#!/usr/bin/env python
#
# Copyright (c) 2012, Intel Corporation.
# All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
#
# The CRC is a python translation of c code generated by (available under MIT license)
# pycrc 0.7.1 (http://www.tty1.net/pycrc/). Command line used:
# './pycrc.py --model=crc-32c --generate c --algorithm=table-driven'
#

import argparse
import os
import struct
import errno

__version__ = "0.0.1a"

#========================================================================
# IAS image creation
#========================================================================

MAGIC  = 0x2E6B7069
HEADER = struct.Struct('IIIIIII')

def image (payload, ext_hdr=''):

    payload_len = round_up(len(payload))
    image_len   = HEADER.size + len(ext_hdr) + payload_len + 4
    bytes       = bytearray (image_len)

    type = 0x30000
    version = 0
    length  = payload_len
    offset  = HEADER.size + len(ext_hdr)
    uncomp  = length	## compression not supported (yet)
    hcrc    = 0
    HEADER.pack_into (bytes, 0,
                      MAGIC, type, version, length, offset, uncomp, hcrc)
    crc = crc32c_buf (bytes[0:24])
    struct.pack_into ('I', bytes, 24, crc)

    bytes[HEADER.size:offset] = ext_hdr
    bytes[offset:offset+len(payload)] = payload
    crc = crc32c_buf(bytes[HEADER.size:offset+length])
    struct.pack_into ('I', bytes, offset+length, crc)

    return bytes

def multi_image (files):

    nfile = len(files)

    subimg = []
    o = 0
    for f in files:
        l = len(f)
        subimg.append((o, l))
        o += round_up(l)

    sizes   = bytearray(4*nfile)
    payload = bytearray(o)
    for i in range(nfile):
        o, l = subimg[i]
        struct.pack_into ('I', sizes, 4*i, l)
        payload[o:o+l] = files[i]

    return image (payload, sizes)

# ========================================================================
# Support functions.
# ========================================================================

def round_up (value, div=4):
    """Round VALUE up to the next multiple of DIV (a power of two)."""
    return (value + div - 1) & ~(div - 1)

# ========================================================================
#
#  CRC32C 
#
# Prehashed table of value to speed script execution
#
_CRC32C_TABLE = (

