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// DGen v1.06+
// MYFM.CPP - interface to YM2612Update
#include <stdio.h>
#include <stdlib.h>
#include "md.h"
extern int sound_is_okay;
// md.h also has include fm.h
// REMEMBER NOT TO USE ANY STATIC variables, because they
// will exist thoughout ALL megadrives!
int md::flush_fm_to_mame()
{
int sid,r;
// If we reset mame's ym2612 code, we need to pass all the values
// to it again
for (sid=0;sid<2;sid++)
{
for (r=0;r<0x100;r++)
{
if (sound_is_okay)
{
if (fm_reg[sid][r]!=-1)
{
YM2612Write(0,sid*2+0,r); // select reg r
YM2612Write(0,sid*2+1,fm_reg[sid][r]); // Write data
}
}
}
}
return 0;
}
int md::myfm_write(int a,int v,int md)
{
int sid=0;
int mame_can_have_it=1;
(void)md;
a&=3;
sid=(a&2)?1:0;
if ((a&1)==0) fm_sel[sid]=v;
else
{
// stash all values
fm_reg[sid] [fm_sel[sid]&0xff] = v;
if (fm_sel[sid]==0x2a) { dac_submit(v); mame_can_have_it=0; }
if (fm_sel[sid]==0x2b) { dac_enable(v); mame_can_have_it=0; }
if ((fm_sel[sid]&0xfc)==0x24) { mame_can_have_it=0; }
if (fm_sel[sid]==0x27)
{
if (v&0x10) fm_tover[0]&=~1;
if (v&0x20) fm_tover[0]&=~2;
// timer ack?
}
}
if (sound_is_okay && mame_can_have_it)
YM2612Write(0,a&3,v);
return 0;
}
int md::myfm_read(int a)
{
if ((a&1)==0)
return fm_tover[0];
else
{
if (sound_is_okay) YM2612Read(0,a&3);
}
return 0;
}
int md::mysn_write(int d)
{
if (sound_is_okay) SN76496Write(0,d);
return 0;
}
// This called once per raster
int md::fm_timer_callback()
{
int amax,bmax, i;
// Our raster lasts 63.61323 microseconds
for (i=0;i<4;i++) ras_fm_ticker[i]+=64;
// if (sound_is_okay) ret=YM2612Read(0,a&3);
// period of timer a is
// 18 * (1024 - ((fm_reg[0][0x24]<<2)+(fm_reg[0][0x25])&3))) microsecs
amax=18 * (1024 - ((fm_reg[0][0x24]<<2)+(fm_reg[0][0x25]&3)) );
bmax=288*(256-fm_reg[0][0x26]);
if (bmax<=0) bmax=1;
if (amax<=0) amax=1;
if (ras_fm_ticker[0]>=amax)
{
fm_tover[0]|=1; ras_fm_ticker[0]-=amax;
}
if (ras_fm_ticker[1]>=bmax)
{
fm_tover[0]|=2; ras_fm_ticker[1]-=bmax;
}
return 0;
}
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