| /* ---------------------------------------------------------------------- |
| * Project: CMSIS DSP Library |
| * Title: arm_cfft_radix2_q15.c |
| * Description: Radix-2 Decimation in Frequency CFFT & CIFFT Fixed point processing function |
| * |
| * $Date: 18. March 2019 |
| * $Revision: V1.6.0 |
| * |
| * Target Processor: Cortex-M cores |
| * -------------------------------------------------------------------- */ |
| /* |
| * Copyright (C) 2010-2019 ARM Limited or its affiliates. All rights reserved. |
| * |
| * SPDX-License-Identifier: Apache-2.0 |
| * |
| * Licensed under the Apache License, Version 2.0 (the License); you may |
| * not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an AS IS BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "arm_math.h" |
| |
| void arm_radix2_butterfly_q15( |
| q15_t * pSrc, |
| uint32_t fftLen, |
| const q15_t * pCoef, |
| uint16_t twidCoefModifier); |
| |
| void arm_radix2_butterfly_inverse_q15( |
| q15_t * pSrc, |
| uint32_t fftLen, |
| const q15_t * pCoef, |
| uint16_t twidCoefModifier); |
| |
| void arm_bitreversal_q15( |
| q15_t * pSrc, |
| uint32_t fftLen, |
| uint16_t bitRevFactor, |
| const uint16_t * pBitRevTab); |
| |
| /** |
| @ingroup groupTransforms |
| */ |
| |
| /** |
| @addtogroup ComplexFFT |
| @{ |
| */ |
| |
| /** |
| @brief Processing function for the fixed-point CFFT/CIFFT. |
| @deprecated Do not use this function. It has been superseded by \ref arm_cfft_q15 and will be removed in the future. |
| @param[in] S points to an instance of the fixed-point CFFT/CIFFT structure |
| @param[in,out] pSrc points to the complex data buffer of size <code>2*fftLen</code>. Processing occurs in-place |
| @return none |
| */ |
| |
| void arm_cfft_radix2_q15( |
| const arm_cfft_radix2_instance_q15 * S, |
| q15_t * pSrc) |
| { |
| |
| if (S->ifftFlag == 1U) |
| { |
| arm_radix2_butterfly_inverse_q15 (pSrc, S->fftLen, S->pTwiddle, S->twidCoefModifier); |
| } |
| else |
| { |
| arm_radix2_butterfly_q15 (pSrc, S->fftLen, S->pTwiddle, S->twidCoefModifier); |
| } |
| |
| arm_bitreversal_q15(pSrc, S->fftLen, S->bitRevFactor, S->pBitRevTable); |
| } |
| |
| /** |
| @} end of ComplexFFT group |
| */ |
| |
| void arm_radix2_butterfly_q15( |
| q15_t * pSrc, |
| uint32_t fftLen, |
| const q15_t * pCoef, |
| uint16_t twidCoefModifier) |
| { |
| #if defined (ARM_MATH_DSP) |
| |
| uint32_t i, j, k, l; |
| uint32_t n1, n2, ia; |
| q15_t in; |
| q31_t T, S, R; |
| q31_t coeff, out1, out2; |
| |
| //N = fftLen; |
| n2 = fftLen; |
| |
| n1 = n2; |
| n2 = n2 >> 1; |
| ia = 0; |
| |
| // loop for groups |
| for (i = 0; i < n2; i++) |
| { |
| coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U)); |
| |
| ia = ia + twidCoefModifier; |
| |
| l = i + n2; |
| |
| T = read_q15x2 (pSrc + (2 * i)); |
| in = ((int16_t) (T & 0xFFFF)) >> 1; |
| T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF); |
| |
| S = read_q15x2 (pSrc + (2 * l)); |
| in = ((int16_t) (S & 0xFFFF)) >> 1; |
| S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF); |
| |
| R = __QSUB16(T, S); |
| |
| write_q15x2 (pSrc + (2 * i), __SHADD16(T, S)); |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| out1 = __SMUAD(coeff, R) >> 16; |
| out2 = __SMUSDX(coeff, R); |
| #else |
| out1 = __SMUSDX(R, coeff) >> 16U; |
