76 lines
1.9 KiB
C
76 lines
1.9 KiB
C
/**
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* @file vga.c
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* @brief Basic functions for interacting with the CRTC controller in VGA text-mode.
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* @author rami
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* @version 0.1
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* @date 2024-02-03
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*/
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#include <vga.h>
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#include <io.h>
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#include <printf.h>
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enum VGA_COLOR vga_color = VGA_COLOR_WHITE;
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uint16_t get_cursor_pos() {
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uint16_t pos = 0;
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/* Tell CRTC controller we want the low cursor position */
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outportb(CRTC_ADDR_PORT, CRTC_CURSOR_LO_REGISTER);
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/* Read it through the data port */
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pos = inportb(CRTC_DATA_PORT);
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/* Repeat with high position */
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outportb(CRTC_ADDR_PORT, CRTC_CURSOR_HI_REGISTER);
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uint16_t hi_pos = 0;
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hi_pos = inportb(CRTC_DATA_PORT);
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pos |= hi_pos << 8;
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return pos;
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}
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void set_cursor_pos(uint16_t pos) {
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/* Tell CRTC controller we want the low cursor position */
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outportb(CRTC_ADDR_PORT, CRTC_CURSOR_LO_REGISTER);
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outportb(CRTC_DATA_PORT, (uint8_t)(pos & 0xFF));
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/* Repeat with high position */
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outportb(CRTC_ADDR_PORT, CRTC_CURSOR_HI_REGISTER);
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outportb(CRTC_DATA_PORT, (uint8_t)((pos >> 8) & 0xFF));
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}
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void clear_screen(void) {
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char *video_memory = (char *)VGA_MEMORY_ADDR;
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for (int i = 0; i < VGA_MAX_COLS * VGA_MAX_ROWS; i++) {
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video_memory[i * 2] = 0;
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}
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set_cursor_pos(0);
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}
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/* Implementation of _putchar. Function is defined in print.h */
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void _putchar(char character) {
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uint16_t pos = get_cursor_pos();
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char *video_memory = (char *)VGA_MEMORY_ADDR + pos * 2;
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if (character == '\n') {
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uint16_t next_line = VGA_MAX_COLS * (pos / VGA_MAX_COLS + 1);
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set_cursor_pos(next_line);
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} else {
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video_memory[0] = character;
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video_memory[1] = vga_color;
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set_cursor_pos(pos + 1);
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}
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}
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void popchar() {
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uint16_t pos = get_cursor_pos();
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if (pos == 0) return;
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char *video_memory = (char *)(VGA_MEMORY_ADDR + (pos - 1) * 2);
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video_memory[0] = 0;
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set_cursor_pos(pos - 1);
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}
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void set_color(enum VGA_COLOR col) {
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vga_color = col;
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}
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