flasher.py: format data packet

diff --git a/flasher.py b/flasher.py
index 7a1463c..1ffe9ae 100644 (file)
--- a/flasher.py
+++ b/flasher.py
@@ -9,6 +9,10 @@ BAU_CMD = 0x34
 SIG_CMD = 0x3A
 ARE_CMD = 0x3B
 
+LOW_PULSE = 0x00
+GENERIC_CODE = 0x55
+BOOT_CODE = 0xC3
+
 TESTID = [
     "0xF0", "0xF1", "0xF2", "0xF3",
     "0xE4", "0xE5", "0xE6", "0xE7",
@@ -16,38 +20,55 @@ TESTID = [
     "0xCC", "0xCD", "0xCE", "0xCF"
 ]
 
+def calc_sum(data):
+    data_len = len(data)
+    lnh = data_len + 1 & 0xFF00
+    lnl = data_len + 1 & 0x00FF
+    res = lnh + lnl
+    for i in range(data_len):
+            if isinstance(data[i], str):
+                res += int(data[i], 16)
+            else:
+                res += ord(data[i])
+    res = ~(res) & 0xFF # two's complement
+    return (lnh, lnl, res)
+
+
+# format of data packet is [SOD|LNH|LNL|COM|byte_data|SUM|ETX]
 def format_command(cmd, data):
-    COM_LEN = len(data)
     SOD = 0x01
     COM = cmd
-    LNH = COM_LEN + 1 & 0xFF00
-    LNL = COM_LEN + 1 & 0x00FF
-    calcsum = LNH + LNL
 
     if isinstance(data, str):
         byte_data = bytes(data.encode('utf-8'))
     else:
         byte_data = bytes([int(x, 16) for x in data])
     
-    for i in range(COM_LEN):
-            if isinstance(data[i], str):
-                calcsum += int(data[i], 16)
-            else:
-                calcsum += ord(data[i])
-    SUM = ~(calcsum) & 0xFF # two's complement
+    LNH, LNL, SUM = calc_sum(data)
     ETX = 0x03
     fmt_header = '<BBBB'
     fmt_footer = 'BB'
     print("sum calculation:", SUM)
-    fmt = fmt_header + str(COM_LEN) + 's' + fmt_footer
+    fmt = fmt_header + str(len(data)) + 's' + fmt_footer
     print(fmt)
     pack = struct.pack(fmt, SOD, LNH, LNL, COM, byte_data, SUM, ETX)
     print(pack)
     return fmt
 
+# format of data packet is [SOD|LNH|LNL|RES|DAT|SUM|ETX]
 def format_data(data):
     SOD = 0x81
+    if (len(data) >= 1024):
+        raise Exception(f'Data packet too large, data length is {DATA_LEN} (>1024)')
+    LNH, LNL, SUM = calc_sum(data)
+    DAT = bytes([int(x, 16) for x in data])
+    RES = 0x13
     ETX = 0x03
+    fmt_header = '<BBBB'
+    fmt_footer = 'BB'
+    fmt = fmt_header + str(len(data)) + 's' + fmt_footer
+    pack = struct.pack(fmt, SOD, LNH, LNL, RES, DAT, SUM, ETX)
+    print(pack)
 
 cmd = format_command(INQ_CMD, "")
 print(cmd, struct.calcsize(cmd))
@@ -58,7 +79,7 @@ print(cmd, struct.calcsize(cmd))
 cmd = format_command(IDA_CMD, TESTID)
 print(cmd, struct.calcsize(cmd))
 
-
+format_data(['0x00','0x01','0x02'])