BizHawk/BizHawk.Emulation.Cores/Consoles/Atari/A7800Hawk/Maria.cs

663 lines
18 KiB
C#

using System;
using BizHawk.Emulation.Common;
using BizHawk.Common.NumberExtensions;
using BizHawk.Common;
namespace BizHawk.Emulation.Cores.Atari.A7800Hawk
{
// Emulates the Atari 7800 Maria graphics chip
public class Maria
{
public A7800Hawk Core { get; set; }
struct GFX_Object
{
public byte palette;
public byte width;
public ushort addr;
public byte h_pos;
// additional entries used only in 5-byte header mode
public bool write_mode;
public bool ind_mode;
public byte[] obj; // up to 32 bytes can compose one object
}
// technically there is no limit on the number of graphics objects, but since dma is automatically killed
// at the end of a scanline, we have an effective limit
GFX_Object[] GFX_Objects = new GFX_Object[128];
public byte[,] line_ram = new byte[2, 320];
byte temp_check = 0;
int GFX_index = 0;
public int[] _palette;
public int[] scanline_buffer = new int[320];
// the Maria chip can directly access memory
public Func<ushort, byte> ReadMemory;
public int cycle;
public int scanline;
public int DLI_countdown;
public bool sl_DMA_complete;
public bool do_dma;
public int DMA_phase = 0;
public int DMA_phase_counter;
public static int DMA_START_UP = 0;
public static int DMA_HEADER = 1;
public static int DMA_GRAPHICS = 2;
public static int DMA_CHAR_MAP = 3;
public static int DMA_SHUTDOWN_OTHER = 4;
public static int DMA_SHUTDOWN_LAST = 5;
public int header_read_time = 8; // default for 4 byte headers (10 for 5 bytes ones)
public int graphics_read_time = 3; // depends on content of graphics header
public int DMA_phase_next;
public ushort display_zone_pointer;
public int display_zone_counter;
public byte current_DLL_offset;
public ushort current_DLL_addr;
public bool current_DLL_DLI;
public bool current_DLL_H16;
public bool current_DLL_H8;
public bool global_write_mode;
public int header_counter;
public int header_pointer; // since headers could be 4 or 5 bytes, we need a seperate pointer
// variables for drawing a pixel
int color;
int local_GFX_index;
int temp_palette;
int temp_bit_0;
int temp_bit_1;
int disp_mode;
int pixel;
// each frame contains 263 scanlines
// each scanline consists of 113.5 CPU cycles (fast access) which equates to 454 Maria cycles
// In total there are 29850.5 CPU cycles (fast access) in a frame
public void RunFrame()
{
scanline = 0;
global_write_mode = false;
Core.Maria_regs[8] = 0x80; // indicates VBlank state
// we start off in VBlank for 20 scanlines
// at the end of vblank is a DMA to set up the display for the start of drawing
// this is free time for the CPU to set up display lists
while (scanline < 20)
{
Core.RunCPUCycle();
cycle++;
if (cycle == 454)
{
scanline++;
cycle = 0;
Core.tia._hsyncCnt = 0;
Core.cpu.RDY = true;
}
}
// "The end of vblank is made up of a DMA startup plus a long shut down"
// Since long shut down loads up the next zone, this basically loads up the DLL for the first zone
sl_DMA_complete = false;
do_dma = false;
Core.Maria_regs[8] = 0; // we have now left VBLank
for (int i=0; i<454;i++)
{
if(i==28 && Core.Maria_regs[0x1C].Bit(6) && !Core.Maria_regs[0x1C].Bit(5))
{
Core.cpu_halt_pending = true;
DMA_phase = DMA_START_UP;
DMA_phase_counter = 0;
do_dma = true;
}
else if (!sl_DMA_complete && do_dma)
{
RunDMA(true);
}
else if (sl_DMA_complete && current_DLL_DLI && !Core.cpu_is_halted)
{
// schedule an NMI for one maria tick into the future
// (but set to 2 since it decrements immediately)
DLI_countdown = 2;
current_DLL_DLI = false;
}
if (DLI_countdown > 0)
