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MCUME/MCUME_pico/picovcs/Tiasound.c

617 wiersze
22 KiB
C
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/*****************************************************************************/
/* */
/* Module: TIA Chip Sound Simulator */
/* Purpose: To emulate the sound generation hardware of the Atari TIA chip. */
/* Author: Ron Fries */
/* */
/* Revision History: */
/* 10-Sep-96 - V1.0 - Initial Release */
/* 14-Jan-97 - V1.1 - Cleaned up sound output by eliminating counter */
/* reset. */
/* */
/*****************************************************************************/
/* */
/* License Information and Copyright Notice */
/* ======================================== */
/* */
/* TiaSound is Copyright(c) 1996 by Ron Fries */
/* */
/* This library is free software; you can redistribute it and/or modify it */
/* under the terms of version 2 of the GNU Library General Public License */
/* as published by the Free Software Foundation. */
/* */
/* This library 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 Library */
/* General Public License for more details. */
/* To obtain a copy of the GNU Library General Public License, write to the */
/* Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
/* */
/* Any permitted reproduction of these routines, in whole or in part, must */
/* bear this legend. */
/* */
/*****************************************************************************/
#include "Atari2600EmulatorGlobals.h"
#include "emuapi.h"
/* define some data types to keep it platform independent */
#define int8 char
#define int16 short
#define int32 int
#define uint8 unsigned int8
#define uint16 unsigned int16
#define uint32 unsigned int32
/* CONSTANT DEFINITIONS */
/* definitions for AUDCx (15, 16) */
#define SET_TO_1 0x00 /* 0000 */
#define POLY4 0x01 /* 0001 */
#define DIV31_POLY4 0x02 /* 0010 */
#define POLY5_POLY4 0x03 /* 0011 */
#define PURE1 0x04 /* 0100 */
#define PURE2 0x05 /* 0101 */
#define DIV31_PURE 0x06 /* 0110 */
#define POLY5_2 0x07 /* 0111 */
#define POLY9 0x08 /* 1000 */
#define POLY5 0x09 /* 1001 */
#define DIV31_POLY5 0x0a /* 1010 */
#define POLY5_POLY5 0x0b /* 1011 */
#define DIV3_PURE 0x0c /* 1100 */
#define DIV3_PURE2 0x0d /* 1101 */
#define DIV93_PURE 0x0e /* 1110 */
#define DIV3_POLY5 0x0f /* 1111 */
#define DIV3_MASK 0x0c
#define AUDC0 0x15
#define AUDC1 0x16
#define AUDF0 0x17
#define AUDF1 0x18
#define AUDV0 0x19
#define AUDV1 0x1a
/* the size (in entries) of the 4 polynomial tables */
#define POLY4_SIZE 0x000f
#define POLY5_SIZE 0x001f
#define POLY9_SIZE 0x01ff
/* channel definitions */
#define CHAN1 0
#define CHAN2 1
//#define FALSE 0
//#define TRUE 1
/* LOCAL GLOBAL VARIABLE DEFINITIONS */
/* structures to hold the 6 tia sound control bytes */
uint8 AUDC[2]; /* AUDCx (15, 16) */
uint8 AUDF[2]; /* AUDFx (17, 18) */
uint8 AUDV[2]; /* AUDVx (19, 1A) */
static uint8 Outvol[2]; /* last output volume for each channel */
/* Initialze the bit patterns for the polynomials. */
/* The 4bit and 5bit patterns are the identical ones used in the tia chip. */
/* Though the patterns could be packed with 8 bits per byte, using only a */
/* single bit per byte keeps the math simple, which is important for */
/* efficient processing. */
static uint8 Bit4[POLY4_SIZE] =
{ 1,1,0,1,1,1,0,0,0,0,1,0,1,0,0 };
static uint8 Bit5[POLY5_SIZE] =
{ 0,0,1,0,1,1,0,0,1,1,1,1,1,0,0,0,1,1,0,1,1,1,0,1,0,1,0,0,0,0,1 };
/* I've treated the 'Div by 31' counter as another polynomial because of */
/* the way it operates. It does not have a 50% duty cycle, but instead */
/* has a 13:18 ratio (of course, 13+18 = 31). This could also be */
