/*____________________________________________________________________________ FreeAmp - The Free MP3 Player MP3 Decoder originally Copyright (C) 1995-1997 Xing Technology Corp. http://www.xingtech.com Portions Copyright (C) 1998-1999 EMusic.com This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. $Id: cdct.c,v 1.11 1999/10/19 07:13:08 elrod Exp $ ____________________________________________________________________________*/ /**** cdct.c *************************************************** mod 5/16/95 first stage in 8 pt dct does not drop last sb mono MPEG audio decoder, dct portable C ******************************************************************/ #include "config.h" #include #include #include #include float coef32[31]; /* 32 pt dct coefs */ // !!!!!!!!!!!!!!!!!! (only generated once (always to same value) /*------------------------------------------------------------*/ float *dct_coef_addr() { return coef32; } /*------------------------------------------------------------*/ static void forward_bf(int m, int n, float x[], float f[], float coef[]) { int i, j, n2; int p, q, p0, k; p0 = 0; n2 = n >> 1; for (i = 0; i < m; i++, p0 += n) { k = 0; p = p0; q = p + n - 1; for (j = 0; j < n2; j++, p++, q--, k++) { f[p] = x[p] + x[q]; f[n2 + p] = coef[k] * (x[p] - x[q]); } } } /*------------------------------------------------------------*/ static void back_bf(int m, int n, float x[], float f[]) { int i, j, n2, n21; int p, q, p0; p0 = 0; n2 = n >> 1; n21 = n2 - 1; for (i = 0; i < m; i++, p0 += n) { p = p0; q = p0; for (j = 0; j < n2; j++, p += 2, q++) f[p] = x[q]; p = p0 + 1; for (j = 0; j < n21; j++, p += 2, q++) f[p] = x[q] + x[q + 1]; f[p] = x[q]; } } /*------------------------------------------------------------*/ void fdct32(float x[], float c[]) { float a[32]; /* ping pong buffers */ float b[32]; int p, q; float *src = x; /* special first stage */ for (p = 0, q = 31; p < 16; p++, q--) { a[p] = src[p] + src[q]; a[16 + p] = coef32[p] * (src[p] - src[q]); } forward_bf(2, 16, a, b, coef32 + 16); forward_bf(4, 8, b, a, coef32 + 16 + 8); forward_bf(8, 4, a, b, coef32 + 16 + 8 + 4); forward_bf(16, 2, b, a, coef32 + 16 + 8 + 4 + 2); back_bf(8, 4, a, b); back_bf(4, 8, b, a); back_bf(2, 16, a, b); back_bf(1, 32, b, c); } /*------------------------------------------------------------*/ void fdct32_dual(float x[], float c[]) { float a[32]; /* ping pong buffers */ float b[32]; int p, pp, qq; /* special first stage for dual chan (interleaved x) */ pp = 0; qq = 2 * 31; for (p = 0; p < 16; p++, pp += 2, qq -= 2) { a[p] = x[pp] + x[qq]; a[16 + p] = coef32[p] * (x[pp] - x[qq]); } forward_bf(2, 16, a, b, coef32 + 16); forward_bf(4, 8, b, a, coef32 + 16 + 8); forward_bf(8, 4, a, b, coef32 + 16 + 8 + 4); forward_bf(16, 2, b, a, coef32 + 16 + 8 + 4 + 2); back_bf(8, 4, a, b); back_bf(4, 8, b, a); back_bf(2, 16, a, b); back_bf(1, 32, b, c); } /*---------------convert dual to mono------------------------------*/ void fdct32_dual_mono(float x[], float c[]) { float a[32]; /* ping pong buffers */ float b[32]; float t1, t2; int p, pp, qq; /* special first stage */ pp = 0; qq = 2 * 31; for (p = 0; p < 16; p++, pp += 2, qq -= 2) { t1 = 0.5F * (x[pp] + x[pp + 1]); t2 = 0.5F * (x[qq] + x[qq + 1]); a[p] = t1 + t2; a[16 + p] = coef32[p] * (t1 - t2); } forward_bf(2, 16, a, b, coef32 + 16); forward_bf(4, 8, b, a, coef32 + 16 + 8); forward_bf(8, 4, a, b, coef32 + 16 + 8 + 4); forward_bf(16, 2, b, a, coef32 + 16 + 8 + 4 + 2); back_bf(8, 4, a, b); back_bf(4, 8, b, a); back_bf(2, 16, a, b); back_bf(1, 32, b, c); } /*------------------------------------------------------------*/ /*---------------- 16 pt fdct -------------------------------*/ void fdct16(float x[], float c[]) { float a[16]; /* ping pong buffers */ float b[16]; int p, q; /* special first stage (drop highest sb) */ a[0] = x[0]; a[8] = coef32[16] * x[0]; for (p = 1, q = 14; p < 8; p++, q--) { a[p] = x[p] + x[q]; a[8 + p] = coef32[16 + p] * (x[p] - x[q]); } forward_bf(2, 8, a, b, coef32 + 16 + 8); forward_bf(4, 4, b, a, coef32 + 16 + 8 + 4); forward_bf(8, 2, a, b, coef32 + 16 + 8 + 4 + 2); back_bf(4, 4, b, a); back_bf(2, 8, a, b); back_bf(1, 16, b, c); } /*------------------------------------------------------------*/ /*---------------- 16 pt fdct dual chan---------------------*/ void fdct16_dual(float x[], float c[]) { float a[16]; /* ping pong buffers */ float b[16]; int p, pp, qq; /* special first stage for interleaved input */ a[0] = x[0]; a[8] = coef32[16] * x[0]; pp = 2; qq = 2 * 14; for (p = 1; p < 8; p++, pp += 2, qq -= 2) { a[p] = x[pp] + x[qq]; a[8 + p] = coef32[16 + p] * (x[pp] - x[qq]); } forward_bf(2, 8, a, b, coef32 + 16 + 8); forward_bf(4, 4, b, a, coef32 + 16 + 8 + 4); forward_bf(8, 2, a, b, coef32 + 16 + 8 + 4 + 2); back_bf(4, 4, b, a); back_bf(2, 8, a, b); back_bf(1, 16, b, c); } /*------------------------------------------------------------*/ /*---------------- 16 pt fdct dual to mono-------------------*/ void fdct16_dual_mono(float x[], float c[]) { float a[16]; /* ping pong buffers */ float b[16]; float t1, t2; int p, pp, qq; /* special first stage */ a[0] = 0.5F * (x[0] + x[1]); a[8] = coef32[16] * a[0]; pp = 2; qq = 2 * 14; for (p = 1; p < 8; p++, pp += 2, qq -= 2) { t1 = 0.5F * (x[pp] + x[pp + 1]); t2 = 0.5F * (x[qq] + x[qq + 1]); a[p] = t1 + t2; a[8 + p] = coef32[16 + p] * (t1 - t2); } forward_bf(2, 8, a, b, coef32 + 16 + 8); forward_bf(4, 4, b, a, coef32 + 16 + 8 + 4); forward_bf(8, 2, a, b, coef32 + 16 + 8 + 4 + 2); back_bf(4, 4, b, a); back_bf(2, 8, a, b); back_bf(1, 16, b, c); } /*------------------------------------------------------------*/ /*---------------- 8 pt fdct -------------------------------*/ void fdct8(float x[], float c[]) { float a[8]; /* ping pong buffers */ float b[8]; int p, q; /* special first stage */ b[0] = x[0] + x[7]; b[4] = coef32[16 + 8] * (x[0] - x[7]); for (p = 1, q = 6; p < 4; p++, q--) { b[p] = x[p] + x[q]; b[4 + p] = coef32[16 + 8 + p] * (x[p] - x[q]); } forward_bf(2, 4, b, a, coef32 + 16 + 8 + 4); forward_bf(4, 2, a, b, coef32 + 16 + 8 + 4 + 2); back_bf(2, 4, b, a); back_bf(1, 8, a, c); } /*------------------------------------------------------------*/ /*---------------- 8 pt fdct dual chan---------------------*/ void fdct8_dual(float x[], float c[]) { float a[8]; /* ping pong buffers */ float b[8]; int p, pp, qq; /* special first stage for interleaved input */ b[0] = x[0] + x[14]; b[4] = coef32[16 + 8] * (x[0] - x[14]); pp = 2; qq = 2 * 6; for (p = 1; p < 4; p++, pp += 2, qq -= 2) { b[p] = x[pp] + x[qq]; b[4 + p] = coef32[16 + 8 + p] * (x[pp] - x[qq]); } forward_bf(2, 4, b, a, coef32 + 16 + 8 + 4); forward_bf(4, 2, a, b, coef32 + 16 + 8 + 4 + 2); back_bf(2, 4, b, a); back_bf(1, 8, a, c); } /*------------------------------------------------------------*/ /*---------------- 8 pt fdct dual to mono---------------------*/ void fdct8_dual_mono(float x[], float c[]) { float a[8]; /* ping pong buffers */ float b[8]; float t1, t2; int p, pp, qq; /* special first stage */ t1 = 0.5F * (x[0] + x[1]); t2 = 0.5F * (x[14] + x[15]); b[0] = t1 + t2; b[4] = coef32[16 + 8] * (t1 - t2); pp = 2; qq = 2 * 6; for (p = 1; p < 4; p++, pp += 2, qq -= 2) { t1 = 0.5F * (x[pp] + x[pp + 1]); t2 = 0.5F * (x[qq] + x[qq + 1]); b[p] = t1 + t2; b[4 + p] = coef32[16 + 8 + p] * (t1 - t2); } forward_bf(2, 4, b, a, coef32 + 16 + 8 + 4); forward_bf(4, 2, a, b, coef32 + 16 + 8 + 4 + 2); back_bf(2, 4, b, a); back_bf(1, 8, a, c); } /*------------------------------------------------------------*/