From 7dc1d5c7ca717ab74ad26cd8ea2e3085f10af586 Mon Sep 17 00:00:00 2001
From: Florian Streibelt <florian@freitagsrunde.org>
Date: Wed, 12 Oct 2011 13:16:45 +0200
Subject: [PATCH] various comments added.

---
 display-daemon/ser.c | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/display-daemon/ser.c b/display-daemon/ser.c
index 8d3d6a8..d640eeb 100644
--- a/display-daemon/ser.c
+++ b/display-daemon/ser.c
@@ -42,30 +42,50 @@ initport (int fd)
   return 1;
 }
 
-
+//reset the display to defaults
 char display_init[] = { 0x1b, 0x40 };
-char display_showtime[] = { 0x1F, 0x54 };
+
+//show or hide the cursor
 char display_cursor_off[] = { 0x1f, 0x43, 0x0 };
 char display_cursor_on[] = { 0x1f, 0x43, 0x1 };
 
+// blink-command: 
+// where the last value defines the blink rate, 
+// with 0=always on, 255=always off
 char display_on[] = { 0x1f, 0x45, 0x0 };
 char display_off[] = { 0x1f, 0x45, 0xff };
 
+//Modes for new chars:
 char display_overwrite[] = { 0x1f, 0x01 };
 char display_vscroll[] = { 0x1f, 0x02 };
 char display_hscroll[] = { 0x1f, 0x03 };
 
+//clear and cursor home
 char display_clear_screen[] = { 0x0c };
 
+// activate timer display in lower right corner.
+// actual time has to be set via display_set_timer.
 char display_time[] = {0x1f,0x55};
+// configures hour and minutes of the internal clock and
+// displays the time in the lower right corner.
+// turns off when something gets written into the line.
+// two bytes have to follow with hour and minute
+char display_set_timer[] = { 0x1F, 0x54 };
+
+// various commands for the display:
 
+// send a command sequence from the heap(!) {sizeof used}
+// only to be used within the macros presented below!
 #define DWC(c)               display_write(c,sizeof(c))
+
+//send a null terminated string:
 #define SEND_TEXT(t)         display_write(t,strlen(t))
 
+//various commands
 #define SEND_DISPLAY_INIT    DWC(display_init)
 #define SEND_CURSOR_OFF      DWC(display_cursor_off)
 #define SEND_CURSOR_ON       DWC(display_cursor_on)
-#define SEND_DEFINE_TIMER    DWC(display_showtime)
+#define SEND_DEFINE_TIMER    DWC(display_set_timer)
 #define SEND_SHOW_TIMER      DWC(display_time)
 #define SEND_MODE_OVERWRITE  DWC(display_overwrite)
 #define SEND_MODE_VSCROLL    DWC(display_vscroll)
@@ -74,6 +94,7 @@ char display_time[] = {0x1f,0x55};
 #define SEND_DISPLAY_ON      DWC(display_on)
 #define SEND_CLEAR           DWC(display_clear_screen);
 
+// internal defines.
 #define TIME_BASE  	     200000
 #define TB_TO_SECS(x)        (x*1000000/TIME_BASE)
 
@@ -83,8 +104,9 @@ char display_time[] = {0x1f,0x55};
 
 #define DEVICE               "/dev/ttyUSB0"
 
-#define PAUSEMSG             "Hallo, bitte melde Dich am Barcodereader an, um das Kassensystem zu benutzen *** Angebot: Die Mate heute nur 0.75 *** "
-   
+#define PAUSEMSG             "Hallo, bitte melde Dich am Barcodereader an, um das Kassensystem zu benutzen *** "
+
+// chars per line in our display:   
 #define LINELEN 20
 
 void