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MTK358
Joined: Tue Apr 20, 2010 9:08 am
Posts: 20
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 Text output does not work Somehow I can't get text output to work right.
I made functions that print a character set the color, set the position, but I just can't get printing strings and scrolling to work.
The OS is booted using GRUB, so it's in 32-bit Protected Mode.
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| Mon Apr 26, 2010 12:39 pm |
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smeezekitty
Joined: Tue Apr 20, 2010 1:39 pm
Posts: 17
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Re: Text output does not work Show code.
You are writing to B800:0000, right?
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| Mon Apr 26, 2010 5:07 pm |
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MTK358
Joined: Tue Apr 20, 2010 9:08 am
Posts: 20
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Re: Text output does not work The scroll() function simply does not work, and when I position it to near the end of the screen and print a few characters it prints the first few characters in two places on the screen and does not scroll. kernel.cCode: #include "vga.h"
void kernel_main( void* mbd, unsigned int magic )
{
if ( magic != 0x2BADB002 ) { // if the bootloader is not Multiboot-compatible
}
// char* boot_loader_name = (char*) ((long*) mbd)[16];
set_color(COLOR_LTAQUA | (COLOR_AQUA << 4));
set_cur(78, 24);
put_character('H');
put_character('e');
put_character('l');
put_character('l');
put_character('o');
}
Code: #include "vga.h"
int curx=0, cury=0;
unsigned char curc = COLOR_GRAY | (COLOR_BLACK << 4);
unsigned short* videoram = (unsigned short*) 0xB8000;
#define videoram_get(x, y) videoram[x + (y * COLS)]
void scroll() {
int x, y;
for(y=1; y<LINES; y++) {
for(x=0; x<COLS; x++) {
videoram_get(x, y-1) = videoram_get(x, y);
}
}
}
void set_color(unsigned char color) {
curc = color;
}
void set_cur(int x, int y) {
curx = x;
cury = y;
}
void put_character(char c) {
if(c == '\n') {
curx = 0;
cury++;
} else {
videoram_get(curx, cury) = c | (curc << 8);
if(++curx == COLS) {
curx = 0;
if(cury+1 == LINES) scroll(); else cury++;
}
}
}
void clear_screen() {
int i;
for(i=0; i<LINES*COLS; i++) {
videoram[i] = ' ' | (curc << 8);
}
} The (improper) output is attached.
Attachments:
hello.jpg [ 37.41 KiB | Viewed 144014 times ]
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| Mon Apr 26, 2010 7:56 pm |
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smeezekitty
Joined: Tue Apr 20, 2010 1:39 pm
Posts: 17
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Re: Text output does not work Code:
void put_character(char c) {
if(c == '\n') {
curx = 0;
cury++;
if(cury+1 == LINES || cury == LINES){scroll();}
} else {
videoram_get(curx, cury) = c | (curc << 8);
if(++curx == COLS) {
curx = 0;
if(cury+1 == LINES || cury == LINES) scroll(); else cury++;
}
}
}
Try that.
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| Mon Apr 26, 2010 9:45 pm |
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MTK358
Joined: Tue Apr 20, 2010 9:08 am
Posts: 20
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Re: Text output does not work smeezekitty wrote: Code:
void put_character(char c) {
if(c == '\n') {
curx = 0;
cury++;
if(cury+1 == LINES || cury == LINES){scroll();}
} else {
videoram_get(curx, cury) = c | (curc << 8);
if(++curx == COLS) {
curx = 0;
if(cury+1 == LINES || cury == LINES) scroll(); else cury++;
}
}
}
Try that. What's the purpose of checking if cury AND cury+1 equals LINES? Why not >=, which will be simpler and more efficient?
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| Tue Apr 27, 2010 5:26 am |
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Kieran
Site Admin
Joined: Sat Jul 25, 2009 7:44 am
Posts: 274
Location: United Kingdom
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Re: Text output does not work Id go with >= too 
_________________
Thank you for reading,
Kieran C G Foot
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| Tue Apr 27, 2010 5:41 am |
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MTK358
Joined: Tue Apr 20, 2010 9:08 am
Posts: 20
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Re: Text output does not work Code: void scroll() {
int x, y;
for(y=1; y<LINES; y++) {
for(x=0; x<COLS; x++) {
videoram_get(x, y-1) = videoram_get(x, y);
}
}
cury--;
}
void put_character(char c) {
if (c == '\n') {
curx = 0;
if (++cury == LINES) scroll();
} else {
videoram_get(curx, cury) = c | (curc << 8);
if (++curx == COLS) {
curx = 0;
if (++cury == LINES) scroll();
}
}
} Newer version, but still the same result.
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| Tue Apr 27, 2010 5:52 am |
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MTK358
Joined: Tue Apr 20, 2010 9:08 am
Posts: 20
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Re: Text output does not work Anyone?
I would like to search it, but I just don't know what. I tried things like "vga characher output" and stuff but 99.9% of the results are completely irrelavent.
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| Tue Apr 27, 2010 7:23 pm |
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Sharpner
Joined: Wed Feb 10, 2010 6:32 am
Posts: 26
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Re: Text output does not work Code: int8u attrib = 0x0F;
void scroll(){
int32u blank = ' ' | (attrib << 8);
if(csr_y >= 25){
int16u i;
for (i = 0; i < 24*80; i++){
vga_ptr[i] = vga_ptr[i+80];
}
for (i = 24*80; i < 25*80; i++){
vga_ptr[i] = blank;
}
csr_y = 24;
}
move_csr();
} I did it like that, maybe it helps you. bye Sharpner
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| Thu Apr 29, 2010 3:38 am |
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