wtbl_aweunits.c

A GTK sound font editor. Sound font files are used to synthesize instruments from audio samples for

/*==================================================================
 * wtbl_aweunits.c - OSS AWE driver unit conversion functions
 * Based on the awesfx utility Copyright (C) 1996-1999 Takashi Iwai
 *
 * Smurf Sound Font Editor
 * Copyright (C) 1999-2001 Josh Green
 *
 * 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., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA or point your web browser to http://www.gnu.org.
 *
 * To contact the author of this program:
 * Email: Josh Green <[e-mail]>
 * Smurf homepage: http://smurf.sourceforge.net
 *==================================================================*/
#include "config.h"

#ifdef AWE_SUPPORT

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "wtbl_aweunits.h"

/*================================================================
 * unit conversion
 *================================================================*/

/*
 * Sample pitch offset for the specified sample rate
 * rate=44100 is no offset, each 4096 is 1 octave (twice).
 * eg, when rate is 22050, this offset becomes -4096.
 */
gint
awe_calc_rate_offset (guint16 Hz)
{
  if (Hz == 44100)
    return 0;
  return (short) (log ((double) Hz / 44100) / log (2.0) * 4096.0);
}

/*================================================================
 * Emu8000 parameters conversion
 *================================================================*/
/*
 * Delay time
 * sf: timecents
 * parm: 0x8000 - msec * 0.725
 */
gint
awe_calc_delay (gint16 amount)
{
  /* completely lost here! */
  gint delay, temp;

  if (amount <= -12000)
    return 0x8000;		/* minimum delay */
  delay = (amount + 0x30E4) << 16;
  delay /= 1200;
  temp = 0x10000 | (delay & 0xffff);	/* SI:BX */
  delay >>= 16;
  temp >>= 16 - (delay & 0xff);
  delay = 0x8000 - temp;
  if (delay < -32768)
    delay = -32768;
  return delay;
}

/*
 * Attack and Hold time
 * This parameter is difficult...
 *
 * ADIP says:
 * bit15 = always 0
 * upper byte = 0x7f - hold time / 92, max 11.68sec at 0, no hold at 0x7f.
 * bit7 = always 0
 * lower byte = encoded attack time, 0 = never attack,
 *      1 = max 11.68sec, 0x7f = min 6msec.
 *
 * In VVSG, 
 *        if AttackTime_ms >= 360ms:
 *          RegisterValue = 11878/AttackTime_ms - 1
 *        if AttackTime_ms < 360ms and AttackTime != 0:
 *          RegisterValue = 32 + [16/log(2)] * log(360_ms/AttackTime_ms)
 *        if AttackTime_ms == 0
 *          RegisterValue = 0x7F
 */
/* attack & decay/release time table (msec) */

gint
awe_calc_attack (gint16 amount)
{
  gint attack, temp1, temp2;

  if (amount >= 4300)
    return 1;
  if (amount > -600)
    {
      attack = (amount + 500) / 150;
      temp1 = ((~attack) & 7) | 8;
      temp2 = attack >> 16;
      attack += temp2 & 7;
      attack >>= 3;
      temp1 >>= attack;
      if (temp1 < 1)
	temp1 = 1;
      return temp1;
    }
  attack = (37 - amount) / 75 + 8;
  if (attack >= 128)
    attack = 127;		/* 128 */
  return attack;
}

gint
awe_calc_hold (gint16 amount)
{
  gint hold, temp;

  if (amount < -5368)
    return 127;			/* maximum hold */
  hold = (amount + 4130) << 16;
  hold /= 1200;
  temp = 0x10000 | (hold & 0xffff);	/* SI:BX */
  hold >>= 16;
  temp >>= 16 - (hold & 0xff);
  hold = 127 - temp;
  if (hold < 0)
    hold = 0;
  return hold;
}

/*
 * Sustain level
 * sf: centibels
 * parm: 0x7f - sustain_level(dB) * 0.75
 */
gint
awe_calc_sustain (gint16 amount)
{
  gint val = 127 - (amount * 127) / 1000;
  if (val < 0)
    return 0;
  else if (val > 127)
    return 127;
  else
    return val;
}

/*
 * Modulation sustain level
 * sf: 0.1%
 * parm: 0x7f - sustain_level(dB) * 0.75
 */
gint
awe_calc_mod_sustain (gint16 amount)
{
  gint val = 127 - (amount * 127) / 1000;
  if (val < 0)
    return 0;
  else if (val > 127)
    return 127;
  else
    return val;
}

/*
 * This parameter is also difficult to understand...
 *
 * ADIP says the value means decay rate, 0x7f minimum time is of 240usec/dB,
 * 0x01 being the max time of 470msec/dB, and 0 begin no decay.
 *
 * In VVSG, 2 * log(0.5) * log(23756/[ms]) (0x7F...0ms), but this is
 * obviously incorrect. But, the max time 23756 seems to be correct.
 * (actually, in NRPN control, decay time is within 0.023 and 23.7 secs.)
 * 
 */
gint
awe_calc_decay (gint16 amount)
{
  gint decay, temp1, temp2;

  if (amount > 1800)
    {
      decay = (amount - 1800) / 150;
      temp1 = ((~decay) & 7) | 8;
      /* here, ASM code has high part of decay & 0x7 too, but we know that
         this is always clear since amount is between 1800 & 32767,
         therefore decay is 0..206
       */
      temp2 = decay >> 3;
      temp1 >>= temp2;
      decay = temp1;
      if (decay < 1)
	decay = 1;
      return decay;
    }

