omos-tcnj2024/sys/video.c

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#include <types.h>
#include <video.h>
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void
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vga_write(s8 *sequence, s16 size, s8 flags)
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{
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if (size > VGA_TEXT_SIZE) {
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s16 using_size = size - VGA_TEXT_SIZE;
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for (s16 i = 0; i <= VGA_TEXT_SIZE; i++) {
vga_vidmem[i * 2] = sequence[using_size + i];
vga_vidmem[i * 2 + 1] = flags;
}
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unused = VGA_SIZE;
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return;
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}
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if (size * 2 + unused > VGA_SIZE) {
s16 needed_space = size * 2;
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for (s16 i = 0; i <= (unused = VGA_SIZE - needed_space); i++) {
vga_vidmem[i] = vga_vidmem[needed_space + i];
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}
}
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for (s16 i = 0; i < size; i++) {
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vga_vidmem[unused++] = sequence[i];
vga_vidmem[unused++] = flags;
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}
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}
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void
vga_clearscreen(void)
{
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unused = 0;
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for (s16 i = 0; i <= VGA_SIZE; i++) {
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vga_vidmem[i] = 0;
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}
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}