Tools for working with Texas Instruments COFF and AIS files

aisgen.py

#!/usr/bin/env python
'''Read fully linked  TI COFF file, and generate AIS format file

Commandline parameters
  enable sequential read,
  pll and emifb configuration
  pinmux configuration
  enable checksums

'Eliot Blennerhassett' <[email protected]>
AudioScience Inc. 2011
'''

from struct import pack, unpack
from collections import namedtuple
from ticoff import Coff
#from binascii import crc32
#from numpy import array, fromstring, uint32

class aisgen(object):

    def __init__(self, aisgen_compatible=False):
        self.funcs = {}
        self.crc_enabled = False
        self.aisgen_compatible = aisgen_compatible
        self.verbosity = 0


    def magic(self):
        self.f.write(pack('<I', 0x41504954))


    def enable_crc(self):
        if self.verbosity > 1:
            print 'Enable CRC'
        self.crc_enabled = True
        self.f.write(pack('<I', 0x58535903))


    def disable_crc(self):
        if self.verbosity > 1:
            print 'Disable CRC'
        self.crc_enabled = False
        self.f.write(pack('<I', 0x58535904))


    def validate_crc(self, crc, seek):
        if self.verbosity > 1:
            print 'Validate CRC 0x%08X, seek %d' % (crc, seek)
        self.f.write(pack('<III', 0x58535902, crc, 0x100000000 + seek))


    def section_load(self, s):
        wlen = len(s.data)
        odd = wlen % 4
        write_data = s.data
        npad = 0
        spad = ''
        if odd:
            npad = (4 - odd)
            write_data += ('\0' * npad)
            #write_data += '\x48\x00\x00' # Test to match particular example from AISgen :(
            spad = ' + %d bytes padding' % npad

        command = pack('<I', 0x58535901)
        if self.aisgen_compatible:
        # Generate matching TI AISgen, size in header includes padding
            if self.verbosity > 1:
                print 'Load section 0x%X[0x%06X] %s' % (s.virt_addr, len(write_data), s.name)
            params = pack('<II', s.virt_addr, len(write_data))
        else:
            # Generate according to spec, size in header excludes padding
            if self.verbosity > 1:
                print 'Load section 0x%X[0x%06X]%s %s' % (s.virt_addr, wlen, spad, s.name)
            params = pack('<II', s.virt_addr, wlen)

        crc_data = params + write_data
        self.f.write(command + crc_data)

        if self.crc_enabled and self.crc_calc:
            crc = self.crc_calc(crc_data)
            # Seek backwards, over section data + 2 headers
            seek = -(len(crc_data) + 16)
            self.validate_crc(crc, seek)

    # These values obtained here:
    # http://e2e.ti.com/support/dsp/tms320c6000_high_performance_dsps/f/115/p/118006/423501.aspx
    fill_types = {'8bit' : 0, '16bit' : 1, '32bit' : 2}

    def section_fill(self, addr, nbytes, fill):
        remainder_to_fill_type = [2, 0, 1, 0]

        if self.verbosity > 1:
            print 'Fill section 0x%X[0x%06X] = 0x%X' % (addr, nbytes, fill)
        odd = nbytes % 4
        fill_type = remainder_to_fill_type[odd]

        command = pack('<I', 0x5853590a)
        params = pack('<IIII', addr, nbytes,  fill_type, fill)
        self.f.write(command + params)

        if self.crc_enabled:
            npad = 0
            if odd:
                npad = (4 - odd)
            crc_data = params + chr(fill & 0xFF) * (nbytes + npad)
            crc = self.crc_calc(crc_data)
            seek = -(4 * (5 + 3)) # back over section fill + validate crc commands
            self.validate_crc(crc, seek)


    def section(self, s):
        f = s.fill_value()
        if f is not None:
            self.section_fill(s.virt_addr, len(s.data), f)
        else:
            self.section_load(s)

    def execute_function(self, fname, params):
        if self.verbosity > 1:
            print 'Execute function %s' % fname,
            for p in params:
                print '0x%X' % p,
            print
        fnum, nparams = self.funcs[fname]
        if len(params) != nparams:
            raise ValueError('Expected %d params for %s', nparams, fname)
        fh = (len(params) << 16) + fnum
        self.f.write(pack('<II', 0x5853590D, fh))
        self.f.write(pack('<%dI' % len(params), *params))