| out2 = __SMUAD(coeff, R); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| write_q15x2 (pSrc + (2U * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF)); |
| |
| coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U)); |
| |
| ia = ia + twidCoefModifier; |
| |
| /* loop for butterfly */ |
| i++; |
| l++; |
| |
| T = read_q15x2 (pSrc + (2 * i)); |
| in = ((int16_t) (T & 0xFFFF)) >> 1; |
| T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF); |
| |
| S = read_q15x2 (pSrc + (2 * l)); |
| in = ((int16_t) (S & 0xFFFF)) >> 1; |
| S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF); |
| |
| R = __QSUB16(T, S); |
| |
| write_q15x2 (pSrc + (2 * i), __SHADD16(T, S)); |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| out1 = __SMUAD(coeff, R) >> 16; |
| out2 = __SMUSDX(coeff, R); |
| #else |
| |
| out1 = __SMUSDX(R, coeff) >> 16U; |
| out2 = __SMUAD(coeff, R); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| write_q15x2 (pSrc + (2U * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF)); |
| |
| } /* groups loop end */ |
| |
| twidCoefModifier = twidCoefModifier << 1U; |
| |
| /* loop for stage */ |
| for (k = fftLen / 2; k > 2; k = k >> 1) |
| { |
| n1 = n2; |
| n2 = n2 >> 1; |
| ia = 0; |
| |
| /* loop for groups */ |
| for (j = 0; j < n2; j++) |
| { |
| coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U)); |
| |
| ia = ia + twidCoefModifier; |
| |
| /* loop for butterfly */ |
| for (i = j; i < fftLen; i += n1) |
| { |
| l = i + n2; |
| |
| T = read_q15x2 (pSrc + (2 * i)); |
| |
| S = read_q15x2 (pSrc + (2 * l)); |
| |
| R = __QSUB16(T, S); |
| |
| write_q15x2 (pSrc + (2 * i), __SHADD16(T, S)); |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| out1 = __SMUAD(coeff, R) >> 16; |
| out2 = __SMUSDX(coeff, R); |
| #else |
| out1 = __SMUSDX(R, coeff) >> 16U; |
| out2 = __SMUAD(coeff, R); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| write_q15x2 (pSrc + (2U * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF)); |
| |
| i += n1; |
| |
| l = i + n2; |
| |
| T = read_q15x2 (pSrc + (2 * i)); |
| |
| S = read_q15x2 (pSrc + (2 * l)); |
| |
| R = __QSUB16(T, S); |
| |
| write_q15x2 (pSrc + (2 * i), __SHADD16(T, S)); |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| out1 = __SMUAD(coeff, R) >> 16; |
| out2 = __SMUSDX(coeff, R); |
| #else |
| out1 = __SMUSDX(R, coeff) >> 16U; |
| out2 = __SMUAD(coeff, R); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| write_q15x2 (pSrc + (2U * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF)); |
| |
| } /* butterfly loop end */ |
| |
| } /* groups loop end */ |
| |
| twidCoefModifier = twidCoefModifier << 1U; |
| } /* stages loop end */ |
| |
| n1 = n2; |
| n2 = n2 >> 1; |
| ia = 0; |
| |
| coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U)); |
| |
| ia = ia + twidCoefModifier; |
| |
| /* loop for butterfly */ |
| for (i = 0; i < fftLen; i += n1) |
| { |
| l = i + n2; |
| |
| T = read_q15x2 (pSrc + (2 * i)); |
| |
| S = read_q15x2 (pSrc + (2 * l)); |
| |
| R = __QSUB16(T, S); |
| |
| write_q15x2 (pSrc + (2 * i), __QADD16(T, S)); |
| |
| write_q15x2 (pSrc + (2 * l), R); |
| |
| i += n1; |
| l = i + n2; |
| |
| T = read_q15x2 (pSrc + (2 * i)); |
| |
| S = read_q15x2 (pSrc + (2 * l)); |
| |
| R = __QSUB16(T, S); |
| |
| write_q15x2 (pSrc + (2 * i), __QADD16(T, S)); |
| |
| write_q15x2 (pSrc + (2 * l), R); |
