fft.rar_TMS320C6748_tms320c6748 fft

/* ======================================================================= */ /* DSPF_sp_fftSPxSP_cn.c -- Forward FFT with Mixed Radix */ /* Natural C Implementation */ /* */ /* Rev 0.0.3 */ /* */ /* Copyright (C) 2011 Texas Instruments Incorporated - http://www.ti.com/ */ /* */ /* */ /* Redistribution and use in source and binary forms, with or without */ /* modification, are permitted provided that the following conditions */ /* are met: */ /* */ /* Redistributions of source code must retain the above copyright */ /* notice, this list of conditions and the following disclaimer. */ /* */ /* Redistributions in binary form must reproduce the above copyright */ /* notice, this list of conditions and the following disclaimer in the */ /* documentation and/or other materials provided with the */ /* distribution. */ /* */ /* Neither the name of Texas Instruments Incorporated nor the names of */ /* its contributors may be used to endorse or promote products derived */ /* from this software without specific prior written permission. */ /* */ /* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS */ /* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT */ /* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR */ /* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT */ /* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, */ /* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT */ /* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, */ /* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY */ /* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT */ /* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE */ /* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /* */ /* ======================================================================= */ #pragma CODE_SECTION(DSPF_sp_fftSPxSP_cn, ".text:natural"); #include "DSPF_sp_fftSPxSP_cn.h" #ifndef _TMS320C6x unsigned int _bitr(unsigned int a) { unsigned int i, b=0; for(i=0; i<32; i++) { b |= (((a >> i) & 0x1) << (31 -i)); } return(b); } #endif void DSPF_sp_fftSPxSP_cn (int N, float *ptr_x, float *ptr_w, float *ptr_y, unsigned char *brev, int n_min, int offset, int n_max) { int i, j, k, l1, l2, h2, predj; int tw_offset, stride, fft_jmp; float x0, x1, x2, x3, x4, x5, x6, x7; float xt0, yt0, xt1, yt1, xt2, yt2, yt3; float yt4, yt5, yt6, yt7; float si1, si2, si3, co1, co2, co3; float xh0, xh1, xh20, xh21, xl0, xl1, xl20, xl21; float x_0, x_1, x_l1, x_l1p1, x_h2, x_h2p1, x_l2, x_l2p1; float xl0_0, xl1_0, xl0_1, xl1_1; float xh0_0, xh1_0, xh0_1, xh1_1; float *x, *w; int l0, radix; float *y0, *ptr_x0, *ptr_x2; radix = n_min; stride = N; /* n is the number of complex samples */ tw_offset = 0; while (stride > radix) { j = 0; fft_jmp = stride + (stride >> 1); h2 = stride >> 1; l1 = stride; l2 = stride + (stride >> 1); x = ptr_x; w = ptr_w + tw_offset; for (i = 0; i < N; i += 4) { co1 = w[j]; si1 = w[j + 1]; co2 = w[j + 2]; si2 = w[j + 3]; co3 = w[j + 4]; si3 = w[j + 5]; x_0 = x[0]; x_1 = x[1]; x_h2 = x[h2]; x_h2p1 = x[h2 + 1]; x_l1 = x[l1]; x_l1p1 = x[l1 + 1]; x_l2 = x[l2]; x_l2p1 = x[l2 + 1]; xh0 = x_0 + x_l1; xh1 = x_1 + x_l1p1; xl0 = x_0 - x_l1; xl1 = x_1 - x_l1p1; xh20 = x_h2 + x_l2; xh21 = x_h2p1 + x_l2p1; xl20 = x_h2 - x_l2; xl21 = x_h2p1 - x_l2p1; ptr_x0 = x; ptr_x0[0] = xh0 + xh20; ptr_x0[1] = xh1 + xh21; ptr_x2 = ptr_x0; x += 2; j += 6; predj = (j - fft_jmp); if (!predj) x += fft_jmp; if (!predj) j = 0; xt0 = xh0 - xh20; yt0 = xh1 - xh21; xt1 = xl0 + xl21; yt2 = xl1 + xl20; xt2 = xl0 - xl21; yt1 = xl1 - xl20; ptr_x2[l1] = xt1 * co1 + yt1 * si1; ptr_x2[l1 + 1] = yt1 * co1 - xt1 * si1; ptr_x2[h2] = xt0 * co2 + yt0 * si2; ptr_x2[h2 + 1] = yt0 * co2 - xt0 * si2; ptr_x2[l2] = xt2 * co3 + yt2 * si3; ptr_x2[l2 + 1] = yt2 * co3 - xt2 * si3; } tw_offset += fft_jmp; stride = stride >> 2; } /* end while */ j = offset >> 2; ptr_x0 = ptr_x; y0 = ptr_y; /* l0 = _norm(n_max) +3; get size of fft */ l0 = 0; for (k = 30; k >= 0; k--) if ((n_max & (1 << k)) == 0) l0++; else break; l0 = l0 + 3; if (radix <= 4) for (i = 0; i < N; i += 4) { /* reversal computation */ k = _bitr(j) >> l0; j++; /* multiple of 4 index */ x0 = ptr_x0[0]; x1 = ptr_x0[1]; x2 = ptr_x0[2]; x3 = ptr_x0[3]; x4 = ptr_x0[4]; x5 = ptr_x0[5]; x6 = ptr_x0[6]; x7 = ptr_x0[7]; ptr_x0 += 8; xh0_0 = x0 + x4; xh1_0 = x1 + x5; xh0_1 = x2 + x6; xh1_1 = x3 + x7; if (radix == 2) { xh0_0 = x0; xh1_0 = x1; xh0_1 = x2; xh1_1 = x3; } yt0 = xh0_0 + xh0_1; yt1 = xh1_0 + xh1_1; yt4 = xh0_0 - xh0_1; yt5 = xh1_0 - xh1_1; xl0_0 = x0 - x4; xl1_0 = x1 - x5; xl0_1 = x2 - x6; xl1_1 = x3 - x7; if (radix == 2) { xl0_0 = x4; xl1_0 = x5; xl1_1 = x6; xl0_1 = x7; } yt2 = xl0_0 + xl1_1; yt3 = xl1_0 - xl0_1; yt6 = xl0_0 - xl1_1; yt7 = xl1_0 + xl0_1; if (radix == 2) { yt7 = xl1_0 - xl0_1; yt3 = xl1_0 + xl0_1; } y0[k] = yt0; y0[k + 1] = yt1; k += n_max >> 1; y0[k] = yt2; y0[k + 1] = yt3; k += n_max >> 1; y0[k] = yt4;