    PllAndClockParams = namedtuple('PllAndClockParams',
                    'pllm postdiv plldiv3 plldiv5 plldiv7 ' +
                    'clkmode pll_lock_cnt spi_prescale')

    def pll_and_spi_clock_config(self, c):
        '''expects parameters to be instance of PllAndClockParams'''
        #print c
        param1 = (c.pllm << 24) + (c.postdiv << 16) + (c.plldiv3 << 8) + c.plldiv5
        param2 = (c.clkmode << 24) + (c.plldiv7 << 16) + c.pll_lock_cnt
        self.execute_function('PLL and Clock Configuration', (param1,  param2,  c.spi_prescale))


    EmifbParams = namedtuple('EmifbParams', 'sdcfg sdtim1 sdtim2 sdrfc')

    def emifb_config(self, c):
        '''expects parameters to be instance of EmifbParams'''
        #print c
        self.execute_function('EMIFB SDRAM Configuration', c)

    def pinmux_config(self, c):
        '''expects parameters to be 2 or 3 element tuple
        (index, value [, mask])
        '''
        c = c + (0xFFFFFFFF, ) # default mask if not provided
        self.execute_function('Pinmux Configuration', (c[0], c[2], c[1]))


    def sequential_read(self):
        if self.verbosity > 1:
            print 'Sequential read enable'
        self.f.write(pack('<I', 0x58535963))


    def jump_and_close(self, addr):
        if self.verbosity > 1:
            print 'Jump and close 0x%X' % addr
        self.f.write(pack('<II', 0x58535906, addr))


    def generate(self, filename, coff, options):
        if self.verbosity > 0:
            print 'Generating for %s...' % self.rom,

        load_sections = coff.loadable_sections
        entry_point = coff.entry_point

        with open(filename, 'wb') as self.f:
            self.magic()
            if options.sequential_read:
                self.sequential_read()

            if options.pll_config:
                pll_params = eval('self.PllAndClockParams(%s)' % options.pll_config)
                self.pll_and_spi_clock_config(pll_params)

            if options.emifb_config:
                emifb_params = eval('self.EmifbParams(%s)' % options.emifb_config)
                self.emifb_config(emifb_params)

            for c in options.pinmux_config:
                params = eval('(%s)' % c)
                self.pinmux_config(params)

            if options.enable_crc:
                self.enable_crc()

            for s in load_sections:
                self.section(s)

            self.jump_and_close(entry_point)

class aisgen_d800k001(aisgen):
    '''Instance of aisgen that implements ROM d800k001
    CRC calculation and special functions'''

    def __init__(self):
        aisgen.__init__(self)
        self.rom = 'd800k001'
        self.funcs =  {
            # func name : (id, param count)
            'PLL0 Configuration' : (0, 2),
            'Peripheral Clock Configuration' : (1, 1),
            'EMIFB SDRAM Configuration' : (2, 4),
            'EMIFA SDRAM Configuration' : (3, 4),
            'EMIFA CE Space Configuration' : (4, 4),
            'PLL and Clock Configuration' : (5, 3),
        }

    def _crc_calc_direct(self, data, crc=0):
        '''Reference implementation of CRC
        Process 32 bit words MSB first
        Data is little endian. Very SLOW!'''
        words = fromstring(data, dtype=uint32)
        for word in words:
            bit_no = 31;
            while bit_no >= 0:
                msb_bit = crc & 0x80000000
                crc = ((word >> bit_no) & 0x1) | (crc << 1)
                if msb_bit:
                    crc ^= 0x04C11DB7
                bit_no -= 1

        return crc & 0xFFFFFFFF

    def crc_calc(self, in_str, crc=0):
        '''Generate CRC to match TI AISgen output, from data zero padded to N*4 bytes.
        This is not the same as standard CRC calculation, lacking the augmentation of
        the input data with 32 zero bits.

