Diff: pccomms/handlers/mode1.c

Revision:

0:0a841b89d614

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/pccomms/handlers/mode1.c	Mon Oct 11 10:34:55 2010 +0000
@@ -0,0 +1,142 @@
+/****************************************************************************
+ *    Copyright 2010 Andy Kirkham, Stellar Technologies Ltd
+ *    
+ *    This file is part of the Satellite Observers Workbench (SOWB).
+ *
+ *    SOWB is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation, either version 3 of the License, or
+ *    (at your option) any later version.
+ *
+ *    SOWB is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with SOWB.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    $Id: main.cpp 5 2010-07-12 20:51:11Z ajk $
+ *    
+ ***************************************************************************/
+
+/*
+MODE 1 Packet handler.
+
+This mode is used by the Host to send a file containing all the TLEs that
+SOWB needs to aquire satellites. The base packet payload itself conatins
+a sub packet as defined below. Note, we assign a number of flash pages to
+the TLE file. Each flash page is 256bytes in size. So, the host sends the
+file in 256byte blocks. The sub-packet header defines the block being sent.
+We add to this block the flash base page and write the 256byte sub-packet
+payload into the flash device. Note, TLE files are ascii characters so the
+sub-packet payload is ASCII itself and doesn't require any conversions.
+
+Subp-acket format   <BBBBCF>.........
+Where:-
+    < is the "start of packet header" character.
+    BBBB is a hex string representation of the uint16_t 256 char block.
+    C is a two's complement checksum of the header from < to > inclusive.
+    F is a char flag. Normally zero.
+    > is the "end of packet header" character.
+    .... is the packet payload, 256 bytes in length.
+
+*/
+
+#include "sowb.h"
+#include "user.h"
+#include "utils.h"
+#include "flash.h"
+#include "pccomms.h"
+
+#define FLASH_BASE_TLE_FILE 10
+
+/* Error flags to send back on failure. */
+#define FLAG_BAD_CHECKSUM   '1'
+#define FLAG_INVALID_LENGTH '2'
+
+/* Base packet payload to sub-packet header definition. */
+typedef struct _pccomms_mode1_header {
+    char        lead_char;
+    char        block[4];
+    char        csum;
+    char        flag;
+    char        trail_char;
+} PCCOMMS_MODE1_HEADER;
+
+/* Base packet payload to sub-packet overall definition. */
+typedef struct _pccomms_mode1 {
+    PCCOMMS_MODE1_HEADER    header;
+    char                    payload[256];
+} PCCOMMS_MODE1;
+
+
+/** pccomms_mode1_failed
+ *
+ * Used to send back a failed packet with a flag "reason for failure".
+ *
+ * @param BASE_PACKET_A *a The original ASCII version of the packet header.
+ * @param char flag The char flag to insert. 
+ */
+void pccomms_mode1_failed(BASE_PACKET_A *a, char flag) {
+    BASE_PACKET_A temp;
+    char *p;
+    int i;
+    
+    memcpy((char *)&temp, (char *)a, sizeof(BASE_PACKET_A));
+    temp.flag = flag;
+    temp.csum = 0;
+    temp.csum = strcsuml((char *)&temp, sizeof(BASE_PACKET_A));
+    for (p = (char *)&temp, i = 0; i < sizeof(BASE_PACKET_A); i++) {
+        Uart3_putc((char)p[i]);
+    }
+}
+
+/** pccomms_mode1_handler
+ *
+ * The packet handler for MODE 1.
+ *
+ * @param BASE_PACKET_B *b
+ * @param BASE_PACKET_A *a
+ * @return int 
+ */
+int pccomms_mode1_handler(BASE_PACKET_B *b, BASE_PACKET_A *a) {
+    PCCOMMS_MODE1 data;
+    char *p;
+    int page, c, i;
+        
+    /* Sanity check, should never fail, should really assert() */    
+    if (b->mode != 1) return PCCOMMS_PACKET_REJECTED;
+    
+    /* Sanity check, should never fail, should really assert() */    
+    if (b->length != sizeof(PCCOMMS_MODE1)) return PCCOMMS_PACKET_REJECTED;
+     
+    /* Copy the base packet payload into our internal data structure. */
+    for(p = (char *)&data, i = 0; i < sizeof(PCCOMMS_MODE1); i++) {
+        c = Uart3_getc(0);
+        if (c != -1) p[i] = (char)c;
+        else {
+            /* This shouldn't happen as once the IRQ system has detected the
+               end of the packet it no longer inserts serial chars into the 
+               buffer. So another sanity check really. Unless the Host did
+               in fact screw up somewhere. */
+            pccomms_mode1_failed(a, FLAG_INVALID_LENGTH);
+            return PCCOMMS_PACKET_REJECTED;
+        }
+    }
+
+    /* Run a checksum check. On failure, send back the Host's packet with "flag" set to "bad checksum". */
+    if (strsuml((char *)&data, sizeof(PCCOMMS_MODE1)) != 0) {
+        pccomms_mode1_failed(a, FLAG_BAD_CHECKSUM);
+        return PCCOMMS_PACKET_REJECTED;
+    }
+    
+    /* Get the block header and add the flash page offset. */
+    page = (int)hex2bin(data.header.block, 4) + FLASH_BASE_TLE_FILE;    
+    
+    /* Assuming we programmed the flash device ok, return packet accepted. */    
+    flash_page_write(page, data.payload);
+    while(flash_write_in_progress()) user_call_process();
+    return PCCOMMS_PACKET_ACCEPTED;
+}
+