printalign & alignment enum etc

drivers/vga.c

@@ -1,6 +1,7 @@
 // VGA Graphics Library
 #include "vga.h"
 #include "../kernel/io.h"
+#include "../lib/str.h"
 
 // Memory
 #define VGA_ADDRESS 	(char*)0xb8000
@@ -50,7 +51,7 @@ void set_cursor_pos(unsigned int col, unsigned int row) {
 void clear_screen() {
 	for( int c = 0; c < MAX_COLS; c++ )
 		for( int r = 0; r < MAX_ROWS; r++ )
-			writechar(0x20, c, r, 0x0f);
+			writechar(0x20, c, r, 0xf0);
 }
 
 /*
@@ -66,4 +67,18 @@ void println(char* str, int attribute_byte) {
 	cursor_row++; // Increment to next y-pos (newline)
 }
 
+void printalign(char* str, int attribute_byte, enum align alignment) {
+	unsigned int strlenbuf = strlen(str);
+
+	if( !alignment || alignment == LEFT ) {
+		print(str, attribute_byte);
+	} else if ( alignment == RIGHT ) {
+		set_cursor_pos(MAX_COLS - strlenbuf, cursor_row);
+	} else if ( alignment == MIDDLE ) {
+		set_cursor_pos((MAX_COLS/2) - (strlenbuf/2), cursor_row);
+	}
+
+	print(str, attribute_byte);
+}
+
 

drivers/vga.h

@@ -1,7 +1,19 @@
+#define VGA_ADDRESS 	(char*)0xb8000
+#define VGA_ADDRESS_MAX	(char*)0xb8fa0
+
+#define MAX_ROWS 25
+#define MAX_COLS 80
+
+static unsigned int cursor_row;
+static unsigned int cursor_col;
+
+enum align {LEFT, RIGHT, MIDDLE};
+
 char* get_memory_charpos(unsigned int col, unsigned int row);
 void writechar(char c, unsigned int col, unsigned int row, int colorcode);
 void clear_screen();
 void set_cursor_pos();
 void print();
 void println();
+void printalign(char* str, int attribute_byte, enum align alignment);
 void vga_init();

kernel/kernel.c

@@ -6,13 +6,18 @@ void main() {
 	vga_init(); 	// Initialize the screen first
 			// i.e. clear the screen et cetera.
 
-	set_cursor_pos(28, 2);
-	print("eOS Version 0.1 2021", 0x0f);
+	char* title = "eOS Version 0.1 2021";
+	set_cursor_pos(0, 2);
+	printalign(title, 0xf0, MIDDLE);
+
+	char* subtitle = "A x86 operating system, licenced under GPL-2.0";
+	set_cursor_pos(0, 3);
+	printalign(subtitle, 0xf8, MIDDLE);
 
 
 	char* strbuf = "Hello";
 	char* str2 = "World!";
 	strbuf = strcat(strbuf, str2); 
 	set_cursor_pos(0, 0);
-	println(strbuf, 0x0f);
+	println(strbuf, 0xf0);
 }