blob: f30e68889572b3013c066ccd6a7a2474a0ecc0f1 (
plain)
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
|
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Simple CGA screen output
package runtime
import "unsafe"
var crt *[25 * 80]uint16
var pos int
func putc(c int) {
const (
port = 0x3d4
color = 0x0700 // white on black
)
if crt == nil {
// init on demand in case printf is called before
// initialization runs.
var mem uintptr = 0xb8000
crt = (*[25 * 80]uint16)(unsafe.Pointer(mem))
pos = 0
for i := range crt[0:] {
crt[i] = 0
}
}
switch c {
case '\n':
pos += 80 - pos%80
default:
crt[pos] = uint16(c&0xff | color)
pos++
}
if pos/80 >= 24 {
copy(crt[0:], crt[80:])
pos -= 80
for i := 0; i < 80; i++ {
crt[24*80+i] = 0
}
}
crt[pos] = ' ' | color
}
func write(fd int32, b []byte) {
for _, c := range b {
putc(int(c))
}
}
|
