) ((-Si1 * S0 + Co1 * S1) >> 16u); |
| |
| /* xb' = (xa+yb-xc-yd)* co1 + (ya-xb-yc+xd)* (si1) */ |
| /* yb' = (ya-xb-yc+xd)* co1 - (xa+yb-xc-yd)* (si1) */ |
| pSrc16[i2 * 2u] = out1; |
| pSrc16[(i2 * 2u) + 1u] = out2; |
| |
| /* Butterfly process for the i0+3fftLen/4 sample */ |
| out1 = (short) ((Si3 * R1 + Co3 * R0) >> 16u); |
| |
| out2 = (short) ((-Si3 * R0 + Co3 * R1) >> 16u); |
| /* xd' = (xa-yb-xc+yd)* Co3 + (ya+xb-yc-xd)* (si3) */ |
| /* yd' = (ya+xb-yc-xd)* Co3 - (xa-yb-xc+yd)* (si3) */ |
| pSrc16[i3 * 2u] = out1; |
| pSrc16[(i3 * 2u) + 1u] = out2; |
| } |
| } |
| /* 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, */ |
| /* pSrc16[i0 + 0], pSrc16[i0 + fftLen/4], pSrc16[i0 + fftLen/2], pSrc16[i0 + 3fftLen/4] */ |
| i1 = i0 + n2; |
| i2 = i1 + n2; |
| i3 = i2 + n2; |
| |
| /* Reading i0, i0+fftLen/2 inputs */ |
| /* Read ya (real), xa(imag) input */ |
| T0 = pSrc16[i0 * 2u]; |
| T1 = pSrc16[(i0 * 2u) + 1u]; |
| |
| /* Read yc (real), xc(imag) input */ |
| S0 = pSrc16[i2 * 2u]; |
| S1 = pSrc16[(i2 * 2u) + 1u]; |
| |
| /* R0 = (ya + yc), R1 = (xa + xc) */ |
| R0 = __SSAT(T0 + S0, 16u); |
| R1 = __SSAT(T1 + S1, 16u); |
| |
| /* S0 = (ya - yc), S1 = (xa - xc) */ |
| S0 = __SSAT(T0 - S0, 16u); |
| S1 = __SSAT(T1 - S1, 16u); |
| |
| /* Reading i0+fftLen/4 , i0+3fftLen/4 inputs */ |
| /* Read yb (real), xb(imag) input */ |
| T0 = pSrc16[i1 * 2u]; |
| T1 = pSrc16[(i1 * 2u) + 1u]; |
| /* Read yd (real), xd(imag) input */ |
| U0 = pSrc16[i3 * 2u]; |
| U1 = pSrc16[(i3 * 2u) + 1u]; |
| |
| /* T0 = (yb + yd), T1 = (xb + xd)) */ |
| T0 = __SSAT(T0 + U0, 16u); |
| T1 = __SSAT(T1 + U1, 16u); |
| |
| /* writing the butterfly processed i0 sample */ |
| /* xa' = xa + xb + xc + xd */ |
| /* ya' = ya + yb + yc + yd */ |
| pSrc16[i0 * 2u] = (R0 >> 1u) + (T0 >> 1u); |
| pSrc16[(i0 * 2u) + 1u] = (R1 >> 1u) + (T1 >> 1u); |
| |
| /* R0 = (ya + yc) - (yb + yd), R1 = (xa + xc) - (xb + xd) */ |
| R0 = (R0 >> 1u) - (T0 >> 1u); |
| R1 = (R1 >> 1u) - (T1 >> 1u); |
| /* Read yb (real), xb(imag) input */ |
| T0 = pSrc16[i1 * 2u]; |
| T1 = pSrc16[(i1 * 2u) + 1u]; |
| |
| /* writing the butterfly processed i0 + fftLen/4 sample */ |
| /* xc' = (xa-xb+xc-xd) */ |
| /* yc' = (ya-yb+yc-yd) */ |
| pSrc16[i1 * 2u] = R0; |
| pSrc16[(i1 * 2u) + 1u] = R1; |
| |
| /* Read yd (real), xd(imag) input */ |
| U0 = pSrc16[i3 * 2u]; |
| U1 = pSrc16[(i3 * 2u) + 1u]; |
| /* T0 = (yb - yd), T1 = (xb - xd) */ |
| T0 = __SSAT(T0 - U0, 16u); |
| T1 = __SSAT(T1 - U1, 16u); |
| |
| /* writing the butterfly processed i0 + fftLen/2 sample */ |
| /* xb' = (xa+yb-xc-yd) */ |
| /* yb' = (ya-xb-yc+xd) */ |
| pSrc16[i2 * 2u] = (S0 >> 1u) + (T1 >> 1u); |
| pSrc16[(i2 * 2u) + 1u] = (S1 >> 1u) - (T0 >> 1u); |
| |
| /* writing the butterfly processed i0 + 3fftLen/4 sample */ |
| /* xd' = (xa-yb-xc+yd) */ |