{
DLI_countdown--;
if (DLI_countdown == 0)
{
Core.cpu.NMI = true;
}
}
Core.RunCPUCycle();
}
scanline++;
cycle = 0;
do_dma = false;
sl_DMA_complete = false;
Core.cpu.RDY = true;
// Now proceed with the remaining scanlines
// the first one is a pre-render line, since we didn't actually put any data into the buffer yet
while (scanline < Core._screen_height)
{
if (cycle == 28 && Core.Maria_regs[0x1C].Bit(6) && !Core.Maria_regs[0x1C].Bit(5))
{
Core.cpu_halt_pending = true;
DMA_phase = DMA_START_UP;
DMA_phase_counter = 0;
do_dma = true;
sl_DMA_complete = false;
}
else if (!sl_DMA_complete && do_dma)
{
RunDMA(false);
}
else if (sl_DMA_complete && current_DLL_DLI && !Core.cpu_is_halted)
{
// schedule an NMI for one maria tick into the future
// (but set to 2 since it decrements immediately)
DLI_countdown = 2;
current_DLL_DLI = false;
}
if (DLI_countdown > 0)
{
DLI_countdown--;
if (DLI_countdown == 0)
{
Core.cpu.NMI = true;
}
}
if (cycle == 428 && !sl_DMA_complete && do_dma && (DMA_phase == DMA_GRAPHICS || DMA_phase == DMA_HEADER))
{
//Console.WriteLine(scanline);
if (current_DLL_offset == 0)
{
DMA_phase = DMA_SHUTDOWN_LAST;
}
else
{
DMA_phase = DMA_SHUTDOWN_OTHER;
}
DMA_phase_counter = 0;
}
Core.RunCPUCycle();
//////////////////////////////////////////////
// Drawing Start
//////////////////////////////////////////////
if (cycle >=133 && cycle < 453 && scanline > 20)
{
pixel = cycle - 133;
local_GFX_index = (GFX_index == 1) ? 0 : 1; // whatever the current index is, we use the opposite
disp_mode = Core.Maria_regs[0x1C] & 0x3;
color = line_ram[local_GFX_index, pixel];
if (disp_mode == 0)
{
// direct read, nothing to do
}
else if (disp_mode == 2) // note: 1 is not used
{
// there is a trick here to be aware of.
// the renderer has no concept of objects, as it only has information on each pixel
// but objects are specified in groups of 8 pixels.
// however, since objects can only be placed in 160 resolution
// we can pick bits based on whether the current pixel is even or odd
temp_palette = color & 0x10;
temp_bit_0 = 0;
temp_bit_1 = 0;
if (pixel % 2 == 0)
{
temp_bit_1 = color & 2;
temp_bit_0 = (color & 8) >> 3;
}
else
{
temp_bit_1 = (color & 1) << 1;
temp_bit_0 = (color & 4) >> 2;
}
color = temp_palette + temp_bit_1 + temp_bit_0;
}
else
{
// same as above, we can use the pixel index to pick the bits out
if (pixel % 2 == 0)
{
color &= 0x1E;
}
else
{
color = (color & 0x1C) + ((color & 1) << 1);
}
}
if ((color & 0x3) != 0)
{
scanline_buffer[pixel] = _palette[Core.Maria_regs[color]];
}
else
{
scanline_buffer[pixel] = _palette[Core.Maria_regs[0x00]];
}
// send buffer to the video buffer
Core._vidbuffer[(scanline - 21) * 320 + pixel] = scanline_buffer[pixel];
// clear the line ram
line_ram[local_GFX_index, pixel] = 0;
}
//////////////////////////////////////////////
// Drawing End
//////////////////////////////////////////////
cycle++;
if (cycle == 454)
{
scanline++;
cycle = 0;
Core.tia._hsyncCnt = 0;
Core.cpu.RDY = true;
// swap sacnline buffers
if (GFX_index == 1)
{
GFX_index = 0;
}
else
{
GFX_index = 1;
}
}
}
}
public void RunDMA(bool short_dma)
{
// During DMA the CPU is HALTED, This appears to happen on the falling edge of Phi2
// Current implementation is that a HALT request must be acknowledged in phi1
// if the CPU is now in halted state, start DMA
if (Core.cpu_is_halted)
{
DMA_phase_counter++;
if (DMA_phase_counter==2 && DMA_phase==DMA_START_UP)
{
DMA_phase_counter = 0;
if (short_dma)
{
DMA_phase = DMA_SHUTDOWN_LAST;
// also here we load up the display list list
// is the timing correct?
