On 07.02.2012 20:32, Reinier Olislagers wrote:
On 7-2-2012 19:48, Sven Barth wrote:
On 07.02.2012 17:12, Reinier Olislagers wrote:
Code bombs at decoder.Read(a, readsize). readsize=0 according to
debugger.
readsize=cardinal; according to help "an unsigned 32-bit integer".
However,
http://wiki.lazarus.freepascal.org/Multiplatform_Programming_Guide#32.2F64_bit
seems to imply Cardinal can vary between 32 bit and 64 bit.
Is that the culprit or am I doing anyth else wrong?
Thanks, Sven!
Does your stream contain at least 4096 bytes? According to the
documentation here
http://www.freepascal.org/docs-html/rtl/objects/tstream.read.html the
Read procedure does not perform any check.
Yes, that should be the case, compressed size is 909094 bytes. The file
uncompresses nicely with the bunzip2 executable.
Ok, then I don't know right now what the problem could be... sorry.
Also "Cardinal" is always 32-Bit wide. The only types that change
depending on bitness are "Pointer", "PtrUInt" and "PtrInt".
Thanks.
Let me verify if I understand correctly. The wiki article
http://wiki.lazarus.freepascal.org/Multiplatform_Programming_Guide#32.2F64_bit
says:
FPC defines two types for this: PtrInt and PtrUInt. PtrInt is a 32bit
signed integer on 32 bit platforms and a 64bit signed integer on 64bit
platforms. The same for PtrUInt, but unsigned integer instead.
Use for code that should work with Delphi and FPC:
{$IFNDEF FPC}
type
PtrInt = integer;
PtrUInt = cardinal;
{$ENDIF}
So in Delphi, presumably cardinal varies between 32 and 64 bit, while in
FPC it is always 32 bit. Or am I interpreting this incorrectly?
Yes, you are interpreting this incorrectly. ;)
The code above was meant for older versions of Delphi which did not
support 64-bit. There PtrInt and PtrUInt is not defined (newer versions
since AFAIK Delphi 2007 definee NativeInt and NativeUInt instead which
is supported in FPC 2.6.0 and 2.7.1 as well). Thus the code above simply
defines PtrInt and PtrUInt in a way that works for non-64-Bit Delphi
versions. In principle you might want to simply use NativeInt and
NativeUInt to stay Delphi compatible and just define these two for older
Delphi versions where that type does not exist yet (similiar to the
above code for Ptr(U)Int).
Regards,
Sven
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