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rockbox/apps/codecs/libgme/ymdeltat.c

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/*
**
** File: ymdeltat.c
**
** YAMAHA DELTA-T adpcm sound emulation subroutine
** used by fmopl.c (Y8950) and fm.c (YM2608 and YM2610/B)
**
** Base program is YM2610 emulator by Hiromitsu Shioya.
** Written by Tatsuyuki Satoh
** Improvements by Jarek Burczynski (bujar at mame dot net)
**
**
** History:
**
** 03-08-2003 Jarek Burczynski:
** - fixed BRDY flag implementation.
**
** 24-07-2003 Jarek Burczynski, Frits Hilderink:
** - fixed delault value for control2 in YM_DELTAT_ADPCM_Reset
**
** 22-07-2003 Jarek Burczynski, Frits Hilderink:
** - fixed external memory support
**
** 15-06-2003 Jarek Burczynski:
** - implemented CPU -> AUDIO ADPCM synthesis (via writes to the ADPCM data reg $08)
** - implemented support for the Limit address register
** - supported two bits from the control register 2 ($01): RAM TYPE (x1 bit/x8 bit), ROM/RAM
** - implemented external memory access (read/write) via the ADPCM data reg reads/writes
** Thanks go to Frits Hilderink for the example code.
**
** 14-06-2003 Jarek Burczynski:
** - various fixes to enable proper support for status register flags: BSRDY, PCM BSY, ZERO
** - modified EOS handling
**
** 05-04-2003 Jarek Burczynski:
** - implemented partial support for external/processor memory on sample replay
**
** 01-12-2002 Jarek Burczynski:
** - fixed first missing sound in gigandes thanks to previous fix (interpolator) by ElSemi
** - renamed/removed some YM_DELTAT struct fields
**
** 28-12-2001 Acho A. Tang
** - added EOS status report on ADPCM playback.
**
** 05-08-2001 Jarek Burczynski:
** - now_step is initialized with 0 at the start of play.
**
** 12-06-2001 Jarek Burczynski:
** - corrected end of sample bug in YM_DELTAT_ADPCM_CALC.
** Checked on real YM2610 chip - address register is 24 bits wide.
** Thanks go to Stefan Jokisch (stefan.jokisch@gmx.de) for tracking down the problem.
**
** TO DO:
** Check size of the address register on the other chips....
**
** Version 0.72
**
** sound chips that have this unit:
** YM2608 OPNA
** YM2610/B OPNB
** Y8950 MSX AUDIO
**
*/
#include "ymdeltat.h"
#define INLINE __inline
#define logerror (void)
#define YM_DELTAT_DELTA_MAX (24576)
#define YM_DELTAT_DELTA_MIN (127)
#define YM_DELTAT_DELTA_DEF (127)
#define YM_DELTAT_DECODE_RANGE 32768
#define YM_DELTAT_DECODE_MIN (-(YM_DELTAT_DECODE_RANGE))
#define YM_DELTAT_DECODE_MAX ((YM_DELTAT_DECODE_RANGE)-1)
/* Forecast to next Forecast (rate = *8) */
/* 1/8 , 3/8 , 5/8 , 7/8 , 9/8 , 11/8 , 13/8 , 15/8 */
static const INT32 ym_deltat_decode_tableB1[16] ICONST_ATTR = {
1, 3, 5, 7, 9, 11, 13, 15,
-1, -3, -5, -7, -9, -11, -13, -15,
};
/* delta to next delta (rate= *64) */
/* 0.9 , 0.9 , 0.9 , 0.9 , 1.2 , 1.6 , 2.0 , 2.4 */
