Screen code

/* Ivion Kernel - The Future Free Kernel
 * Copyright(C)2013 Muhammad Irvan H.
 * Software ini boleh dimiliki, disebarkan, diubah dengan bebas.
 * Dengan catatan:
 * > Boleh menambah, namun dilarang mengubah komentar ini.
 * > Hanya dipakai untuk edukasi dan non-profit(non-komersil).
 * > Dilarang mendokumentasikan kode dalam bentuk buku atau semacamnya,
 *   sebelum izin kepada kru Ivion. (Izin GRATIS)
 */

#include "struct.h"
#include "type.h"

char* current_video_mem = (char*)0xB8000;
uchar current_col;
uchar current_row;
const uchar MAX_COL = 80;
const uchar MAX_ROW = 25;
const uint VIDEO_MEM_BASE = 0xB8000;
const uchar BYTES_PER_CHAR = 2;
ushort cursor_pos;

void move_cursor(short, short);
void new_line();

/* *
 * Print String from char * strings with attributes
 * */
void print_str(char* strings, uchar attributes)
{
    int i = 0;

    while(strings[i] != 0)
    {
        if (strings[i] == '\n')
        {
            new_line();
            i++;
        }
        else
        {
            *current_video_mem = strings[i];
            current_video_mem++;
            *current_video_mem = attributes;
            current_video_mem++;
            i++;

            if (current_col == 79)
            {
                new_line();
            }
            else
            {
                current_col++;
            }
        }
    }
    move_cursor(current_col,current_row);
}

/* *
 * Print Single Character from char character, with attributes
 * */
void putch(char character, char attributes)
{
    char the_char[2];
    the_char[0] = character;
    the_char[1] = 0;
    print_str(&the_char[0],attributes);
}

/* *
 * New Line with auto scrolling
 * */
void new_line()
{
    int i;
    char* location=(char*)VIDEO_MEM_BASE;

    if (current_row == 24)
    {
        for (i = 0; i <= 80*25*2; i++)
        {
            location[i] = location[i+80*2];
        }
        current_row = 24;
        current_col = 0;

    }
    else
    {
        current_row++;
        current_col=0;
    }
    current_video_mem = (char*)VIDEO_MEM_BASE + ((current_row * 80 + current_col) * 2);
    move_cursor(current_col,current_row);
}

/* *
 * Clear screen
 * */
void clear_scr()
{
    int i;
    short* location = (short*)VIDEO_MEM_BASE;

    for(i=0; i<MAX_COL*MAX_ROW; i++)
    {
        *location = 0x0f00;
        location++;

    }
    move_cursor(0,0);

}

/* *
 * Move caret/cursor to X, Y
 * */
void move_cursor(short x, short y)
{
    cursor_pos = (y * MAX_COL) + x;
    asm (".intel_syntax noprefix");
    asm ("mov al,14");
    asm ("mov dx,0x3d4");
    asm ("out dx,al");
    asm ("mov ax,[cursor_pos]");
    asm ("shr ax,8");
    asm ("mov dx,0x3d5");
    asm ("out dx,al");

    asm ("mov al,15");
    asm ("mov dx,0x3d4");
    asm ("out dx,al");
    asm ("mov ax,[cursor_pos]");
    asm ("mov dx, 0x3d5");
    asm ("out dx,al");

}

void get_cursor_pos(cursor_position_struct* cursor_pos_struct)
{
    cursor_pos_struct->x = current_col;
    cursor_pos_struct->y = current_row;
}

/* *
 * Convert Integer Number to Hexadecimal Number
 * Number saved to char* buffer
 * */
char hexadecimal[9];
void int_to_hex_str(uint number, char* buffer)
{
    int i,j=0;

    //process
    for (i=0;number / 0x10 != 0; i++)
    {
        if(number % 0x10 > 9)
        {
            hexadecimal[i] = (number % 0x10) + 0x37;
        }
        else
        {
            hexadecimal[i] = (number % 0x10) + 0x30;
        }
        number /= 0x10;
    }
    if(number % 0x10 > 9)
    {
        hexadecimal[i] = (number % 0x10) + 0x37;
    }
    else
    {
        hexadecimal[i] = (number % 0x10) + 0x30;
    }

    //save
    while(i != 0)
    {
        buffer[j] = hexadecimal[i];
        i--;
        j++;
    }
    buffer[j] = hexadecimal[i];
    buffer[j+1] = 0;
}

/* *
 * Convert Unsigned Integer Number to Decimal String
 * Number saved to char* buffer
 * */
 char decimal[15];
void uint_to_decimal_str(uint number, char* buffer)
{
    int i,j=0;

    //process
    for (i=0;number / 10 != 0; i++)
    {
        decimal[i] = (number % 10) + 0x30;
        number /= 10;
    }
    decimal[i] = number + 0x30;
    //save
    while(i != 0)
    {
        buffer[j] = decimal[i];
        i--;
        j++;
    }
    buffer[j] = decimal[i];
    buffer[j+1] = 0;
}

/* *
 * Convert Signed Integer Number to Decimal String
 * Number saved to char* buffer
 * */
void sint_to_decimal_str(sint snumber, char* buffer)
{
    int i,j=0,number;
    //compare
    if(snumber < 0)
    {
        number = (snumber * -1);
    }
    else
    {
        number = snumber;
    }

    //process
    for (i=0;number / 10 != 0; i++)
    {
        decimal[i] = (number % 10) + 0x30;
        number /= 10;
    }
    decimal[i] = number + 0x30;

    //set sign
    if (snumber < 0)
    {
        buffer[j] = 0x2d;   //strip (-)
        j++;
    }
    //save
    while(i != 0)
    {
        buffer[j] = decimal[i];
        i--;
        j++;
    }
    buffer[j] = decimal[i];
    buffer[j+1] = 0;
}