emulator/src/main.cpp

#include <bits/stdint-uintn.h>
#include <cstring>
#include <fstream>
#include <stdexcept>
#include <array>
#include <filesystem>
#include <functional>

#include <SDL2/SDL.h>
#include <SDL2/SDL_error.h>
#include <SDL2/SDL_hints.h>
#include <SDL2/SDL_image.h>
#include <SDL2/SDL_log.h>
#include <SDL2/SDL_main.h>
#include <SDL2/SDL_render.h>
#include <SDL2/SDL_video.h>
#include <string>

#include "Z/types/base.h"
#include "Z80.h"

template <int W, int H>
class Emulator {
	public:
		Emulator(std::filesystem::path rom_name) {
			// SDL
			int render_flags = SDL_RENDERER_ACCELERATED;
			int window_flags = 0;

			if (SDL_Init(SDL_INIT_VIDEO) < 0) {
				throw std::runtime_error("Failed to initialize SDL2: " + std::string(SDL_GetError()));
			}

			window = SDL_CreateWindow("Z80 Emulator", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, W*16, H*16, window_flags);
			if (!window) {
				throw std::runtime_error("Failed to open window: " + std::string(SDL_GetError()));
			}

			SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "linear");
			renderer = SDL_CreateRenderer(window, -1, render_flags);
			if (!window) {
				throw std::runtime_error("Failed to create rendere: " + std::string(SDL_GetError()));
			}

			if (!IMG_Init(IMG_INIT_PNG)) {
				throw std::runtime_error("Failed to initialize SDL2_image: " + std::string(SDL_GetError()));
			}

			SDL_LogMessage(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO, "Loading '../convert-font/font.png'");
			font = IMG_LoadTexture(renderer, "../convert-font/font.png");

			if (!font) {
				throw std::runtime_error("Failed to open font: " + std::string(IMG_GetError()));
			}

			// Z80
			std::ifstream rom_file(rom_name, std::ios::in | std::ios::binary);

			rom_file.seekg(0, std::ios::end);
			size_t rom_size = rom_file.tellg();
			rom_file.seekg(0, std::ios::beg);

			rom_file.read(reinterpret_cast<char*>(memory.data()), rom_size);

			z.context = this;
			z.read = z_read;
			z.write = z_write;
			z.in = z_in;
			z.out = z_out;
			z.int_data = z_int_data;

			z80_reset(&z);
		}

		~Emulator() {
			SDL_DestroyRenderer(renderer);

			SDL_DestroyWindow(window);

			SDL_Quit();
		}

		static zuint8 z_read(void* context, zuint16 address) {
			auto e = (Emulator<W,H>*)context;
			return e->memory[address];
		}

		static void z_write(void* context, zuint16 address, zuint8 value) {
			auto e = (Emulator<W,H>*)context;
			e->memory[address] = value;
		}

		static zuint8 z_in(void* /* context */, zuint16 port) {
			switch (port & 0xFF) {
				case 0x03:
					return 0x01;

				// char
				case 0x1E:
					return 0x00;

				// has_input
				case 0x1F:
					return 0x00;

				default:
					SDL_LogMessage(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO, "IO Read @ 0x%X\n", (port & 0xFF));

					return 0x00;
			}
		}

		static void z_out(void* context, zuint16 port, zuint8 value) {
			auto e = (Emulator<W,H>*)context;

			switch (port & 0xFF) {
				case 0x02:
					e->input(value);
					break;

				default:
					SDL_LogMessage(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO, "IO Wrte 0x%X @ 0x%X\n", value, (port & 0xFF));
					break;
			}
		}

		static zuint32 z_int_data(void* /* context */) {
			return 0x00;
		}

		void update() {
			z80_run(&z, 1);
		}

		// @todo This should handle the input properly (same as fpga)
		void input(char c) {
			buffer[cursor.y*W + cursor.x] = c;

			cursor.x++;
			if (cursor.x > W) {
				cursor.x = 0;
				cursor.y++;
			}
		}

		void draw_buffer() {
			SDL_Rect src;
			src.w = 16;
			src.h = 16;

			SDL_Rect dest;
			dest.w = 16;
			dest.h = 16;

			SDL_SetTextureColorMod(font, 255, 255, 255);

			for (int x = 0; x < W; ++x) {
				for (int y = 0; y < H; ++y) {
					char c = buffer[y*W + x];
					src.x = (c % 16) * 16;
					src.y = (c / 16) * 16;

					dest.x = x * 16;
					dest.y = y * 16;

					SDL_RenderCopy(renderer, font, &src, &dest);
				}
			}
		}

		bool handle_events() {
			SDL_Event event;

			while (SDL_PollEvent(&event)) {
				switch (event.type) {
					case SDL_QUIT:
						return false;

					default:
						break;
				}
			}

			return true;
		}

		void prepare() {
			SDL_SetRenderDrawColor(renderer, 96, 128, 255, 255);
			SDL_RenderClear(renderer);
		}

		void render() {
			SDL_RenderPresent(renderer);
		}

	private:
		SDL_Renderer* renderer = nullptr;
		SDL_Window* window = nullptr;
		SDL_Texture* font = nullptr;

		std::array<char, W*H> buffer = {0};

		struct {
			int x = 0;
			int y = 0;
		} cursor;

		Z80 z;
		std::array<uint8_t, 0xFFFF> memory;
};

int main() {
	Emulator<80, 45> e("../../software/monitor/.build/rom_monitor.bin");

	while (e.handle_events()) {
		e.prepare();

		e.update();

		e.draw_buffer();

		e.render();
	}
}