| /* yd' = (ya+xb-yc-xd) */ |
| pSrc16[i3 * 2u] = (S0 >> 1u) - (T1 >> 1u); |
| pSrc16[(i3 * 2u) + 1u] = (S1 >> 1u) + (T0 >> 1u); |
| |
| } |
| |
| /* 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 */ |
| |
| #endif /* #ifndef ARM_MATH_CM0 */ |
| |
| } |
| |
| |
| /** |
| * @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) |
| { |
| |
| #ifndef ARM_MATH_CM0 |
| |
| /* Run the below code for Cortex-M4 and Cortex-M3 */ |
| |
| 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]; |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* 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); |
| |
| #else |
| |
| /* xc' = (ya-yb+yc-yd)* co2 + (xa-xb+xc-xd)* (si2) */ |
| out1 = __SMUADX(C2, R) >> 16u; |
| /* yc' = (xa-xb+xc-xd)* co2 - (ya-yb+yc-yd)* (si2) */ |
| out2 = __SMUSD(-C2, R); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* 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); |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* 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); |
| |
| #else |
| |
| /* 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); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* co1 & si1 are read from SIMD Coefficient pointer */ |
| C1 = pCoeff[ic]; |
| /* Butterfly process for the i0+fftLen/2 sample */ |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* 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); |
| |
| #else |
| |
| /* xb' = (ya+xb-yc-xd)* co1 + (xa-yb-xc+yd)* (si1) */ |
| out1 = __SMUADX(C1, S) >> 16u; |
| /* yb' = (xa-yb-xc+yd)* co1 - (ya+xb-yc-xd)* (si1) */ |
| out2 = __SMUSD(-C1, S); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* 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 */ |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* 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); |
| |
| #else |
| |
| /* xd' = (ya-xb-yc+xd)* co3 + (xa+yb-xc-yd)* (si3) */ |
| out1 = __SMUADX(C3, R) >> 16u; |
| /* yd' = (xa+yb-xc-yd)* co3 - (ya-xb-yc+xd)* (si3) */ |
| out2 = __SMUSD(-C3, R); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* 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); |
| |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* (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); |
| |
| #else |
| |
| /* (ya-yb+yc-yd)* co2 + (xa-xb+xc-xd)* (si2) */ |
| out1 = __SMUADX(R, C2) >> 16u; |
| /* (ya-yb+yc-yd)* (si2) - (xa-xb+xc-xd)* co2 */ |
| out2 = __SMUSD(-C2, R); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* 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); |
| |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* 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); |
| |
| #else |
| |
| /* 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 = __SMUADX(S, C1) >> 16u; |
