120 lines
3.3 KiB
C
120 lines
3.3 KiB
C
#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <string.h>
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#include <kernel/tty.h>
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#include "vga.h"
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#include "../../kernel/asm_helper.h" // FIXME
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static const size_t VGA_WIDTH = 80;
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static const size_t VGA_HEIGHT = 25;
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static uint16_t* const VGA_MEMORY = (uint16_t*) 0xB8000;
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static size_t terminal_row;
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static size_t terminal_column;
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static uint8_t terminal_color;
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static uint16_t* terminal_buffer;
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void terminal_initialize(void) {
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terminal_row = 0;
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terminal_column = 0;
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terminal_color = vga_entry_color(VGA_COLOR_LIGHT_GREY, VGA_COLOR_BLACK);
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terminal_buffer = VGA_MEMORY;
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for (size_t y = 0; y < VGA_HEIGHT; y++) {
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for (size_t x = 0; x < VGA_WIDTH; x++) {
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const size_t index = y * VGA_WIDTH + x;
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terminal_buffer[index] = vga_entry(' ', terminal_color);
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}
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}
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}
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void terminal_setcolor(uint8_t color) {
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terminal_color = color;
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}
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void terminal_putentryat(unsigned char c, uint8_t color, size_t x, size_t y) {
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const size_t index = y * VGA_WIDTH + x;
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terminal_buffer[index] = vga_entry(c, color);
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}
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// Updates the hardware cursor.
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static void move_cursor()
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{
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// The screen is 80 characters wide...
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uint16_t cursorLocation = terminal_row * 80 + terminal_column;
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outb(0x3D4, 14); // Tell the VGA board we are setting the high cursor byte.
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outb(0x3D5, cursorLocation >> 8); // Send the high cursor byte.
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outb(0x3D4, 15); // Tell the VGA board we are setting the low cursor byte.
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outb(0x3D5, cursorLocation); // Send the low cursor byte.
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}
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void terminal_scroll(int line) {
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// Get a space character with the default colour attributes.
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int attributeByte = (0 /*black*/ << 4) | (15 /*white*/ & 0x0F);
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uint16_t blank = 0x20 /* space */ | (attributeByte << 8);
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// Row 25 is the end, this means we need to scroll up
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if(terminal_row >= 25)
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{
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// Move the current text chunk that makes up the screen
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// back in the buffer by a line
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int i;
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for (i = 0*80; i < 24*80; i++)
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{
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terminal_buffer[i] = terminal_buffer[i+80];
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}
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// The last line should now be blank. Do this by writing
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// 80 spaces to it.
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for (i = 24*80; i < 25*80; i++)
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{
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terminal_buffer[i] = blank;
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}
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// The cursor should now be on the last line.
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terminal_row = 24;
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}
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}
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void terminal_delete_last_line() {
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int x, *ptr;
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for(x = 0; x < VGA_WIDTH * 2; x++) {
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ptr = 0xB8000 + (VGA_WIDTH * 2) * (VGA_HEIGHT - 1) + x;
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*ptr = 0;
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}
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}
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void terminal_putchar(char c) {
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unsigned char uc = c;
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terminal_putentryat(uc, terminal_color, terminal_column, terminal_row);
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if (c != '\n') {
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if (++terminal_column == VGA_WIDTH) {
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terminal_column = 0;
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if (++terminal_row == VGA_HEIGHT) {
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for(int line = 1; line <= VGA_HEIGHT - 1; line++) {
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terminal_scroll(line);
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}
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terminal_delete_last_line();
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terminal_row = VGA_HEIGHT - 1;
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}
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}
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} else {
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terminal_row += 1;
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terminal_column = 0;
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}
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terminal_scroll(terminal_row);
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move_cursor();
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}
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void terminal_write(const char* data, size_t size) {
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for (size_t i = 0; i < size; i++)
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terminal_putchar(data[i]);
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}
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void terminal_writestring(const char* data) {
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terminal_write(data, strlen(data));
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}
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