Gracious Monks, I'm writing a simple utility to convert 3D vertex information from one file format to another. While reading and parsing the file information I can't seem to figure out why I'm getting very wierd information. For example in a variable that acts as a flag and it's values could be 0-2 it comes in as an arbitrary number in the billions.

Since the file structure is documented as a series of C structs, I tried writing the utility in C which yielded worse results than Perl. At least with Perl I get about 1/4 of the fields back with correct information. Any help or guidance in the right direction would be most appreciated. Here's the code and header structure I'm working with:
*----------- C Code --------------* 
struct block1 {
    char version[64];
    char comments[128];
    char dummy[8];            
    long img_param_flag;      
    long img_data_type;       
    float invalid_point;      
    long  arr_width;           
    long  arr_height;          
    long  db_length;           
    long scale;               
    float iscale;             
    float jscale;
    long trns_matrix_f;       
    double trns_matrix[16];   
    long img_color;           
    long clr_blk_length;      
    long cam_pos_f;           
    float cam_x;
    float cam_y;
    float cam_z;
} *blk1;

[download]

*----------- Perl Code --------------* 
use strict;
use Dumpvalue;
use POSIX;

sub dump_ref  {
    my $ref = shift;
    my $dumper = new Dumpvalue;
    print "Content-Type:text/html\n\n";
    print "<pre>";
    $dumper->dumpValues($ref);
    print "</pre>";
    exit;
}

# read in the 3D info.
# use unpack to parse the structure
my ($block1, $block2);
open(FP, "<./file.pf") || die("Error opening file: $!\n");
binmode(FP);
read(FP, $block1, 512); # 512 byte binary c structure

# Note that the longs are in Network order
my @block1_info = unpack("a64a128a8NNfNNNNffNd16NNNfffN30",$block1);

dump_ref(\@block1_info);
exit;

[download]
*UPDATE* Apparently the only one coming in erroneous (in Perl) is the transformation matrix... the array of 16 doubles. I'm getting numbers like "3.03865194161742e-319" and when I apply them to the data I get numbers even smaller. Indices 13-28 is what I'm referring to... it's a 4 X 4 transformation matrix for conversion to another coordinate system. Here's a dump of the info I'm getting back: 
0  ARRAY(0x80d54b0)
   0  "PIF Format v2.0"
   1  ""
   2  ""
   3  0
   4  1
   5  0
   6  149
   7  78
   8  139464
   9  0
   10  0
   11  0
   12  2
   13  '3.03865194161742e-319'
   14  0
   15  0
   16  0
   17  0
   18  0
   19  '3.04497598188419e-319'
   20  0
   21  0
   22  '3.03865194161742e-319'
   23  0
   24  0
   25  0
   26  0
   27  0
   28  '3.03865194161742e-319'
   29  1
   30  11622
   31  1
   32  0
   33  0
   34  0
   35  0
   36  0
   37  0
   38  0
   39  0
   40  0
   41  0
   42  0
   43  0
   44  0
   45  0
   46  0
   47  0
   48  0
   49  0
   50  0
   51  0
   52  0
   53  0
   54  0
   55  0
   56  0
   57  0
   58  0
   59  0
   60  0
   61  0
   62  0
   63  0
   64  0

[download]

~hb

In reply to C Struct Data Problem by heroin_bob

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.