| out2 = __SMUSD(-C1, S); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* 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 */ |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| out1 = __SMUSD(C3, R) >> 16u; |
| out2 = __SMUADX(C3, R); |
| |
| #else |
| |
| out1 = __SMUADX(C3, R) >> 16u; |
| out2 = __SMUSD(-C3, R); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| /* 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); |
| |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| |
| /* 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); |
| |
| |
| #else |
| |
| /* 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); |
| |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| } |
| /* 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 */ |
| |
| |
| #else |
| |
| /* Run the below code for Cortex-M0 */ |
| |
| q15_t R0, R1, S0, S1, T0, T1, U0, U1; |
| q15_t Co1, Si1, Co2, Si2, Co3, Si3, out1, out2; |
| uint32_t n1, n2, ic, i0, i1, i2, i3, j, k; |
| |
| /* Total process is divided into three stages */ |
| |
| /* process first stage, middle stages, & last stage */ |
| |
| /* 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, */ |
| /* pSrc16[i0 + 0], pSrc16[i0 + fftLen/4], pSrc16[i0 + fftLen/2], pSrc16[i0 + 3fftLen/4] */ |
| i1 = i0 + n2; |
| i2 = i1 + n2; |
| i3 = i2 + n2; |
| |
| /* Reading i0, i0+fftLen/2 inputs */ |
| /* input is down scale by 4 to avoid overflow */ |
| /* Read ya (real), xa(imag) input */ |
| T0 = pSrc16[i0 * 2u] >> 2u; |
| T1 = pSrc16[(i0 * 2u) + 1u] >> 2u; |
| /* input is down scale by 4 to avoid overflow */ |
| /* Read yc (real), xc(imag) input */ |
| S0 = pSrc16[i2 * 2u] >> 2u; |
| S1 = pSrc16[(i2 * 2u) + 1u] >> 2u; |
| |
| /* R0 = (ya + yc), R1 = (xa + xc) */ |
| R0 = __SSAT(T0 + S0, 16u); |
| R1 = __SSAT(T1 + S1, 16u); |
| /* S0 = (ya - yc), S1 = (xa - xc) */ |
| S0 = __SSAT(T0 - S0, 16u); |
| S1 = __SSAT(T1 - S1, 16u); |
| |
| /* Reading i0+fftLen/4 , i0+3fftLen/4 inputs */ |
| /* input is down scale by 4 to avoid overflow */ |
| /* Read yb (real), xb(imag) input */ |
| T0 = pSrc16[i1 * 2u] >> 2u; |
| T1 = pSrc16[(i1 * 2u) + 1u] >> 2u; |
| /* Read yd (real), xd(imag) input */ |
| /* input is down scale by 4 to avoid overflow */ |
| U0 = pSrc16[i3 * 2u] >> 2u; |
| U1 = pSrc16[(i3 * 2u) + 1u] >> 2u; |
| |
| /* T0 = (yb + yd), T1 = (xb + xd) */ |
| T0 = __SSAT(T0 + U0, 16u); |
| T1 = __SSAT(T1 + U1, 16u); |
| |
| /* writing the butterfly processed i0 sample */ |
| /* xa' = xa + xb + xc + xd */ |
| /* ya' = ya + yb + yc + yd */ |
| pSrc16[i0 * 2u] = (R0 >> 1u) + (T0 >> 1u); |
| pSrc16[(i0 * 2u) + 1u] = (R1 >> 1u) + (T1 >> 1u); |
| |
| /* R0 = (ya + yc) - (yb + yd), R1 = (xa + xc)- (xb + xd) */ |
| R0 = __SSAT(R0 - T0, 16u); |
| R1 = __SSAT(R1 - T1, 16u); |
| /* co2 & si2 are read from Coefficient pointer */ |
