shithub: 9ferno

Download patch

ref: 358eb31bb6e86f153a8a9261256a99ead7f1a08e
parent: 98a4d15507d812192519ab53fa552927eb2311eb
author: joe9 <joe9mail@gmail.com>
date: Tue Jul 13 13:22:58 EDT 2021

cga cursor move bug in vmx

vmx is moving the cursor by 2 characters for each character pressed
vmx debug prints show the position moved by 1
0x3d4 val 14
0x3d5 val 7
0x3d4 val 15
0x3d5 val 132
0x3d4 val 14
0x3d5 val 7
0x3d4 val 15
0x3d5 val 133
0x3d4 val 14
0x3d5 val 7
0x3d4 val 15
0x3d5 val 134
but the display is moving by 2.

Also, cgascreenputc is only used by cgascreenputs. Hence, doing the movetocursor() after the string is printed

--- a/os/pc/cga.c
+++ b/os/pc/cga.c
@@ -31,7 +31,7 @@
 						 */
 };
 
-#define CGASCREENBASE	((uchar*)KADDR(0xB8000))
+#define CGASCREENBASE	((uchar*)0xB8000)
 
 static int cgapos;
 static Lock cgascreenlock;
@@ -50,11 +50,6 @@
 	outb(0x3D4+1, data);
 }
 
-/* TODO BUG the cursor is 2 characters beyond
- * could use pos = cgapos -2
- * but skips a character when 'd' is pressed
- * is it a bug in the shell prompt?
- */
 static void
 movecursor(void)
 {
@@ -97,12 +92,14 @@
 		}
 		cgapos = Width*(Height-1);
 	}
-	movecursor();
 }
 
 static void
 cgascreenputs(char* s, int n)
 {
+	int i,j;
+	/*char pre[512] = "";*/
+
 	if(!islo()){
 		/*
 		 * Don't deadlock trying to
@@ -114,6 +111,10 @@
 	else
 		lock(&cgascreenlock);
 
+	/*j = snprint(pre,512,"-%d %d-",n, cgapos);
+	for(i=0;i<j&&i<512;i++){
+		outb(0x3D6, pre[i]);
+	}*/
 	while(n-- > 0){
 		outb(0x3D6, *s);
 		// outb(0x3D6, '-');
@@ -120,6 +121,7 @@
 		cgascreenputc(*s++);
 		// outb(0x3D6, '_');
 	}
+	movecursor();
 
 	unlock(&cgascreenlock);
 		// outb(0x3D6, ',');