    0x00000000, 0xF26B8303, 0xE13B70F7, 0x1350F3F4, 0xC79A971F, 0x35F1141C, 0x26A1E7E8, 0xD4CA64EB,
    0x8AD958CF, 0x78B2DBCC, 0x6BE22838, 0x9989AB3B, 0x4D43CFD0, 0xBF284CD3, 0xAC78BF27, 0x5E133C24,
    0x105EC76F, 0xE235446C, 0xF165B798, 0x030E349B, 0xD7C45070, 0x25AFD373, 0x36FF2087, 0xC494A384,
    0x9A879FA0, 0x68EC1CA3, 0x7BBCEF57, 0x89D76C54, 0x5D1D08BF, 0xAF768BBC, 0xBC267848, 0x4E4DFB4B,
    0x20BD8EDE, 0xD2D60DDD, 0xC186FE29, 0x33ED7D2A, 0xE72719C1, 0x154C9AC2, 0x061C6936, 0xF477EA35,
    0xAA64D611, 0x580F5512, 0x4B5FA6E6, 0xB93425E5, 0x6DFE410E, 0x9F95C20D, 0x8CC531F9, 0x7EAEB2FA,
    0x30E349B1, 0xC288CAB2, 0xD1D83946, 0x23B3BA45, 0xF779DEAE, 0x05125DAD, 0x1642AE59, 0xE4292D5A,
    0xBA3A117E, 0x4851927D, 0x5B016189, 0xA96AE28A, 0x7DA08661, 0x8FCB0562, 0x9C9BF696, 0x6EF07595,
    0x417B1DBC, 0xB3109EBF, 0xA0406D4B, 0x522BEE48, 0x86E18AA3, 0x748A09A0, 0x67DAFA54, 0x95B17957,
    0xCBA24573, 0x39C9C670, 0x2A993584, 0xD8F2B687, 0x0C38D26C, 0xFE53516F, 0xED03A29B, 0x1F682198,
    0x5125DAD3, 0xA34E59D0, 0xB01EAA24, 0x42752927, 0x96BF4DCC, 0x64D4CECF, 0x77843D3B, 0x85EFBE38,
    0xDBFC821C, 0x2997011F, 0x3AC7F2EB, 0xC8AC71E8, 0x1C661503, 0xEE0D9600, 0xFD5D65F4, 0x0F36E6F7,
    0x61C69362, 0x93AD1061, 0x80FDE395, 0x72966096, 0xA65C047D, 0x5437877E, 0x4767748A, 0xB50CF789,
    0xEB1FCBAD, 0x197448AE, 0x0A24BB5A, 0xF84F3859, 0x2C855CB2, 0xDEEEDFB1, 0xCDBE2C45, 0x3FD5AF46,
    0x7198540D, 0x83F3D70E, 0x90A324FA, 0x62C8A7F9, 0xB602C312, 0x44694011, 0x5739B3E5, 0xA55230E6,
    0xFB410CC2, 0x092A8FC1, 0x1A7A7C35, 0xE811FF36, 0x3CDB9BDD, 0xCEB018DE, 0xDDE0EB2A, 0x2F8B6829,
    0x82F63B78, 0x709DB87B, 0x63CD4B8F, 0x91A6C88C, 0x456CAC67, 0xB7072F64, 0xA457DC90, 0x563C5F93,
    0x082F63B7, 0xFA44E0B4, 0xE9141340, 0x1B7F9043, 0xCFB5F4A8, 0x3DDE77AB, 0x2E8E845F, 0xDCE5075C,
    0x92A8FC17, 0x60C37F14, 0x73938CE0, 0x81F80FE3, 0x55326B08, 0xA759E80B, 0xB4091BFF, 0x466298FC,
    0x1871A4D8, 0xEA1A27DB, 0xF94AD42F, 0x0B21572C, 0xDFEB33C7, 0x2D80B0C4, 0x3ED04330, 0xCCBBC033,
    0xA24BB5A6, 0x502036A5, 0x4370C551, 0xB11B4652, 0x65D122B9, 0x97BAA1BA, 0x84EA524E, 0x7681D14D,
    0x2892ED69, 0xDAF96E6A, 0xC9A99D9E, 0x3BC21E9D, 0xEF087A76, 0x1D63F975, 0x0E330A81, 0xFC588982,
    0xB21572C9, 0x407EF1CA, 0x532E023E, 0xA145813D, 0x758FE5D6, 0x87E466D5, 0x94B49521, 0x66DF1622,
    0x38CC2A06, 0xCAA7A905, 0xD9F75AF1, 0x2B9CD9F2, 0xFF56BD19, 0x0D3D3E1A, 0x1E6DCDEE, 0xEC064EED,
    0xC38D26C4, 0x31E6A5C7, 0x22B65633, 0xD0DDD530, 0x0417B1DB, 0xF67C32D8, 0xE52CC12C, 0x1747422F,
    0x49547E0B, 0xBB3FFD08, 0xA86F0EFC, 0x5A048DFF, 0x8ECEE914, 0x7CA56A17, 0x6FF599E3, 0x9D9E1AE0,
    0xD3D3E1AB, 0x21B862A8, 0x32E8915C, 0xC083125F, 0x144976B4, 0xE622F5B7, 0xF5720643, 0x07198540,
    0x590AB964, 0xAB613A67, 0xB831C993, 0x4A5A4A90, 0x9E902E7B, 0x6CFBAD78, 0x7FAB5E8C, 0x8DC0DD8F,
    0xE330A81A, 0x115B2B19, 0x020BD8ED, 0xF0605BEE, 0x24AA3F05, 0xD6C1BC06, 0xC5914FF2, 0x37FACCF1,
    0x69E9F0D5, 0x9B8273D6, 0x88D28022, 0x7AB90321, 0xAE7367CA, 0x5C18E4C9, 0x4F48173D, 0xBD23943E,
    0xF36E6F75, 0x0105EC76, 0x12551F82, 0xE03E9C81, 0x34F4F86A, 0xC69F7B69, 0xD5CF889D, 0x27A40B9E,
    0x79B737BA, 0x8BDCB4B9, 0x988C474D, 0x6AE7C44E, 0xBE2DA0A5, 0x4C4623A6, 0x5F16D052, 0xAD7D5351
)

def crc32c (byte, crc=0xffffffff):

    crc = (crc >> 8) ^ _CRC32C_TABLE[(crc ^ byte) & 0xff]
    return crc

def crc32c_buf (buf, crc=0xffffffff):

    for b in buf:
        crc = crc32c (b, crc)
    return crc

# ========================================================================

#========================================================================
# Main program: Argument handling.
#========================================================================

def parse_args():
    """Parse the command line and return an argparse.Namespace object."""

    parser = argparse.ArgumentParser(description='Create a NON SIGNED IAS image to be used with DEVEL-ABL.')

    parser.add_argument ('-V', '--version',
                         action='version', version='%(prog)s ' + __version__)
    parser.add_argument ('-o', '--output',
                         default='image.bin',
                         help='write final image to OUTPUT')
    parser.add_argument ('-i', '--ignore',
                         default='',
                         help='provided for script compatibility with full featured ias_image_app',)

    parser.add_argument ('file',
                         help='add FILE to payload of IMAGE being created',
                         nargs='+',
                         metavar='file')

    return parser.parse_args()

# ------------------------------------------------------------------------

def main():

    a = parse_args()
    try:
        data = [open(f, 'rb').read() for f in a.file]
    except IOError:
        print ('error: Cannot open', a.file)
        exit (1) 
    print ('Creating NON signed Linux Kernel for ABL')
    img = multi_image(data)
    try:
        open (a.output, 'wb').write (img)
    except IOError as err:
        print ('error: Cannot open for write', a.output)
        exit (2)     

if __name__ == '__main__':
    main()

# ========================================================================