static const INT32 ym_deltat_decode_tableB2[16] ICONST_ATTR = {
57, 57, 57, 57, 77, 102, 128, 153,
57, 57, 57, 57, 77, 102, 128, 153
};
#if 0
void YM_DELTAT_BRDY_callback(YM_DELTAT *DELTAT)
{
logerror("BRDY_callback reached (flag set) !\n");
/* set BRDY bit in status register */
if(DELTAT->status_set_handler)
if(DELTAT->status_change_BRDY_bit)
(DELTAT->status_set_handler)(DELTAT->status_change_which_chip, DELTAT->status_change_BRDY_bit);
}
#endif
UINT8 YM_DELTAT_ADPCM_Read(YM_DELTAT *DELTAT)
{
UINT8 v = 0;
/* external memory read */
if ( (DELTAT->portstate & 0xe0)==0x20 )
{
/* two dummy reads */
if (DELTAT->memread)
{
DELTAT->now_addr = DELTAT->start << 1;
DELTAT->memread--;
return 0;
}
if ( DELTAT->now_addr != (DELTAT->end<<1) )
{
v = DELTAT->memory[DELTAT->now_addr>>1];
/*logerror("YM Delta-T memory read $%08x, v=$%02x\n", DELTAT->now_addr >> 1, v);*/
DELTAT->now_addr+=2; /* two nibbles at a time */
/* reset BRDY bit in status register, which means we are reading the memory now */
if(DELTAT->status_reset_handler)
if(DELTAT->status_change_BRDY_bit)
(DELTAT->status_reset_handler)(DELTAT->status_change_which_chip, DELTAT->status_change_BRDY_bit);
/* setup a timer that will callback us in 10 master clock cycles for Y8950
* in the callback set the BRDY flag to 1 , which means we have another data ready.
* For now, we don't really do this; we simply reset and set the flag in zero time, so that the IRQ will work.
*/
/* set BRDY bit in status register */
if(DELTAT->status_set_handler)
if(DELTAT->status_change_BRDY_bit)
(DELTAT->status_set_handler)(DELTAT->status_change_which_chip, DELTAT->status_change_BRDY_bit);
}
else
{
/* set EOS bit in status register */
if(DELTAT->status_set_handler)
if(DELTAT->status_change_EOS_bit)
(DELTAT->status_set_handler)(DELTAT->status_change_which_chip, DELTAT->status_change_EOS_bit);
}
}
return v;
}
/* 0-DRAM x1, 1-ROM, 2-DRAM x8, 3-ROM (3 is bad setting - not allowed by the manual) */
static const UINT8 dram_rightshift[4] ICONST_ATTR ={3,0,0,0};
/* DELTA-T ADPCM write register */
void YM_DELTAT_ADPCM_Write(YM_DELTAT *DELTAT,int r,int v)
{
if(r>=0x10) return;
DELTAT->reg[r] = v; /* stock data */
switch( r )
{
case 0x00:
/*
START:
Accessing *external* memory is started when START bit (D7) is set to "1", so
you must set all conditions needed for recording/playback before starting.
If you access *CPU-managed* memory, recording/playback starts after
read/write of ADPCM data register $08.
REC:
0 = ADPCM synthesis (playback)
1 = ADPCM analysis (record)
MEMDATA:
0 = processor (*CPU-managed*) memory (means: using register $08)
1 = external memory (using start/end/limit registers to access memory: RAM or ROM)
SPOFF:
controls output pin that should disable the speaker while ADPCM analysis
RESET and REPEAT only work with external memory.
