initial work

.gitignore

@@ -0,0 +1,3 @@
+build
+*.o
+.git

src/Makefile

@@ -0,0 +1,17 @@
+TARGET=editor
+CC=gcc
+
+OBJ = main.o draw.o term.o 
+
+$(TARGET): $(OBJ)
+	mkdir -p ../build
+	$(CC) -o $(TARGET) $(OBJ) -g
+	mv $(TARGET) ../build/
+
+main.o: term.h draw.h
+term.o: term.h draw.h
+draw.o: term.h draw.h
+
+.PHONY: clean
+clean:
+	rm -rf ../build $(OBJ)

src/draw.c

@@ -0,0 +1,25 @@
+#include <unistd.h>
+
+#include "draw.h"
+#include "term.h"
+
+/** BEGIN extern section **/
+
+extern editor_t editor;
+extern screen_buffer_t screen_buffer;
+
+/** END extern section **/
+
+void refresh_screen(void)
+{
+	draw_editor_rows();
+
+	write(STDOUT_FILENO, screen_buffer.text, screen_buffer.len);			
+}
+
+void draw_editor_rows(void)
+{
+	size_t i;
+	for (i = 0; i < editor.rows - 1; i++)
+		screen_buffer_append(&screen_buffer, "~\r\n", 3);
+}

src/draw.h

@@ -0,0 +1,8 @@
+#ifndef DRAW_H
+#define DRAW_H
+
+void refresh_screen(void);
+
+void draw_editor_rows(void);
+
+#endif

src/main.c

@@ -0,0 +1,27 @@
+#include <unistd.h>
+
+#include "draw.h"
+#include "term.h"
+
+editor_t editor;
+screen_buffer_t screen_buffer;
+
+int main(void)
+{
+	char c;
+
+	setup_terminal();
+
+	refresh_screen(); // want to draw first since we're going to be waiting on the read
+
+	while (1) {
+		read(STDIN_FILENO, &c, 1);
+		if (c == '\004')
+			break;
+		refresh_screen();
+	}
+
+	kill_application();
+
+	return EXIT_SUCCESS;
+}

