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BizHawk/BizHawk.Emulation/Consoles/Intellivision/STIC.cs

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-Separated the STIC and PSG memory map logic into new objects. -Foreground / Background | Color Stack Mode --Actually made a boolean for it (FGBG). --Reading from a write-only STIC alias of $21 does change the STIC into Color Stack mode, but it doesn't actually read. --Color stack mode is enabled when $21 or its alias is read and it is disabled (FGBG) when written its written, both having to occur during VBlank Period 1. ---This is what I gathered from the wiki, but I'm confused as to why it says that "The STIC stays in this mode until the program accesses location $21 again." I'm assuming this doesn't mean the mode changes on every access because then I don't understand why a read would change to a different mode than a write. --FGBG is disabled by default. I don't think it matters.
2012-08-08 23:05:55 +00:00
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace BizHawk.Emulation.Consoles.Intellivision
{
public sealed class STIC
{
Scratchpad RAM, Graphics ROM, and Graphics RAM are apparently all 8-bit.
2012-08-10 20:40:34 +00:00
private bool Sr1, Sr2, Fgbg = false;
private ushort[] Register = new ushort[64];
-Separated the STIC and PSG memory map logic into new objects. -Foreground / Background | Color Stack Mode --Actually made a boolean for it (FGBG). --Reading from a write-only STIC alias of $21 does change the STIC into Color Stack mode, but it doesn't actually read. --Color stack mode is enabled when $21 or its alias is read and it is disabled (FGBG) when written its written, both having to occur during VBlank Period 1. ---This is what I gathered from the wiki, but I'm confused as to why it says that "The STIC stays in this mode until the program accesses location $21 again." I'm assuming this doesn't mean the mode changes on every access because then I don't understand why a read would change to a different mode than a write. --FGBG is disabled by default. I don't think it matters.
2012-08-08 23:05:55 +00:00
public ushort? ReadSTIC(ushort addr)
{
switch (addr & 0xF000)
{
case 0x0000:
if (addr <= 0x003F)
{
// TODO: OK only during VBlank Period 1.
if (addr == 0x0021)
Scratchpad RAM, Graphics ROM, and Graphics RAM are apparently all 8-bit.
2012-08-10 20:40:34 +00:00
Fgbg = false;
return Register[addr];
-Separated the STIC and PSG memory map logic into new objects. -Foreground / Background | Color Stack Mode --Actually made a boolean for it (FGBG). --Reading from a write-only STIC alias of $21 does change the STIC into Color Stack mode, but it doesn't actually read. --Color stack mode is enabled when $21 or its alias is read and it is disabled (FGBG) when written its written, both having to occur during VBlank Period 1. ---This is what I gathered from the wiki, but I'm confused as to why it says that "The STIC stays in this mode until the program accesses location $21 again." I'm assuming this doesn't mean the mode changes on every access because then I don't understand why a read would change to a different mode than a write. --FGBG is disabled by default. I don't think it matters.
2012-08-08 23:05:55 +00:00
}
else if (addr <= 0x007F)
// TODO: OK only during VBlank Period 2.
Scratchpad RAM, Graphics ROM, and Graphics RAM are apparently all 8-bit.
2012-08-10 20:40:34 +00:00
return Register[addr - 0x0040];
-Separated the STIC and PSG memory map logic into new objects. -Foreground / Background | Color Stack Mode --Actually made a boolean for it (FGBG). --Reading from a write-only STIC alias of $21 does change the STIC into Color Stack mode, but it doesn't actually read. --Color stack mode is enabled when $21 or its alias is read and it is disabled (FGBG) when written its written, both having to occur during VBlank Period 1. ---This is what I gathered from the wiki, but I'm confused as to why it says that "The STIC stays in this mode until the program accesses location $21 again." I'm assuming this doesn't mean the mode changes on every access because then I don't understand why a read would change to a different mode than a write. --FGBG is disabled by default. I don't think it matters.
2012-08-08 23:05:55 +00:00
break;
case 0x4000:
if (addr <= 0x403F)
{
// TODO: OK only during VBlank Period 1.
if (addr == 0x4021)
Scratchpad RAM, Graphics ROM, and Graphics RAM are apparently all 8-bit.
2012-08-10 20:40:34 +00:00
Fgbg = false;
-Separated the STIC and PSG memory map logic into new objects. -Foreground / Background | Color Stack Mode --Actually made a boolean for it (FGBG). --Reading from a write-only STIC alias of $21 does change the STIC into Color Stack mode, but it doesn't actually read. --Color stack mode is enabled when $21 or its alias is read and it is disabled (FGBG) when written its written, both having to occur during VBlank Period 1. ---This is what I gathered from the wiki, but I'm confused as to why it says that "The STIC stays in this mode until the program accesses location $21 again." I'm assuming this doesn't mean the mode changes on every access because then I don't understand why a read would change to a different mode than a write. --FGBG is disabled by default. I don't think it matters.
2012-08-08 23:05:55 +00:00
}
break;
case 0x8000:
if (addr <= 0x803F)
{
// TODO: OK only during VBlank Period 1.
if (addr == 0x8021)
Scratchpad RAM, Graphics ROM, and Graphics RAM are apparently all 8-bit.
2012-08-10 20:40:34 +00:00
Fgbg = false;
-Separated the STIC and PSG memory map logic into new objects. -Foreground / Background | Color Stack Mode --Actually made a boolean for it (FGBG). --Reading from a write-only STIC alias of $21 does change the STIC into Color Stack mode, but it doesn't actually read. --Color stack mode is enabled when $21 or its alias is read and it is disabled (FGBG) when written its written, both having to occur during VBlank Period 1. ---This is what I gathered from the wiki, but I'm confused as to why it says that "The STIC stays in this mode until the program accesses location $21 again." I'm assuming this doesn't mean the mode changes on every access because then I don't understand why a read would change to a different mode than a write. --FGBG is disabled by default. I don't think it matters.
