Printing To Screen: Difference between revisions
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Why doesn't rollback affect only the last edit? :-/
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m (Reverted edits by Bellezzasolo (talk) to last revision by Solar) |
m (Why doesn't rollback affect only the last edit? :-/) |
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Line 27:
If you have a pointer to video memory and want to write a string, here is how you might do it;
<source lang="c">
// note this example will always write to the top
// line of the screen
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}
}
</
This simply cycles through each character in the string, and copies it to the appropriate place in video memory.
Line 108:
The good news are that <tt>stdarg.h</tt> is part of a freestanding implementation, so you can #include it even from your kernel source files. Under [[GCC]], the following simple implementation uses the gcc's built-in functionality to do all the work for you:
<source lang="c">
#define va_start(v,l) __builtin_va_start(v,l)
#define va_arg(v,l) __builtin_va_arg(v,l)
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#define va_copy(d,s) __builtin_va_copy(d,s)
typedef __builtin_va_list va_list;
</
An implementation of <tt>stdarg.h</tt> and <tt>printf()</tt> is available from geezer/osd ([http://my.execpc.com/~geezer/osd/code/inc/stdarg.h stdarg.h], [http://my.execpc.com/~geezer/osd/code/inc/_printf.h _printf.h], [http://my.execpc.com/~geezer/osd/code/tinylib/stdio/doprintf.c doprintf.c]).
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