/* implemented by using counters. */
static uint8 Div31[POLY5_SIZE] =
{ 0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0 };
/* Rather than have a table with 511 entries, I use a random number */
/* generator. */
static uint8 Bit9[POLY9_SIZE];
static uint8 P4[2]; /* Position pointer for the 4-bit POLY array */
static uint8 P5[2]; /* Position pointer for the 5-bit POLY array */
static uint16 P9[2]; /* Position pointer for the 9-bit POLY array */
static uint8 Div_n_cnt[2]; /* Divide by n counter. one for each channel */
static uint8 Div_n_max[2]; /* Divide by n maximum, one for each channel */
/* In my routines, I treat the sample output as another divide by N counter. */
/* For better accuracy, the Samp_n_cnt has a fixed binary decimal point */
/* which has 8 binary digits to the right of the decimal point. */
static uint16 Samp_n_max; /* Sample max, multiplied by 256 */
static uint16 Samp_n_cnt; /* Sample cnt. */
extern unsigned char *sounddata;
/*****************************************************************************/
/* Module: Tia_sound_init() */
/* Purpose: to handle the power-up initialization functions */
/* these functions should only be executed on a cold-restart */
/* */
/* Author: Ron Fries */
/* Date: September 10, 1996 */
/* */
/* Inputs: sample_freq - the value for the '30 Khz' Tia audio clock */
/* playback_freq - the playback frequency in samples per second */
/* */
/* Outputs: Adjusts local globals - no return value */
/* */
/*****************************************************************************/
void Tia_sound_init (uint16 sample_freq, uint16 playback_freq)
{
uint8 chan;
int16 n;
/* fill the 9bit polynomial with random bits */
for (n=0; n<POLY9_SIZE; n++)
{
Bit9[n] = rand() & 0x01; /* fill poly9 with random bits */
}
/* calculate the sample 'divide by N' value based on the playback freq. */
Samp_n_max = (uint16)(((uint32)sample_freq<<8)/playback_freq);
Samp_n_cnt = 0; /* initialize all bits of the sample counter */
/* initialize the local globals */
for (chan = CHAN1; chan <= CHAN2; chan++)
{
Outvol[chan] = 0;
Div_n_cnt[chan] = 0;
Div_n_max[chan] = 0;
AUDC[chan] = 0;
AUDF[chan] = 0;
AUDV[chan] = 0;
P4[chan] = 0;
P5[chan] = 0;
P9[chan] = 0;
}
#ifdef HAS_SND
emu_sndInit();
#endif
}
/*****************************************************************************/
/* Module: Update_tia_sound() */
/* Purpose: To process the latest control values stored in the AUDF, AUDC, */
/* and AUDV s. It pre-calculates as much information as */
/* possible for better performance. This routine has not been */
/* optimized. */
/* */
/* Author: Ron Fries */
/* Date: January 14, 1997 */
/* */
/* Inputs: addr - the address of the parameter to be changed */
/* val - the new value to be placed in the specified address */
/* */
/* Outputs: Adjusts local globals - no return value */
/* */
/*****************************************************************************/
//This file was modified from its original version for use in PocketVCS
// by Stuart Russell
void Update_tia_sound (uint16 addr, uint8 val)
{
uint16 new_val = 0;
uint8 chan;
if (nOptions_SoundOn){
/* determine which address was changed */
switch (addr)
{
case AUDC0:
AUDC[0] = val & 0x0f;
chan = 0;
break;
case AUDC1:
AUDC[1] = val & 0x0f;
chan = 1;
break;
case AUDF0:
AUDF[0] = val & 0x1f;
chan = 0;
break;
case AUDF1:
AUDF[1] = val & 0x1f;
chan = 1;
break;
case AUDV0:
AUDV[0] = (val & 0x0f) << 3;
chan = 0;
break;
case AUDV1:
AUDV[1] = (val & 0x0f) << 3;
chan = 1;
break;
default:
chan = 255;
break;
}
/* if the output value changed */
if (chan != 255)
{
/* an AUDC value of 0 is a special case */
if (AUDC[chan] == SET_TO_1)
{