some examples:
value: START, REC, MEMDAT, REPEAT, SPOFF, x,x,RESET meaning:
C8 1 1 0 0 1 0 0 0 Analysis (recording) from AUDIO to CPU (to reg $08), sample rate in PRESCALER register
E8 1 1 1 0 1 0 0 0 Analysis (recording) from AUDIO to EXT.MEMORY, sample rate in PRESCALER register
80 1 0 0 0 0 0 0 0 Synthesis (playing) from CPU (from reg $08) to AUDIO,sample rate in DELTA-N register
a0 1 0 1 0 0 0 0 0 Synthesis (playing) from EXT.MEMORY to AUDIO, sample rate in DELTA-N register
60 0 1 1 0 0 0 0 0 External memory write via ADPCM data register $08
20 0 0 1 0 0 0 0 0 External memory read via ADPCM data register $08
*/
/* handle emulation mode */
if(DELTAT->emulation_mode == YM_DELTAT_EMULATION_MODE_YM2610)
{
v |= 0x20; /* YM2610 always uses external memory and doesn't even have memory flag bit. */
}
DELTAT->portstate = v & (0x80|0x40|0x20|0x10|0x01); /* start, rec, memory mode, repeat flag copy, reset(bit0) */
if( DELTAT->portstate&0x80 )/* START,REC,MEMDATA,REPEAT,SPOFF,--,--,RESET */
{
/* set PCM BUSY bit */
DELTAT->PCM_BSY = 1;
/* start ADPCM */
DELTAT->now_step = 0;
DELTAT->acc = 0;
DELTAT->prev_acc = 0;
DELTAT->adpcml = 0;
DELTAT->adpcmd = YM_DELTAT_DELTA_DEF;
DELTAT->now_data = 0;
}
if( DELTAT->portstate&0x20 ) /* do we access external memory? */
{
DELTAT->now_addr = DELTAT->start << 1;
DELTAT->memread = 2; /* two dummy reads needed before accesing external memory via register $08*/
/* if yes, then let's check if ADPCM memory is mapped and big enough */
if(DELTAT->memory == 0)
{
logerror("YM Delta-T ADPCM rom not mapped\n");
DELTAT->portstate = 0x00;
DELTAT->PCM_BSY = 0;
}
else
{
if( DELTAT->end >= DELTAT->memory_size ) /* Check End in Range */
{
/* logerror("YM Delta-T ADPCM end out of range: $%08x\n", DELTAT->end); */
DELTAT->end = DELTAT->memory_size - 1;
}
if( DELTAT->start >= DELTAT->memory_size ) /* Check Start in Range */
{
/* logerror("YM Delta-T ADPCM start out of range: $%08x\n", DELTAT->start); */
DELTAT->portstate = 0x00;
DELTAT->PCM_BSY = 0;
}
}
}
else /* we access CPU memory (ADPCM data register $08) so we only reset now_addr here */
{
DELTAT->now_addr = 0;
}
if( DELTAT->portstate&0x01 )
{
DELTAT->portstate = 0x00;
/* clear PCM BUSY bit (in status register) */
DELTAT->PCM_BSY = 0;
/* set BRDY flag */
if(DELTAT->status_set_handler)
if(DELTAT->status_change_BRDY_bit)
(DELTAT->status_set_handler)(DELTAT->status_change_which_chip, DELTAT->status_change_BRDY_bit);
}
break;
case 0x01: /* L,R,-,-,SAMPLE,DA/AD,RAMTYPE,ROM */
/* handle emulation mode */
if(DELTAT->emulation_mode == YM_DELTAT_EMULATION_MODE_YM2610)
{
v |= 0x01; /* YM2610 always uses ROM as an external memory and doesn't tave ROM/RAM memory flag bit. */
}
DELTAT->pan = &DELTAT->output_pointer[(v>>6)&0x03];
if ((DELTAT->control2 & 3) != (v & 3))
{
/*0-DRAM x1, 1-ROM, 2-DRAM x8, 3-ROM (3 is bad setting - not allowed by the manual) */
if (DELTAT->DRAMportshift != dram_rightshift[v&3])
{
DELTAT->DRAMportshift = dram_rightshift[v&3];
/* final shift value depends on chip type and memory type selected:
8 for YM2610 (ROM only),
5 for ROM for Y8950 and YM2608,
5 for x8bit DRAMs for Y8950 and YM2608,
2 for x1bit DRAMs for Y8950 and YM2608.
