From 23be234762b93338ca71cf225b05614d1bca7e56 Mon Sep 17 00:00:00 2001
From: Valentin Lenhart <valentin.lenhart@posteo.de>
Date: Wed, 9 Oct 2019 22:05:29 +0200
Subject: [PATCH] print value of memory pointer when no arguments are given

---
 kernel/shell.asm | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/kernel/shell.asm b/kernel/shell.asm
index d46e465..6e49612 100644
--- a/kernel/shell.asm
+++ b/kernel/shell.asm
@@ -220,13 +220,19 @@ shellPrintErr:
 ;                 directive *just* after your '.inc "shell.asm"'. Voila!
 ;
 
-; Set memory pointer to the specified address (word).
+; Set memory pointer to the specified address (word) ors print the current value.
 ; Example: mptr 01fe
 shellMptrCmd:
-	.db	"mptr", 0b011, 0b001, 0
+	.db	"mptr", 0b111, 0b001, 0
 shellMptr:
 	push	hl
 
+	ld	a, (hl)
+	inc	hl
+	and (hl)
+	dec hl
+    jr z, .print
+
 	; reminder: z80 is little-endian
 	ld	a, (hl)
 	ld	(SHELL_MEM_PTR+1), a
@@ -234,6 +240,7 @@ shellMptr:
 	ld	a, (hl)
 	ld	(SHELL_MEM_PTR), a
 
+.print:
 	ld	hl, (SHELL_MEM_PTR)
 	ld	a, h
 	call	printHex