// Copyright 2018 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include "common/microprofile.h"
#include "core/core.h"
#include "core/memory.h"
#include "video_core/dma_pusher.h"
#include "video_core/engines/maxwell_3d.h"
#include "video_core/gpu.h"
#include "video_core/memory_manager.h"

namespace Tegra {

DmaPusher::DmaPusher(Core::System& system, GPU& gpu) : gpu{gpu}, system{system} {}

DmaPusher::~DmaPusher() = default;

MICROPROFILE_DEFINE(DispatchCalls, "GPU", "Execute command buffer", MP_RGB(128, 128, 192));

void DmaPusher::DispatchCalls() {
    MICROPROFILE_SCOPE(DispatchCalls);

    // On entering GPU code, assume all memory may be touched by the ARM core.
    gpu.Maxwell3D().OnMemoryWrite();

    dma_pushbuffer_subindex = 0;

    while (system.IsPoweredOn()) {
        if (!Step()) {
            break;
        }
    }
    gpu.FlushCommands();
}

bool DmaPusher::Step() {
    if (!ib_enable || dma_pushbuffer.empty()) {
        // pushbuffer empty and IB empty or nonexistent - nothing to do
        return false;
    }

    const CommandList& command_list{dma_pushbuffer.front()};
    ASSERT_OR_EXECUTE(!command_list.empty(), {
        // Somehow the command_list is empty, in order to avoid a crash
        // We ignore it and assume its size is 0.
        dma_pushbuffer.pop();
        dma_pushbuffer_subindex = 0;
        return true;
    });
    const CommandListHeader command_list_header{command_list[dma_pushbuffer_subindex++]};
    GPUVAddr dma_get = command_list_header.addr;
    GPUVAddr dma_put = dma_get + command_list_header.size * sizeof(u32);
    bool non_main = command_list_header.is_non_main;

    if (dma_pushbuffer_subindex >= command_list.size()) {
        // We've gone through the current list, remove it from the queue
        dma_pushbuffer.pop();
        dma_pushbuffer_subindex = 0;
    }

    if (command_list_header.size == 0) {
        return true;
    }

    // Push buffer non-empty, read a word
    command_headers.resize(command_list_header.size);
    gpu.MemoryManager().ReadBlockUnsafe(dma_get, command_headers.data(),
                                        command_list_header.size * sizeof(u32));

    for (const CommandHeader& command_header : command_headers) {

        // now, see if we're in the middle of a command
        if (dma_state.length_pending) {
            // Second word of long non-inc methods command - method count
            dma_state.length_pending = 0;
            dma_state.method_count = command_header.method_count_;
        } else if (dma_state.method_count) {
            // Data word of methods command
            CallMethod(command_header.argument);

            if (!dma_state.non_incrementing) {
                dma_state.method++;
            }

            if (dma_increment_once) {
                dma_state.non_incrementing = true;
            }

            dma_state.method_count--;
        } else {
            // No command active - this is the first word of a new one
            switch (command_header.mode) {
            case SubmissionMode::Increasing:
                SetState(command_header);
                dma_state.non_incrementing = false;
                dma_increment_once = false;
                break;
            case SubmissionMode::NonIncreasing:
                SetState(command_header);
                dma_state.non_incrementing = true;
                dma_increment_once = false;
                break;
            case SubmissionMode::Inline:
                dma_state.method = command_header.method;
                dma_state.subchannel = command_header.subchannel;
                CallMethod(command_header.arg_count);
                dma_state.non_incrementing = true;
                dma_increment_once = false;
                break;
            case SubmissionMode::IncreaseOnce:
                SetState(command_header);
                dma_state.non_incrementing = false;
                dma_increment_once = true;
                break;
            default:
                break;
            }
        }
    }

    if (!non_main) {
        // TODO (degasus): This is dead code, as dma_mget is never read.
        dma_mget = dma_put;
    }

    return true;
}

void DmaPusher::SetState(const CommandHeader& command_header) {
    dma_state.method = command_header.method;
    dma_state.subchannel = command_header.subchannel;
    dma_state.method_count = command_header.method_count;
}

void DmaPusher::CallMethod(u32 argument) const {
    gpu.CallMethod({dma_state.method, argument, dma_state.subchannel, dma_state.method_count});
}

} // namespace Tegra