        Applies to C6747/5/3 devices ROM d800k003,  but not C6748/6/2, see
        http://e2e.ti.com/support/dsp/tms320c6000_high_performance_dsps/f/115/p/119062/426491.aspx
        '''
        nbytes = len(in_str)
        for w in range(0, nbytes, 4):
            # in-place endian reversal to
            # process little endian words MSbyte first
            for b in range(3, -1, -1):
                ofs = w + b
                c = in_str[ofs]
                octet = ord(c)
                for i in range(8):
                    topbit = crc & 0x80000000
                    crc = ((octet >> (7 - i)) & 0x01) | ((crc << 1) & 0xFFFFFFFF)
                    if topbit:
                        crc ^= 0x04C11DB7

        return crc

class aisgen_d800k003(aisgen_d800k001):
    '''Instance of aisgen that implements ROM d800k003
    CRC calculation and special functions'''

    def __init__(self):
        aisgen_d800k001.__init__(self)
        self.rom = 'd800k003'
        self.funcs['Power and Sleep Controller Configuration'] =   (6, 1)
        self.funcs['Pinmux Configuration'] = (7, 3)


roms = {
    'd800k001' : aisgen_d800k001,
    'd800k003' : aisgen_d800k003
}

if __name__ == '__main__':
    from optparse import OptionParser
    from sys import exit

    parser = OptionParser(usage='%prog [options] input.coff output.ais')

    parser.add_option('-c', '--enable-crc', action='store_true',
                        default=False, help='enable per-section CRCs')

    parser.add_option('-r', '--rom', action='store',  choices=roms.keys(), metavar='ROM_VERSION',
                        default='d800k003', help='one of %s' % roms.keys())

    parser.add_option('-s', '--sequential-read', action='store_true',
                        default=False, help='use SPI sequential read')

    parser.add_option('-v', '--verbosity', action='store', type='int',
                        default=1, help='verbosity of output')

    parser.add_option('-b', '--emifb-config', action='store', type='string',
        help='E.g. --emifb-config="sdcfg=0x10620, sdtim1=0x01912a08, sdtim2=0x70080005, sdrfc=0x8000079e"')

    parser.add_option('-p', '--pll-config', action='store', type='string',
        help='E.g. --pll-config="pllm=29, postdiv=1, plldiv3=3, plldiv5=2, plldiv7=5, clkmode=1, pll_lock_cnt=402, spi_prescale=6"')

    parser.add_option('-m', '--pinmux-config', action='append', type='string',
        default=[], help='PINMUX_CONFIG=regnum,value[,optional mask]. May be used more than once\n'+
        'E.g. --pinmux-config=0,0x10011101 -m1,0x1001,0xFFFF')

    options, args = parser.parse_args()

    #
    if args[0][0] == '@':
        fa = []
        with open(args[0][1:]) as f:
            for l in f:
                fa.append(l.strip())
        fa = fa + args[1:]
        options, args = parser.parse_args(args=fa, values=options)

    if len(args) < 2:
        parser.print_help()
        exit()

    coff = Coff(args[0])

    gen = roms[options.rom]()
    gen.verbosity = options.verbosity

    gen.generate(args[1], coff, options)

    if options.verbosity:
        print 'Finished'

aisread.py

#!/usr/bin/env python
"""
Parse AIS file, and optionally generate C array

"Eliot Blennerhassett" <[email protected]>
AudioScience Inc. 2011
"""

import os
import struct
import sys
from optparse import OptionParser

def read(format):
    datalen = struct.calcsize(format)
    data = Input.read(datalen)
    if len(data) != datalen:
        raise EOFError
    ret = struct.unpack(format, data)
    if len(ret) < 2:
        ret = ret[0]
    return ret

def section_load():
    address = read('I')
    size = read('I')
    # data length is rounded up from size to multiple o4
    data = read('%dI' %  ((size + 3) / 4))
    try:
        len(data)
    except TypeError:
        data = [data]

    print '// Section load %#x[%#x]' % (address, size)
    if all([d == data[0] for d in data]):
        print '//   ^ could use Section fill with %#x command' % data[0]
    if gen_h:
        print '%#x, %#x,' % (address, size)
        for i in xrange(len(data)):
            print '0x%08x,' % data[i],
            if not((i + 1) % 8):
                print
        if (i + 1) % 8:
            print


