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 ++++++++++++++++++++++++++----------------------
 downloader/proto.txt     | 52 ++++++++++++++++++++++++-----------------------
 2 files changed, 56 insertions(+), 49 deletions(-)

(limited to 'downloader')

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
diff --git a/downloader/proto.txt b/downloader/proto.txt
index e85368e..17dec93 100644
--- a/downloader/proto.txt
+++ b/downloader/proto.txt
@@ -17,11 +17,13 @@ Command List:
 Description:
 ------------
 
-Every command consits of one byte command code, a fixed number of bytes as
-arguments and ends with a XOR checksum over all bytes sent. All data is
+Every command consits of one byte command code, one byte length which counts all
+bytes of the command including the command code and checksum. The length is followed
+by zero or more data and a XOR checksum over all bytes sent. All data is
 transferred LSB first (aka little endian). All addresses and words are 2bytes long.
-Every answer to a command starts with the command code. One byte return value,
-optionally some data and a checksum (XOR over all bytes received)
+Every answer to a command starts with the command code a length field which counts all
+bytes of the answer, one byte return value optionally some data and a checksum
+(XOR over all bytes received).
 The return codes have the following meaning:
 
   code | Error
@@ -38,10 +40,10 @@ The return codes have the following meaning:
 identify:
 ~~~~~~~~~
   command:
-    1 | <csum> (in this case <csum> will always be 1)
+    1 | len=3 | <csum>
 
   answer:
-    1 | <ret> | version | name | devid | fss | mess | supported | <csum>
+    1 | len=22 | <ret> | version | name | devid | fss | mess | supported | <csum>
 
       version:
          2bytes, protocol version
@@ -64,7 +66,7 @@ identify:
          operation first.
 
       mess:
-         2bytes, maximum eeprom segment size
+         1byte, maximum eeprom segment size
          This represents the maximum number of eeprom bytes which may be written or
          read at once. Unlike <fss> value it is ok to write or read less than <mess>
          bytes.
@@ -89,10 +91,10 @@ boot:
 ~~~~~
 
   command:
-    2 | <csum> (in this case <csum> will always be 2)
+    2 | len=3 | <csum>
 
   answer:
-    2 | <ret> | <csum>
+    2 | len=4 | <ret> | <csum>
 
   This instucts the bootloader to boot to the user application directly (no reset)
 
@@ -101,10 +103,10 @@ reset:
 ~~~~~~
 
   command:
-    3 | <csum> (in this case <csum> will always be 3)
+    3 | len=3 | <csum>
 
   answer:
-    3 | <ret> | <csum>
+    3 | len=4 | <ret> | <csum>
 
   The device performs a reboot. If the boot condition (i.e.: port pin) is not met
   this instructs the device to boot to the user application.
@@ -114,10 +116,10 @@ read flash:
 ~~~~~~~~~~~
 
   command:
-    4 | addr | <csum>
+    4 | len=5 | addr | <csum>
 
   answer:
-    4 | <ret> | data | <csum>
+    4 | len=4+2*<fss> | <ret> | data | <csum>
 
   The bootloader reads <fss> words from flash address <addr> and returns it as
   <data>.
@@ -127,10 +129,10 @@ write flash:
 ~~~~~~~~~~~~
 
   command:
-    5 | addr | data | <csum>
+    5 | len=5+2*<fss> | addr | data | <csum>
 
   answer:
-    5 | <ret> | <csum>
+    5 | len=4 | <ret> | <csum>
 
   The bootloader writes <data> (which has to contain exactly <fss> words) to address
   <addr> inside the flash. The start address has to be aligned to <fss> boundaries.
@@ -142,36 +144,36 @@ read eeprom:
 ~~~~~~~~~~~~
 
   command:
-    6 | addr | len | <csum>
+    6 | len=5 | addr | len | <csum>
 
   answer:
-    6 | <ret> | data | <csum>
+    6 | len=4+<len> | <ret> | data | <csum>
 
   The bootloader reads <len> bytes from eeprom at address <addr> and returns it as
-  <data>. len is 2bytes long.
+  <data>. len is 1byte long.
 
 
 write eeprom:
 ~~~~~~~~~~~~~
 
   command:
-    7 | addr | len | data | <csum>
+    7 | len=4+2<len(data) | addr | data | <csum>
 
   answer:
-    7 | <ret> | <csum>
+    7 | len=4 | <ret> | <csum>
 
   The bootloader writes <data> (which has to contain exactly <len> bytes) to address
-  <addr> inside the eeprom. len is 2bytes long and the value must not exceed <mess> bytes.
+  <addr> inside the eeprom. len is 1byte long and the value must not exceed <mess> bytes.
 
 
 read config:
 ~~~~~~~~~~~~
 
   command:
-    8 | nr | <csum>
+    8 | len=3 | nr | <csum>
 
   answer:
-    8 | <ret> | word | <csum>
+    8 | len=6 | <ret> | word | <csum>
 
   The bootloader reads and returns the configuration word number <nr>. <nr> is one
   byte long.
@@ -181,10 +183,10 @@ write config:
 ~~~~~~~~~~~~~
 
   command:
-    9 | nr | word | <csum>
+    9 | len=5 | nr | word | <csum>
 
   answer:
-    9 | <ret> | <csum>
+    9 | len=4 | <ret> | <csum>
 
   The bootloader writes <word> onto configuration word number <nr>. <nr> is one
   byte long.
-- 
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