139 lines
3.9 KiB
C
139 lines
3.9 KiB
C
//
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// Created by rick on 8/18/19.
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//
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#include <string.h>
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#include <myke/drivers/vgascreen.h>
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#include <myke/drivers/ports.h>
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char *_vga_character_memory = (char *) VGA_CHARACTER_MEMORY_LOCATION;
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int get_offset(int col, int row);
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int get_cursor_offset();
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void set_cursor_offset(int offset);
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int get_offset_row(int offset);
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int get_offset_col(int offset);
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int print_char(char character, int col, int row, char attributes);
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void vga_clear_screen() {
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int size = VGA_COL_MAX * VGA_ROW_MAX;
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for (int i = 0; i < size; ++i) {
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_vga_character_memory[i * 2] = ' ';
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_vga_character_memory[i * 2 + 1] = VGA_WHITE | (VGA_BLACK << VGA_SHIFT_BG);
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}
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set_cursor_offset(0);
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}
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void kprint_at(const char *message, int col, int row) {
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int offset;
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if (col > 0 && row > 0) {
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offset = get_offset(col, row);
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} else {
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offset = get_cursor_offset();
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row = get_offset_row(offset);
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col = get_offset_col(offset);
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}
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int i = 0;
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while (message[i] != 0) {
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offset = print_char(message[i++], col, row, VGA_WHITE | (VGA_BLACK << VGA_SHIFT_BG));
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row = get_offset_row(offset);
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col = get_offset_col(offset);
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}
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}
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void vga_kprint(const char *message) {
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kprint_at(message, -1, -1);
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}
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int print_char(char character, int col, int row, char attributes) {
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if (!attributes) attributes = VGA_WHITE | (VGA_BLACK < VGA_SHIFT_BG);
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if (col >= VGA_COL_MAX || row > +VGA_ROW_MAX) {
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_vga_character_memory[2 * (VGA_COL_MAX) * (VGA_ROW_MAX) - 2] = 'E';
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_vga_character_memory[2 * (VGA_COL_MAX) * (VGA_ROW_MAX) - 1] = VGA_RED | (VGA_WHITE < VGA_SHIFT_BG);
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return get_offset(col, row);
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}
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int offset;
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if (col >= 0 && row >= 0) {
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offset = get_offset(col, row);
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} else {
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offset = get_cursor_offset();
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}
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switch (character) {
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case '\n':
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row = get_offset_row(offset);
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offset = get_offset(0, row + 1);
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break;
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case '\t':
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col = (col + 4) & (~0b11);
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if (col > VGA_COL_MAX) {
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row = get_offset_row(offset);
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offset = get_offset(0, row + 1);
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} else {
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offset = get_offset(col, row);
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}
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break;
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case '\r':
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row = get_offset_row(offset);
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offset = get_offset(0, row);
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break;
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default:
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_vga_character_memory[offset] = character;
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_vga_character_memory[offset + 1] = attributes;
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offset += 2;
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break;
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}
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if (offset >= (VGA_COL_MAX * 2 * VGA_ROW_MAX)) {
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memcpy(_vga_character_memory,
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_vga_character_memory + (VGA_COL_MAX * 2),
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(2 * VGA_COL_MAX * VGA_ROW_MAX) - (2 * VGA_COL_MAX));
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for (int i = 0; i < VGA_COL_MAX; ++i) {
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_vga_character_memory[get_offset(i, VGA_ROW_MAX - 1)] = ' ';
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}
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offset = get_offset(0, VGA_ROW_MAX - 1);
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}
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set_cursor_offset(offset);
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return offset;
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}
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int get_cursor_offset() {
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port_byte_out(PORT_REG_SCREEN_CTRL, PORT_REG_SCREEN_CTRL_CURSOR_H);
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int offset = ((int) port_byte_in(PORT_REG_SCREEN_DATA)) << 8;
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port_byte_out(PORT_REG_SCREEN_CTRL, PORT_REG_SCREEN_CTRL_CURSOR_L);
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offset += port_byte_in(PORT_REG_SCREEN_DATA);
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return offset * 2;
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}
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void set_cursor_offset(int offset) {
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offset /= 2;
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port_byte_out(PORT_REG_SCREEN_CTRL, PORT_REG_SCREEN_CTRL_CURSOR_L);
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port_byte_out(PORT_REG_SCREEN_DATA, (unsigned char) (offset & 0xFF));
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port_byte_out(PORT_REG_SCREEN_CTRL, PORT_REG_SCREEN_CTRL_CURSOR_H);
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port_byte_out(PORT_REG_SCREEN_DATA, (unsigned char) (offset >> 8) & 0xFF);
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}
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int get_offset(int col, int row) {
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return (row * VGA_COL_MAX + col) * 2;
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}
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int get_offset_row(int offset) {
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return offset / (VGA_COL_MAX * 2);
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}
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int get_offset_col(int offset) {
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return (offset - (get_offset_row(offset) * 2 * VGA_COL_MAX)) / 2;
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}
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