Syncboot/arch/i386/tty.c

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>

#include "kernel/tty.h"
#include "kernel/utils.h"

static const size_t TERM_WIDTH=80;
static const size_t TERM_HEIGHT=25;

static size_t terminal_row;
static size_t terminal_column;

static uint8_t current_color;
static uint16_t* term_buffer;
static uint16_t* const vga_buffer = (uint16_t*) 0xB8000;

void screen_initialize(void) {

	terminal_row = 0;
	terminal_column = 0;
	current_color = vga_color_set(LIGHT_GREY, BLACK);
	term_buffer = vga_buffer;

	for (size_t y = 0; y < TERM_HEIGHT; y++) {
		for(size_t x = 0; x < TERM_WIDTH; x++) {
			const size_t offset = y * TERM_WIDTH + x;
			term_buffer[offset] = vga_entry(' ', current_color);
		}
	}
}

void term_setcolor(enum vga_colors color) {
	current_color = color;
}

void term_putentryat (char c, uint8_t color, size_t x, size_t y) {
	const size_t offset = y * TERM_WIDTH + x;
	term_buffer[offset] = vga_entry(c, color);
}

void term_putchar(char c) {
	unsigned char uc = c;

	//Handle escaped characters, such as newline, and crtn.
	switch (uc) {
		case '\n':
			terminal_column = 0;
			terminal_row += 1;
			break;
		default:
			term_putentryat(uc, current_color, terminal_column, terminal_row);
			if (++terminal_column == TERM_WIDTH) {
				terminal_column = 0;
				if (++terminal_row == TERM_HEIGHT) {
					term_scroll(false);
					terminal_row = 0;
				}
			}
			break;
	}

}

struct csi_sequence parse_csi(const char* data, size_t size) {
	enum State { PARAMETER, INTERMEDIATE, FINAL, INVALID };
	enum State state = PARAMETER;

	struct csi_sequence sequence = {
		.parameter = NULL,
		.parameter_len = 0,
		.intermediate = NULL,
		.intermediate_len = 0,
		.final = NULL,
		.valid = false
	};

	for (size_t j = 0; j < size; j++) {
		uint8_t c = data[j];
		if (state == PARAMETER && (c >= 0x30 && c <= 0x3F)) {
			if (!sequence.parameter)
				sequence.parameter = data + j;
			sequence.parameter_len++;
		} else if (c >= 0x20 && c <= 0x2F) {
			if (!sequence.intermediate)
				sequence.intermediate = data + j;
			sequence.intermediate_len++;
			state = INTERMEDIATE;
		} else if (c >= 0x40 && c <= 0x7F) {
			sequence.final = data + j;
			sequence.valid = true;
			state = FINAL;
			break;
		} else {
			// Parameter found in intermediate byte location, or byte out of
			// range
			state = INVALID;
			break;
		}
	}
	return sequence;
}

void term_write(const char* data, size_t size) {
	for(size_t i = 0; i < size; i++) {
		//Begin handling ANSI escape codes.
		if(data[i] == 0x1b) { //The current character is ESC - the start of ANSI codes.
			//term_writes("ANSI Code encountered: ");

			bool string_terminated = false; //Flag used in some of the escape codes

			// TODO: Should only progress if we have at least 2 more bytes

			switch ((uint8_t)data[i + 1]) {
				case '[': //CSI - Control Sequence Introducer (The most common one, hence it comes first)
					{
						struct csi_sequence sequence = parse_csi(data + i + 2, size - (i + 2));
						if (sequence.valid) {
							// Send it off to our handler function to keep this part clean
							handleControlSequence(sequence);
							i += sequence.parameter_len + sequence.intermediate_len + 2; // Move past sequence
						}
					}
					break;
				//Single shifts are not handled, so just print them and exit
				case 'N': //SS2 - Single Shift Two
					term_writes("Single Shift Two\n");
					break;
				case 'O': //SS3 - Single Shift Three
					term_writes("Single Shift Three\n");
					break;

				//Control Strings
				case 'P': //DCS - Device Control String
					term_writes("Device Control String");
					string_terminated = false;
					break;
				case '\\': //ST - String Terminator 
					term_writes("String Terminator\n");
					string_terminated = true;
					break;
				case ']': //OSC - Operating System Command
					term_writes("Operating System Command\n");
					string_terminated = false;
					break;
				case 'X': //SOS - Start Of String
					term_writes("Start of String");
					string_terminated = false;
					break;
				case '^': //PM - Privacy Message
					term_writes("Privacy Message\n");
					break;
				case '_': //APC - Application Program Command
					term_writes("Application Program Command\n");
					break;
			}
		} else {
			term_putchar(data[i]);
		}
	}
}

void term_writes(const char* data) {
	term_write(data, strlen(data));
}

void puts(const char* string) {
	term_write(string, strlen(string));
	term_putchar('\n');
}

void handleControlSequence(struct csi_sequence sequence) {
	//Check for our failsafes