*/
/* refresh addresses */
DELTAT->start = (DELTAT->reg[0x3]*0x0100 | DELTAT->reg[0x2]) << (DELTAT->portshift - DELTAT->DRAMportshift);
DELTAT->end = (DELTAT->reg[0x5]*0x0100 | DELTAT->reg[0x4]) << (DELTAT->portshift - DELTAT->DRAMportshift);
DELTAT->end += (1 << (DELTAT->portshift-DELTAT->DRAMportshift) ) - 1;
DELTAT->limit = (DELTAT->reg[0xd]*0x0100 | DELTAT->reg[0xc]) << (DELTAT->portshift - DELTAT->DRAMportshift);
}
}
DELTAT->control2 = v;
break;
case 0x02: /* Start Address L */
case 0x03: /* Start Address H */
DELTAT->start = (DELTAT->reg[0x3]*0x0100 | DELTAT->reg[0x2]) << (DELTAT->portshift - DELTAT->DRAMportshift);
/*logerror("DELTAT start: 02=%2x 03=%2x addr=%8x\n",DELTAT->reg[0x2], DELTAT->reg[0x3],DELTAT->start );*/
break;
case 0x04: /* Stop Address L */
case 0x05: /* Stop Address H */
DELTAT->end = (DELTAT->reg[0x5]*0x0100 | DELTAT->reg[0x4]) << (DELTAT->portshift - DELTAT->DRAMportshift);
DELTAT->end += (1 << (DELTAT->portshift-DELTAT->DRAMportshift) ) - 1;
/*logerror("DELTAT end : 04=%2x 05=%2x addr=%8x\n",DELTAT->reg[0x4], DELTAT->reg[0x5],DELTAT->end );*/
break;
case 0x06: /* Prescale L (ADPCM and Record frq) */
case 0x07: /* Prescale H */
break;
case 0x08: /* ADPCM data */
/*
some examples:
value: START, REC, MEMDAT, REPEAT, SPOFF, x,x,RESET meaning:
C8 1 1 0 0 1 0 0 0 Analysis (recording) from AUDIO to CPU (to reg $08), sample rate in PRESCALER register
E8 1 1 1 0 1 0 0 0 Analysis (recording) from AUDIO to EXT.MEMORY, sample rate in PRESCALER register
80 1 0 0 0 0 0 0 0 Synthesis (playing) from CPU (from reg $08) to AUDIO,sample rate in DELTA-N register
a0 1 0 1 0 0 0 0 0 Synthesis (playing) from EXT.MEMORY to AUDIO, sample rate in DELTA-N register
60 0 1 1 0 0 0 0 0 External memory write via ADPCM data register $08
20 0 0 1 0 0 0 0 0 External memory read via ADPCM data register $08
*/
/* external memory write */
if ( (DELTAT->portstate & 0xe0)==0x60 )
{
if (DELTAT->memread)
{
DELTAT->now_addr = DELTAT->start << 1;
DELTAT->memread = 0;
}
/*logerror("YM Delta-T memory write $%08x, v=$%02x\n", DELTAT->now_addr >> 1, v);*/
if ( DELTAT->now_addr != (DELTAT->end<<1) )
{
DELTAT->memory[DELTAT->now_addr>>1] = v;
DELTAT->now_addr+=2; /* two nibbles at a time */
/* reset BRDY bit in status register, which means we are processing the write */
if(DELTAT->status_reset_handler)
if(DELTAT->status_change_BRDY_bit)
(DELTAT->status_reset_handler)(DELTAT->status_change_which_chip, DELTAT->status_change_BRDY_bit);
/* setup a timer that will callback us in 10 master clock cycles for Y8950
* in the callback set the BRDY flag to 1 , which means we have written the data.
* For now, we don't really do this; we simply reset and set the flag in zero time, so that the IRQ will work.
