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comparison cos/kernel/video.c @ 9:92ace1ca50a8

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64 bits kernel without interrupts but with printf in C
author windel
date Sun, 13 Nov 2011 12:47:47 +0100
parents
children 6129643f5c34
comparison
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8:edd70006d3e4 9:92ace1ca50a8
1 #include "kernel.h"
2
3 #define VIDMEM 0xB8000
4
5 #define NUM_COLS 80
6 #define NUM_ROWS 25
7 #define SCREEN_SIZE (NUM_COLS * NUM_ROWS)
8
9 #define SCREEN_ATTR 0x0F
10
11 static int row, col;
12
13 void
14 clear_screen()
15 {
16 unsigned char *vidmem = (unsigned char *) VIDMEM;
17 int loop;
18
19 for (loop = 0; loop < SCREEN_SIZE; loop++) {
20 *vidmem++ = 0x20;
21 *vidmem++ = SCREEN_ATTR;
22 }
23 }
24
25 void
26 init_screen()
27 {
28 row = col = 0;
29 clear_screen();
30 }
31
32
33 static void
34 scroll_screen()
35 {
36 unsigned short* v;
37 int i;
38 int n = SCREEN_SIZE;
39
40 for (v = (unsigned short*) VIDMEM, i = 0; i < n; i++ ) {
41 *v = *(v + NUM_COLS);
42 ++v;
43 }
44
45 for (v = (unsigned short*) VIDMEM + n, i = 0; i < NUM_COLS; i++) {
46 *v++ = SCREEN_ATTR & (0x20 << 8);
47 }
48 }
49
50 static void
51 new_line()
52 {
53 ++row;
54 col = 0;
55 if (row == NUM_ROWS) {
56 scroll_screen();
57 row = NUM_ROWS - 1;
58 }
59 }
60
61 static void
62 clear_to_EOL()
63 {
64 int loop;
65 unsigned char *v = (unsigned char *) ((uint64_t)(VIDMEM + row * NUM_COLS * 2 + col * 2));
66
67 for (loop = col; loop < NUM_COLS; loop++) {
68 *v++ = ' ';
69 *v++ = SCREEN_ATTR;
70 }
71 }
72
73 static void
74 print_char(int c)
75 {
76 unsigned char *v = (unsigned char *) ((uint64_t)(VIDMEM + row * NUM_COLS * 2 + col * 2));
77
78 switch(c) {
79 case '\n':
80 clear_to_EOL();
81 new_line();
82 break;
83 default:
84 *v++ = (unsigned char) c;
85 *v = SCREEN_ATTR;
86
87 if (col < NUM_COLS - 1)
88 ++col;
89 else
90 new_line();
91 }
92 }
93
94 void
95 print_string(const char *s)
96 {
97 while (*s != '\0') {
98 print_char(*s++);
99 }
100 }
101