	if (sequence.valid) {
		int n = 0; //Default of the flag used for a few items

		// Parse parameters, we only care about a max 2 of number only parameters
		// for now
		int params[2] = {0};
		int param_count = 0;
		if (sequence.parameter_len) {
			for (size_t i = 0; i < sequence.parameter_len && param_count < 1; i++) {
				char c = sequence.parameter[i];
				if (isDigit(c)) {
					n = (n*10) + (sequence.parameter[i] - '0');
				} else if (c == ';') {
					params[param_count++] = n;
				}
			}
			params[param_count++] = n;
		}

		switch (*(sequence.final)) {
			case 'H': case 'f': // CUP - Cursor Position
				// TODO: Check to see if we have 2 paramaters
				if (params[0]) params[0]--;
				if (params[1]) params[1]--;
				set_cursor(params[0], params[1]);
				break;
			case 'A': //CUU - Cursor Up
				if (!params[0]) params[0] = 1;
				set_cursor(terminal_column, terminal_row - params[0]);
				break;
			case 'B': //CUD - Cursor Down
				if (!params[0]) params[0] = 1;
				set_cursor(terminal_column, terminal_row + params[0]);
				break;
			case 'C': //CUF - Cursor Forward
				if (!params[0]) params[0] = 1;
				set_cursor(terminal_column + params[0], terminal_row);
				break;
			case 'D': //CUB - Cursor Back
				if (!params[0]) params[0] = 1;
				set_cursor(terminal_column - params[0], terminal_row);
				break;
			case 'E': //CNL - Cursor Next Line
				if (!params[0]) params[0] = 1;
				set_cursor(0, terminal_row + params[0]);
				break;
			case 'F': //CPL - Cursor Previous Line
				if (!params[0]) params[0] = 1;
				set_cursor(0, terminal_row - params[0]);
				break;
			case 'G': //CHA - Cursor Horizontal Absolute
				if (params[0]) params[0]--;
				set_cursor(params[0], terminal_row);
				break;
			case 'J': //ED - Erase in Display
				//current cursor pos = y * width + x
				{
					int pos = terminal_row * 80 + terminal_column;
					if (params[0] == 0) { // Clear from cursor to end of screen
						for(; pos < (25 * 80); pos++) {
							vga_buffer[pos] = '\0';
						}
					} else if(params[0] == 1) { // Clear from cursor to beginning
						for(; pos > 0; pos--) {
							vga_buffer[pos] = '\0';
						}
					} else if(params[0] == 2 || params[0] == 3) { // Clear entire screen
						// TODO: Support scrollback buffer? (n = 3)
						for(int i = 0; i < (25*80); i++) {
							vga_buffer[0] = '\0';
						}
					}
				}
				break;
			case 'K': //EL - Erase in Line
				{
					int pos = terminal_row * 80 + terminal_column;
					if(params[0] == 0) { // From cursor to end of line
						int endPos = (terminal_row + 1) * 80 - 1; // End of line = current row + 25 columns = current row + 1
						for(; pos < endPos; pos++) {
							vga_buffer[pos] = '\0';
						}
					} else if (params[0] == 1) { // From cursor to start of line
						int endPos = terminal_row * 80; // Start of line = end of previous line + 1 == current line
						for(; pos > endPos; pos--) {
							vga_buffer[pos] = '\0';
						}
					} else if(params[0] == 2) { // Entire current line
						pos = terminal_row * 80;
						int endPos = (terminal_row + 1) * 80 - 1;
						for(; pos < endPos; pos++) {
							vga_buffer[pos] = '\0';
						}
					}
				}
				break;
			case 'S': //SU - Scroll Up
				term_scroll(true);
				break;
			case 'T': //SD - Scroll Down
				term_scroll(false);
				break;
		}
	}

}

bool isDigit(char c) {
	return c >= '0' && c <= '9';
}

void set_cursor(int n, int m) {
	terminal_column = n;
	terminal_row = m;
}

void term_scroll(bool down) {

	int current_pos;
	if(down) {
		current_pos = 25 * 80; //Start of the last line.
	} else {
		current_pos = 160; //Start of the second line.
	}

	unsigned char* term_buffer = (unsigned char*) vga_buffer;

	if(down) { //To scroll down, move every character into the one below it, or "pull" every character down
		while(current_pos > 80) {
			term_buffer[current_pos + 160] = vga_buffer[current_pos];
			term_buffer[current_pos + 159] = vga_buffer[current_pos - 1];
			current_pos -= 2;
		}
	} else {
		while (current_pos <= 4000) {
			term_buffer[current_pos - 160 /*The character immediately below it*/] = vga_buffer[current_pos];      //Move each character up a line
			term_buffer[current_pos - 159 /*The color of the character below*/] = vga_buffer[current_pos + 1];    //As well as its color
			current_pos += 2; //Move to next char
		}
	}
	
	if(down) {
		current_pos = 0; //Start of first line
		for(; current_pos < 80; current_pos++) {
			term_buffer[current_pos] = '\0';
			current_pos += 2;
		}
	} else {
		; //Start of the last line
		//Wipe out the bottom line
		for(current_pos = 3840; current_pos <= 3920; current_pos += 2) {
			term_buffer[current_pos] = 0;
		}
	}
	terminal_row = 24; //Start writing on the last line
	terminal_column = 0;
}