From fc547cad2fffcaa354b170694796beddf37dd4a1 Mon Sep 17 00:00:00 2001
From: Christian Pointner <equinox@spreadspace.org>
Date: Sun, 7 Jul 2013 01:48:13 +0000
Subject: added length field for messages

git-svn-id: https://svn.spreadspace.org/pic/trunk@46 a09c6847-51d9-44de-8ef2-e725cf50f3c7
---
 downloader/downloader.py | 53 ++++++++++++++++++++++++++----------------------
 1 file changed, 29 insertions(+), 24 deletions(-)

(limited to 'downloader/downloader.py')

diff --git a/downloader/downloader.py b/downloader/downloader.py
index 9efb30e..f90eced 100755
--- a/downloader/downloader.py
+++ b/downloader/downloader.py
@@ -100,7 +100,7 @@ def calc_csum(str):
         cs ^= c
     return cs
 
-def exec_command(dev, cmd, answer):
+def exec_command(dev, cmd, param, answer):
     import struct
 
     return_codes = { 0: "OK", 1: "invalid command", 2: "bad checksum",
@@ -108,21 +108,22 @@ def exec_command(dev, cmd, answer):
                      5: "address invalid", 6: "address prohibited",
                      7: "value out of bounds" }
 
-    cstr = bytearray(cmd)
+    cstr = bytearray(struct.pack('<BB', cmd, 0) + param)
     cstr.extend(struct.pack("<B", calc_csum(cstr)))
+    cstr[1] = len(cstr)
     dev.write(cstr)
 
     astr = bytearray()
-    astr += dev.read(3)
-    if len(astr) < 3:
-        print "ERROR: timeout while reading response header"
+    astr += dev.read(4)
+    if len(astr) < 4:
+        print "ERROR: timeout while reading response header (expected %d bytes, got %d)" % (4, len(astr))
         sys.exit(4)
 
     if astr[0] != cstr[0]:
         print "ERROR: bootloader returned wrong command code"
         sys.exit(4)
 
-    ret = astr[1]
+    ret = astr[2]
     if ret != 0:
         rstr = "invalid return code"
         try:
@@ -132,12 +133,16 @@ def exec_command(dev, cmd, answer):
         print "ERROR: bootloader returned %d: %s" % (ret, rstr)
         sys.exit(4)
 
-    answer_len = struct.calcsize(answer)
+    answer_len = astr[1] - 4
+    if answer_len < struct.calcsize(answer):
+        print "ERROR: short answer %d bytes received: expected %s bytes" % (answer_len, struct.calcsize(answer))
+        sys.exit(4)
+
     if answer_len > 0:
         tmp = bytearray()
         tmp += dev.read(answer_len)
         if len(tmp) < answer_len:
-            print "ERROR: timeout while reading response"
+            print "ERROR: timeout while reading response (expected %d bytes, got %d)" % (answer_len, len(tmp))
             sys.exit(4)
 
         astr += tmp
@@ -146,12 +151,12 @@ def exec_command(dev, cmd, answer):
         print "ERROR: checksum error"
         sys.exit(4)
 
-    return struct.unpack_from(answer, astr, 2)
+    return struct.unpack_from(answer, astr, 3)
 
 ### Commands
 
 def identify(dev):
-    data = exec_command(dev, struct.pack('<B', 1), '<BB10sHBHH')
+    data = exec_command(dev, 1, '', '<BB10sHBBH')
     id = { 'ver_min': data[0], 'ver_maj': data[1], 'name': data[2], 'devid': data[3],
            'fss': data[4], 'mess': data[5], 'supported': data[6] }
 
@@ -166,35 +171,35 @@ def identify(dev):
     return id
 
 def boot(dev):
-    exec_command(dev, struct.pack('<B', 2), '<')
+    exec_command(dev, 2, '', '<')
 
 def reset(dev, id):
-    exec_command(dev, struct.pack('<B', 3), '<')
+    exec_command(dev, 3, '', '<')
 
 def read_flash_segment(dev, id, addr):
-    cmd = struct.pack('<BH', 4, addr)
-    return exec_command(dev, cmd, '<%dH' % id['fss'])
+    param = struct.pack('<H', addr)
+    return exec_command(dev, 4, param, '<%dH' % id['fss'])
 
 def write_flash_segment(dev, id, addr, data):
-    cmd = struct.pack('<BH%dH' % id['fss'], 5, addr, *data)
-    return exec_command(dev, cmd, '<')
+    param = struct.pack('<H%dH' % id['fss'], addr, *data)
+    return exec_command(dev, 5, param, '<')
 
 def read_eeprom(dev, id, addr, len):
-    cmd = struct.pack('<BHH', 6, addr, len)
-    return exec_command(dev, cmd, '<%dB' % len)
+    param = struct.pack('<HB', addr, len)
+    return exec_command(dev, 6, param, '<%dB' % len)
 
 def write_eeprom(dev, id, addr, data):
-    cmd = struct.pack('<BHH%dB' % len(data), 7, addr, len(data), *data)
-    return exec_command(dev, cmd, '<')
+    param = struct.pack('<HB%dB' % len(data), addr, len(data), *data)
+    return exec_command(dev, 7, param, '<')
 
 def read_config(dev, id, nr):
-    cmd = struct.pack('<BB', 8, nr)
-    data = exec_command(dev, cmd, '<H')
+    param = struct.pack('<B', nr)
+    data = exec_command(dev, 8, param, '<H')
     return data[0]
 
 def write_config(dev, id, nr, word):
-    cmd = struct.pack('<BBH', 9, nr, word)
-    return exec_command(dev, cmd, '<')
+    param = struct.pack('<BH', nr, word)
+    return exec_command(dev, 9, param, '<')
 
 
 ### Main
-- 
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