| Co2 = pCoef16[2u * ic * 2u]; |
| Si2 = pCoef16[(2u * ic * 2u) + 1u]; |
| /* xc' = (xa-xb+xc-xd)* co2 - (ya-yb+yc-yd)* (si2) */ |
| out1 = (short) ((Co2 * R0 - Si2 * R1) >> 16u); |
| /* yc' = (ya-yb+yc-yd)* co2 + (xa-xb+xc-xd)* (si2) */ |
| out2 = (short) ((Si2 * R0 + Co2 * R1) >> 16u); |
| |
| /* Reading i0+fftLen/4 */ |
| /* input is down scale by 4 to avoid overflow */ |
| /* T0 = yb, T1 = xb */ |
| T0 = pSrc16[i1 * 2u] >> 2u; |
| T1 = pSrc16[(i1 * 2u) + 1u] >> 2u; |
| |
| /* writing the butterfly processed i0 + fftLen/4 sample */ |
| /* writing output(xc', yc') in little endian format */ |
| pSrc16[i1 * 2u] = out1; |
| pSrc16[(i1 * 2u) + 1u] = out2; |
| |
| /* Butterfly calculations */ |
| /* input is down scale by 4 to avoid overflow */ |
| /* U0 = yd, U1 = xd) */ |
| U0 = pSrc16[i3 * 2u] >> 2u; |
| U1 = pSrc16[(i3 * 2u) + 1u] >> 2u; |
| |
| /* T0 = yb-yd, T1 = xb-xd) */ |
| T0 = __SSAT(T0 - U0, 16u); |
| T1 = __SSAT(T1 - U1, 16u); |
| /* R0 = (ya-yc) - (xb- xd) , R1 = (xa-xc) + (yb-yd) */ |
| R0 = (short) __SSAT((q31_t) (S0 + T1), 16); |
| R1 = (short) __SSAT((q31_t) (S1 - T0), 16); |
| /* S = (ya-yc) + (xb- xd), S1 = (xa-xc) - (yb-yd) */ |
| S0 = (short) __SSAT((q31_t) (S0 - T1), 16); |
| S1 = (short) __SSAT((q31_t) (S1 + T0), 16); |
| |
| /* co1 & si1 are read from Coefficient pointer */ |
| Co1 = pCoef16[ic * 2u]; |
| Si1 = pCoef16[(ic * 2u) + 1u]; |
| /* Butterfly process for the i0+fftLen/2 sample */ |
| /* xb' = (xa-yb-xc+yd)* co1 - (ya+xb-yc-xd)* (si1) */ |
| out1 = (short) ((Co1 * S0 - Si1 * S1) >> 16u); |
| /* yb' = (ya+xb-yc-xd)* co1 + (xa-yb-xc+yd)* (si1) */ |
| out2 = (short) ((Si1 * S0 + Co1 * S1) >> 16u); |
| /* writing output(xb', yb') in little endian format */ |
| pSrc16[i2 * 2u] = out1; |
| pSrc16[(i2 * 2u) + 1u] = out2; |
| |
| /* Co3 & si3 are read from Coefficient pointer */ |
| Co3 = pCoef16[3u * ic * 2u]; |
| Si3 = pCoef16[(3u * ic * 2u) + 1u]; |
| /* Butterfly process for the i0+3fftLen/4 sample */ |
| /* xd' = (xa+yb-xc-yd)* Co3 - (ya-xb-yc+xd)* (si3) */ |
| out1 = (short) ((Co3 * R0 - Si3 * R1) >> 16u); |
| /* yd' = (ya-xb-yc+xd)* Co3 + (xa+yb-xc-yd)* (si3) */ |
| out2 = (short) ((Si3 * R0 + Co3 * R1) >> 16u); |
| /* writing output(xd', yd') in little endian format */ |
| pSrc16[i3 * 2u] = out1; |
| pSrc16[(i3 * 2u) + 1u] = out2; |
| |
| /* 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 */ |
| Co1 = pCoef16[ic * 2u]; |
| Si1 = pCoef16[(ic * 2u) + 1u]; |
| Co2 = pCoef16[2u * ic * 2u]; |
| Si2 = pCoef16[2u * ic * 2u + 1u]; |
| Co3 = pCoef16[3u * ic * 2u]; |
| Si3 = pCoef16[(3u * ic * 2u) + 1u]; |
| |
| /* Twiddle coefficients index modifier */ |
| ic = ic + twidCoefModifier; |
| |
| /* Butterfly implementation */ |
| for (i0 = j; i0 < fftLen; i0 += n1) |
| { |
| /* index calculation for the input as, */ |