  /* here, amount < 1800 */
  decay = (37 - amount) / 75 + 39;
  if (decay >= 128)
    decay = 127;
  return decay;
}

/*
 * Cutoff frequency; return (0-255)
 * sf: abs cents (cents above 8.176Hz)
 * parm: quarter semitone; 0 = 125Hz, 0xff=8kHz?
 * (in VVS, cutoff(Hz) = value * 31.25 + 100)
 */
gint
awe_calc_cutoff (gint16 amount)
{
  gint cutoff = (amount + 0xf) / 0x1d - 0x99;
  if (cutoff < 0)
    return 0;
  else if (cutoff > 255)
    return 255;
  else
    return cutoff;
}

/*
 * Initial filter Q; return (0-15)
 * sf: centibels above DC gain.
 * parm: 0 = no attenuation, 15 = 24dB
 */
gint
awe_calc_filterQ (gint16 amount)
{
  gint Q = amount / 12;
  if (Q < 0)
    return 0;
  else if (Q > 15)
    return 15;
  else
    return Q;
}

/*
 * Pitch modulation height (0-255)
 * sf: cents, 100 = 1 semitone
 * parm: signed char, 0x80 = 1 octave
 */
gint
awe_calc_pitch_shift (gint16 amount)
{
  gint val = (amount * 0x1b4f) >> 16;
  if (val < -128)
    val = -128;
  else if (val > 127)
    val = 127;
  if (val < 0)
    return 0x100 + val;
  else
    return val;
}

/*
 * Filter cutoff for modulation envelope (0-255)
 * sf: 1200 = +1 octave
 * par: 0x80 = +6(modenv) octave
 */
gint
awe_calc_modenv_cutoff (gint16 amount)
{
  gint val;

  val = (amount * 0x048D) >> 16;

  if (val < -128)
    val = -128;
  if (val > 127)
    val = 127;

  if (val < 0)
    return (guint8) (0x100 + val);
  else
    return (guint8) val;
}

/*
 * Filter cutoff for modulation LFO (0-255)
 * sf: 1200 = +1 octave
 * par: 0x80 = +3(lfo1) octave
 */
gint
awe_calc_modlfo_cutoff (gint16 amount)
{
  gint val;

  val = (amount * 0x0919) >> 16;

  if (val < -128)
    val = -128;
  if (val > 127)
    val = 127;

  if (val < 0)
    return (guint8) (0x100 + val);
  else
    return (guint8) val;
}

/*
 * Tremolo volume (0-255)
 * sf: cB, 10 = 1dB
 * parm: 0x7f = +/-12dB, 0x80 = -/+12dB
 */
gint
awe_calc_tremolo (gint16 amount)
{
  gint val = (amount << 7) / 0x78;
  if (val < -128)
    val = -128;
  if (val > 127)
    val = 127;
  if (val < 0)
    val = 0x100 + val;
  return (guint8) val;
}

/*
 * Envelope/LFO frequency (0-255)
 * sf: cents 
 * parm: mHz / 42 (42mHz step; 0xff=10.72Hz)
 */
gint
awe_calc_freq (gint16 amount)
{
  gint freq, temp;

  if (amount <= -16000)
    return 0;			/* minimum freq. shift */

  freq = (amount + 0x23A6) << 16;
  freq /= 1200;
  temp = 0x10000 | (freq & 0xffff);	/* DX:AX */
  freq >>= 16;			/* SI:BX */
  temp >>= 16 - (freq & 0xff);
  if (temp > 255)
    temp = 255;
  return temp;
}

/*
 * Panning position (0-127)
 * sf: (left) -500 - 500 (right) (0=center)
 * parm: (left) 0 - 127 (right), as same as MIDI parameter.
 *
 * NOTE:
 *   The value above is converted in the driver to the actual emu8000
 *   parameter, 8bit, 0 (right) - 0xff (left).
 */
gint
awe_calc_pan (gint16 val)
{
  if (val < -500)
    return 0;
  else if (val > 500)
    return 127;
  return (gint8) ((val + 500) * 127 / 1000);
}

/*
 * Value in 0.1% units
 * sf: 0 - 1000 (max)
 * parm: 0 - 255 (max)
 */
gint
awe_calc_tenthpercent (gint16 val)
{
  if (val < 0)
    return 0;
  else if (val > 1000)
    val = 255;
  return (guint8) (val * 255 / 1000);
}

/*
 * Initial volume attenuation (0-255)
 * sf: centibels, eg. 60 = 6dB below from full scale
 * parm: dB * 8 / 3
 */
gint
awe_calc_attenuation (gint16 amount)
{
  gint atten;
  atten = (amount + 12) / 24;
  atten = (atten * 8) / 3;
  if (atten > 255)
    atten = 255;
  if (atten < 0)
    atten = 0;
  return atten;
}

#endif /* #ifdef AWE_SUPPORT */