src/term.c

@@ -0,0 +1,143 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <termios.h>
+#include <unistd.h>
+
+
+#include "term.h"
+
+/** BEGIN extern section **/
+
+extern editor_t editor;
+extern screen_buffer_t screen_buffer;
+
+/** END extern section **/
+
+void reset_input_mode(void)
+{
+	int err;
+	/**
+	 * STDIN_FILENO - the file descriptor for STDIN, provuded by unistd
+	 * TCSANOW - means to enact the change NOW, provided by termios
+	 */
+	err = tcsetattr(STDIN_FILENO, TCSANOW, &(editor.term_settings));
+	if (-1 == err) {
+		fprintf(stderr, "tcsetattr failed.\n");
+		exit(EXIT_FAILURE);
+	}
+}
+
+void save_input_mode(void)
+{
+	int err;
+
+	err = tcgetattr(STDIN_FILENO, &(editor.term_settings));
+	if (-1 == err) {
+		fprintf(stderr, "tcgetattr failed.\n");
+		exit(EXIT_FAILURE);
+	}
+	atexit(kill_application);
+}
+
+void set_input_mode(void)
+{
+	struct termios tattr;
+	int err;
+
+	// make sure we're actually in a terminal
+	if (!isatty(STDIN_FILENO)) {
+		fprintf(stderr, "Not a terminal.\n");
+		exit(EXIT_FAILURE);
+	}
+
+	// need to save the terminal settings so that
+	// we can restore them on kill
+	save_input_mode();
+
+	err = tcgetattr(STDIN_FILENO, &tattr);
+	if (-1 == err) {
+		fprintf(stderr, "tcgetattr failed.\n");
+		exit(EXIT_FAILURE);
+	}
+	tattr.c_lflag &= ~(ICANON|ECHO); // clears icanon and echo flags
+	
+	/**
+	 * This is the minimum number of bytes in the input
+	 * queue in order for read to return.
+	 * We need this as one because it will be constantly looking for one char input.
+	 *
+	 * Zero would be consistently reading null,
+	 * any higher would bel ooking for a specific amount
+	 * of characters each time it tries to read.
+	 */
+	tattr.c_cc[VMIN] = 1;
+
+	/**
+	 * This is specifying how long we want to wait for input
+	 * before returning.
+	 * We want this to be set to zero so that
+	 * we are constantly reading.
+	 */
+	tattr.c_cc[VTIME] = 0;
+
+	/**
+	 * TCSAFLUSH waits for all of the output in the buffer
+	 * to be outputted before we discard all of the settings
+	 * and reset the terminal mode
+	 */
+	err = tcsetattr(STDIN_FILENO, TCSAFLUSH, &tattr);
+	if (-1 == err) {
+		fprintf(stderr, "tcsetattr failed.\n");
+		exit(EXIT_FAILURE);
+	}
+}
+
+void setup_terminal(void)
+{
+	struct winsize win;
+	int err;
+
+	set_input_mode();
+
+	err = ioctl(STDOUT_FILENO, TIOCGWINSZ, &win);
+	if (-1 == err) {
+		fprintf(stderr, "ioctl w/ TIOCGWINSZ failed to fetch screen size.\n");
+		exit(EXIT_FAILURE);
+	}
+
+	editor.cols = win.ws_col;
+	editor.rows = win.ws_row;
+}
+
+void kill_application(void)
+{
+	/**
+	 * TODO: implement more things that need to be cleaned up when
+	 * killing the application
+	 */
+	reset_input_mode();
+
+	screen_buffer_free(&screen_buffer);
+}
+
+
+int screen_buffer_append(screen_buffer_t *buf, const char *in, size_t len)
+{
+	// Need to realloc to allow for the input to fit into the buffer
+	char* new = realloc(buf->text, buf->len + len);
+
+	if (NULL == new) return -1;
+
+	memcpy(&new[buf->len], in, len);
+	buf->text = new;
+	buf->len += len;
+	
+	return 0;
+}
+
+void screen_buffer_free(screen_buffer_t *buf)
+{
+	free(buf->text);
+}

src/term.h

@@ -0,0 +1,87 @@
+#include <stdlib.h>
+#include <termios.h>
+
+#ifndef TERM_H
+#define TERM_H
+
+typedef struct {
+	struct termios term_settings;
+	size_t cols, rows;
+	int cx, cy; // cursor pos
+} editor_t;
+
+typedef struct {
+	char* text;
+	size_t len;
+} screen_buffer_t;
+
+/**
+ * # reset_input_mode
+ *
+ * Resets the term settings back to their original configuration
+ *
+ */
+void reset_input_mode(void);
+
+/**
+ * # save_input_mode
+ *
+ * Saves the current terminal settings, so that they can be restored
+ *
+ */
+void save_input_mode(void);
+
+/**
+ * # set_input_mode
+ *
+ * Sets the current terminal settings to enable non-canonical mode
+ * so we can fully control the screen to employ the editor
+ *
+ */
+void set_input_mode(void);
+
+/**
+ * # setup_terminal
+ *
+ * Sets the variables and initializes various things to make
+ * the editor usable
+ *
+ */
+void setup_terminal(void);
+
+/**
+ * # kill_application
+ *
+ * Frees, resets, etc the things we need to do when closing the
+ * application so everything returns to normal after closing
+ *
+ */
+void kill_application(void);
+
+/**
+ * # screen_buffer_append
+ *
+ * - screen_buffer_t* buf : The screen buffer
+ * - const char* in : The input text
+ * - size_t len : Length of the input text
+ *
+ * Adds to the screen buffer
+ *
+ * ## RETURN VALUE
+ *
+ * Returns -1 on failure, 0 on success
+ *
+ */
+int screen_buffer_append(screen_buffer_t* buf, const char* in, size_t len);
+
+/**
+ * # screen_buffer_free
+ *
+ * - screen_buffer_t* buf
+ *
+ * Frees the screen buffer
+ *
+ */
+void screen_buffer_free(screen_buffer_t* buf);
+
+#endif