A poorly written OS for the x86 arch. (WIP)
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eOS/drivers/vga.c

75 lines
1.7 KiB

// VGA Graphics Library
#include "vga.h"
#include "../kernel/io.h"
#include "../lib/str.h"
static unsigned int cursor_row = 0;
static unsigned int cursor_col = 0;
void vga_init() {
// Disable cursor
port_outb(0x3d4, 0x0a);
port_outb(0x3d5, 0x20);
// Clear screen
clear_screen();
}
/*
VGA & Memory Functions
*/
char* get_memory_charpos(unsigned int col, unsigned int row) {
return (char*)(VGA_ADDRESS + 2*((row*80) + col));
}
void writechar(char c, unsigned int col, unsigned int row, int attribute_byte) {
if( !attribute_byte )
attribute_byte = 0x0f;
char* mem = get_memory_charpos(col, row);
*mem = c; // Write the character
*(mem+1) = attribute_byte; // Write the attribute_byte
}
void set_cursor_pos(unsigned int col, unsigned int row) {
cursor_col = col;
cursor_row = row;
}
/*
Graphics Functions
*/
void clear_screen() {
for( int c = 0; c < MAX_COLS; c++ )
for( int r = 0; r < MAX_ROWS; r++ )
writechar(0x20, c, r, 0xf0);
}
/*
General Printing Functions
*/
void print(char* str, int attribute_byte) {
for( char* c = str; *c != '\0'; c++ )
writechar(*c, (unsigned int)(c - str) + cursor_col, cursor_row, attribute_byte);
}
void println(char* str, int attribute_byte) {
print(str, attribute_byte);
cursor_row++; // Increment to next y-pos (newline)
}
void printalign(char* str, int attribute_byte, enum align alignment) {
unsigned int strlenbuf = strlen(str);
if( !alignment || alignment == LEFT ) {
print(str, attribute_byte);
} else if ( alignment == RIGHT ) {
set_cursor_pos(MAX_COLS - strlenbuf, cursor_row);
} else if ( alignment == MIDDLE ) {
set_cursor_pos((MAX_COLS/2) - (strlenbuf/2), cursor_row);
}
print(str, attribute_byte);
}