| |
| } /* groups loop end */ |
| |
| |
| #else /* #if defined (ARM_MATH_DSP) */ |
| |
| uint32_t i, j, k, l; |
| uint32_t n1, n2, ia; |
| q15_t xt, yt, cosVal, sinVal; |
| |
| |
| // N = fftLen; |
| n2 = fftLen; |
| |
| n1 = n2; |
| n2 = n2 >> 1; |
| ia = 0; |
| |
| /* loop for groups */ |
| for (j = 0; j < n2; j++) |
| { |
| cosVal = pCoef[(ia * 2)]; |
| sinVal = pCoef[(ia * 2) + 1]; |
| ia = ia + twidCoefModifier; |
| |
| /* loop for butterfly */ |
| for (i = j; i < fftLen; i += n1) |
| { |
| l = i + n2; |
| xt = (pSrc[2 * i] >> 1U) - (pSrc[2 * l] >> 1U); |
| pSrc[2 * i] = ((pSrc[2 * i] >> 1U) + (pSrc[2 * l] >> 1U)) >> 1U; |
| |
| yt = (pSrc[2 * i + 1] >> 1U) - (pSrc[2 * l + 1] >> 1U); |
| pSrc[2 * i + 1] = ((pSrc[2 * l + 1] >> 1U) + |
| (pSrc[2 * i + 1] >> 1U) ) >> 1U; |
| |
| pSrc[2 * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) + |
| ((int16_t) (((q31_t) yt * sinVal) >> 16))); |
| |
| pSrc[2U * l + 1] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) - |
| ((int16_t) (((q31_t) xt * sinVal) >> 16))); |
| |
| } /* butterfly loop end */ |
| |
| } /* groups loop end */ |
| |
| twidCoefModifier = twidCoefModifier << 1U; |
| |
| /* loop for stage */ |
| for (k = fftLen / 2; k > 2; k = k >> 1) |
| { |
| n1 = n2; |
| n2 = n2 >> 1; |
| ia = 0; |
| |
| /* loop for groups */ |
| for (j = 0; j < n2; j++) |
| { |
| cosVal = pCoef[ia * 2]; |
| sinVal = pCoef[(ia * 2) + 1]; |
| ia = ia + twidCoefModifier; |
| |
| /* loop for butterfly */ |
| for (i = j; i < fftLen; i += n1) |
| { |
| l = i + n2; |
| xt = pSrc[2 * i] - pSrc[2 * l]; |
| pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1U; |
| |
| yt = pSrc[2 * i + 1] - pSrc[2 * l + 1]; |
| pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1U; |
| |
| pSrc[2 * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) + |
| ((int16_t) (((q31_t) yt * sinVal) >> 16))); |
| |
| pSrc[2U * l + 1] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) - |
| ((int16_t) (((q31_t) xt * sinVal) >> 16))); |
| |
| } /* butterfly loop end */ |
| |
| } /* groups loop end */ |
| |
| twidCoefModifier = twidCoefModifier << 1U; |
| } /* stages loop end */ |
| |
| n1 = n2; |
| n2 = n2 >> 1; |
| ia = 0; |
| |
| /* loop for groups */ |
| for (j = 0; j < n2; j++) |
| { |
| cosVal = pCoef[ia * 2]; |
| sinVal = pCoef[(ia * 2) + 1]; |
| |
| ia = ia + twidCoefModifier; |
| |
| /* loop for butterfly */ |
| for (i = j; i < fftLen; i += n1) |
| { |
| l = i + n2; |
| xt = pSrc[2 * i] - pSrc[2 * l]; |
| pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]); |
| |
| yt = pSrc[2 * i + 1] - pSrc[2 * l + 1]; |
| pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]); |
| |
| pSrc[2 * l] = xt; |
| |
| pSrc[2 * l + 1] = yt; |
| |
| } /* butterfly loop end */ |
| |
| } /* groups loop end */ |
| |
| twidCoefModifier = twidCoefModifier << 1U; |
| |
| #endif /* #if defined (ARM_MATH_DSP) */ |
| |
| } |
| |
| |
| void arm_radix2_butterfly_inverse_q15( |
| q15_t * pSrc, |
| uint32_t fftLen, |
| const q15_t * pCoef, |
| uint16_t twidCoefModifier) |
| { |
| #if defined (ARM_MATH_DSP) |
| |
| uint32_t i, j, k, l; |
| uint32_t n1, n2, ia; |
| q15_t in; |
| q31_t T, S, R; |
| q31_t coeff, out1, out2; |
| |
| // N = fftLen; |
| n2 = fftLen; |
| |
| n1 = n2; |
| n2 = n2 >> 1; |
| ia = 0; |
| |
| /* loop for groups */ |
| for (i = 0; i < n2; i++) |