*/
/* set BRDY bit in status register */
if(DELTAT->status_set_handler)
if(DELTAT->status_change_BRDY_bit)
(DELTAT->status_set_handler)(DELTAT->status_change_which_chip, DELTAT->status_change_BRDY_bit);
}
else
{
/* set EOS bit in status register */
if(DELTAT->status_set_handler)
if(DELTAT->status_change_EOS_bit)
(DELTAT->status_set_handler)(DELTAT->status_change_which_chip, DELTAT->status_change_EOS_bit);
}
return;
}
/* ADPCM synthesis from CPU */
if ( (DELTAT->portstate & 0xe0)==0x80 )
{
DELTAT->CPU_data = v;
/* Reset BRDY bit in status register, which means we are full of data */
if(DELTAT->status_reset_handler)
if(DELTAT->status_change_BRDY_bit)
(DELTAT->status_reset_handler)(DELTAT->status_change_which_chip, DELTAT->status_change_BRDY_bit);
return;
}
break;
case 0x09: /* DELTA-N L (ADPCM Playback Prescaler) */
case 0x0a: /* DELTA-N H */
DELTAT->delta = (DELTAT->reg[0xa]*0x0100 | DELTAT->reg[0x9]);
DELTAT->step = (UINT32)( (double)(DELTAT->delta /* *(1<<(YM_DELTAT_SHIFT-16)) */ ) * (DELTAT->freqbase) );
/*logerror("DELTAT deltan:09=%2x 0a=%2x\n",DELTAT->reg[0x9], DELTAT->reg[0xa]);*/
break;
case 0x0b: /* Output level control (volume, linear) */
{
INT32 oldvol = DELTAT->volume;
DELTAT->volume = (v&0xff) * (DELTAT->output_range/256) / YM_DELTAT_DECODE_RANGE;
/* v * ((1<<16)>>8) >> 15;
* thus: v * (1<<8) >> 15;
* thus: output_range must be (1 << (15+8)) at least
* v * ((1<<23)>>8) >> 15;
* v * (1<<15) >> 15;
*/
/*logerror("DELTAT vol = %2x\n",v&0xff);*/
if( oldvol != 0 )
{
DELTAT->adpcml = (int)((double)DELTAT->adpcml / (double)oldvol * (double)DELTAT->volume);
}
}
break;
case 0x0c: /* Limit Address L */
case 0x0d: /* Limit Address H */
DELTAT->limit = (DELTAT->reg[0xd]*0x0100 | DELTAT->reg[0xc]) << (DELTAT->portshift - DELTAT->DRAMportshift);
/*logerror("DELTAT limit: 0c=%2x 0d=%2x addr=%8x\n",DELTAT->reg[0xc], DELTAT->reg[0xd],DELTAT->limit );*/
break;
}
}
void YM_DELTAT_ADPCM_Reset(YM_DELTAT *DELTAT,int pan,int emulation_mode)
{
DELTAT->now_addr = 0;
DELTAT->now_step = 0;
DELTAT->step = 0;
DELTAT->start = 0;
DELTAT->end = 0;
DELTAT->limit = ~0; /* this way YM2610 and Y8950 (both of which don't have limit address reg) will still work */
DELTAT->volume = 0;
DELTAT->pan = &DELTAT->output_pointer[pan];
DELTAT->acc = 0;
DELTAT->prev_acc = 0;
DELTAT->adpcmd = 127;
DELTAT->adpcml = 0;
DELTAT->emulation_mode = (UINT8)emulation_mode;
DELTAT->portstate = (emulation_mode == YM_DELTAT_EMULATION_MODE_YM2610) ? 0x20 : 0;
DELTAT->control2 = (emulation_mode == YM_DELTAT_EMULATION_MODE_YM2610) ? 0x01 : 0; /* default setting depends on the emulation mode. MSX demo called "facdemo_4" doesn't setup control2 register at all and still works */
DELTAT->DRAMportshift = dram_rightshift[DELTAT->control2 & 3];
/* The flag mask register disables the BRDY after the reset, however
** as soon as the mask is enabled the flag needs to be set. */
/* set BRDY bit in status register */
if(DELTAT->status_set_handler)
if(DELTAT->status_change_BRDY_bit)
