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#include "monitor.h"
#include "sys.h"
static int cursor_x = 0, cursor_y = 0;
static uint16_t *video_memory = (uint16_t*)0xE00B8000;
static uint8_t attribute = 0x07; // 0 = background = black, 7 = foreground = white
/* For internal use only. Tells hardware to move the cursor at (cursor_x, cursor_y). */
static void move_cursor() {
uint16_t cursor_location = cursor_y * 80 + cursor_x;
outb(0x3D4, 14); //Sending high cursor byte
outb(0x3D5, cursor_location >> 8);
outb(0x3D4, 15); //Sending high cursor byte
outb(0x3D5, cursor_location);
}
/* For internal use only. Scrolls everything up one line. */
static void scroll() {
uint16_t blank = (attribute << 8) | 0x20;
if (cursor_y >= 25) {
int i;
for (i = 0; i < 80*24; i++) {
video_memory[i] = video_memory[i+80];
}
for (i = 80*24; i < 80*25; i++) {
video_memory[i] = blank;
}
cursor_y = 24;
}
}
/* Put one character on the screen. This function handles special characters \b, \t, \r and \n. */
void monitor_put(char c) {
if (c == '\b' && cursor_x) { //Backspace
cursor_x--;
} else if (c == '\t') { //Tab
cursor_x = (cursor_x + 8) & ~(8 - 1);
} else if (c == '\r') { //Carriage return
cursor_x = 0;
} else if (c == '\n') { //New line
cursor_x = 0;
cursor_y++;
} else if (c >= ' ') { //Any printable character
video_memory[cursor_y * 80 + cursor_x] = c | (attribute << 8);
cursor_x++;
}
if (cursor_x >= 80) {
cursor_x = 0;
cursor_y++;
}
scroll();
move_cursor();
}
/* Clears the screen and moves cursor to (0,0) (top left corner) */
void monitor_clear() {
uint16_t blank = (attribute << 8) | 0x20;
int i;
for (i = 0; i < 80*25; i++) {
video_memory[i] = blank;
}
cursor_x = 0; cursor_y = 0;
move_cursor();
}
/* Writes a string to the monitor */
void monitor_write(char *s) {
while (*s) {
monitor_put(*(s++));
}
}
/* Writes a number in hexadecimal notation to the monitor */
void monitor_writeHex(uint32_t v) {
int i;
monitor_put('0'); monitor_put('x');
char hexdigits[] = "0123456789abcdef";
for (i = 0; i < 8; i++) {
monitor_put(hexdigits[v >> 28]);
v = v << 4;
}
}
/* Writes a number in decimal notation to the monitor */
void monitor_writeDec(uint32_t v) {
if (v == 0) {
monitor_put('0');
return;
}
char numbers[] = "0123456789";
while (v > 0) {
int order = 1, no = 1;
while (v / order > 0) order *= 10;
order /= 10;
monitor_put(numbers[v / order]);
v = v - (v / order * order);
while (v / no > 0) no *= 10;
while (no < order) {
monitor_put('0');
no *= 10;
}
}
}
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