def section_fill():
    address = read('I')
    size = read('I')
    type = read('I')
    pattern = read('I')
    print '// Section Fill type %d %#x[%#x] = %#x' % (type, address, size, pattern)
    if gen_h:
        print '%#x, %#x, %#x, %#x' % (address, size, type, pattern)


def boot_table():
    type = read('I')
    address = read('I')
    data = read('I')
    sleep = read('I')
    print '// Boot table type %d *%#x = %#x, sleep %d' % (type, address, data, sleep )
    if gen_h:
        print '%#x, %#x, %#x, %#x' % (type, address, data, sleep)


# This function list comes from sprab1b.pdf 'Using the TMS320C6747/45/43 Bootloader'
funcs = {
    0 : ('PLL0 Configuration', 2),
    1 : ('Peripheral Clock Configuration', 1),
    2 : ('EMIFB SDRAM Configuration', 4),
    3 : ('EMIFA SDRAM Configuration', 4),
    4 : ('EMIFA CE Space Configuration', 4),
    5 : ('PLL and Clock Configuration', 3),
    6 : ('Power and Sleep Controller Configuration', 1),
    7 : ('Pinmux Configuration', 3),
}


def function_execute():
    arg = read('I')
    func = arg & 0xFFFF
    ac = (arg & 0xFFFF0000) >> 16
    try:
        fn, ac1 = funcs[func]
    except KeyError:
        fn = 'Unkown %#x' % func
        ac1 = 0

    assert ac == ac1, 'Arg count mismatch %d %d' % (ac, ac1)

    print '// Function %d : %s(' % (func, fn),
    args = []
    for i in range(ac):
        args.append(read('I'))
        print '%#x, ' % args[i],
    print ')'
    if gen_h:
        print '%#x,' % arg,
        for i in range(ac):
            print '%#x, ' % args[i],
        print


def jump_and_close():
    address = read('I')
    print '// Close and jump to %#x' % address
    if gen_h:
        print '%#x,' % address


def jump(op):
    address = read('I')
    print '// Jump to %#x' % address
    if gen_h:
        print '%#x,' % address


def validate_crc():
    crc = read('I')
    seek = read('I')
    print '// Validate CRC %#x, seek %x' % (crc, seek)
    if gen_h:
        print '%#x, %#x,' % (crc, seek)


def enable_crc():
    print '// Enable CRC'


def disable_crc():
    print '// Enable CRC'


def sequential_read():
    print '// Sequential read enable'


opcodes = {
    0x58535901 : section_load,
    0x58535902 : validate_crc,
    0x58535903 : enable_crc,
    0x58535904 : disable_crc,
    0x58535905 : jump,
    0x58535906 : jump_and_close,
    0x58535907 : boot_table,
    0x5853590a : section_fill,
    0x5853590D : function_execute,
    0x58535963 : sequential_read,
}


parser = OptionParser()
parser.add_option("-g", "--generate-header",
                  action="store_true", dest="gen_h", default=False,
                  help="generate full header file on stdout")

(options, args) = parser.parse_args()

fname = args[0]
fsize = os.path.getsize(fname)

gen_h = options.gen_h

if gen_h:
    print '''// Generated from %s
#include <stdint.h>
uint32_t ais_array[] = {'''


with open (fname, 'rb') as Input:
    magic = read('I')
    if not (magic == 0x41504954):
        sys.exit('Incorrect magic, not an AIS file?')

    print '// AIS magic ID'
    if gen_h:
        print '%#x,' %  magic

    while True:
        try:
            opcode = read('I')
        except EOFError:
            break
        try:
            command = opcodes[opcode]
        except KeyError:
            print 'unknown opcode %#x' % opcode

        if gen_h:
            print '%#x,' % opcode,

        command()
    if gen_h:
        print '};'

    assert Input.tell() == fsize, 'file  not consumed?'

asi_license.txt

Copyright (C) 1997-2016 AudioScience, Inc.

This software is provided 'as-is', without any express or implied warranty.
In no event will AudioScience Inc. be held liable for any damages arising
from the use of this software.

Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not
   claim that you wrote the original software. If you use this software
   in a product, an acknowledgment in the product documentation would be
   appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
   misrepresented as being the original software.
3. This copyright notice and list of conditions may not be altered or removed
   from any source distribution.

AudioScience, Inc. <[email protected]>

( This license is GPL compatible see http://www.gnu.org/licenses/license-list.html#GPLCompatibleLicenses )

pinsetup.py

#!/usr/bin/env python
'''Read TI pinmux data files, and pinmux config file
and generate pinmux register values, and comments.

Requires mux[1-5].txt from TI pinsetup utility OMAP-L1x7_C6747-5-3_pinsetup

There are 20 pinmux registers, each with 8 4-bit fields

"Eliot Blennnerhassett" <[email protected]>
'''
from sys import exit

def read_pin_data():
    '''Read pin data into 2 dictionaries.
    pd key is pin function name, value is (reg_idx, field_idx, field value, ?)
    pf  key (reg_idx, field_idx), value is [list of pin names]

    pin data files contain lines like
        AXR0[0],10,1,1,830
        pin_func_name, reg_idx, field_idx, field_value, ??
        not sure what the last value represents?
    '''
    pd = {} # setups per pin function
    pf = {} # pin functions per register field
    for fi in range(1, 6):
        fn = 'mux%d.txt' % fi
        with open(fn) as f:
            for l in f:
                t = l.strip().split(',')
                if len(l) < 5:
                    continue
                pin_name = t[0]
                p = tuple([int(s) for s in t[1:]])
                pi = p[0:2]
                # ((reg_idx, field_idx) : ['pin_name', ...]
                if pf.has_key(pi):
                    pf[pi].append(pin_name)
                else:
                    pf[pi] = [pin_name]

                # 'pin_name' : (reg_idx, field_idx, field value, ?)
                pd[pin_name] = p
    return pd, pf


def read_pin_config(fn, pd):
    '''read pin config from file named fn, and add pinmux setup data from pd
    pin config is a list of pin function names, one per line
    '''
    pins = []
    with open(fn) as f:
        for l in f:
            n = l.strip()
            if not len(n):
                continue
            ps = pd[n]
            pins.append((n, ps))
    return pins


def print_alpha_pinlist(pins):
    '''print list of pin names in alphabetical order'''
    pins.sort() # pin name order
    print '/*\nDefined pins:',
    wrap = 0
    for pin in pins:
        if wrap > 70:
            print
            wrap = 0
        print pin[0],
        wrap += len(pin[0]) + 1
    print '\n*/'

def print_muxfield_pinlist(pins):
    '''print list of pin names grouped by mux field value'''
    pins.sort(key=lambda p : (p[1][2], p[1][0], p[1][1]))
    prev_mux = None
    print '/*\nPins by mux field setting:',
    for pin in pins:
        mux = pin[1][2]
        if mux != prev_mux:
            print '\n\nMUX%d Pins:' % mux
            prev_mux = mux
            wrap = 0
        if wrap > 70:
            print
            wrap = 0
        print pin[0],
        wrap += len(pin[0]) + 1
    print '\n*/'


def print_pinmux_pinlist(pins):
    '''print list of pin names grouped by pinmux register'''
    pins.sort(key=lambda p : (p[1][0], p[1][1]))
    print '/* Pins by pinmux register'
    prev_regidx = None
    for pin in pins:
        regidx = pin[1][0]
        if regidx != prev_regidx:
            print '\npinmux[%d] pins' % regidx
            prev_regidx = regidx
        print pin[0],
    print '\n*/'


def calculate_pinmux_values(pins, pd, pf):
    '''convert the selected pin data into appropriate bitfields
    in registers
    '''
    regs = [0] * 20
    error = False
    for pin in pins:
        ps = pin[1]
        reg = ps[0]
        field_ofs = ps[1] * 4
        field_mask = 0xF << field_ofs
        field_val = ps[2] << field_ofs

        if (regs[reg] & field_mask):
            fv = (regs[reg] & field_mask) >> field_ofs
            # find which pin already assigned to the field
            current = (reg, ps[1], fv)
            shared = pf[ps[0:2]]
            for name in shared:
                id = pd[name][0:3]
                if current == id:
                    break;

