utility script to adjust MAC

Author: oilulio

scripts/adjustMAC.py

@@ -0,0 +1,87 @@
+#!/usr/bin/python3
+
+# Quick MAC address adjustment script
+# Takes a Net.hex file in Intel format
+# Looks for a MAC address (strictly 6 consecutive bytes) of a known pattern
+
+# Changes that MAC address as required and outputs a new Net.hex file of
+# "NetXXXXXXXXXXXX.hex" where XX..XX is the new MAC in hex digits
+
+# Avoids recompile to allows rapid production of many devices
+
+# Fails if the 6-byte sequence is not unique in the file, or not in the file at all.
+
+import sys
+import re
+
+NEW_MAC="AABBCCDDEEFF" # Hex digits (6 bytes)
+OLD_MAC="324050607080"
+
+with open("Net.hex") as f:
+  lines=f.readlines()
+
+lineStarts={}
+code=""
+newFile=[]
+for n,line in enumerate(lines):
+  newFile.append(line.rstrip())
+  if (line[0]!=":"): continue
+  recLen=int(line[1:3],16)
+  if (line[7:9]!="00"): continue
+
+  if (len(line.rstrip())!=(9+2*(recLen+1))): continue
+
+  lineStarts[len(code)]=n
+  code+=line[9:9+recLen*2]
+
+allMACs=re.findall(OLD_MAC,code)
+
+print (allMACs)
+
+if (len(allMACs)>1):
+  print ("MAC address not unique in file.  Exiting")
+  sys.exit(0)
+
+location=code.find(OLD_MAC)
+
+if (location<0):
+  print ("Old MAC address not detected.  Exiting")
+  sys.exit(0)
+
+print (location)
+offset=0
+while (not (location-offset) in lineStarts):
+  offset+=2
+
+sourceLine=location-offset
+source=newFile[lineStarts[sourceLine]]
+CS=int(source[-2:],16)
+replacement=source[0:9+offset]
+copyOffset=0
+
+for i in range(6):
+  if (9+offset+2*i+2>=len(source)): # move onto next line
+    newFile[lineStarts[sourceLine]]=replacement+"{:02X}".format(CS&0xFF)
+    print ("Replaced",lines[lineStarts[sourceLine]],"with   ",newFile[lineStarts[sourceLine]])
+    sourceLine+=int(lines[lineStarts[location-offset]][1:3],16)*2
+    source=newFile[lineStarts[sourceLine]]
+    CS=int(source[-2:],16)
+    offset=0
+    copyOffset=i
+    replacement=source[0:9+offset]
+  replacement+=NEW_MAC[i*2:i*2+2]
+  delta=int(OLD_MAC[i*2:i*2+2],16)-int(NEW_MAC[i*2:i*2+2],16)
+  
+  CS+=delta
+  if (i==5):
+    replacement+=source[9+offset+2*(i-copyOffset)+2:-2]
+    newFile[lineStarts[sourceLine]]=replacement+"{:02X}".format(CS&0xFF)
+    print ("Replaced",lines[lineStarts[sourceLine]],"with   ",newFile[lineStarts[sourceLine]])
+    
+f=open("Net"+NEW_MAC+".hex","w")
+for line in newFile:
+  f.write(line+"\n")
+f.close()
+print ("New file created ","Net"+NEW_MAC+".hex")
+
+