78 lines
2.2 KiB
C
78 lines
2.2 KiB
C
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/*
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* Musepack audio compression
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* Copyright (C) 1999-2004 Buschmann/Klemm/Piecha/Wolf
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "mpcdec/mpcmath.h"
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#ifdef FAST_MATH
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const float tabatan2 [ 2*TABSTEP+1] [2];
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const float tabcos [26*TABSTEP+1] [2];
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const float tabsqrt_ex [256];
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const float tabsqrt_m [ TABSTEP+1] [2];
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void Init_FastMath ( void )
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{
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int i; mpc_floatint X, Y; double xm, x0, xp, x, y; float* p;
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p = (float*) tabatan2;
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for ( i = -TABSTEP; i <= TABSTEP; i++ ) {
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xm = atan ((i-0.5)/TABSTEP);
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x0 = atan ((i+0.0)/TABSTEP);
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xp = atan ((i+0.5)/TABSTEP);
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x = x0/2 + (xm + xp)/4;
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y = xp - xm;
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*p++ = x;
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*p++ = y;
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}
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p = (float*) tabcos;
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for ( i = -13*TABSTEP; i <= 13*TABSTEP; i++ ) {
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xm = cos ((i-0.5)/TABSTEP);
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x0 = cos ((i+0.0)/TABSTEP);
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xp = cos ((i+0.5)/TABSTEP);
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x = x0/2 + (xm + xp)/4;
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y = xp - xm;
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*p++ = x;
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*p++ = y;
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}
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p = (float*) tabsqrt_ex;
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for ( i = 0; i < 255; i++ ) {
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X.n = (i << 23);
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Y.n = (i << 23) + (1<<23) - 1;
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*p++ = sqrt(X.f);
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}
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X.n = (255 << 23) - 1;
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*p++ = sqrt(X.f);
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p = (float*) tabsqrt_m;
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for ( i = 1*TABSTEP; i <= 2*TABSTEP; i++ ) {
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xm = sqrt ((i-0.5)/TABSTEP);
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x0 = sqrt ((i+0.0)/TABSTEP);
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xp = sqrt ((i+0.5)/TABSTEP);
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x = x0/2 + (xm + xp)/4;
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y = xp - xm;
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*p++ = x;
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*p++ = y;
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}
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}
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#endif
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