49 lines
1.1 KiB
C
49 lines
1.1 KiB
C
#include "port.h"
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#include "vga.h"
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static unsigned char get_color(unsigned char fg, unsigned char bg) {
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return (bg << 4) + fg;
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}
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static unsigned get_offset(unsigned col, unsigned row) {
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return row * COLS + col;
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}
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static unsigned get_row_from_offset(unsigned offset) {
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return offset / COLS;
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}
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unsigned vga_get_cursor() {
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port_byte_out(VGA_CTRL_REGISTER, VGA_OFFSET_HIGH);
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unsigned offset = port_byte_in(VGA_DATA_REGISTER) << 8;
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port_byte_out(VGA_CTRL_REGISTER, VGA_OFFSET_LOW);
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offset += port_byte_in(VGA_DATA_REGISTER);
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return offset;
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}
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void vga_set_char(unsigned offset, char c) {
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video_memory[2 * offset] = c;
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video_memory[2 * offset + 1] = get_color(light_gray, black);
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}
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static unsigned offset;
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void vga_clear_screen() {
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for (unsigned i = 0; i < ROWS * COLS; ++i) {
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vga_set_char(i, ' ');
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}
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}
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void vga_print_string_noscroll(const char* s) {
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while (*s != 0) {
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if (*s == '\n') {
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offset = get_offset(0, get_row_from_offset(offset) + 1);
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} else {
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vga_set_char(offset, *s);
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offset++;
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}
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offset %= COLS * ROWS;
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s++;
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}
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}
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