1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
|
/* needs to stay the first line */
asm(".code16gcc\njmp $0, $main");
/* space for additional code */
char WRITE_CHARACTER_TTY = 0x0E;
// Syscall found here http://www.ctyme.com/intr/rb-0106.htm
void putc(char c) {
short command = WRITE_CHARACTER_TTY << 8 | c;
// volatile because there is no output, so the function might get optimized
// away
// clang-format off
asm volatile(
"int $0x10;"
::"a"(command)
);
// clang-format on
}
void print(char const *const str) {
for (int i = 0; str[i] != '\0'; ++i) {
putc(str[i]);
}
}
// Syscall found here http://www.ctyme.com/intr/rb-1754.htm
char getc() {
char ret;
asm volatile(
".no_key:"
"xor %%ax, %%ax;"
"mov $0x0100, %%ax;" // check for keystroke:
"int $0x16;" // http://www.ctyme.com/intr/rb-1755.htm
"jz .no_key;" // wait for a key
".done:"
"xor %%ax, %%ax;"
"mov $0x1000, %%ax;" // get keystroke: http://www.ctyme.com/intr/rb-1754.htm
"int $0x16;"
"mov %%al, %%bl;" // temp store char in bl
"mov $0400, %%ax;" // clear keyboard buffer:
"int $0x16;" // http://www.ctyme.com/intr/rb-1759.htm
: "=b"(ret)
:
: "ax");
return ret;
}
void sleep(short ms) {
long ys = ms * 1000;
short cx = ys >> 16;
short dx = ys;
// http://www.ctyme.com/intr/rb-1525.htm : Int 15/AH=86h bios wait
char ah = 0x86;
char al = 0x00;
short command = ah << 8 | al;
asm volatile("int $0x15;" : : "a"(command), "cx"(cx), "dx"(dx));
}
void main(void) {
print("Hello!\n\r");
while (1) {
char buf[9];
for (unsigned char i = 0; i < 8; i++) {
char c = getc();
if (c == '\r') {
if (i == 0) { // empty entry
print("Reboot!");
/*asm volatile(
"mov $0x5307, %%ax;" // TURN OFF SYSTEM:
// http://www.ctyme.com/intr/rb-1356.htm
"mov $0x0001, %%bx;"
"mov $0x0003, %%cx;"
"int $0x15" ::
: "ax", "bx", "cx");*/
asm volatile("xor %%eax, %%eax\n"
"push %%eax\n"
"push %%ax\n"
"lidt (%%esp)\n"
"mov %%ss, %%eax" ::
: "eax");
return;
} else {
break;
}
}
buf[i] = c;
putc('*');
}
buf[8] = '\0';
while (1) {
if (getc() == '\r')
break;
}
print("\n\r");
print(buf);
print("\n\r");
}
}
|