From cf0d7eb6e96fb57caafe095c584e70d7d2b468d3 Mon Sep 17 00:00:00 2001
From: Valentin Lenhart <valentin.lenhart@posteo.de>
Date: Thu, 10 Oct 2019 13:05:53 +0200
Subject: [PATCH] introduce command to print the memory pointer

---
 kernel/parse.asm |  3 ++-
 kernel/shell.asm | 32 ++++++++++++++++++++------------
 2 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/kernel/parse.asm b/kernel/parse.asm
index 1bd81b2..e69d181 100644
--- a/kernel/parse.asm
+++ b/kernel/parse.asm
@@ -79,7 +79,8 @@ parseHexPair:
 ;                  you still need to have a specifier for the second part of
 ;                  the multibyte.
 ; Bit 2 - optional: If set and not present during parsing, we don't error out
-;		    and write zero
+;		    and write zero. Unfortunately there is currently no way to distinguish
+;           a value that a not present and a value that is zero.
 ;
 ; Bit 3 - String argument: If set, this argument is a string. A pointer to the
 ;                          read string, null terminated (max 0x20 chars) will
diff --git a/kernel/shell.asm b/kernel/shell.asm
index 6e49612..26a0fe5 100644
--- a/kernel/shell.asm
+++ b/kernel/shell.asm
@@ -33,7 +33,8 @@
 ; *** CONSTS ***
 
 ; number of entries in shellCmdTbl
-.equ	SHELL_CMD_COUNT		6+SHELL_EXTRA_CMD_COUNT
+.equ	SHELL_INTERNAL_CMD_COUNT	7
+.equ	SHELL_CMD_COUNT				SHELL_INTERNAL_CMD_COUNT+SHELL_EXTRA_CMD_COUNT
 
 ; *** VARIABLES ***
 ; Memory address that the shell is currently "pointing at" for peek, load, call
@@ -220,19 +221,13 @@ shellPrintErr:
 ;                 directive *just* after your '.inc "shell.asm"'. Voila!
 ;
 
-; Set memory pointer to the specified address (word) ors print the current value.
+; Set memory pointer to the specified address (word).
 ; Example: mptr 01fe
 shellMptrCmd:
-	.db	"mptr", 0b111, 0b001, 0
+	.db	"mptr", 0b011, 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
@@ -240,7 +235,20 @@ shellMptr:
 	ld	a, (hl)
 	ld	(SHELL_MEM_PTR), a
 
-.print:
+	call	shellMptrPrint
+
+	pop	hl
+	xor	a
+	ret
+
+
+; Print the current value of the memory pointer.
+; Example: pptr
+shellMptrPrintCmd:
+	.db	"pptr", 0, 0, 0
+shellMptrPrint:
+	push	hl
+
 	ld	hl, (SHELL_MEM_PTR)
 	ld	a, h
 	call	printHex
@@ -362,6 +370,6 @@ shellIOWRCmd:
 ; This table is at the very end of the file on purpose. The idea is to be able
 ; to graft extra commands easily after an include in the glue file.
 shellCmdTbl:
-	.dw shellMptrCmd, shellPeekCmd, shellPokeCmd, shellCallCmd
-	.dw shellIORDCmd, shellIOWRCmd
+	.dw shellMptrCmd, shellMptrPrintCmd, shellPeekCmd, shellPokeCmd
+	.dw shellCallCmd, shellIORDCmd, shellIOWRCmd