improved response handling

git-svn-id: https://svn.spreadspace.org/pic/trunk@32 a09c6847-51d9-44de-8ef2-e725cf50f3c7

1 files changed, 12 insertions, 8 deletions

diff --git a/downloader/downloader.py b/downloader/downloader.py
index c918357..8f3fc3b 100755
--- a/downloader/downloader.py
+++ b/downloader/downloader.py
@@ -125,22 +125,21 @@ def exec_command(dev, cmd, answer):
                      3: "not implemented", 4: "flash write error",
                      5: "address invalid", 6: "address prohibited" }
 
-    answer = '<cB' + answer + 'B'
-    answer_len = struct.calcsize(answer)
+    answer = '<' + answer + 'B'
+    answer_len = struct.calcsize(answer) + 2
 
     cstr = cmd + calc_csum(cmd)
     os.write(dev, cstr)
 
     astr = b''
-    while len(astr) < answer_len:
+    while len(astr) < 2:
         astr += os.read(dev, answer_len - len(astr))
-    data = list(struct.unpack(answer, astr))
-    code = data.pop(0)
-    ret = data.pop(1)
-    checksum = data.pop()
-    if code != cmd[0]:
+
+    if astr[0] != cmd[0]:
         print "ERROR: bootloader returned wrong command code"
         sys.exit(4)
+
+    ret = ord(astr[1])
     if ret != 0:
         rstr = "invalid return code"
         try:
@@ -149,6 +148,11 @@ def exec_command(dev, cmd, answer):
             pass
         print "ERROR: bootloader returned %d: %s" % (ret, rstr)
         sys.exit(4)
+
+    while len(astr) < answer_len:
+        astr += os.read(dev, answer_len - len(astr))
+
+    data = struct.unpack_from(answer, astr, 2)
     if 0 != calc_csum(astr):
         print "ERROR: checksum error"
         sys.exit(4)