raze-gles/polymer/eduke32/source/jaudiolib/src/pitch.c

113 lines
2.9 KiB
C
Raw Normal View History

/*
Copyright (C) 1994-1995 Apogee Software, Ltd.
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.
*/
/**********************************************************************
module: PITCH.C
author: James R. Dose
date: June 14, 1993
Routines for pitch scaling.
(c) Copyright 1993 James R. Dose. All Rights Reserved.
**********************************************************************/
#include <stdlib.h>
#include <math.h>
#include "pitch.h"
#define MAXDETUNE 50
static uint32_t PitchTable[ 12 ][ MAXDETUNE ];
static int32_t PITCH_Installed = 0;
/*---------------------------------------------------------------------
Function: PITCH_Init
Initializes pitch table.
---------------------------------------------------------------------*/
void PITCH_Init(void)
{
int32_t note;
int32_t detune;
if (!PITCH_Installed)
{
for (note = 0; note < 12; note++)
{
for (detune = 0; detune < MAXDETUNE; detune++)
{
PitchTable[ note ][ detune ] = 0x10000 *
pow(2, (note * MAXDETUNE + detune) / (12.0 * MAXDETUNE));
}
}
PITCH_Installed = 1;
}
}
/*---------------------------------------------------------------------
Function: PITCH_GetScale
Returns a fixed-point value to scale number the specified amount.
---------------------------------------------------------------------*/
uint32_t PITCH_GetScale(int32_t pitchoffset)
{
uint32_t scale;
int32_t octaveshift;
int32_t noteshift;
int32_t note;
int32_t detune;
if ( !PITCH_Installed )
PITCH_Init();
if (pitchoffset == 0)
return PitchTable[ 0 ][ 0 ];
noteshift = pitchoffset % 1200;
if (noteshift < 0)
noteshift += 1200;
note = noteshift / 100;
detune = (noteshift % 100) / (100 / MAXDETUNE);
octaveshift = (pitchoffset - noteshift) / 1200;
if (detune < 0)
{
detune += (100 / MAXDETUNE);
note--;
if (note < 0)
{
note += 12;
octaveshift--;
}
}
scale = PitchTable[ note ][ detune ];
return (octaveshift < 0) ? (scale >> -octaveshift) : (scale <<= octaveshift);
}