2012-08-08 23:05:55 +00:00
}
break;
case 0xC000:
if (addr <= 0xC03F)
{
// TODO: OK only during VBlank Period 1.
if (addr == 0xC021)
Scratchpad RAM, Graphics ROM, and Graphics RAM are apparently all 8-bit.
2012-08-10 20:40:34 +00:00
Fgbg = false;
-Separated the STIC and PSG memory map logic into new objects. -Foreground / Background | Color Stack Mode --Actually made a boolean for it (FGBG). --Reading from a write-only STIC alias of $21 does change the STIC into Color Stack mode, but it doesn't actually read. --Color stack mode is enabled when $21 or its alias is read and it is disabled (FGBG) when written its written, both having to occur during VBlank Period 1. ---This is what I gathered from the wiki, but I'm confused as to why it says that "The STIC stays in this mode until the program accesses location $21 again." I'm assuming this doesn't mean the mode changes on every access because then I don't understand why a read would change to a different mode than a write. --FGBG is disabled by default. I don't think it matters.
2012-08-08 23:05:55 +00:00
}
break;
}
return null;
}
public bool WriteSTIC(ushort addr, ushort value)
{
switch (addr & 0xF000)
{
case 0x0000:
if (addr <= 0x003F)
{
// TODO: OK only during VBlank Period 1.
if (addr == 0x0021)
Scratchpad RAM, Graphics ROM, and Graphics RAM are apparently all 8-bit.
2012-08-10 20:40:34 +00:00
Fgbg = true;
Register[addr] = value;
-Separated the STIC and PSG memory map logic into new objects. -Foreground / Background | Color Stack Mode --Actually made a boolean for it (FGBG). --Reading from a write-only STIC alias of $21 does change the STIC into Color Stack mode, but it doesn't actually read. --Color stack mode is enabled when $21 or its alias is read and it is disabled (FGBG) when written its written, both having to occur during VBlank Period 1. ---This is what I gathered from the wiki, but I'm confused as to why it says that "The STIC stays in this mode until the program accesses location $21 again." I'm assuming this doesn't mean the mode changes on every access because then I don't understand why a read would change to a different mode than a write. --FGBG is disabled by default. I don't think it matters.
2012-08-08 23:05:55 +00:00
return true;
}
else if (addr <= 0x007F)
// Read-only STIC.
break;
break;
case 0x4000:
if (addr <= 0x403F)
{
// TODO: OK only during VBlank Period 1.
if (addr == 0x4021)
Scratchpad RAM, Graphics ROM, and Graphics RAM are apparently all 8-bit.
2012-08-10 20:40:34 +00:00
Fgbg = true;
Register[addr - 0x4000] = value;
-Separated the STIC and PSG memory map logic into new objects. -Foreground / Background | Color Stack Mode --Actually made a boolean for it (FGBG). --Reading from a write-only STIC alias of $21 does change the STIC into Color Stack mode, but it doesn't actually read. --Color stack mode is enabled when $21 or its alias is read and it is disabled (FGBG) when written its written, both having to occur during VBlank Period 1. ---This is what I gathered from the wiki, but I'm confused as to why it says that "The STIC stays in this mode until the program accesses location $21 again." I'm assuming this doesn't mean the mode changes on every access because then I don't understand why a read would change to a different mode than a write. --FGBG is disabled by default. I don't think it matters.
2012-08-08 23:05:55 +00:00
return true;
}
break;
case 0x8000:
if (addr <= 0x803F)
{
// TODO: OK only during VBlank Period 1.
if (addr == 0x8021)
Scratchpad RAM, Graphics ROM, and Graphics RAM are apparently all 8-bit.
2012-08-10 20:40:34 +00:00
Fgbg = true;
Register[addr & 0x003F] = value;
-Separated the STIC and PSG memory map logic into new objects. -Foreground / Background | Color Stack Mode --Actually made a boolean for it (FGBG). --Reading from a write-only STIC alias of $21 does change the STIC into Color Stack mode, but it doesn't actually read. --Color stack mode is enabled when $21 or its alias is read and it is disabled (FGBG) when written its written, both having to occur during VBlank Period 1. ---This is what I gathered from the wiki, but I'm confused as to why it says that "The STIC stays in this mode until the program accesses location $21 again." I'm assuming this doesn't mean the mode changes on every access because then I don't understand why a read would change to a different mode than a write. --FGBG is disabled by default. I don't think it matters.
2012-08-08 23:05:55 +00:00
return true;
}
break;
case 0xC000:
if (addr <= 0xC03F)
{
// TODO: OK only during VBlank Period 1.
if (addr == 0xC021)
Scratchpad RAM, Graphics ROM, and Graphics RAM are apparently all 8-bit.
2012-08-10 20:40:34 +00:00
Fgbg = true;
Register[addr - 0xC000] = value;
-Separated the STIC and PSG memory map logic into new objects. -Foreground / Background | Color Stack Mode --Actually made a boolean for it (FGBG). --Reading from a write-only STIC alias of $21 does change the STIC into Color Stack mode, but it doesn't actually read. --Color stack mode is enabled when $21 or its alias is read and it is disabled (FGBG) when written its written, both having to occur during VBlank Period 1. ---This is what I gathered from the wiki, but I'm confused as to why it says that "The STIC stays in this mode until the program accesses location $21 again." I'm assuming this doesn't mean the mode changes on every access because then I don't understand why a read would change to a different mode than a write. --FGBG is disabled by default. I don't think it matters.
2012-08-08 23:05:55 +00:00
return true;
}
break;
}
return false;
}
}
}