$Bill wrote:
>Suresh Govindachar wrote:
>>
>> The following code is meant for a Big-endian processor running
>> linux. The code reads binary files and assigns values to
>> structures. I would like to read the same data files in perl on
>> Windows on little endian x86. Any tips on doing the translation?
>
> I would just use unpack - you could write your own char-by-char
> conversion routines if you wanted to (get_long, get_ulong,
> get_short, etc). Longs and shorts are considered to be 32/16
> bits and ints are based on build type, but there are native
> options. Read the pack info in perlfunc man page.
>
> sysopen IN, $file, O_RDONLY or die "open $file: $! ($^E)";
> binmode IN;
I had to open the file via:
open (IN, "<:raw", $file_name) or die "Unable to open $file_name for
reading:$!\n";
binmode IN;
Perl complained about bareword O_RDONLY -- see reproducible code
below.
> my $bytes = sysread IN, $data, 4;
> die "Wrong length data ($bytes): $! ($^E)" if $bytes != 4;
> printf "data=%d\n", unpack 'N', $data; # convert network order long
> close IN;
>
> # or read the whole struct into $data and unpack it in one call:
>
> my ($type, $x, $y, $w, ... ) = unpack 'nNNN...', $data;
Monk ikegami pointed out Convert::Binary::C. This module worked
after two tweaks:
1) It did not recognize 'bool'. Determined that size of bool was
1 byte and so replaced bool by char.
2) Total of sizes of members of one structure was 22. C-code
automatically padded 2 bytes. I had to add a short into the
structure at the right spot.
But I was having trouble reading the file into scalars to be
unpacked by Convert::Binary::C -- till I saw "sysread " in
this post!
#!/usr/bin/perl
BEGIN {(*STDERR = *STDOUT) || die;}
use diagnostics;
use warnings;
use strict;
$| = 1;
my $file = 'foofile';
sysopen IN, $file, O_RDONLY or die "open $file: $! ($^E)"; # this is
line 10
__END__
Uncaught exception from user code:
Bareword "O_RDONLY" not allowed while "strict subs" in use at
foo.pl line 10.
Execution of foo.pl aborted due to compilation errors.
Thanks,
--Suresh
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