120 lines
2.5 KiB
C
120 lines
2.5 KiB
C
#include "vga.h"
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#include "stddef.h"
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#define ROWS 25
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#define COLUMNS 80
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typedef struct
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{
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uint8_t character;
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uint8_t color;
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} vga_char_t;
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static vga_char_t* vga_buffer = (vga_char_t*)0xb8000;
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static uint8_t cursor_row = 0;
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static uint8_t cursor_col = 0;
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void vga_put_char(char character, uint8_t color)
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{
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switch (character)
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{
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case '\n':
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{
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cursor_row += 1;
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cursor_col = 0;
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break;
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}
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case '\r':
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{
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cursor_col = 0;
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break;
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}
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case '\t':
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{
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uint8_t remainder = 4 - (cursor_col % 4);
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cursor_col += remainder;
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break;
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}
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case '\b':
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{
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if (cursor_col > 0)
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{
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cursor_col -= 1;
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}
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else if (cursor_row > 0)
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{
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cursor_row -= 1;
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cursor_col = 0;
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for (int col = COLUMNS - 1; col >= 0; col--)
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{
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vga_char_t cell = vga_buffer[cursor_row * COLUMNS + col];
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if (cell.character != ' ')
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{
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cursor_col = col;
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break;
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}
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}
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}
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vga_buffer[cursor_row * COLUMNS + cursor_col] = (vga_char_t){
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.character = ' ',
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.color = VGA_DEFAULT_COLOR,
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};
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break;
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}
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default:
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{
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vga_buffer[COLUMNS * cursor_row + cursor_col] = (vga_char_t){
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.character = character,
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.color = color,
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};
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cursor_col += 1;
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break;
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}
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}
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if (cursor_col >= COLUMNS)
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{
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cursor_col = 0;
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cursor_row += 1;
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}
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if (cursor_row >= ROWS)
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{
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for (size_t row = 1; row < ROWS; row++)
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{
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for (size_t col = 0; col < COLUMNS; col++)
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{
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vga_buffer[COLUMNS * (row - 1) + col] = vga_buffer[COLUMNS * row + col];
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}
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}
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for (size_t col = 0; col < COLUMNS; col++)
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{
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vga_buffer[COLUMNS * (ROWS - 1) + col] = (vga_char_t){
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.character = ' ',
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.color = VGA_DEFAULT_COLOR,
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};
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};
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cursor_row = ROWS - 1;
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}
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}
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void vga_clear()
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{
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for (size_t row = 0; row < ROWS; row++)
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{
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for (size_t col = 0; col < COLUMNS; col++)
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{
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vga_buffer[COLUMNS * row + col] = (vga_char_t){
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.character = ' ',
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.color = VGA_DEFAULT_COLOR,
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};
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}
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}
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cursor_row = 0;
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cursor_col = 0;
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} |