| { |
| coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U)); |
| |
| ia = ia + twidCoefModifier; |
| |
| l = i + n2; |
| |
| T = read_q15x2 (pSrc + (2 * i)); |
| in = ((int16_t) (T & 0xFFFF)) >> 1; |
| T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF); |
| |
| S = read_q15x2 (pSrc + (2 * l)); |
| in = ((int16_t) (S & 0xFFFF)) >> 1; |
| S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF); |
| |
| R = __QSUB16(T, S); |
| |
| write_q15x2 (pSrc + (2 * i), __SHADD16(T, S)); |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| out1 = __SMUSD(coeff, R) >> 16; |
| out2 = __SMUADX(coeff, R); |
| #else |
| out1 = __SMUADX(R, coeff) >> 16U; |
| out2 = __SMUSD(__QSUB(0, coeff), R); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| write_q15x2 (pSrc + (2 * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF)); |
| |
| coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U)); |
| |
| ia = ia + twidCoefModifier; |
| |
| /* loop for butterfly */ |
| i++; |
| l++; |
| |
| T = read_q15x2 (pSrc + (2 * i)); |
| in = ((int16_t) (T & 0xFFFF)) >> 1; |
| T = ((T >> 1) & 0xFFFF0000) | (in & 0xFFFF); |
| |
| S = read_q15x2 (pSrc + (2 * l)); |
| in = ((int16_t) (S & 0xFFFF)) >> 1; |
| S = ((S >> 1) & 0xFFFF0000) | (in & 0xFFFF); |
| |
| R = __QSUB16(T, S); |
| |
| write_q15x2 (pSrc + (2 * i), __SHADD16(T, S)); |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| out1 = __SMUSD(coeff, R) >> 16; |
| out2 = __SMUADX(coeff, R); |
| #else |
| out1 = __SMUADX(R, coeff) >> 16U; |
| out2 = __SMUSD(__QSUB(0, coeff), R); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| write_q15x2 (pSrc + (2 * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF)); |
| |
| } /* groups loop end */ |
| |
| twidCoefModifier = twidCoefModifier << 1U; |
| |
| /* loop for stage */ |
| for (k = fftLen / 2; k > 2; k = k >> 1) |
| { |
| n1 = n2; |
| n2 = n2 >> 1; |
| ia = 0; |
| |
| /* loop for groups */ |
| for (j = 0; j < n2; j++) |
| { |
| coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U)); |
| |
| ia = ia + twidCoefModifier; |
| |
| /* loop for butterfly */ |
| for (i = j; i < fftLen; i += n1) |
| { |
| l = i + n2; |
| |
| T = read_q15x2 (pSrc + (2 * i)); |
| |
| S = read_q15x2 (pSrc + (2 * l)); |
| |
| R = __QSUB16(T, S); |
| |
| write_q15x2 (pSrc + (2 * i), __SHADD16(T, S)); |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| out1 = __SMUSD(coeff, R) >> 16; |
| out2 = __SMUADX(coeff, R); |
| #else |
| out1 = __SMUADX(R, coeff) >> 16U; |
| out2 = __SMUSD(__QSUB(0, coeff), R); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| write_q15x2 (pSrc + (2 * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF)); |
| |
| i += n1; |
| |
| l = i + n2; |
| |
| T = read_q15x2 (pSrc + (2 * i)); |
| |
| S = read_q15x2 (pSrc + (2 * l)); |
| |
| R = __QSUB16(T, S); |
| |
| write_q15x2 (pSrc + (2 * i), __SHADD16(T, S)); |
| |
| #ifndef ARM_MATH_BIG_ENDIAN |
| out1 = __SMUSD(coeff, R) >> 16; |
| out2 = __SMUADX(coeff, R); |
| #else |
| out1 = __SMUADX(R, coeff) >> 16U; |
| out2 = __SMUSD(__QSUB(0, coeff), R); |
| #endif /* #ifndef ARM_MATH_BIG_ENDIAN */ |
| |
| write_q15x2 (pSrc + (2 * l), (q31_t) ((out2) & 0xFFFF0000) | (out1 & 0x0000FFFF)); |
| |
| } /* butterfly loop end */ |
| |
| } /* groups loop end */ |
| |
| twidCoefModifier = twidCoefModifier << 1U; |