(DELTAT->status_set_handler)(DELTAT->status_change_which_chip, DELTAT->status_change_BRDY_bit);
}
#if 0
void YM_DELTAT_postload(YM_DELTAT *DELTAT,UINT8 *regs)
{
int r;
/* to keep adpcml */
DELTAT->volume = 0;
/* update */
for(r=1;r<16;r++)
YM_DELTAT_ADPCM_Write(DELTAT,r,regs[r]);
DELTAT->reg[0] = regs[0];
/* current rom data */
if (DELTAT->memory)
DELTAT->now_data = *(DELTAT->memory + (DELTAT->now_addr>>1) );
}
void YM_DELTAT_savestate(const device_config *device,YM_DELTAT *DELTAT)
{
#ifdef __STATE_H__
state_save_register_device_item(device, 0, DELTAT->portstate);
state_save_register_device_item(device, 0, DELTAT->now_addr);
state_save_register_device_item(device, 0, DELTAT->now_step);
state_save_register_device_item(device, 0, DELTAT->acc);
state_save_register_device_item(device, 0, DELTAT->prev_acc);
state_save_register_device_item(device, 0, DELTAT->adpcmd);
state_save_register_device_item(device, 0, DELTAT->adpcml);
#endif
}
#endif
#define YM_DELTAT_Limit(val,max,min) \
{ \
if ( val > max ) val = max; \
else if ( val < min ) val = min; \
}
static INLINE void YM_DELTAT_synthesis_from_external_memory(YM_DELTAT *DELTAT)
{
UINT32 step;
int data;
DELTAT->now_step += DELTAT->step;
if ( DELTAT->now_step >= (1<<YM_DELTAT_SHIFT) )
{
step = DELTAT->now_step >> YM_DELTAT_SHIFT;
DELTAT->now_step &= (1<<YM_DELTAT_SHIFT)-1;
do{
if ( DELTAT->now_addr == (DELTAT->limit<<1) )
DELTAT->now_addr = 0;
if ( DELTAT->now_addr == (DELTAT->end<<1) ) { /* 12-06-2001 JB: corrected comparison. Was > instead of == */
if( DELTAT->portstate&0x10 ){
/* repeat start */
DELTAT->now_addr = DELTAT->start<<1;
DELTAT->acc = 0;
DELTAT->adpcmd = YM_DELTAT_DELTA_DEF;
DELTAT->prev_acc = 0;
}else{
/* set EOS bit in status register */
if(DELTAT->status_set_handler)
if(DELTAT->status_change_EOS_bit)
(DELTAT->status_set_handler)(DELTAT->status_change_which_chip, DELTAT->status_change_EOS_bit);
/* clear PCM BUSY bit (reflected in status register) */
DELTAT->PCM_BSY = 0;
DELTAT->portstate = 0;
DELTAT->adpcml = 0;
DELTAT->prev_acc = 0;
return;
}
}
if( DELTAT->now_addr&1 ) data = DELTAT->now_data & 0x0f;
else
{
DELTAT->now_data = *(DELTAT->memory + (DELTAT->now_addr>>1));
data = DELTAT->now_data >> 4;
}
DELTAT->now_addr++;
/* 12-06-2001 JB: */
/* YM2610 address register is 24 bits wide.*/
/* The "+1" is there because we use 1 bit more for nibble calculations.*/
/* WARNING: */
/* Side effect: we should take the size of the mapped ROM into account */
DELTAT->now_addr &= ( (1<<(24+1))-1);
/* store accumulator value */
DELTAT->prev_acc = DELTAT->acc;
/* Forecast to next Forecast */
DELTAT->acc += (ym_deltat_decode_tableB1[data] * DELTAT->adpcmd / 8);
YM_DELTAT_Limit(DELTAT->acc,YM_DELTAT_DECODE_MAX, YM_DELTAT_DECODE_MIN);
/* delta to next delta */
DELTAT->adpcmd = (DELTAT->adpcmd * ym_deltat_decode_tableB2[data] ) / 64;
YM_DELTAT_Limit(DELTAT->adpcmd,YM_DELTAT_DELTA_MAX, YM_DELTAT_DELTA_MIN );
/* ElSemi: Fix interpolator. */
/*DELTAT->prev_acc = prev_acc + ((DELTAT->acc - prev_acc) / 2 );*/
}while(--step);
}
/* ElSemi: Fix interpolator. */