/* indicate the clock is zero so no processing will occur */
new_val = 0;
/* and set the output to the selected volume */
Outvol[chan] = AUDV[chan];
}
else
{
/* otherwise calculate the 'divide by N' value */
new_val = AUDF[chan] + 1;
/* if bits 2 & 3 are set, then multiply the 'div by n' count by 3 */
if ((AUDC[chan] & DIV3_MASK) == DIV3_MASK)
{
new_val *= 3;
}
}
#ifdef HAS_SND
emu_sndPlaySound(chan, Outvol[chan], new_val);
#endif
/* only reset those channels that have changed */
if (new_val != Div_n_max[chan])
{
/* reset the divide by n counters */
Div_n_max[chan] = new_val;
/* if the channel is now volume only or was volume only */
if ((Div_n_cnt[chan] == 0) || (new_val == 0))
{
/* reset the counter (otherwise let it complete the previous) */
Div_n_cnt[chan] = new_val;
}
}
}
}
}
/*****************************************************************************/
/* Module: Tia_process_2() */
/* Purpose: To fill the output buffer with the sound output based on the */
/* tia chip parameters. This routine has not been optimized. */
/* Though it is not used by the program, I've left it for reference.*/
/* */
/* Author: Ron Fries */
/* Date: September 10, 1996 */
/* */
/* Inputs: *buffer - pointer to the buffer where the audio output will */
/* be placed */
/* n - size of the playback buffer */
/* */
/* Outputs: the buffer will be filled with n bytes of audio - no return val */
/* */
/*****************************************************************************/
void Tia_process ( unsigned char *buffer, uint16 n)
{
uint8 chan;
/* loop until the buffer is filled */
while (n)
{
/* loop through the channels */
for (chan = CHAN1; chan <= CHAN2; chan++)
{
/* NOTE: this routine intentionally does not count down to zero */
/* since 0 is used as a special case - no clock */
/* if the divide by N counter can count down */
if (Div_n_cnt[chan] > 1)
{
/* decrement and loop */
Div_n_cnt[chan]--;
}
/* otherwise if we've reached the bottom */
else if (Div_n_cnt[chan] == 1)
{
/* reset the counter */
Div_n_cnt[chan] = Div_n_max[chan];
/* the P5 counter has multiple uses, so we inc it here */
P5[chan]++;
if (P5[chan] == POLY5_SIZE)
P5[chan] = 0;
/* check clock modifier for clock tick */
/* if we're using pure tones OR
we're using DIV31 and the DIV31 bit is set OR
we're using POLY5 and the POLY5 bit is set */
if (((AUDC[chan] & 0x02) == 0) ||
(((AUDC[chan] & 0x01) == 0) && Div31[P5[chan]]) ||
(((AUDC[chan] & 0x01) == 1) && Bit5[P5[chan]]))
{
if (AUDC[chan] & 0x04) /* pure modified clock selected */
{
if (Outvol[chan]) /* if the output was set */
Outvol[chan] = 0; /* turn it off */
else
Outvol[chan] = AUDV[chan]; /* else turn it on */
}
else if (AUDC[chan] & 0x08) /* check for p5/p9 */
{
if (AUDC[chan] == POLY9) /* check for poly9 */
{
/* inc the poly9 counter */
P9[chan]++;
if (P9[chan] == POLY9_SIZE)
P9[chan] = 0;
if (Bit9[P9[chan]]) /* if poly9 bit is set */
Outvol[chan] = AUDV[chan];
else
Outvol[chan] = 0;
}
else /* must be poly5 */
{
if (Bit5[P5[chan]])
Outvol[chan] = AUDV[chan];
else
Outvol[chan] = 0;
}
}
else /* poly4 is the only remaining option */
{
/* inc the poly4 counter */
P4[chan]++;
if (P4[chan] == POLY4_SIZE)
P4[chan] = 0;
if (Bit4[P4[chan]])
Outvol[chan] = AUDV[chan];
else
Outvol[chan] = 0;
}
}
}
}
/* decrement the sample counter - value is 256 since the lower
byte contains the fractional part */
Samp_n_cnt -= 256;
/* if the count down has reached zero */
if (Samp_n_cnt < 256)
{
/* adjust the sample counter */
Samp_n_cnt += Samp_n_max;
/* calculate the latest output value and place in buffer */
*(buffer++) = Outvol[0] + Outvol[1];
/* and indicate one less byte to process */
n--;
}
}
}
/*****************************************************************************/