display_zone_pointer = (ushort)((Core.Maria_regs[0xC] << 8) | Core.Maria_regs[0x10]);
display_zone_counter = -1;
}
else
{
DMA_phase = DMA_HEADER;
}
return;
}
if (DMA_phase == DMA_HEADER)
{
// get all the data from the display list header
if (DMA_phase_counter==1)
{
header_counter++;
GFX_Objects[header_counter].addr = ReadMemory((ushort)(current_DLL_addr + header_pointer));
header_pointer++;
byte temp = ReadMemory((ushort)(current_DLL_addr + header_pointer));
// if there is no width, then we must have an extended header
// or at the end of this list
if ((temp & 0x1F) == 0)
{
if (!temp.Bit(6))
{
// at the end of the list, time to end the DMA
// check if we are at the end of the zone
if (current_DLL_offset == 0)
{
DMA_phase_next = DMA_SHUTDOWN_LAST;
}
else
{
DMA_phase_next = DMA_SHUTDOWN_OTHER;
}
header_read_time = 8;
header_pointer++;
}
else
{
// we are in 5 Byte header mode (i.e. using the character map)
GFX_Objects[header_counter].write_mode = temp.Bit(7);
global_write_mode = temp.Bit(7);
GFX_Objects[header_counter].ind_mode = temp.Bit(5);
header_pointer++;
temp = (byte)(ReadMemory((ushort)(current_DLL_addr + header_pointer)));
GFX_Objects[header_counter].addr |= (ushort)(temp << 8);
header_pointer++;
temp = ReadMemory((ushort)(current_DLL_addr + header_pointer));
int temp_w = (temp & 0x1F); // this is the 2's complement of width (for reasons that escape me)
if (temp_w == 0)
{
// important note here. In 5 byte mode, width 0 actually counts as 32
GFX_Objects[header_counter].width = 32;
}
else
{
temp_w = (temp_w - 1);
temp_w = (0x1F - temp_w);
GFX_Objects[header_counter].width = (byte)(temp_w & 0x1F);
}
GFX_Objects[header_counter].palette = (byte)((temp & 0xE0) >> 5);
header_pointer++;
GFX_Objects[header_counter].h_pos = ReadMemory((ushort)(current_DLL_addr + header_pointer));
header_pointer++;
DMA_phase_next = DMA_GRAPHICS;
header_read_time = 10;
}
}
else
{
int temp_w = (temp & 0x1F); // this is the 2's complement of width (for reasons that escape me)
temp_w = (temp_w - 1);
temp_w = (0x1F - temp_w);
GFX_Objects[header_counter].width = (byte)(temp_w & 0x1F);
GFX_Objects[header_counter].palette = (byte)((temp & 0xE0) >> 5);
header_pointer++;
temp = (byte)(ReadMemory((ushort)(current_DLL_addr + header_pointer)));
GFX_Objects[header_counter].addr |= (ushort)(temp << 8);
header_pointer++;
GFX_Objects[header_counter].h_pos = ReadMemory((ushort)(current_DLL_addr + header_pointer));
header_pointer++;
DMA_phase_next = DMA_GRAPHICS;
GFX_Objects[header_counter].write_mode = global_write_mode;
GFX_Objects[header_counter].ind_mode = false;
header_read_time = 8;
}
}
else if (DMA_phase_counter == header_read_time)
{
DMA_phase_counter = 0;
DMA_phase = DMA_phase_next;
}
return;
}
if (DMA_phase == DMA_GRAPHICS)
{
if (DMA_phase_counter == 1)
{
ushort addr_t = 0;
// in 5 byte mode, we first have to check if we are in direct or indirect mode
if (GFX_Objects[header_counter].ind_mode)
{
int ch_size = 0;
if (Core.Maria_regs[0x1C].Bit(4))
{
graphics_read_time = 9 * GFX_Objects[header_counter].width;
ch_size = 2;
}
else
{
graphics_read_time = 6 * GFX_Objects[header_counter].width;
ch_size = 1;
}
// the address here is specified by CHAR_BASE maria registers
// ushort addr = (ushort)(GFX_Objects[header_counter].addr & 0xFF);
for (int i = 0; i < GFX_Objects[header_counter].width; i++)
{
addr_t = ReadMemory((ushort)(GFX_Objects[header_counter].addr + i));
addr_t |= (ushort)((Core.Maria_regs[0x14] + current_DLL_offset) << 8);
if (((current_DLL_H16 && addr_t.Bit(12)) || (current_DLL_H8 && addr_t.Bit(11))) && (addr_t >= 0x8000))
{
if (i * ch_size < 128)
{
GFX_Objects[header_counter].obj[i * ch_size] = 0;
}
if ((i * ch_size + 1 < 128) && (ch_size == 2))
{
GFX_Objects[header_counter].obj[i * ch_size + 1] = 0;
}
if (i != 0)
{
if (ch_size == 1)
{
graphics_read_time -= 6;
}
else
{
graphics_read_time -= 9;
}
}
}
else
{
if (i * ch_size < 128)
{
GFX_Objects[header_counter].obj[i * ch_size] = ReadMemory(addr_t);
fill_line_ram(GFX_Objects[header_counter].h_pos * 2, i, 0, ch_size, GFX_Objects[header_counter].obj[i * ch_size], GFX_Objects[header_counter].write_mode);