            print 'Conflict setting %s : pinmux[%d][%d] already set to %s' % (pin[0], reg, ps[1], name)
            error = True
        else:
            regs[reg] = regs[reg] | field_val;

    if error:
        exit(1)

    return regs


formats = {
    'aisgen' : '--pinmux-config=%d,0x%08X',
    'array' : '\t/* %d */ 0x%08X,',
    'define' : '#define PINMUX%d_VALUE 0x%08X',
}

def print_pinmux_values(format, regs):
    '''print the pinmux register value list
    formatted for various uses
    '''
    fs = formats[format]
    if format == 'array':
        print 'unsigned int pinmux_values = {'
    for i in range(len(regs)):
        print fs % (i, regs[i])
    if format == 'array':
        print '};'


def print_known_pins(pf):
    pl = list( pf.iteritems())
    pl.sort(key=lambda p : (p[0][0], p[0][1]))
    for p in pl:
        print 'pinmux %s selects %s' % p

if __name__ == '__main__':
    from optparse import OptionParser

    parser = OptionParser(usage='%prog [options] input.pin')

    parser.add_option('-a', '--print-alpha', action='store_true',
                        default=False, help='Print alphabetical pinlist comment')

    parser.add_option('-m', '--print-muxfield', action='store_true',
                        default=False, help='Print pinlist by mux value comment')

    parser.add_option('-r', '--print-register', action='store_true',
                        default=False, help='Print pinlist by register comment')

    parser.add_option('-f', '--format', action='store',  choices=formats.keys(),
                        default='define', help='one of %s' % formats.keys())

    parser.add_option('-p', '--print-known', action='store_true',
                        default=False, help='print known pins')

    options, args = parser.parse_args()

    pd, pf = read_pin_data()

    if options.print_known:
        print_known_pins(pf)
        exit(0)

    pins = read_pin_config(args[0], pd)

    regs = calculate_pinmux_values(pins, pd, pf)

    if options.print_alpha:
        print_alpha_pinlist(pins)
    if options.print_muxfield:
        print_muxfield_pinlist(pins)
    if options.print_register:
        print_pinmux_pinlist(pins)

    print_pinmux_values(options.format, regs)

ticoff.py

#!/usr/bin/env python
"""
Read TI COFF file into a python object

"Eliot Blennerhassett" <[email protected]>
AudioScience Inc. 2011
"""

from array import array
from collections import namedtuple
from optparse import OptionParser
from struct import unpack, calcsize

def read_struct(file, format):
    '''read struct data formatted according to format'''
    datalen = calcsize(format)
    data = file.read(datalen)
    if len(data) != datalen:
        raise EOFError
    ret = unpack(format, data)
    if len(ret) < 2:
        ret = ret[0]
    return ret


def read_cstr(file):
    '''read zero terminated c string from file'''
    output = ""
    while True:
        char = file.read(1)
        if len(char) == 0:
            raise RuntimeError ("EOF while reading cstr")
        if char == '\0':
            break
        output += char
    return output

# From spraao8.pdf table 7
class Section(namedtuple('Section',
    'name, virt_size, virt_addr, raw_data_size, raw_data_ptr, relocation_ptr,' +
    'linenum_ptr, linenum_count, reloc_count, flags, reserved, mem_page, data')):

    __slots__ = () # prevent creation of instance dictionaries
    section_fmt = '<8s9L2H'
    section_flags = [
        (0x00000001, 'STYP_DSECT'), (0x00000002, 'STYP_NOLOAD'),
        (0x00000004, 'STYP_GROUPED'), (0x00000008, 'STYP_PAD'),
        (0x00000010, 'STYP_COPY'), (0x00000020, 'STYP_TEXT'),
        (0x00000040, 'STYP_DATA'), (0x00000080, 'STYP_BSS'),
        (0x00000100, 'STYP_100'), (0x00000200, 'STYP_200'),
        (0x00000200, 'STYP_400'), (0x00000800, 'STYP_800'),
        (0x00001000, 'STYP_BLOCK'), (0x00002000, 'STYP_PASS'),
        (0x00004000, 'STYP_CLINK'),(0x00008000, 'STYP_VECTOR'),
        (0x00010000, 'STYP_PADDED'),
    ]

