Merge branch 'main' into 'sd2'

# Conflicts:
#   main.cc

cga.cc

@@ -0,0 +1,34 @@
+unsigned char* buffer = (unsigned char*) 0xb8000;
+
+
+char make_attribute ( char foreground ,
+		char background , char blink ) {
+	foreground &= 0 xf ; // ffff ffff -> 0000 ffff
+	background &= 0 x7 ; // bbbb bbbb -> 0000 0 bbb
+	blink &= 1; // BBBB BBBB -> 0000 000 B
+	background <<= 4; // 0000 0 bbb -> 0 bbb 0000
+	blink <<= 7; // 0000 000 B -> B000 0000
+	return foreground | background | blink ; // Bbbb ffff
+}
+
+int puts(const char *s){
+    for(int i=0; *(s+i) != 0; i++){
+	buffer[2*i] = *(s+i);
+	buffer[(2*i)+1] = 0x14;
+    }
+    return 0;
+}
+
+void clear_display(void){
+    for(int i=0; i<(80*25); i++){
+	buffer[i] = 0;
+    }
+}
+
+void iterate(void){
+    for(int i=0; i<(80*25); i++){
+	buffer[2*i] = i%256;
+	buffer[1+(2*i)] = i%256;
+    }
+} 
+

cga.h

@@ -0,0 +1,5 @@
+
+extern unsigned char* buffer;
+int puts(const char *s);
+void clear_display(void);
+void iterate(void);

main.cc

@@ -1,4 +1,3 @@
-
 #include "arch/lapic.h"
 #include "boot/startup_ap.h"
 #include "debug/output.h"