}
if (((i * ch_size + 1) < 128) && (ch_size == 2))
{
GFX_Objects[header_counter].obj[i * ch_size + 1] = ReadMemory((ushort)(addr_t + 1));
fill_line_ram(GFX_Objects[header_counter].h_pos * 2, i, 1, ch_size, GFX_Objects[header_counter].obj[i * ch_size + 1], GFX_Objects[header_counter].write_mode);
}
}
}
}
else
{
graphics_read_time = 3 * GFX_Objects[header_counter].width;
for (int i = 0; i < GFX_Objects[header_counter].width; i++)
{
addr_t = (ushort)(GFX_Objects[header_counter].addr + (current_DLL_offset << 8) + i);
if (((current_DLL_H16 && addr_t.Bit(12)) || (current_DLL_H8 && addr_t.Bit(11))) && (addr_t >= 0x8000))
{
GFX_Objects[header_counter].obj[i] = 0;
if (i != 0)
{
graphics_read_time -= 3;
}
}
else
{
GFX_Objects[header_counter].obj[i] = ReadMemory(addr_t);
fill_line_ram(GFX_Objects[header_counter].h_pos * 2, i, 0, 1, GFX_Objects[header_counter].obj[i], GFX_Objects[header_counter].write_mode);
}
}
}
}
if (DMA_phase_counter == graphics_read_time || graphics_read_time == 0)
{
// We have read the graphics data, for this header, now return to the header list
// This loop will continue until a header indicates its time to stop
DMA_phase = DMA_HEADER;
DMA_phase_counter = 0;
}
return;
}
if (DMA_phase == DMA_SHUTDOWN_OTHER)
{
if (DMA_phase_counter == 6)
{
Core.cpu_resume_pending = true;
sl_DMA_complete = true;
current_DLL_offset -= 1; // this is reduced by one for each scanline, which changes where graphics are fetched
header_counter = -1;
header_pointer = 0;
}
return;
}
if (DMA_phase == DMA_SHUTDOWN_LAST)
{
if (DMA_phase_counter==12)
{
Core.cpu_resume_pending = true;
sl_DMA_complete = true;
// on the last line of a zone, we load up the disply list list for the next zone.
display_zone_counter++;
ushort temp_addr = (ushort)(display_zone_pointer + 3 * display_zone_counter);
byte temp = ReadMemory(temp_addr);
current_DLL_addr = (ushort)(ReadMemory((ushort)(temp_addr + 1)) << 8);
current_DLL_addr |= ReadMemory((ushort)(temp_addr + 2));
current_DLL_offset = (byte)(temp & 0xF);
current_DLL_DLI = temp.Bit(7);
current_DLL_H16 = temp.Bit(6);
current_DLL_H8 = temp.Bit(5);
header_counter = -1;
header_pointer = 0;
}
return;
}
}
}
public void fill_line_ram(int temp_start, int index, int doub_size, int ch_s, byte temp_byte, bool w_m)
{
if (w_m)
{
temp_start = temp_start + index * ch_s * 4 + doub_size * 4;
for (int z = 0; z < 4; z++)
{
if ((temp_start + z) % 512 < 320)
{
if (z < 2)
{
temp_check = (byte)((temp_byte & 0xC) + ((temp_byte >> 6) & 0x3));
}
else
{
temp_check = (byte)(((temp_byte & 0x3) << 2) + ((temp_byte >> 4) & 0x3));
}
if ((temp_check & 3) != 0)
{
line_ram[GFX_index, (temp_start + z) % 512] = temp_check;
line_ram[GFX_index, (temp_start + z) % 512] += (byte)((GFX_Objects[header_counter].palette & 4) << 2);
}
else if (Core.Maria_regs[0x1C].Bit(2))
{
// kangaroo mode, override transparency with zero
line_ram[GFX_index, (temp_start + z) % 512] = 0;
}
}
}
}
else
{
temp_start = temp_start + index * ch_s * 8 + doub_size * 8;
for (int z = 0; z < 8; z++)
{
if (((temp_start + z) % 512) < 320)
{
if (z < 2)
{
temp_check = (byte)((temp_byte >> 6) & 0x3);
}
else if (z < 4)
{
temp_check = (byte)((temp_byte >> 4) & 0x3);
}
else if (z < 6)
{
temp_check = (byte)((temp_byte >> 2) & 0x3);
}
else
{
temp_check = (byte)(temp_byte & 0x3);
}
if (temp_check != 0)
{
line_ram[GFX_index, (temp_start + z) % 512] = temp_check;
line_ram[GFX_index, (temp_start + z) % 512] += (byte)(GFX_Objects[header_counter].palette << 2);
}
else if (Core.Maria_regs[0x1C].Bit(2))
{
// kangaroo mode, override transparency with zero
line_ram[GFX_index, (temp_start + z) % 512] = 0;
}
}
}
}
}
public void Reset()
{
for (int i = 0; i < 128; i++)
{
GFX_Objects[i].obj = new byte[128];
}
}
// Most of the Maria state is captured in Maria Regs in the core
// Only write Mode is persistent and outside of the regs
// also since DMA is always killed at scanline boundaries, most related check variables are also not needed
public void SyncState(Serializer ser)
{
ser.BeginSection("Maria");
ser.Sync("GFX_index", ref GFX_index);
ser.EndSection();
}
}
}