cowos/kernel/drivers/video/framebuffer.c

#include <drivers/video/framebuffer.h>
#include <klibc/string.h>
#include <stddef.h>
#include <stdarg.h>
#include <limine_requests.h>
#include <drivers/video/font8x16.h>

static fb_console_t console;

void fb_init(void)
{
    if (framebuffer_request.response == NULL || 
        framebuffer_request.response->framebuffer_count < 1) {
        return;
    }

    console.fb = framebuffer_request.response->framebuffers[0];
    console.fg_color = 0xFFFFFF; // White
    console.bg_color = 0x000000; // Black
    console.cursor_x = 0;
    console.cursor_y = 0;
    console.cols = console.fb->width / FB_CHAR_WIDTH;
    console.rows = console.fb->height / FB_CHAR_HEIGHT;
    
    fb_clear();
}

void fb_clear(void)
{
    if (!console.fb) return;
    
    uint32_t *fb = (uint32_t *)console.fb->address;
    size_t pixels = (console.fb->pitch / 4) * console.fb->height;
    
    for (size_t i = 0; i < pixels; i++) {
        fb[i] = console.bg_color;
    }
    
    console.cursor_x = 0;
    console.cursor_y = 0;
}

void fb_draw_rect(uint32_t x, uint32_t y, uint32_t w, uint32_t h, uint32_t color)
{
    if (!console.fb) return;
    
    uint32_t *fb = (uint32_t *)console.fb->address;
    uint32_t pitch_pixels = console.fb->pitch / 4;
    
    for (uint32_t row = y; row < y + h && row < console.fb->height; row++) {
        for (uint32_t col = x; col < x + w && col < console.fb->width; col++) {
            fb[row * pitch_pixels + col] = color;
        }
    }
}

void fb_set_color(uint32_t fg, uint32_t bg)
{
    console.fg_color = fg;
    console.bg_color = bg;
}

static void draw_char(uint32_t x, uint32_t y, char c, uint32_t fg_color, uint32_t bg_color)
{
    if (!console.fb) return;
    
    uint32_t *fb = (uint32_t *)console.fb->address;
    uint32_t pitch_pixels = console.fb->pitch / 4;
    
    // Get the font data for this character
    const uint8_t *char_data = &IBM_VGA_8x16[c * 16];
    
    // Draw each row of the character
    for (uint32_t row = 0; row < FB_CHAR_HEIGHT; row++) {
        uint8_t font_row = char_data[row];
        
        // Draw each pixel in the row
        for (uint32_t col = 0; col < FB_CHAR_WIDTH; col++) {
            uint32_t px = x + col;
            uint32_t py = y + row;
            
            // Check bounds
            if (px >= console.fb->width || py >= console.fb->height) continue;
            
            // Check if this pixel should be set (bit test)
            if (font_row & (0x80 >> col)) {
                fb[py * pitch_pixels + px] = fg_color;
            } else {
                fb[py * pitch_pixels + px] = bg_color;
            }
        }
    }
}

static void scroll_up(void)
{
    if (!console.fb) return;
    
    uint32_t *fb = (uint32_t *)console.fb->address;
    uint32_t pitch_pixels = console.fb->pitch / 4;
    
    // Move all lines up by one character height
    for (uint32_t y = 0; y < console.fb->height - FB_CHAR_HEIGHT; y++) {
        for (uint32_t x = 0; x < console.fb->width; x++) {
            fb[y * pitch_pixels + x] = fb[(y + FB_CHAR_HEIGHT) * pitch_pixels + x];
        }
    }
    
    // Clear the last line
    for (uint32_t y = console.fb->height - FB_CHAR_HEIGHT; y < console.fb->height; y++) {
        for (uint32_t x = 0; x < console.fb->width; x++) {
            fb[y * pitch_pixels + x] = console.bg_color;
        }
    }
}

void fb_putchar(char c)
{
    if (!console.fb) return;
    
    // Handle special characters
    switch (c) {
        case '\n':
            console.cursor_x = 0;
            console.cursor_y++;
            break;
        case '\r':
            console.cursor_x = 0;
            break;
        case '\t':
            console.cursor_x = (console.cursor_x + 8) & ~7;
            break;
        case '\b':
            if (console.cursor_x > 0) {
                console.cursor_x--;
                draw_char(console.cursor_x * FB_CHAR_WIDTH, 
                         console.cursor_y * FB_CHAR_HEIGHT, 
                         ' ', console.fg_color, console.bg_color);
            }
            break;
        default:
            // Draw the character
            draw_char(console.cursor_x * FB_CHAR_WIDTH, 
                     console.cursor_y * FB_CHAR_HEIGHT, 
                     c, console.fg_color, console.bg_color);
            console.cursor_x++;
            break;
    }
    
    // Handle line wrapping
    if (console.cursor_x >= console.cols) {
        console.cursor_x = 0;
        console.cursor_y++;
    }
    
    // Handle scrolling
    if (console.cursor_y >= console.rows) {
        scroll_up();
        console.cursor_y = console.rows - 1;
    }
}

void fb_puts(const char *str)
{
    while (*str) {
        fb_putchar(*str++);
    }
}

static void print_number(unsigned long num, int base, int width, char pad)
{
    char digits[] = "0123456789ABCDEF";
    char buffer[32];
    int pos = 0;
    
    // Convert number to string (reversed)
    if (num == 0) {
        buffer[pos++] = '0';
    } else {
        while (num > 0) {
            buffer[pos++] = digits[num % base];
            num /= base;
        }
    }
    
    // Add padding if needed
    while (pos < width) {
        buffer[pos++] = pad;
    }
    
    // Print reversed
    while (pos > 0) {
        fb_putchar(buffer[--pos]);
    }
}

static void print_signed(long num, int width, char pad)
{
    if (num < 0) {
        fb_putchar('-');
        print_number(-num, 10, width, pad);
    } else {
        print_number(num, 10, width, pad);
    }
}

void fb_printf(const char *fmt, ...)
{
    va_list args;
    va_start(args, fmt);
    
    while (*fmt) {
        if (*fmt == '%') {
            fmt++;
            
            // Handle width and padding
            char pad = ' ';
            int width = 0;
            
            if (*fmt == '0') {
                pad = '0';
                fmt++;
            }
            
            while (*fmt >= '0' && *fmt <= '9') {
                width = width * 10 + (*fmt - '0');
                fmt++;
            }
            
            // Handle format specifiers
            switch (*fmt) {
                case 'd':
                case 'i':
                    print_signed(va_arg(args, int), width, pad);
                    break;
                    
                case 'u':
                    print_number(va_arg(args, unsigned int), 10, width, pad);
                    break;
                    
                case 'x':
                    print_number(va_arg(args, unsigned int), 16, width, pad);
                    break;
                    
                case 'X':
                    print_number(va_arg(args, unsigned int), 16, width, pad);
                    break;
                    
                case 'p':
                    fb_puts("0x");
                    print_number((unsigned long)va_arg(args, void*), 16, 16, '0');
                    break;
                    
                case 'c':
                    fb_putchar(va_arg(args, int));
                    break;
                    
                case 's':
                    {
                        const char *str = va_arg(args, const char*);
                        if (str) {
                            fb_puts(str);
                        } else {
                            fb_puts("(null)");
                        }
                    }
                    break;
                    
                case '%':
                    fb_putchar('%');
                    break;
                    
                default:
                    fb_putchar('%');
                    fb_putchar(*fmt);
                    break;
            }
        } else {
            fb_putchar(*fmt);
        }
        fmt++;
    }
    
    va_end(args);
}