From 33fd225a0fdf4bb65ed08682d5b9f99fc1995289 Mon Sep 17 00:00:00 2001
From: "Daniele Verducci (ZenPenguin)" <danieleverducci@gmail.com>
Date: Mon, 23 Nov 2020 08:47:23 +0100
Subject: [PATCH] WIP: Monitor asm file stub

---
 assembly/bios/driver_hd44780.asm |  3 ++-
 assembly/bios/main.asm           | 27 +++++++++++++++++++++++++++
 assembly/bios/monitor.asm        | 26 ++++++++++++++++++++++++++
 3 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 assembly/bios/monitor.asm

diff --git a/assembly/bios/driver_hd44780.asm b/assembly/bios/driver_hd44780.asm
index 8b22530..0bbb5c7 100644
--- a/assembly/bios/driver_hd44780.asm
+++ b/assembly/bios/driver_hd44780.asm
@@ -9,7 +9,8 @@ LCD_DATA_REG: EQU IO_0 + 1
 LCD_LINES_LEFT: DB 0x80, 0xA8, 0x94, 0xBC  ;array defining lcd command codes for the first char of every line
 
 ; variables
-lcd_cur_x: EQU DRV_VAR_SPACE
+LCD_VAR_SPACE: EQU DRV_VAR_SPACE
+lcd_cur_x: EQU LCD_VAR_SPACE
 lcd_cur_y: EQU lcd_cur_x + 1
 
 ; functions
diff --git a/assembly/bios/main.asm b/assembly/bios/main.asm
index db1b42c..2c57014 100644
--- a/assembly/bios/main.asm
+++ b/assembly/bios/main.asm
@@ -49,6 +49,33 @@ SYSINIT_GREETING:
 ;include 'driver_keyboard.asm'
 include 'driver_arduino_terminal.asm'
 
+; SYSTEM CALLS
+; User I/O
+
+; Prints string
+; @param BC Pointer to a null-terminated string first character
+Print:
+    call Term_print
+    ret
+
+; Writes a single character
+; @param A Value of character to print
+Printc:
+    call Term_printc
+    ret
+
+; Reads a single character
+; @return A The read character
+Readc:
+    call Term_readc
+    ret
+
+; Reads a line
+; @return BC The pointer to a null-terminated read string
+Readline:
+    call Term_readline
+    ret
+
 ; System initialization
 Sysinit:
     ;call Lcd_init
diff --git a/assembly/bios/monitor.asm b/assembly/bios/monitor.asm
new file mode 100644
index 0000000..ccfeedd
--- /dev/null
+++ b/assembly/bios/monitor.asm
@@ -0,0 +1,26 @@
+; Pat80 Memory Monitor
+; @author Daniele Verducci
+;
+; Monitor commands (CMD $arg):
+;   DMP $pos Dumps first 100 bytes of memory starting at $pos
+;   SET $pos $val Replaces byte at $pos with $val
+;   LOA $pos $val Loads all the incoming bytes in memory starting from $pos
+;   RUN $pos Starts executing code from $pos
+
+; CONSTANTS
+; All monitor commands are 3 chars long.
+MON_COMMAND_DMP: DB "DMP",0  ; null terminated strings
+MON_COMMAND_DMP: DB "SET",0
+MON_COMMAND_DMP: DB "LOA",0
+MON_COMMAND_DMP: DB "RUN",0
+
+Monitor_main:
+    ; Read from command line
+    
+    ret
+
+; Parses a command
+; TODO: This is not very efficient, should be implemented as a tree, but for few commands is ok...
+; return A The interpreted command, or 0 if not found
+monitor_parse:
+    ret