| } /* stages loop end */ |
| |
| n1 = n2; |
| n2 = n2 >> 1; |
| ia = 0; |
| |
| /* loop for groups */ |
| for (j = 0; j < n2; j++) |
| { |
| coeff = read_q15x2 ((q15_t *)pCoef + (ia * 2U)); |
| |
| ia = ia + twidCoefModifier; |
| |
| /* loop for butterfly */ |
| for (i = j; i < fftLen; i += n1) |
| { |
| l = i + n2; |
| |
| T = read_q15x2 (pSrc + (2 * i)); |
| |
| S = read_q15x2 (pSrc + (2 * l)); |
| |
| R = __QSUB16(T, S); |
| |
| write_q15x2 (pSrc + (2 * i), __QADD16(T, S)); |
| |
| write_q15x2 (pSrc + (2 * l), R); |
| |
| } /* butterfly loop end */ |
| |
| } /* groups loop end */ |
| |
| twidCoefModifier = twidCoefModifier << 1U; |
| |
| #else /* #if defined (ARM_MATH_DSP) */ |
| |
| uint32_t i, j, k, l; |
| uint32_t n1, n2, ia; |
| q15_t xt, yt, cosVal, sinVal; |
| |
| // N = fftLen; |
| n2 = fftLen; |
| |
| n1 = n2; |
| n2 = n2 >> 1; |
| ia = 0; |
| |
| /* loop for groups */ |
| for (j = 0; j < n2; j++) |
| { |
| cosVal = pCoef[(ia * 2)]; |
| sinVal = pCoef[(ia * 2) + 1]; |
| ia = ia + twidCoefModifier; |
| |
| /* loop for butterfly */ |
| for (i = j; i < fftLen; i += n1) |
| { |
| l = i + n2; |
| xt = (pSrc[2 * i] >> 1U) - (pSrc[2 * l] >> 1U); |
| pSrc[2 * i] = ((pSrc[2 * i] >> 1U) + (pSrc[2 * l] >> 1U)) >> 1U; |
| |
| yt = (pSrc[2 * i + 1] >> 1U) - (pSrc[2 * l + 1] >> 1U); |
| pSrc[2 * i + 1] = ((pSrc[2 * l + 1] >> 1U) + |
| (pSrc[2 * i + 1] >> 1U) ) >> 1U; |
| |
| pSrc[2 * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) - |
| ((int16_t) (((q31_t) yt * sinVal) >> 16))); |
| |
| pSrc[2 * l + 1] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) + |
| ((int16_t) (((q31_t) xt * sinVal) >> 16))); |
| |
| } /* butterfly loop end */ |
| |
| } /* groups loop end */ |
| |
| twidCoefModifier = twidCoefModifier << 1U; |
| |
| /* loop for stage */ |
| for (k = fftLen / 2; k > 2; k = k >> 1) |
| { |
| n1 = n2; |
| n2 = n2 >> 1; |
| ia = 0; |
| |
| /* loop for groups */ |
| for (j = 0; j < n2; j++) |
| { |
| cosVal = pCoef[(ia * 2)]; |
| sinVal = pCoef[(ia * 2) + 1]; |
| ia = ia + twidCoefModifier; |
| |
| /* loop for butterfly */ |
| for (i = j; i < fftLen; i += n1) |
| { |
| l = i + n2; |
| xt = pSrc[2 * i] - pSrc[2 * l]; |
| pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]) >> 1U; |
| |
| yt = pSrc[2 * i + 1] - pSrc[2 * l + 1]; |
| pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]) >> 1U; |
| |
| pSrc[2 * l] = (((int16_t) (((q31_t) xt * cosVal) >> 16)) - |
| ((int16_t) (((q31_t) yt * sinVal) >> 16)) ); |
| |
| pSrc[2 * l + 1] = (((int16_t) (((q31_t) yt * cosVal) >> 16)) + |
| ((int16_t) (((q31_t) xt * sinVal) >> 16)) ); |
| |
| } /* butterfly loop end */ |
| |
| } /* groups loop end */ |
| |
| twidCoefModifier = twidCoefModifier << 1U; |
| } /* stages loop end */ |
| |
| n1 = n2; |
| n2 = n2 >> 1; |
| ia = 0; |
| |
| cosVal = pCoef[(ia * 2)]; |
| sinVal = pCoef[(ia * 2) + 1]; |
| |
| ia = ia + twidCoefModifier; |
| |
| /* loop for butterfly */ |
| for (i = 0; i < fftLen; i += n1) |
| { |
| l = i + n2; |
| xt = pSrc[2 * i] - pSrc[2 * l]; |
| pSrc[2 * i] = (pSrc[2 * i] + pSrc[2 * l]); |
| |
| yt = pSrc[2 * i + 1] - pSrc[2 * l + 1]; |
| pSrc[2 * i + 1] = (pSrc[2 * l + 1] + pSrc[2 * i + 1]); |
| |
| pSrc[2 * l] = xt; |
| |
| pSrc[2 * l + 1] = yt; |
| |
| } /* groups loop end */ |
| |
| |
| #endif /* #if defined (ARM_MATH_DSP) */ |
| |
| } |