kernel.c

#define FONT8x16_IMPLEMENTATION
#include "font8x16.h"
#include <stdint.h>

typedef unsigned int uint32_t;

extern void irq12_handler_stub();

#define CURSOR_W 16
#define CURSOR_H 16

typedef struct {
    uint16_t offset_low;
    uint16_t selector;
    uint8_t zero;
    uint8_t type_attr;
    uint16_t offset_high;
} __attribute__((packed)) idt_entry_t;

idt_entry_t idt[256];
struct {
    uint16_t limit;
    uint32_t base;
} __attribute__((packed)) idt_ptr;

unsigned char cursor_shape[CURSOR_H*2] = {
    0b10000000,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b11000000,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b11100000,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b11110000,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b11111000,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b11111100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b11111110,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b11111111,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b11111110,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b11110100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b11001100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b10000110,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b00000110,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b00001100,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b00011000,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
    0b00110000,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
};

uint32_t mouse_x = 200;
uint32_t mouse_y = 200;
uint32_t saved_bg[CURSOR_H*CURSOR_W];
uint8_t mouse_packet[3];
int mouse_phase = 0;

static inline void outb(uint16_t port, uint8_t val) {
    __asm__ volatile ("outb %0,%1" : : "a"(val), "Nd"(port));
}
static inline uint8_t inb(uint16_t port) {
    uint8_t ret;
    __asm__ volatile ("inb %1,%0" : "=a"(ret) : "Nd"(port));
    return ret;
}

void draw_char(uint32_t* fb, int pitch, int x, int y, char c, uint32_t color) {
    unsigned char* glyph = font8x16[(unsigned char)c];

    for (int dy = 0; dy < 16; dy++) {
        for (int dx = 0; dx < 8; dx++) {
            if ((glyph[dy] << dx) & 0x80) {
                fb[(y + dy) * (pitch / 4) + (x + dx)] = color;
            }
        }
    }
}

void draw_string(uint32_t* fb, int pitch, int x, int y, const char* str, uint32_t color) {
    for (int i = 0; str[i] != '\0'; i++) {
        draw_char(fb, pitch, x + (i * 8), y, str[i], color);
    }
}

void draw_rect(uint32_t* fb, int scanline, int x, int y, int w, int h, uint32_t color) {
    for (int i = y; i < y + h; i++) {
        for (int j = x; j < x + w; j++) {
            fb[i * (scanline / 4) + j] = color;
        }
    }
}

void draw_cursor(uint32_t* fb, int pitch) {
    for(int y=0;y<CURSOR_H;y++)
        for(int x=0;x<CURSOR_W;x++)
            saved_bg[y*CURSOR_W+x] = fb[(mouse_y+y)*(pitch/4)+(mouse_x+x)];

    for(int y=0;y<CURSOR_H;y++)
        for(int x=0;x<CURSOR_W;x++)
            if(cursor_shape[y*2 + x/8] & (0x80>>(x%8)))
                fb[(mouse_y+y)*(pitch/4)+(mouse_x+x)] = 0xFFFFFF;
}

void erase_cursor(uint32_t* fb,int pitch) {
    for(int y=0;y<CURSOR_H;y++)
        for(int x=0;x<CURSOR_W;x++)
            fb[(mouse_y+y)*(pitch/4)+(mouse_x+x)] = saved_bg[y*CURSOR_W + x];
}

void mouse_write(uint8_t val) {
    while (inb(0x64) & 0x02);
    outb(0x64, 0xD4);
    while (inb(0x64) & 0x02);
    outb(0x60, val);
}

void idt_set_gate(int n, uint32_t handler) {
    idt[n].offset_low = handler & 0xFFFF;
    idt[n].selector = 0x08;
    idt[n].zero = 0;
    idt[n].type_attr = 0x8E;
    idt[n].offset_high = (handler >> 16) & 0xFFFF;
}

void idt_load() {
    idt_ptr.limit = sizeof(idt) - 1;
    idt_ptr.base = (uint32_t)&idt;
    __asm__ volatile("lidtl (%0)" : : "r"(&idt_ptr));
}

void setup_idt_irq() {
    idt_set_gate(44, (uint32_t)irq12_handler_stub);
    idt_load();
}

void mouse_init() {
    mouse_write(0xF6);
    mouse_write(0xF4);
}

void mouse_irq_handler(uint32_t* fb,int pitch,int width,int height) {
    uint8_t data = inb(0x60);

    if(mouse_phase == 0) {
        if(data == 0xFA) mouse_phase = 1;
    } else {
        mouse_packet[mouse_phase-1] = data;
        mouse_phase++;
        if(mouse_phase == 4) {
            int dx = (int8_t)mouse_packet[1];
            int dy = (int8_t)mouse_packet[2];

            erase_cursor(fb,pitch);
            mouse_x += dx;
            mouse_y -= dy;
            if(mouse_x < 0) mouse_x = 0;
            if(mouse_y < 0) mouse_y = 0;
            if(mouse_x > width-CURSOR_W) mouse_x = width-CURSOR_W;
            if(mouse_y > height-CURSOR_H) mouse_y = height-CURSOR_H;
            draw_cursor(fb,pitch);

            mouse_phase = 1;
        }
    }

    outb(0x20,0x20);
}

extern void idt_set_gate(int n,uint32_t handler);

void pic_init() {
    outb(0x20,0x11);
    outb(0x21,0x20);
    outb(0x21,0x04);
    outb(0x21,0x01);

    outb(0xA0,0x11);
    outb(0xA1,0x28);
    outb(0xA1,0x02);
    outb(0xA1,0x01);

    outb(0x21,0xF8);
    outb(0xA1,0xEF);
}

void kmain(uint32_t magic, uint32_t* addr) {
    (void)magic;
    (void)addr;
    
    uint32_t* fb = (uint32_t*)0xfd000000;
    int width = 1024;
    int height = 768;
    int pitch = width * 4;

    for(int i = 0; i < width * height; i++) fb[i] = 0x0000FF;

    draw_rect(fb, pitch, 100, 100, 400, 300, 0xCCCCCC);
    draw_rect(fb, pitch, 100, 100, 400, 30,  0x000088);
    draw_rect(fb, pitch, 470, 105, 20,  20,  0xFF0000);

    draw_string(fb, pitch, 110, 105, "Hello MiniOS Pro!", 0xFFFFFF);
    draw_string(fb, pitch, 120, 150, "Hello", 0x000000);

    setup_idt_irq();
    pic_init();
    mouse_init();
    draw_cursor(fb, pitch);

    while (1) {

    }
}