cleans up the arch folder some

kernel/arch/io/tty.c

@@ -0,0 +1,131 @@
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <kernel/tty.h>
+
+#include "vga.h"
+#include "io.h"
+
+/* I/O ports */
+#define VGA_COMMAND_PORT 0x3D4
+#define VGA_DATA_PORT 0x3D5
+
+/* I/O port commands */
+#define VGA_HIGH_BYTE_COMMAND 14
+#define VGA_LOW_BYTE_COMMAND 15
+
+static const size_t VGA_WIDTH = 80;
+static const size_t VGA_HEIGHT = 25;
+static uint16_t* const VGA_MEMORY = (uint16_t*) 0xB8000;
+
+static size_t terminal_row;
+static size_t terminal_column;
+static uint8_t terminal_colour;
+static struct vga_entry* terminal_buffer;
+
+struct vga_entry {
+	char c;
+	unsigned char colour;
+} __attribute__((packed));
+
+void terminal_set_colour(uint8_t colour)
+{
+	terminal_colour = colour;
+}
+
+void terminal_clear(void)
+{
+	for (size_t y = 0; y < VGA_HEIGHT; y++)
+		for (size_t x = 0; x < VGA_WIDTH; x++)
+			terminal_write_cell((y * VGA_WIDTH) + x, ' ');
+	terminal_move_cursor(0);
+}
+
+void terminal_initialize(void)
+{
+	terminal_row = 0;
+	terminal_column = 0;
+
+	terminal_buffer = (struct vga_entry*) VGA_MEMORY;
+	terminal_set_colour(vga_entry_colour(VGA_COLOUR_LIGHT_GREY, VGA_COLOUR_BLACK));
+
+	terminal_clear();
+}
+
+void terminal_move_cursor(unsigned short pos)
+{
+	if (terminal_row >= VGA_HEIGHT)
+		terminal_scroll_screen();
+
+	outb(VGA_COMMAND_PORT, VGA_HIGH_BYTE_COMMAND);
+	outb(VGA_DATA_PORT, ((pos >> 8) & 0x00FF));
+	outb(VGA_COMMAND_PORT, VGA_LOW_BYTE_COMMAND);
+	outb(VGA_DATA_PORT, pos & 0x00FF);
+}
+
+inline size_t terminal_get_pos(void)
+	{return (terminal_row * VGA_WIDTH) + terminal_column;}
+
+void terminal_write_cell(unsigned int i, char c)
+{
+	struct vga_entry entry;
+
+	entry.c = c;
+	entry.colour = terminal_colour;
+
+	terminal_buffer[i] = entry;
+}
+
+void terminal_write_character(unsigned int i, char c)
+{
+	switch(c) {
+		case '\n':
+			terminal_row += 1;
+			__attribute__((fallthrough));
+		case '\r':
+			terminal_column = 0;
+			terminal_move_cursor(terminal_get_pos());
+			break;
+		default:
+			terminal_write_cell(i, c);
+
+			terminal_column += 1;
+			if (terminal_column >= VGA_WIDTH) {
+				terminal_column = 0;
+				terminal_row += 1;
+			}
+
+			terminal_move_cursor(terminal_get_pos());
+	}
+}
+
+void terminal_write(const char* buf, size_t len)
+{
+	for (size_t i = 0; i < len; i++)
+		terminal_write_character(terminal_get_pos(), buf[i]);
+}
+
+void terminal_writestring(const char* buf)
+{
+	terminal_write(buf, strlen(buf));
+}
+
+void terminal_scroll_screen(void)
+{
+	size_t y, x;
+	for (y = 0; y < VGA_HEIGHT -1; y++) {
+		for (x = 0; x < VGA_WIDTH; x++) {
+			terminal_buffer[(y * VGA_WIDTH) + x] =
+				terminal_buffer[((y + 1) * VGA_WIDTH) + x];
+		}
+	}
+	for (x = 0; x < VGA_WIDTH; x++)
+		terminal_write_cell(((VGA_HEIGHT - 1) * VGA_WIDTH) + x, ' ');
+
+	terminal_row -= 1;
+	terminal_column = 0;
+	terminal_move_cursor(terminal_get_pos());
+}
+