melonDS/GPU3D.cpp

/*
    Copyright 2016-2017 StapleButter

    This file is part of melonDS.

    melonDS is free software: you can redistribute it and/or modify it under
    the terms of the GNU General Public License as published by the Free
    Software Foundation, either version 3 of the License, or (at your option)
    any later version.

    melonDS is distributed in the hope that it will be useful, but WITHOUT ANY
    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with melonDS. If not, see http://www.gnu.org/licenses/.
*/

#include <stdio.h>
#include <string.h>
#include "NDS.h"
#include "GPU.h"
#include "FIFO.h"


namespace GPU3D
{

const u32 CmdNumParams[256] =
{
    // 0x00
    0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    // 0x10
    1, 0, 1, 1, 1, 0, 16, 12, 16, 12, 9, 3, 3,
    0, 0, 0,
    // 0x20
    1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1,
    0, 0, 0, 0,
    // 0x30
    1, 1, 1, 1, 32,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    // 0x40
    1, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    // 0x50
    1,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    // 0x60
    1,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    // 0x70
    3, 2, 1,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    // 0x80+
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

const s32 CmdNumCycles[256] =
{
    // 0x00
    0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    // 0x10
    1, 17, 36, 17, 36, 19, 34, 30, 35, 31, 28, 22, 22,
    0, 0, 0,
    // 0x20
    1, 9, 1, 9, 8, 8, 8, 8, 8, 1, 1, 1,
    0, 0, 0, 0,
    // 0x30
    4, 4, 6, 1, 32,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    // 0x40
    1, 1,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    // 0x50
    392,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    // 0x60
    1,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    // 0x70
    103, 9, 5,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    // 0x80+
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

typedef struct
{
    u8 Command;
    u32 Param;

} CmdFIFOEntry;

FIFO<CmdFIFOEntry>* CmdFIFO;
FIFO<CmdFIFOEntry>* CmdPIPE;

u32 NumCommands, CurCommand, ParamCount, TotalParams;

u32 GXStat;

u32 ExecParams[32];
u32 ExecParamCount;
s32 CycleCount;


bool Init()
{
    CmdFIFO = new FIFO<CmdFIFOEntry>(256);
    CmdPIPE = new FIFO<CmdFIFOEntry>(4);

    return true;
}

void DeInit()
{
    delete CmdFIFO;
    delete CmdPIPE;
}

void Reset()
{
    CmdFIFO->Clear();
    CmdPIPE->Clear();

    NumCommands = 0;
    CurCommand = 0;
    ParamCount = 0;
    TotalParams = 0;

    GXStat = 0;

    memset(ExecParams, 0, 32*4);
    ExecParamCount = 0;
    CycleCount = 0;
}


void CmdFIFOWrite(CmdFIFOEntry& entry)
{
    if (CmdFIFO->IsEmpty() && !CmdPIPE->IsFull())
    {
        CmdPIPE->Write(entry);
    }
    else
    {
        if (CmdFIFO->IsFull())
        {
            printf("!!! GX FIFO FULL\n");
            return;
        }

        CmdFIFO->Write(entry);
    }
}

CmdFIFOEntry CmdFIFORead()
{
    CmdFIFOEntry ret = CmdPIPE->Read();

    if (CmdPIPE->Level() <= 2)
    {
        if (!CmdFIFO->IsEmpty())
            CmdPIPE->Write(CmdFIFO->Read());
        if (!CmdFIFO->IsEmpty())
            CmdPIPE->Write(CmdFIFO->Read());
    }

    CheckFIFOIRQ();
    return ret;
}




void ExecuteCommand()
{
    CmdFIFOEntry entry = CmdFIFORead();

    ExecParams[ExecParamCount] = entry.Param;
    ExecParamCount++;

    if (ExecParamCount >= CmdNumParams[entry.Command])
    {
        CycleCount += CmdNumCycles[entry.Command];
        ExecParamCount = 0;

        // TODO: actually execute the command, maybe
        //printf("3D CMD %02X\n", entry.Command);

        switch (entry.Command)
        {
        case 0x18:
        case 0x19:
        case 0x1A:
            // TODO: more cycles if MTX_MODE=2
            break;

        case 0x21:
            // TODO: more cycles if lights are enabled
            break;

        case 0x50:
            // TODO: make it happen upon VBlank, not right now
            break;
        }
    }
}

void Run(s32 cycles)
{
    if (CycleCount <= 0)
    {
        while (CycleCount <= 0 && !CmdPIPE->IsEmpty())
            ExecuteCommand();

        if (CmdPIPE->IsEmpty())
            CycleCount = 0;
    }
    else
        CycleCount -= cycles;
}


void CheckFIFOIRQ()
{
    bool irq = false;
    switch (GXStat >> 30)
    {
    case 1: irq = (CmdFIFO->Level() < 128); break;
    case 2: irq = CmdFIFO->IsEmpty(); break;
    }

    if (irq) NDS::TriggerIRQ(0, NDS::IRQ_GXFIFO);
}


u8 Read8(u32 addr)
{
    return 0;
}

u16 Read16(u32 addr)
{
    return 0;
}

u32 Read32(u32 addr)
{
    switch (addr)
    {
    case 0x04000320:
        return 46; // TODO, eventually

    case 0x04000600:
        {
            u32 fifolevel = CmdFIFO->Level();

            return GXStat |
                   // matrix stack levels, TODO
                   (fifolevel << 16) |
                   (fifolevel < 128 ? (1<<25) : 0) |
                   (fifolevel == 0  ? (1<<26) : 0) |
                   (CycleCount > 0  ? (1<<27) : 0);
        }
    }
    return 0;
}

void Write8(u32 addr, u8 val)
{
    //
}

void Write16(u32 addr, u16 val)
{
    //
}

void Write32(u32 addr, u32 val)
{
    switch (addr)
    {
    case 0x04000600:
        if (val & 0x8000) GXStat &= ~0x8000;
        val &= 0xC0000000;
        GXStat &= 0x3FFFFFFF;
        GXStat |= val;
        return;
    }

    if (addr >= 0x04000400 && addr < 0x04000440)
    {
        if (NumCommands == 0)
        {
            NumCommands = 4;
            CurCommand = val;
            ParamCount = 0;
            TotalParams = CmdNumParams[CurCommand & 0xFF];
        }
        else
            ParamCount++;

        while (ParamCount == TotalParams)
        {
            CmdFIFOEntry entry;
            entry.Command = CurCommand & 0xFF;
            entry.Param = val;
            CmdFIFOWrite(entry);

            CurCommand >>= 8;
            NumCommands--;
            if (NumCommands == 0) break;

            ParamCount = 0;
            TotalParams = CmdNumParams[CurCommand & 0xFF];
        }
    }

    if (addr >= 0x04000440 && addr < 0x040005CC)
    {
        CmdFIFOEntry entry;
        entry.Command = (addr & 0x1FC) >> 2;
        entry.Param = val;
        CmdFIFOWrite(entry);
        return;
    }
}

}