vga.c

#include "vga.h"

/*
See Intel® OpenSource HD Graphics PRM pdf file
for following defined data for each vga register
and its explaination
*/
uint8* vga_buffer;


static uint8 seq_data[5] = {0x03, 0x01, 0x0F, 0x00, 0x0E};
static uint8 crtc_data[25] = {0x5F, 0x4F, 0x50, 0x82,
                              0x54, 0x80, 0xBF, 0x1F,
                              0x00, 0x41, 0x00, 0x00,
                              0x00, 0x00, 0x00, 0x00,
                              0x9C, 0x0E, 0x8F, 0x28,
                              0x40, 0x96, 0xB9, 0xA3,
                              0xFF};

static uint8 gc_data[9] = {0x00, 0x00, 0x00, 0x00,
                           0x00, 0x40, 0x05, 0x0F,
                           0xFF};

static uint8 ac_data[21] = {0x00, 0x01, 0x02, 0x03,
                            0x04, 0x05, 0x06, 0x07,
                            0x08, 0x09, 0x0A, 0x0B,
                            0x0C, 0x0D, 0x0E, 0x0F,
                            0x41, 0x00, 0x0F, 0x00,
                            0x00};

uint8 inb(uint16 port)
{
    uint8 data;
    asm volatile("inb %1, %0" : "=a"(data) : "Nd"(port));
    return data;
}

void outb(uint16 port, uint8 data)
{
    asm volatile("outb %0, %1" : : "a"(data), "Nd"(port));
}

void set_misc()
{
    outb(VGA_MISC_WRITE, 0x63);
}

void set_seq()
{
    // write sequence data to index of 0-4
    for(uint8 index = 0; index < 5; index++){
        // first set index
        outb(VGA_SEQ_INDEX, index);
        // write data at that index
        outb(VGA_SEQ_DATA, seq_data[index]);
    }
}

void set_crtc()
{
    // write crtc data to index of 0-24
    for(uint8 index = 0; index < 25; index++){
        outb(VGA_CRTC_INDEX, index);
        outb(VGA_CRTC_DATA, crtc_data[index]);
    }
}

void set_gc()
{
    // write gc data to index of 0-8
    for(uint8 index = 0; index < 9; index++){
        outb(VGA_GC_INDEX, index);
        outb(VGA_GC_DATA, gc_data[index]);
    }
}

void set_ac()
{
    uint8 d;
    // write ac data to index of 0-20
    for(uint8 index = 0; index < 21; index++){
        outb(VGA_AC_INDEX, index);
        outb(VGA_AC_WRITE, ac_data[index]);
    }
    d = inb(VGA_INSTAT_READ);
    outb(VGA_AC_INDEX, d | 0x20);
}

void clear_screen()
{
    for(uint32 index = 0; index < VGA_MAX; index++)
        vga_buffer[index] = 0;
}

void clear_color(uint8 color)
{
    for(uint32 index = 0; index < VGA_MAX; index++)
        vga_buffer[index] = color;
}

void init_vga()
{
    set_misc();
    set_seq();
    set_crtc();
    set_gc();
    set_ac();

    vga_buffer = (uint8*)VGA_ADDRESS;

    clear_screen();
}

void putpixel(uint16 x, uint16 y, uint8 color)
{
    uint32 index = 0;
    index = 320 * y + x;
    if(index < VGA_MAX)
        vga_buffer[index] = color;
}

void draw_line(uint16 x1, uint16 y1, uint16 x2, uint16 y2, uint8 color)
{
    if(y1 == y2){
        for(uint16 i = x1; i <= x2; i++)
            putpixel(i, y1, color);
        return;
    }

    if(x1 == x2){
        for(uint16 i = y1; i <= y2; i++){
            putpixel(x1, i, color);
        }
        return;
    }
}

void draw_rect(uint16 x, uint16 y, uint16 width, uint16 height, uint8 color)
{
    draw_line(x, y, x, y + height, color);
    draw_line(x, y, x + width, y, color);
    draw_line(x + width, y, x + width, y + height, color);
    draw_line(x, y + height, x + width, y + height, color);
}

void draw_bresenham_circle(int xc, int yc, int x, int y, uint8 color)
{
    putpixel(xc+x, yc+y, color);
    putpixel(xc-x, yc+y, color);
    putpixel(xc+x, yc-y, color);
    putpixel(xc-x, yc-y, color);
    putpixel(xc+y, yc+x, color);
    putpixel(xc-y, yc+x, color);
    putpixel(xc+y, yc-x, color);
    putpixel(xc-y, yc-x, color);
}

void draw_circle(uint16 x, uint16 y, uint16 radius, uint8 color)
{
    int x2 = 0, y2 = radius;
    int d = 3 - 2 * radius;
    draw_bresenham_circle(x, y, x2, y2, color);
    while(y2 >= x2){
        x2++;
        if(d > 0){
            y2--;
            d = d + 4 * (x2 - y2) + 10;
        }else{
            d = d + 4 * x2 + 6;
        }
        draw_bresenham_circle(x, y, x2, y2, color);
    }
}

void draw_diamond(uint16 x, uint16 y, uint16 radius, uint8 color)
{
    uint16 x2 = 0, y2 = radius;
    uint16 d = 3 - 2 * radius;
    draw_bresenham_circle(x, y, x2, y2, color);
    while(y2 >= x2){
        x2++;
        if(d > 0){
            y2--;
            d = d + 4 * (x2 - y2) + 10;
        }else{
            d = d + 4 * x2 + 6;
        }
        draw_bresenham_circle(x, y, x2, y2, color);
    }
}