/* Module: Tia_process() */
/* Purpose: To fill the output buffer with the sound output based on the */
/* tia chip parameters. This routine has been optimized. */
/* */
/* Author: Ron Fries */
/* Date: September 10, 1996 */
/* */
/* Inputs: *buffer - pointer to the buffer where the audio output will */
/* be placed */
/* n - size of the playback buffer */
/* */
/* Outputs: the buffer will be filled with n bytes of audio - no return val */
/* */
/*****************************************************************************/
void Tia_process_2 ( unsigned short *buffer, uint16 n)
{
uint8 audc0,audv0,audc1,audv1;
uint8 div_n_cnt0,div_n_cnt1;
uint8 p5_0, p5_1,outvol_0,outvol_1;
audc0 = AUDC[0];
audv0 = AUDV[0];
audc1 = AUDC[1];
audv1 = AUDV[1];
/* make temporary local copy */
p5_0 = P5[0];
p5_1 = P5[1];
outvol_0 = Outvol[0];
outvol_1 = Outvol[1];
div_n_cnt0 = Div_n_cnt[0];
div_n_cnt1 = Div_n_cnt[1];
/* loop until the buffer is filled */
while (n)
{
/* Process channel 0 */
if (div_n_cnt0 > 1)
{
div_n_cnt0--;
}
else if (div_n_cnt0 == 1)
{
div_n_cnt0 = Div_n_max[0];
/* the P5 counter has multiple uses, so we inc it here */
p5_0++;
if (p5_0 == POLY5_SIZE)
p5_0 = 0;
/* check clock modifier for clock tick */
if (((audc0 & 0x02) == 0) ||
(((audc0 & 0x01) == 0) && Div31[p5_0]) ||
(((audc0 & 0x01) == 1) && Bit5[p5_0]))
{
if (audc0 & 0x04) /* pure modified clock selected */
{
if (outvol_0) /* if the output was set */
outvol_0 = 0; /* turn it off */
else
outvol_0 = audv0; /* else turn it on */
}
else if (audc0 & 0x08) /* check for p5/p9 */
{
if (audc0 == POLY9) /* check for poly9 */
{
/* inc the poly9 counter */
P9[0]++;
if (P9[0] == POLY9_SIZE)
P9[0] = 0;
if (Bit9[P9[0]])
outvol_0 = audv0;
else
outvol_0 = 0;
}
else /* must be poly5 */
{
if (Bit5[p5_0])
outvol_0 = audv0;
else
outvol_0 = 0;
}
}
else /* poly4 is the only remaining option */
{
/* inc the poly4 counter */
P4[0]++;
if (P4[0] == POLY4_SIZE)
P4[0] = 0;
if (Bit4[P4[0]])
outvol_0 = audv0;
else
outvol_0 = 0;
}
}
}
/* Process channel 1 */
if (div_n_cnt1 > 1)
{
div_n_cnt1--;
}
else if (div_n_cnt1 == 1)
{
div_n_cnt1 = Div_n_max[1];
/* the P5 counter has multiple uses, so we inc it here */
p5_1++;
if (p5_1 == POLY5_SIZE)
p5_1 = 0;
/* check clock modifier for clock tick */
if (((audc1 & 0x02) == 0) ||
(((audc1 & 0x01) == 0) && Div31[p5_1]) ||
(((audc1 & 0x01) == 1) && Bit5[p5_1]))
{
if (audc1 & 0x04) /* pure modified clock selected */
{
if (outvol_1) /* if the output was set */
outvol_1 = 0; /* turn it off */
else
outvol_1 = audv1; /* else turn it on */
}
else if (audc1 & 0x08) /* check for p5/p9 */
{
if (audc1 == POLY9) /* check for poly9 */
{
/* inc the poly9 counter */
P9[1]++;
if (P9[1] == POLY9_SIZE)
P9[1] = 0;
if (Bit9[P9[1]])
outvol_1 = audv1;
else
outvol_1 = 0;
}
else /* must be poly5 */
{
if (Bit5[p5_1])
outvol_1 = audv1;
else
outvol_1 = 0;
}
}
else /* poly4 is the only remaining option */
{
/* inc the poly4 counter */
P4[1]++;
if (P4[1] == POLY4_SIZE)
P4[1] = 0;
if (Bit4[P4[1]])
outvol_1 = audv1;
else
outvol_1 = 0;
}
}
}
/* decrement the sample counter - value is 256 since the lower
byte contains the fractional part */
Samp_n_cnt -= 256;
/* if the count down has reached zero */
if (Samp_n_cnt < 256)
{
/* adjust the sample counter */
Samp_n_cnt += Samp_n_max;
/* calculate the latest output value and place in buffer */
*(buffer++) = (outvol_0 + outvol_1)*256;
/* and indicate one less byte to process */
n--;
}
}
/* save for next round */
P5[0] = p5_0;
P5[1] = p5_1;
Outvol[0] = outvol_0;
Outvol[1] = outvol_1;
Div_n_cnt[0] = div_n_cnt0;
Div_n_cnt[1] = div_n_cnt1;
}
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