From b1333cb9e35058191b43df84269bd5ee5823310f Mon Sep 17 00:00:00 2001
From: John Tsiombikas <nuclear@member.fsf.org>
Date: Mon, 14 Jun 2021 01:03:10 +0300
Subject: [PATCH] console cursor positioning

---
 sys1/kern/src/con.c  |   34 ++++++++++++++++++++++++++++++++++
 sys1/kern/src/con.h  |    7 ++++++-
 sys1/kern/src/main.c |   11 ++++++++---
 3 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/sys1/kern/src/con.c b/sys1/kern/src/con.c
index b110272..6627f95 100644
--- a/sys1/kern/src/con.c
+++ b/sys1/kern/src/con.c
@@ -13,6 +13,10 @@ static int tbuf_first, tbuf_last;
 
 static int curx, cury, scroll;
 
+#define CURSTACK_SIZE	16
+static unsigned int savecur[CURSTACK_SIZE];
+static int savecur_top;
+
 
 static void newline(void);
 
@@ -29,6 +33,36 @@ void con_reset(void)
 	curx = cury = scroll = 0;
 	tbuf_first = tbuf_last = 0;
 	memset(textbuf[0], 0, sizeof textbuf[0]);
+
+	savecur_top = 0;
+}
+
+void con_setcur(int x, int y)
+{
+	curx = x < 0 ? 0 : (x >= NCOLS ? NCOLS - 1 : x);
+	cury = y < 0 ? 0 : (y >= NROWS ? NROWS - 1 : y);
+}
+
+void con_getcur(int *x, int *y)
+{
+	*x = curx;
+	*y = cury;
+}
+
+void con_pushcur(void)
+{
+	if(savecur_top >= CURSTACK_SIZE) return;
+
+	savecur[savecur_top++] = curx | (cury << 16);
+}
+
+void con_popcur(void)
+{
+	if(savecur_top <= 0) return;
+
+	savecur_top--;
+	curx = savecur[savecur_top] & 0xffff;
+	cury = savecur[savecur_top] >> 16;
 }
 
 void con_putchar(int c)
diff --git a/sys1/kern/src/con.h b/sys1/kern/src/con.h
index 5beb167..51cb544 100644
--- a/sys1/kern/src/con.h
+++ b/sys1/kern/src/con.h
@@ -6,7 +6,12 @@
 void con_init(void);
 
 void con_reset(void);
-#define con_color(fg, bg)	vga_setcolor(fg, bg)
+#define con_setcolor(fg, bg)	vga_setcolor(fg, bg)
+
+void con_setcur(int x, int y);
+void con_getcur(int *x, int *y);
+void con_pushcur(void);
+void con_popcur(void);
 
 void con_putchar(int c);
 
diff --git a/sys1/kern/src/main.c b/sys1/kern/src/main.c
index e45e929..3c93cab 100644
--- a/sys1/kern/src/main.c
+++ b/sys1/kern/src/main.c
@@ -19,11 +19,16 @@ void kmain(void)
 	for(;;) {
 		printf("line %d", line++);
 
-		for(i=0; i<65536 * 128; i++) {
-			if((i & 0x3ffff) == 0) {
-				con_putchar('.');
+		con_pushcur();
+		con_setcur(30, 0);
+		for(i=0; i<65536 * 300; i++) {
+			if((i & 0xfffff) == 0) {
+				con_setcolor(VGA_BRIGHT | (line & 7), VGA_BLACK);
+				con_putchar('>');
 			}
 		}
+		con_setcolor(VGA_WHITE, VGA_BLACK);
+		con_popcur();
 		con_putchar('\n');
 	}
 }
-- 
1.7.10.4