#!/usr/bin/python
#
#  spreadspace pic utils
#
#
#  Copyright (C) 2011 Christian Pointner <equinox@spreadspace.org>
#
#  This file is part of spreadspace pic utils.
#
#  spreadspace pic utils is free software: you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation, either version 3 of the License, or
#  any later version.
#
#  spreadspace pic utils is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with spreadspace pic utils. If not, see <http://www.gnu.org/licenses/>.
#

'''spreadspace simple pic downloader.'''

VERSION_MAJ = 0
VERSION_MIN = 1

### HEX File Magic

def load_hex(file):
    from intelhex import IntelHex

    fin = file
    if fin == '-':
        fin = sys.stdin
    elif not os.path.isfile(fin):
        print "ERROR: File not found: %s" % fin
        sys.exit(1)

    codedata = {}
    ih = IntelHex(fin)
    for a in ih.addresses():
        if a/2 not in codedata.keys():
            codedata[a/2] = 0
        if a%2 == 0:
            codedata[a/2] += ih[a]
        else:
            codedata[a/2] += (ih[a] << 8)

    return codedata

def get_lowest_flash_addr(codedata, fss):
    lowest_code_addr = sorted(codedata.keys())[0]
    return lowest_code_addr - (lowest_code_addr%fss)

def get_highest_flash_addr(codedata, fss):
    highest_code_addr = sorted(codedata.keys())[-1]
    return highest_code_addr + (fss - highest_code_addr%fss)

def create_flash_image(codedata, fss, sa, ea):
    img = ( sa, [0xFFFF]*(ea-sa) )
    for a,d in codedata.items():
        img[1][a-sa] = d
    return img

def create_flash_segments(codedata, fss):
    sa = get_lowest_flash_addr(codedata, fss)
    ea = get_highest_flash_addr(codedata, fss)
    img = create_flash_image(codedata, fss, sa, ea)
    for i in xrange(0, ea, fss):
        slice = img[1][i:i+fss]
        if not all( (elem == 0xFFFF) for elem in slice):
            yield (i, slice)


### Interface to Bootloader

def open_serial(device, baud):
    import os
    import tty
    import termios
    import serial

    print "opening %s (%s Baud)" % (device, baud)

    try:
        dev = serial.Serial(port=device, baudrate=baud, timeout=3)
        dev.flushInput()
        dev.flushOutput()
        return dev

    except (ValueError, serial.SerialException), msg:
        print "ERROR: opening serial device: %s" % msg
        sys.exit(3)

def calc_csum(str):
    cs = 0
    for c in str:
        cs ^= c
    return cs

def exec_command(dev, cmd, param, answer):
    import struct

    return_codes = { 0: "OK", 1: "invalid command", 2: "bad checksum",
                     3: "not implemented", 4: "flash write error",
                     5: "address invalid", 6: "address prohibited",
                     7: "value out of bounds" }

    dev.flushInput()
    dev.flushOutput()

    cstr = bytearray(struct.pack('<BB', cmd, len(param)+3) + param)
    cstr.extend(struct.pack("<B", calc_csum(cstr)))
    dev.write(cstr)

    astr = bytearray()
    astr += dev.read(4)
    if len(astr) < 4:
        print "ERROR: timeout while reading response header (expected %d bytes, got %d)" % (4, len(astr))
        sys.exit(4)

    if astr[0] != cstr[0]:
        print "ERROR: bootloader returned wrong command code"
        sys.exit(4)

    ret = astr[2]
    if ret != 0:
        rstr = "invalid return code"
        try:
            rstr = return_codes[ret]
        except KeyError:
            pass
        print "ERROR: bootloader returned %d: %s" % (ret, rstr)
        sys.exit(4)

    answer_len = astr[1] - 4
    if answer_len < struct.calcsize(answer):
        print "ERROR: short answer %d bytes received: expected %s bytes" % (answer_len, struct.calcsize(answer))
        sys.exit(4)

    if answer_len > 0:
        tmp = bytearray()
        tmp += dev.read(answer_len)
        if len(tmp) < answer_len:
            print "ERROR: timeout while reading response (expected %d bytes, got %d)" % (answer_len, len(tmp))
            sys.exit(4)

        astr += tmp

    if 0 != calc_csum(astr):
        print "ERROR: checksum error"
        sys.exit(4)

    return struct.unpack_from(answer, astr, 3)