| /* pSrc16[i0 + 0], pSrc16[i0 + fftLen/4], pSrc16[i0 + fftLen/2], pSrc16[i0 + 3fftLen/4] */ |
| i1 = i0 + n2; |
| i2 = i1 + n2; |
| i3 = i2 + n2; |
| |
| /* Reading i0, i0+fftLen/2 inputs */ |
| /* Read ya (real), xa(imag) input */ |
| T0 = pSrc16[i0 * 2u]; |
| T1 = pSrc16[(i0 * 2u) + 1u]; |
| |
| /* Read yc (real), xc(imag) input */ |
| S0 = pSrc16[i2 * 2u]; |
| S1 = pSrc16[(i2 * 2u) + 1u]; |
| |
| |
| /* R0 = (ya + yc), R1 = (xa + xc) */ |
| R0 = __SSAT(T0 + S0, 16u); |
| R1 = __SSAT(T1 + S1, 16u); |
| /* S0 = (ya - yc), S1 = (xa - xc) */ |
| S0 = __SSAT(T0 - S0, 16u); |
| S1 = __SSAT(T1 - S1, 16u); |
| |
| /* Reading i0+fftLen/4 , i0+3fftLen/4 inputs */ |
| /* Read yb (real), xb(imag) input */ |
| T0 = pSrc16[i1 * 2u]; |
| T1 = pSrc16[(i1 * 2u) + 1u]; |
| |
| /* Read yd (real), xd(imag) input */ |
| U0 = pSrc16[i3 * 2u]; |
| U1 = pSrc16[(i3 * 2u) + 1u]; |
| |
| /* T0 = (yb + yd), T1 = (xb + xd) */ |
| T0 = __SSAT(T0 + U0, 16u); |
| T1 = __SSAT(T1 + U1, 16u); |
| |
| /* writing the butterfly processed i0 sample */ |
| /* xa' = xa + xb + xc + xd */ |
| /* ya' = ya + yb + yc + yd */ |
| pSrc16[i0 * 2u] = ((R0 >> 1u) + (T0 >> 1u)) >> 1u; |
| pSrc16[(i0 * 2u) + 1u] = ((R1 >> 1u) + (T1 >> 1u)) >> 1u; |
| |
| /* R0 = (ya + yc) - (yb + yd), R1 = (xa + xc) - (xb + xd) */ |
| R0 = (R0 >> 1u) - (T0 >> 1u); |
| R1 = (R1 >> 1u) - (T1 >> 1u); |
| |
| /* (ya-yb+yc-yd)* (si2) - (xa-xb+xc-xd)* co2 */ |
| out1 = (short) ((Co2 * R0 - Si2 * R1) >> 16); |
| /* (ya-yb+yc-yd)* co2 + (xa-xb+xc-xd)* (si2) */ |
| out2 = (short) ((Si2 * R0 + Co2 * R1) >> 16); |
| |
| /* Reading i0+3fftLen/4 */ |
| /* Read yb (real), xb(imag) input */ |
| T0 = pSrc16[i1 * 2u]; |
| T1 = pSrc16[(i1 * 2u) + 1u]; |
| |
| /* 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) */ |
| pSrc16[i1 * 2u] = out1; |
| pSrc16[(i1 * 2u) + 1u] = out2; |
| |
| /* Butterfly calculations */ |
| /* Read yd (real), xd(imag) input */ |
| U0 = pSrc16[i3 * 2u]; |
| U1 = pSrc16[(i3 * 2u) + 1u]; |
| |
| /* T0 = yb-yd, T1 = xb-xd) */ |
| T0 = __SSAT(T0 - U0, 16u); |
| T1 = __SSAT(T1 - U1, 16u); |
| |
| /* R0 = (ya-yc) - (xb- xd) , R1 = (xa-xc) + (yb-yd) */ |
| R0 = (S0 >> 1u) + (T1 >> 1u); |
| R1 = (S1 >> 1u) - (T0 >> 1u); |
| |
| /* S1 = (ya-yc) + (xb- xd), S1 = (xa-xc) - (yb-yd) */ |
| S0 = (S0 >> 1u) - (T1 >> 1u); |
| S1 = (S1 >> 1u) + (T0 >> 1u); |
| |
| /* Butterfly process for the i0+fftLen/2 sample */ |
| out1 = (short) ((Co1 * S0 - Si1 * S1) >> 16u); |
| out2 = (short) ((Si1 * S0 + Co1 * S1) >> 16u); |
| /* xb' = (xa-yb-xc+yd)* co1 - (ya+xb-yc-xd)* (si1) */ |
| /* yb' = (ya+xb-yc-xd)* co1 + (xa-yb-xc+yd)* (si1) */ |
| pSrc16[i2 * 2u] = out1; |
| pSrc16[(i2 * 2u) + 1u] = out2; |
| |
| /* Butterfly process for the i0+3fftLen/4 sample */ |
| out1 = (short) ((Co3 * R0 - Si3 * R1) >> 16u); |
| |
