238 lines
6.5 KiB
C++
238 lines
6.5 KiB
C++
/* FluidSynth - A Software Synthesizer
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*
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* Copyright (C) 2003 Peter Hanappe and others.
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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 Library General Public License
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* as published by the Free Software Foundation; either version 2 of
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* 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, but
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* 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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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the Free
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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* 02111-1307, USA
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*/
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#include "conv.h"
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namespace FluidS {
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/* conversion tables */
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static float fluid_cb2amp_tab[FLUID_CB_AMP_SIZE];
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static float fluid_atten2amp_tab[FLUID_ATTEN_AMP_SIZE];
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static float fluid_concave_tab[128];
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static float fluid_convex_tab[128];
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static float fluid_pan_tab[FLUID_PAN_SIZE];
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/*
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* void fluid_synth_init
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*
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* Does all the initialization for this module.
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*/
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void fluid_conversion_config()
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{
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/* centibels to amplitude conversion
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* Note: SF2.01 section 8.1.3: Initial attenuation range is
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* between 0 and 144 dB. Therefore a negative attenuation is
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* not allowed.
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*/
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for (int i = 0; i < FLUID_CB_AMP_SIZE; i++)
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fluid_cb2amp_tab[i] = (float) pow(10.0, (double) i / -200.0);
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/* NOTE: EMU8k and EMU10k devices don't conform to the SoundFont
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* specification in regards to volume attenuation. The below calculation
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* is an approx. equation for generating a table equivelant to the
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* cb_to_amp_table[] in tables.c of the TiMidity++ source, which I'm told
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* was generated from device testing. By the spec this should be centibels.
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*/
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for (int i = 0; i < FLUID_ATTEN_AMP_SIZE; i++)
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fluid_atten2amp_tab[i] = (float) pow(10.0, (double) i / FLUID_ATTEN_POWER_FACTOR);
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/* initialize the conversion tables (see fluid_mod.c
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fluid_mod_get_value cases 4 and 8) */
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/* concave unipolar positive transform curve */
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fluid_concave_tab[0] = 0.0;
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fluid_concave_tab[127] = 1.0;
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/* convex unipolar positive transform curve */
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fluid_convex_tab[0] = 0;
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fluid_convex_tab[127] = 1.0;
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/* There seems to be an error in the specs. The equations are
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implemented according to the pictures on SF2.01 page 73. */
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for (int i = 1; i < 127; i++) {
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double x = -20.0 / 96.0 * log((i * i) / (127.0 * 127.0)) / log(10.0);
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fluid_convex_tab[i] = (float) (1.0 - x);
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fluid_concave_tab[127 - i] = (float) x;
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}
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/* initialize the pan conversion table */
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double x = M_PI / 2.0 / (FLUID_PAN_SIZE - 1.0);
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for (int i = 0; i < FLUID_PAN_SIZE; i++)
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fluid_pan_tab[i] = (float) sin(i * x);
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}
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/*
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* fluid_cb2amp
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*
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* in: a value between 0 and 960, 0 is no attenuation
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* out: a value between 1 and 0
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*/
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float fluid_cb2amp(float cb)
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{
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/*
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* cb: an attenuation in 'centibels' (1/10 dB)
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* SF2.01 page 49 # 48 limits it to 144 dB.
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* 96 dB is reasonable for 16 bit systems, 144 would make sense for 24 bit.
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*/
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/* minimum attenuation: 0 dB */
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if (cb < 0)
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return 1.0;
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if (cb >= FLUID_CB_AMP_SIZE)
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return 0.0;
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return fluid_cb2amp_tab[(int) cb];
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}
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/*
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* fluid_atten2amp
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*
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* in: a value between 0 and 1440, 0 is no attenuation
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* out: a value between 1 and 0
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*
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* Note: Volume attenuation is supposed to be centibels but EMU8k/10k don't
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* follow this. Thats the reason for separate fluid_cb2amp and fluid_atten2amp.
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*/
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float fluid_atten2amp(float atten)
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{
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if (atten < 0)
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return 1.0;
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else if (atten >= FLUID_ATTEN_AMP_SIZE)
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return 0.0;
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else
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return fluid_atten2amp_tab[(int) atten];
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}
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/*
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* fluid_tc2sec_delay
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*/
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float fluid_tc2sec_delay(float tc)
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{
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/* SF2.01 section 8.1.2 items 21, 23, 25, 33
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* SF2.01 section 8.1.3 items 21, 23, 25, 33
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*
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* The most negative number indicates a delay of 0. Range is limited
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* from -12000 to 5000
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*/
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if (tc <= -32768.0f)
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return (float) 0.0f;
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if (tc < -12000.)
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tc = (float) -12000.0f;
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if (tc > 5000.0f)
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tc = (float) 5000.0f;
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return (float) pow(2.0, (double) tc / 1200.0);
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}
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/*
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* fluid_tc2sec_attack
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*/
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float fluid_tc2sec_attack(float tc)
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{
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/* SF2.01 section 8.1.2 items 26, 34
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* SF2.01 section 8.1.3 items 26, 34
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* The most negative number indicates a delay of 0
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* Range is limited from -12000 to 8000 */
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if (tc<=-32768.)
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return (float) 0.0;
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if (tc<-12000.)
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tc=(float) -12000.0;
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if (tc>8000.)
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tc=(float) 8000.0;
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return (float) pow(2.0, (double) tc / 1200.0);
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}
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/*
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* fluid_tc2sec
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*/
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float fluid_tc2sec(float tc)
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{
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/* No range checking here! */
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return (float) pow(2.0, (double) tc / 1200.0);
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}
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/*
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* fluid_tc2sec_release
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*/
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float fluid_tc2sec_release(float tc)
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{
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/* SF2.01 section 8.1.2 items 30, 38
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* SF2.01 section 8.1.3 items 30, 38
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* No 'most negative number' rule here!
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* Range is limited from -12000 to 8000
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*/
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if (tc<=-32768.)
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return (float) 0.0;
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if (tc<-12000.)
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tc=(float) -12000.0;
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if (tc>8000.)
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tc=(float) 8000.0;
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return (float) pow(2.0, (double) tc / 1200.0);
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}
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/*
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* fluid_act2hz
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*
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* Convert from absolute cents to Hertz
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*/
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float fluid_act2hz(float c)
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{
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return (float) (8.176 * pow(2.0, (double) c / 1200.0));
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}
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/*
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* fluid_pan
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*/
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float fluid_pan(float c, int left)
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{
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if (left)
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c = -c;
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if (c < -500)
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return (float) 0.0;
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else if (c > 500)
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return (float) 1.0;
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else
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return fluid_pan_tab[(int) (c + 500)];
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}
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/*
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* fluid_concave
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*/
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float fluid_concave(float val)
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{
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if (val < 0)
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return 0;
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else if (val > 127)
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return 1;
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return fluid_concave_tab[(int) val];
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}
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/*
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* fluid_convex
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*/
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float fluid_convex(float val)
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{
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if (val < 0)
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return 0;
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else if (val > 127)
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return 1;
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return fluid_convex_tab[(int) val];
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}
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}
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