DELTAT->adpcml = DELTAT->prev_acc * (int)((1<<YM_DELTAT_SHIFT)-DELTAT->now_step);
DELTAT->adpcml += (DELTAT->acc * (int)DELTAT->now_step);
DELTAT->adpcml = (DELTAT->adpcml>>YM_DELTAT_SHIFT) * (int)DELTAT->volume;
/* output for work of output channels (outd[OPNxxxx])*/
*(DELTAT->pan) += DELTAT->adpcml;
}
static INLINE void YM_DELTAT_synthesis_from_CPU_memory(YM_DELTAT *DELTAT)
{
UINT32 step;
int data;
DELTAT->now_step += DELTAT->step;
if ( DELTAT->now_step >= (1<<YM_DELTAT_SHIFT) )
{
step = DELTAT->now_step >> YM_DELTAT_SHIFT;
DELTAT->now_step &= (1<<YM_DELTAT_SHIFT)-1;
do{
if( DELTAT->now_addr&1 )
{
data = DELTAT->now_data & 0x0f;
DELTAT->now_data = DELTAT->CPU_data;
/* after we used CPU_data, we set BRDY bit in status register,
* which means we are ready to accept another byte of data */
if(DELTAT->status_set_handler)
if(DELTAT->status_change_BRDY_bit)
(DELTAT->status_set_handler)(DELTAT->status_change_which_chip, DELTAT->status_change_BRDY_bit);
}
else
{
data = DELTAT->now_data >> 4;
}
DELTAT->now_addr++;
/* store accumulator value */
DELTAT->prev_acc = DELTAT->acc;
/* Forecast to next Forecast */
DELTAT->acc += (ym_deltat_decode_tableB1[data] * DELTAT->adpcmd / 8);
YM_DELTAT_Limit(DELTAT->acc,YM_DELTAT_DECODE_MAX, YM_DELTAT_DECODE_MIN);
/* delta to next delta */
DELTAT->adpcmd = (DELTAT->adpcmd * ym_deltat_decode_tableB2[data] ) / 64;
YM_DELTAT_Limit(DELTAT->adpcmd,YM_DELTAT_DELTA_MAX, YM_DELTAT_DELTA_MIN );
}while(--step);
}
/* ElSemi: Fix interpolator. */
DELTAT->adpcml = DELTAT->prev_acc * (int)((1<<YM_DELTAT_SHIFT)-DELTAT->now_step);
DELTAT->adpcml += (DELTAT->acc * (int)DELTAT->now_step);
DELTAT->adpcml = (DELTAT->adpcml>>YM_DELTAT_SHIFT) * (int)DELTAT->volume;
/* output for work of output channels (outd[OPNxxxx])*/
*(DELTAT->pan) += DELTAT->adpcml;
}
/* ADPCM B (Delta-T control type) */
void YM_DELTAT_ADPCM_CALC(YM_DELTAT *DELTAT)
{
/*
some examples:
value: START, REC, MEMDAT, REPEAT, SPOFF, x,x,RESET meaning:
80 1 0 0 0 0 0 0 0 Synthesis (playing) from CPU (from reg $08) to AUDIO,sample rate in DELTA-N register
a0 1 0 1 0 0 0 0 0 Synthesis (playing) from EXT.MEMORY to AUDIO, sample rate in DELTA-N register
C8 1 1 0 0 1 0 0 0 Analysis (recording) from AUDIO to CPU (to reg $08), sample rate in PRESCALER register
E8 1 1 1 0 1 0 0 0 Analysis (recording) from AUDIO to EXT.MEMORY, sample rate in PRESCALER register
60 0 1 1 0 0 0 0 0 External memory write via ADPCM data register $08
20 0 0 1 0 0 0 0 0 External memory read via ADPCM data register $08
*/
if ( (DELTAT->portstate & 0xe0)==0xa0 )
{
YM_DELTAT_synthesis_from_external_memory(DELTAT);
return;
}
if ( (DELTAT->portstate & 0xe0)==0x80 )
{
/* ADPCM synthesis from CPU-managed memory (from reg $08) */
YM_DELTAT_synthesis_from_CPU_memory(DELTAT); /* change output based on data in ADPCM data reg ($08) */
return;
}
//todo: ADPCM analysis
// if ( (DELTAT->portstate & 0xe0)==0xc0 )
// if ( (DELTAT->portstate & 0xe0)==0xe0 )
return;
}
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