| out2 = (short) ((Si3 * R0 + Co3 * R1) >> 16u); |
| /* xd' = (xa+yb-xc-yd)* Co3 - (ya-xb-yc+xd)* (si3) */ |
| /* yd' = (ya-xb-yc+xd)* Co3 + (xa+yb-xc-yd)* (si3) */ |
| pSrc16[i3 * 2u] = out1; |
| pSrc16[(i3 * 2u) + 1u] = out2; |
| |
| |
| } |
| } |
| /* 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, */ |
| /* pSrc16[i0 + 0], pSrc16[i0 + fftLen/4], pSrc16[i0 + fftLen/2], pSrc16[i0 + 3fftLen/4] */ |
| i1 = i0 + n2; |
| i2 = i1 + n2; |
| i3 = i2 + n2; |
| |
| /* Reading i0, i0+fftLen/2 inputs */ |
| /* Read ya (real), xa(imag) input */ |
| T0 = pSrc16[i0 * 2u]; |
| T1 = pSrc16[(i0 * 2u) + 1u]; |
| /* Read yc (real), xc(imag) input */ |
| S0 = pSrc16[i2 * 2u]; |
| S1 = pSrc16[(i2 * 2u) + 1u]; |
| |
| /* R0 = (ya + yc), R1 = (xa + xc) */ |
| R0 = __SSAT(T0 + S0, 16u); |
| R1 = __SSAT(T1 + S1, 16u); |
| /* S0 = (ya - yc), S1 = (xa - xc) */ |
| S0 = __SSAT(T0 - S0, 16u); |
| S1 = __SSAT(T1 - S1, 16u); |
| |
| /* Reading i0+fftLen/4 , i0+3fftLen/4 inputs */ |
| /* Read yb (real), xb(imag) input */ |
| T0 = pSrc16[i1 * 2u]; |
| T1 = pSrc16[(i1 * 2u) + 1u]; |
| /* Read yd (real), xd(imag) input */ |
| U0 = pSrc16[i3 * 2u]; |
| U1 = pSrc16[(i3 * 2u) + 1u]; |
| |
| /* T0 = (yb + yd), T1 = (xb + xd) */ |
| T0 = __SSAT(T0 + U0, 16u); |
| T1 = __SSAT(T1 + U1, 16u); |
| |
| /* writing the butterfly processed i0 sample */ |
| /* xa' = xa + xb + xc + xd */ |
| /* ya' = ya + yb + yc + yd */ |
| pSrc16[i0 * 2u] = (R0 >> 1u) + (T0 >> 1u); |
| pSrc16[(i0 * 2u) + 1u] = (R1 >> 1u) + (T1 >> 1u); |
| |
| /* R0 = (ya + yc) - (yb + yd), R1 = (xa + xc) - (xb + xd) */ |
| R0 = (R0 >> 1u) - (T0 >> 1u); |
| R1 = (R1 >> 1u) - (T1 >> 1u); |
| |
| /* Read yb (real), xb(imag) input */ |
| T0 = pSrc16[i1 * 2u]; |
| T1 = pSrc16[(i1 * 2u) + 1u]; |
| |
| /* writing the butterfly processed i0 + fftLen/4 sample */ |
| /* xc' = (xa-xb+xc-xd) */ |
| /* yc' = (ya-yb+yc-yd) */ |
| pSrc16[i1 * 2u] = R0; |
| pSrc16[(i1 * 2u) + 1u] = R1; |
| |
| /* Read yd (real), xd(imag) input */ |
| U0 = pSrc16[i3 * 2u]; |
| U1 = pSrc16[(i3 * 2u) + 1u]; |
| /* T0 = (yb - yd), T1 = (xb - xd) */ |
| T0 = __SSAT(T0 - U0, 16u); |
| T1 = __SSAT(T1 - U1, 16u); |
| |
| /* writing the butterfly processed i0 + fftLen/2 sample */ |
| /* xb' = (xa-yb-xc+yd) */ |
| /* yb' = (ya+xb-yc-xd) */ |
| pSrc16[i2 * 2u] = (S0 >> 1u) - (T1 >> 1u); |
| pSrc16[(i2 * 2u) + 1u] = (S1 >> 1u) + (T0 >> 1u); |
| |
| |
| /* writing the butterfly processed i0 + 3fftLen/4 sample */ |
| /* xd' = (xa+yb-xc-yd) */ |
| /* yd' = (ya-xb-yc+xd) */ |
| pSrc16[i3 * 2u] = (S0 >> 1u) + (T1 >> 1u); |
| pSrc16[(i3 * 2u) + 1u] = (S1 >> 1u) - (T0 >> 1u); |
| } |
| /* 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 */ |
| |
| #endif /* #ifndef ARM_MATH_CM0 */ |
| |
| } |
| |
| |
| /* |
| * @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; |
| } |
| } |
