drop.py

#
#
# OpenOCD library: https://github.com/screwer/OpenOCD
#
# change line 193
# if not self.Name:
#
# to run: python2 drop.py
#

from OpenOCD import OpenOCD

ocd = OpenOCD()
ocd.Reset(Halt=True)

pc = ocd.Reg('pc')
reg = []

# create r0 through r12 register objects to read
for i in range(0,13):
  reg.append(ocd.Reg("r%d" % i))

# Read() returns a number
pc_reset_val = pc.Read()

# run first 10 instructions trying to find a suitable instruction
for run in range(10):

  # loop over all registers, calling Write(4) to set all registers to a value of 4
  for i in range(len(reg)):
    reg[i].Write(4)

  print("Step %d, [pc:0x%08X]" % (run, pc.Read()))
  ocd.Step()
  
  for i in range(len(reg)):
    reg_val = reg[i].Read()
    if not reg_val:
      print("reg[%d]"%i, "is None")
      continue
    print("reg_val:", reg_val)
    print("pc_reset_val:", pc_reset_val)
    if abs(reg_val - pc_reset_val) < 2:
      print("found possible instruction at 0x%08X" % (pc.Read()))
      print("r%d = 0x%08X, pc = 0x%08X" % (i, reg_val, pc_reset_val))
      break

########## GOODIES ########################
# found possible instruction at 0x000006D6
# r4 = 0x000006D1, pc = 0x000006D0
# 
# found possible instruction at 0x000006DE
# r3 = 0x000006D1, pc = 0x000006D0
###########################################