### Commands

def identify(dev):
    data = exec_command(dev, 1, '', '<BB10sHBBH')
    id = { 'ver_min': data[0], 'ver_maj': data[1], 'name': data[2], 'devid': data[3],
           'fss': data[4], 'mess': data[5], 'supported': data[6] }

    if id['ver_maj'] != VERSION_MAJ:
        print "incompatible protocol version, expected: %d, got: %d" % (VERSION_MAJ, id['ver_maj'])
        sys.exit(4)
    if id['fss'] == 0:
        print "FSS value is 0 "
        sys.exit(4)

    print "connected with Bootloader '%s' Version %d.%d, (ID=%04X, FSS=%d, MESS=%d)" % (id['name'], id['ver_maj'], id['ver_min'], id['devid'], id['fss'], id['mess'])
    return id

def boot(dev):
    exec_command(dev, 2, '', '<')

def reset(dev, id):
    exec_command(dev, 3, '', '<')

def read_flash_segment(dev, id, addr):
    param = struct.pack('<H', addr)
    return exec_command(dev, 4, param, '<%dH' % id['fss'])

def write_flash_segment(dev, id, addr, data):
    param = struct.pack('<H%dH' % id['fss'], addr, *data)
    return exec_command(dev, 5, param, '<')

def read_eeprom(dev, id, addr, len):
    param = struct.pack('<HB', addr, len)
    return exec_command(dev, 6, param, '<%dB' % len)

def write_eeprom(dev, id, addr, data):
    param = struct.pack('<HB%dB' % len(data), addr, len(data), *data)
    return exec_command(dev, 7, param, '<')

def read_config(dev, id, nr):
    param = struct.pack('<B', nr)
    data = exec_command(dev, 8, param, '<H')
    return data[0]

def write_config(dev, id, nr, word):
    param = struct.pack('<BH', nr, word)
    return exec_command(dev, 9, param, '<')


### Main

if __name__ == '__main__':
    import getopt
    import sys
    import os
    import struct

    usage = '''spreadspace simple pic downloader.
Usage:
    python downloader.py [options] INFILE

Arguments:
    INFILE      name of hex file for downloading.
                Use '-' for reading from stdin.

Options:
    -h, --help              this help message.
    -v, --version           version info.
    --device=N              the serial port to use (default: /dev/ttyUSB0).
    --baud=N                baudrate to use (default: 57600).
'''

    device = "/dev/ttyUSB0"
    baudrate = 57600

    try:
        opts, args = getopt.getopt(sys.argv[1:], "hv",
                                  ["help", "version", "device=", "baud="])

        for o, a in opts:
            if o in ("-h", "--help"):
                print(usage)
                sys.exit(0)
            elif o in ("-v", "--version"):
                print("Version %d.%d" % (VERSION_MAJ, VERSION_MIN))
                sys.exit(0)
            elif o in ("--device"):
                device = a
            elif o in ("--baud"):
                baudrate = a

        if not args:
            raise getopt.GetoptError('Input file is not specified')

        if len(args) > 1:
            raise getopt.GetoptError('Too many arguments')

    except getopt.GetoptError, msg:
        print "ERROR: %s" % msg
        print usage
        sys.exit(2)

    dev = open_serial(device, baudrate)
    codedata = load_hex(args[0])
    id = identify(dev)

    # for segment in create_flash_segments(codedata, id['fss']):
    #     print "%05X: %s" % (segment[0], ''.join('%04X'%i for i in segment[1]))