/* lcdc_trans()
Main LCDC emulation routine
*/
void lcdc_trans()
{
if (R_LCDC & 0x80)
{
/* LCDC operation enabled */
while (C <= 0)
{
/* Update current state */
switch ((byte)(R_STAT & 3))
{
case 0: /* after hblank */
/* FIXME: first line of first frame will be skipped
each time LCDC is started */
if (++R_LY <= 143)
{
stat_change(2); /* -> search */
}
else
{
stat_change(1); /* -> vblank */
/* See "NOTE A" above */
/*if (cpu.halt)
{
hw_interrupt(IF_VBLANK, IF_VBLANK);
C += 228;
}
else
{
C += 10;
continue;
}*/
break;
}
break;
case 2: /* after search */
stat_change(3); /* -> transfer */
break;
case 3: /* after transfer */
stat_change(0); /* -> hblank */
break;
case 1: /* after (in) vblank */
if (R_LY == 0)
{
stat_change(2); /* -> search */
}
break;
}
/* Handle current state */
switch ((byte)(R_STAT & 3))
{
case 2: /* search */
if (R_LY == 0)
{
lcd_begin();
}
C += 40;
break;
case 3: /* transfer */
lcd_refreshline();
C += 86;
break;
case 0: /* hblank */
if (hw.hdma & 0x80) {
hw_hdma();
}
C += 102;
break;
case 1: /* vblank */
if (!(hw.ilines & IF_VBLANK))
{
C += 228; /*C += 218; See "NOTE A" above */
hw_interrupt(IF_VBLANK, IF_VBLANK);
}
else
{
R_LY++;
if (R_LY < 153)
{
C += 228;
}
else if (R_LY == 153)
{
/* Handling special case on the last line
part 1; see docs/HACKING */
C += 28;
}
else
{
/* Handling special case on the last line
part 2; see docs/HACKING */
R_LY = 0;
C += 200;
}
stat_trigger();
}
break;
} /* switch(state) */
} /* while (C <= 0) */
} /* if (R_LCDC & 0x80) */
else
{
/* LCDC operation disabled (short route) */
if (C <= 0) /* Original code does in fact return after each pass, there is no loop here */
{
switch ((byte)(R_STAT & 3))
{
case 2: /* after search */
stat_change(3);
C += 86;
break;
case 3: /* after transfer */
stat_change(0);
C += 102;
break;
case 0: /* after hblank */
stat_change(2);
R_LY++;
C += 40;
break;
case 1: /* after (in) vblank */
stat_change(2);
C += 40;
break;
}
}
}
}
void lcdc_trans()
{
if (!(R_LCDC & 0x80))
{
while (C <= 0)
{
switch ((byte)(R_STAT & 3))
{
case 0:
case 1:
stat_change(2);
C += 40;
break;
case 2:
stat_change(3);
C += 86;
break;
case 3:
stat_change(0);
if (hw.hdma & 0x80)
hw_hdma();
else
C += 102;
break;
}
return;
}
}
while (C <= 0)
{
switch ((byte)(R_STAT & 3))
{
case 1:
if (!(hw.ilines & IF_VBLANK))
{
C += 218;
hw_interrupt(IF_VBLANK, IF_VBLANK);
break;
}
if (R_LY == 0)
{
lcd_begin();
stat_change(2);
C += 40;
break;
}
else if (R_LY < 152)
C += 228;
else if (R_LY == 152)
C += 28;
else
{
R_LY = -1;
C += 200;
}
R_LY++;
stat_trigger();
break;
case 2:
lcd_refreshline();
stat_change(3);
C += 86;
break;
case 3:
stat_change(0);
if (hw.hdma & 0x80)
hw_hdma();
/* FIXME -- how much of the hblank does hdma use?? */
/* else */
C += 102;
break;
case 0:
if (++R_LY >= 144)
{
if (cpu.halt)
{
hw_interrupt(IF_VBLANK, IF_VBLANK);
C += 228;
}
else C += 10;
stat_change(1);
break;
}
stat_change(2);
C += 40;
break;
}
}
}