    @property
    def is_zero_filled(self):
        return (self.data is not None) and not any([d != '\0' for d in self.data])

    def fill_value(self):
        if self.data is  None:
            return None

        if len(self.data) % 4:
            return None # only handle 32 bit fill

        a = array('I', self.data)
        if all([d == a[0] for d in a]):
            return a[0]
        else:
            return None

    @property
    def is_loadable(self):
        return not(self.flags & 0x00000010 or self.data is None)

    def __str__(self):
        s = 'Section %s' % self.name
        if self.flags:
            s += ' Flags ='
            for f in Section.section_flags:
                if self.flags & f[0]:
                    s = s + ' ' + f[1]
        for fv in self._asdict().iteritems():
            if fv[0] == 'data' or fv[0] == 'name': continue
            s = s + '\n\t%s = 0x%X' % fv
        return s

class Coff(object):
    Header = namedtuple('Header',
        'machine_type, section_count, time_date, symbol_table_ptr, ' +
        'symbol_count, optional_header_size, flags, target_id')
    header_fmt = '<2H3L3H'

    OptionalHeader = namedtuple('OptionalHeader',
        'magic, version, exe_size, init_data_size, uninit_data_size, entry_point, exe_start, init_start')
    optheader_fmt = '<2H6L'

    def __init__(self, filename=None):
        self.header = None
        self.optheader = None
        self.sections = []
        if filename is not None:
            self.from_file(filename)

    def from_file(self, name):
        with open(name, 'rb') as f:
            self.from_stream(f)

    def from_stream(self, f):
        self.header = self.Header(*read_struct(f, self.header_fmt))
        self.optheader = self.OptionalHeader(*read_struct(f, self.optheader_fmt))
        self.sections = []
        for i in range(self.header.section_count):
            section = Section(*read_struct(f, Section.section_fmt), data=None)
            section = section._replace(name=self.symname(f, section.name))
            if section.raw_data_ptr and section.raw_data_size:
                here = f.tell()
                f.seek(section.raw_data_ptr)
                data = f.read(section.raw_data_size)
                f.seek(here)
                section = section._replace(data=data)
            self.sections.append(section)

        self.entry_point = self.optheader.entry_point
        self.sections.sort(key=lambda s: s.virt_addr)

    @property
    def loadable_sections(self):
        return [s for s in self.sections if s.is_loadable]

    def string_table_entry (self, f, offset):
        here = f.tell()
        seek = self.header.symbol_table_ptr + self.header.symbol_count * 18 + offset
        f.seek(seek)
        s = read_cstr(f)
        f.seek(here)
        return s

    def symname(self, f, value):
        parts = unpack("<2L", value)
        if parts[0] == 0:
            return self.string_table_entry(f, parts[1])
        else:
            return value.rstrip('\0')

    def __str__(self):
        s = 'TI coff file'
        if self.header is not None:
            for fv in self.header._asdict().iteritems():
                s = s + '\n\t%s = 0x%X' % fv
        if self.optheader is not None:
            s += '\nOptional Header'
            for fv in self.optheader._asdict().iteritems():
                s = s + '\n\t%s = 0x%X' % fv
        return s

if __name__ == '__main__':
    parser = OptionParser()
    parser.add_option("-d", "--dump_data",
                      action="store_true", dest="dump", default=False,
                      help="dump section data")

    options, args = parser.parse_args()

    c = Coff(args[0])
    print c

    for section in c.sections:
        print section
        if section.data is not None and options.dump:
            print repr(section)

(...) I looked at the read and noticed that it does not account for each memory location containing 2-bytes. (...)
I have not looked yet at how consistent this is across products or if it is detectable from something in the COFF file.

It may depend on the target CPU, which is mentioned in the COFF file, in the field 'target_id' in the header (NB: this field seems to be an addition made by TI to the normal COFF header).

I have noticed this issue in a COFF with Target ID 0x9D, aka. TMS320C2800.