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some thing about printing string
Posted: Thu Jan 12, 2012 7:57 pm
by sebastian93921
I'm the beginner or OSdev
but i having a problem in kernel in C language.
Code: Select all
int k_main(void)
{
kclrscr();
kprint("Protected Mode process ...\n");
kprint("First prototype - Sebastian Ko \n\nDate: 12/01/2012\n");
kprintc("\nNO \\t or value type \n",GRAY_TXT);
kprint("Register checking ... ");
if(reg() == 0)kprintc("OK\n",GRAY_TXT);
else kprintc("Fail\n",GRAY_TXT);
return 0;
}
while my kernel is type as above, it will show this output
but while i add the same code with copying kprint("First prototype - Sebastian Ko \n\nDate: 12/01/2012\n"); twice next to the same sentence.
the output will becomes this
Can any people help me ??
the Method of kprint and kprintc
Code: Select all
unsigned int line = 0; //Line in screen (Text)
unsigned int text_pos = 0; //Text position
//Easiest print method
void kprint(char *message){kprintc(message,0x0B);};
void kprintc(char *message,double text_color) //Print with change default color
{
char *vidmem = (char *) 0xb8000; //define video memory
unsigned int i = 0; //define memory position
i=((line*80*2)+(text_pos*2)); //Memory MUST be line * colume * TxtSpace (160 Means Over Screen of line,line++)
while(*message!=0)
{
if(line > CONSOLE_MAX_LINE)line = 0;
//\n \r \t is 1 char
if(*message == '\n') //Check for a new line
{
text_pos = 0; //reset text position
line++;
i=(line*80*2);
*message++;
}else if(*message == '\r'){ //Return to head from line
text_pos = 0; //reset text position
i = (line*80*2);
*message++;
}else{ //print Message (Char)
vidmem[i]=*message;
*message++;
i++;
vidmem[i]=text_color;
i++;
text_pos++;
}
}
};
Re: some thing about printing string
Posted: Fri Jan 13, 2012 7:23 am
by bluemoon
Re: some thing about printing string
Posted: Fri Jan 13, 2012 7:46 am
by bluemoon
Yes it works and harmless, but for one engaging OSDev one should not mix up message++ with *message++. For the size of kernel codebase, this habit may lead to unmaintainable code.
Re: some thing about printing string
Posted: Fri Jan 13, 2012 1:02 pm
by sebastian93921
THX for reply
i fix the *message++ with no pointer on it now
it works!!
and double color I changed to "unsigned int color"
would it be correct?
and why I use message++ but don't use *(message++) since message is a array ??
THX
Re: some thing about printing string
Posted: Fri Jan 13, 2012 1:23 pm
by bluemoon
I kindly advice to read the C++ reference for the difference between message++ and *message++.
Re: some thing about printing string
Posted: Sat Jan 14, 2012 11:40 am
by sebastian93921
berkus wrote:sebastian93921 wrote:and why I use message++ but don't use *(message++) since message is a array ??
message is not an array. It's a pointer. And since you need to learn up what a pointer is, I call for missing Required_Knowledge. It would be beneficial for you to program some applications in C first. You're bound to fail with kernel development.
i know this is a pointer, but the pointer can use message++, such as the message[i++]
now i have the problem with changed the code of kprint() with your advice.
but when i executing the kernel by these code.
Code: Select all
int k_main(void)
{
kclrscr();
kprint("Anti-Web OS - Protected Mode process ...\n");
kprint("First prototype - Sebastian Ko \n");
kprint("First prototype - Sebastian Ko \n");
kprint("First prototype - Sebastian Ko \n");
kprint("First prototype - Sebastian Ko \n");
kprint("First prototype - Sebastian Ko \n");
kprint("First prototype - Sebastian Ko \n");
kprint("\nDate : ");kprint(COM_DATE);kprint("\n");
kprintc("\nNO \\t or value type \n",GRAY_TXT);
kprint("Register checking ... ");
if(reg() == 0)kprintc("OK\n",GRAY_TXT);
else kprintc("Fail\n",GRAY_TXT);
//for(;;)kgetChar();
}
it will having the same problem, like this
is it the problem of the stack pointer of ESP?
how can it fix?
THX
Re: some thing about printing string
Posted: Sat Jan 14, 2012 1:41 pm
by VolTeK
I have never used qemu, but i believe it has a debugger.
Problems like those can be solved by you debugging. In fact it will solve ther other 40% (or more) problems you will have in future. Look into it
Re: some thing about printing string
Posted: Sat Jan 14, 2012 4:13 pm
by gravaera
Man, these printf things are so hard to get right. Printf too ADVANCED D:
EDIT: I have a solution, we should dumb things down a bit, like make a multiple-choice version of printf where you choose from a set of predefined messages and distribute it as a library.
Re: some thing about printing string
Posted: Sun Jan 15, 2012 10:46 am
by sebastian93921
gravaera wrote:Man, these printf things are so hard to get right. Printf too ADVANCED D:
EDIT: I have a solution, we should dumb things down a bit, like make a multiple-choice version of printf where you choose from a set of predefined messages and distribute it as a library.
Can you explain more ??
THX
Re: some thing about printing string
Posted: Mon Jan 16, 2012 12:13 am
by sebastian93921
i know the problems now, when i set the floppy drive(load disk?) in bootloader, i just set 2 of sector need to be read in disk
Re: some thing about printing string
Posted: Mon Jan 16, 2012 1:52 am
by VolTeK
Did you write your bootloader.