#!/usr/bin/python3.1

# scans for BusPirate port
# Writes a byte at a give address
# TODO: Catch all exceptions to return BP to sane state

import serial, time, sys

infile='org.img'

candidates = ['/dev/ttyUSB0','/dev/ttyUSB1','/dev/ttyUSB2','/dev/ttyUSB3',
        '/dev/ttyUSB4','/dev/ttyUSB5','/dev/ttyUSB6','/dev/ttyUSB7',
        '/dev/ttyUSB8','/dev/ttyUSB9','/dev/ttyUSB10','/dev/ttyUSB11',
        '/dev/ttyUSB12','/dev/ttyUSB13','/dev/ttyUSB14','/dev/ttyUSB15']

def test_if(name):
  try:
    s = serial.Serial(port=name, baudrate=115200, timeout=0.05)
  except Exception as e:
    return None
  else:
    return s

    
def test_bp(s):
  if s == None:
    return None 
  else:  
    s.write(b'#\n')
    i = s.read(10000)
    sl = i.splitlines() 

    if len(sl) < 4 or \
       ( sl[2][0:10] != b'Bus Pirate' and \
         sl[3][0:10] != b'Bus Pirate'):
       return None;
    return True


def find_bp():
  # tests list of candidates. Returns serial instance if exactly one found. 
  # If several found, aborts with exception.
  # If none found, returns None           
  cnt = 0
  s_bp = None
  n_bp = None
  n_str = ''
  for n in candidates:
    s = test_if(n)
    is_bp = test_bp(s)
    if is_bp: 
      cnt += 1
      s_bp = s
      n_bp = n
      n_str += n + '\n'
  if cnt > 1:
    raise IOError('More than one Bus Pirate found! Interfaces: \n'+n_str)
  return (s_bp, n_bp)  
    
    
def adr24(n):
  # takes an int and returns a 24 but hex address MSB,...,LSB
  # e.g. 0x01 0x00 0x23 
  b1 = n//65535
  b2 = (n//256)%256
  b3 = n%256
  s = '0x{:02x} '.format(b1) + '0x{:02x} '.format(b2) + '0x{:02x}'.format(b3)     
  print('adr24: ',n,' -> ', s)
  return(s.encode('ascii'))  


def b2h(b):
  # takes an int 0...255 and converts it to 0xnn
  if not (0 <= b and b <= 255):
    raise ValueError('argument to b2h out of range: '+ str(b))
  s = '0x{:02x} '.format(b)
  return(s.encode('ascii'))
      
    
def safe_exit(msg):
  # exit with BP reset
  print('  ** ERROR -- safe_exit() called **')
  print('  MSG: ',msg)
  s.write(b'#\n')
  i = s.read(100)
  sl = i.decode('ascii').splitlines()
#  print(sl)
  # Note: seems reset from SPI does sometimes not echo the #...
  if sl[0]!= 'RESET' and sl[1] != 'RESET': 
    print('  ** error exit reset failed! **')
  sys.exit(-1)  
  

a = find_bp()
(s,n) = a
#print('device:    ', n)
#print('seri_inst: ', s) 
 
# Start interaction
s = serial.Serial(port=n, baudrate=115200, timeout=0.1)

# reset just in case
s.write(b'#\n')
i = s.read(200)
#sl = i.decode('ascii').splitlines()
#print(sl)
#if sl[1] != 'RESET': safe_exit('initiial reset failed')

# m set SPI
s.write(b'm\n') # 'm'
i = s.read(100)
sl = i.decode('ascii').splitlines()
#print(sl)
    
# SPI
s.write(b'5\n') # Menu item 5 = SPI
i = s.read(100)
sl = i.decode('ascii').splitlines()
#print(sl)

s.write(b'4\n') # 1=30khz, 2=125kHz, 3=250kHz, 4=1MHz
i = s.read(100)
sl = i.decode('ascii').splitlines()
#print(sl)

s.write(b'1\n') # 1= clock idle low (default)  2: clock idle high
i = s.read(100)
sl = i.decode('ascii').splitlines()
#print(sl)

s.write(b'2\n') # 1:idle to active 2:active to idle (default)
# note: for the 25x40 the datasheet seems to indicate 1 is
# correct, but 2 works also. But for a a25l040, 1 fails while
# 2 works. So likely 2 is really the usually correct choice.
i = s.read(100)
sl = i.decode('ascii').splitlines()
#print(sl)

s.write(b'1\n') # sample signal 1: middle  2:end
i = s.read(100)
sl = i.decode('ascii').splitlines()
#print(sl)

s.write(b'2\n') # 1:CS 2:/CS
i = s.read(100)
sl = i.decode('ascii').splitlines()
#print(sl)

s.write(b'2\n') # 1: H=Hi-Z 2: H=3v3 Note: Pullups are problematic
i = s.read(100)
sl = i.decode('ascii').splitlines()
#print(sl)
if sl[1] != 'Ready': safe_exit('SPI detail setting failed')

s.write(b'W\n') # Activate power
i = s.read(100)
sl = i.decode('ascii').splitlines()
#print(sl)
if sl[1] != 'Power supplies ON' and \
   sl[1] != 'POWER SUPPLIES ON':
     safe_exit('power ON failed')
      
# give is a bit of time to come up and settle
time.sleep(0.200)


#
# SPI now working. Do the actual stuff
#

inf = open(infile, 'rb')

write_size = 32 # Do not go over 32, or writes will get corrupted!
                # The reason is that the BP can deal only with 255 
                # characters per line
                 
for adr in range(0, 0x80000, 32):
#for adr in range(0, 256, write_size):  # only 256 bytes for debugging
#  print('writing at 0x{:010X} '.format(adr))
  data = inf.read(write_size)
  if len(data) != write_size:
    raise IOError('short read when reading input file: '+str(len(data)))

  # write enable (WREN)
  print('setting WREN')
  s.timeout = 0.01
  s.write(b'[0x06 r:0]\n')
  i = s.read(1000)
  sl = i.decode('ascii').splitlines()

  # write wbyte at specified address
  cmd = b'[0x02 '+adr24(adr)+ b' ' 
  for b in data:
    cmd += b2h(b)+b''
  cmd += b' r:0]\n'
  
#  print('cmd:', cmd) 

  s.timeout = 0.02  
  s.write(cmd)
  i = s.read(10000)
  sl = i.decode('ascii').splitlines()
  #print(sl)

  s.timeout = 0.01
  t1 = time.time()
  # wait for done
  while 1:
    s.write(b'[0x05 r:1]\n') 
    i = s.read(1000)
    sl = i.decode('ascii').splitlines()
    #  print(sl)
    r = sl[3]
    if r[0:6] != 'READ: ': safe_exit('status register read failed')
    ds = r[6:]
    dss = ds.split()
    sr = int(dss[0], 16)
    if sr & 1 == 0: break # finished
  t2 = time.time()

# report time taken
  print('time taken: ', t2 - t1, 'sec')




# Final reset
s.write(b'#\n')
i = s.read(200)
#sl = i.decode('ascii').splitlines()
#print(sl)
# Note: Seems reset from SPI does sometimes not echo the '#'
#if sl[0] != 'RESET' and sl[1] != 'RESET': safe_exit('final reset failed')