43 lines
2.4 KiB
C
43 lines
2.4 KiB
C
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/****************************************************************
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* *
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* Copyright 2009 Fidelity Information Services, Inc *
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* *
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* This source code contains the intellectual property *
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* of its copyright holder(s), and is made available *
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* under a license. If you do not know the terms of *
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* the license, please stop and do not read further. *
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* *
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****************************************************************/
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#ifndef GTM_SIZEOF_H_INCLUDED
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#define GTM_SIZEOF_H_INCLUDED
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/* Note: sizeof returns a "UNSIGNED long" type by default. When one of the operand in a relational operation
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* (<, <= etc.) is a SIGNED type and the other is UNSIGNED, both operands are typecast to UNSIGNED (NOT SIGNED)
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* before performing the comparison. This has unexpected consequences. For example, if a variable XYZ is signed
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* and has a negative value of -1, one would expect an "if (X < sizeof(char))" to return TRUE (because X is
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* negative and sizeof of anything is positive) but it actually returns FALSE. We have gotten bit by this at least
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* twice (C9E09-002635 and C9J10-003208). Therefore we define a SIZEOF macro that returns a "SIGNED long" type and
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* use it throughout the code base. This way "if (X < SIZEOF(char))" will evaluate correctly irrespective of
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* whether X is signed or unsigned (if X is signed, since SIZEOF is also signed, a signed comparison occurs;
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* if X is unsigned, since SIZEOF is signed, C's typecasting rules cause a unsigned comparison to occur).
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*
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* In a platform where long is 64-bits and SIZEOF is used in comparisons involving 32-bit variables, a compiler
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* warning is issued for every 64->32 bit auto cast (zOS compiler for now). To avoid this warning, we define the
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* SIZEOF macro to return a "SIGNED int" type on zOS. This will take care of the most common sizeof usages.
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* Whenever SIZEOF needs to be used in expressions involving 64-bit pointer quantities, use ((INTPTR_T)SIZEOF(...)).
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* Whenever SIZEOF needs to be used in expressions involving 64-bit integer quantities, use ((long)SIZEOF(...)).
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*
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* Some modules (like getcaps.c, gtm_tparm.c etc) do not include mdef.h for reasons stated in the corresponding
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* files but yet use sizeof. To enable those modules to use the safer SIZEOF macro as well, we create a separate
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* header file gtm_sizeof.h that is included explicitly by them as well as by mdef.h.
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*/
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#if defined(__MVS__)
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# define SIZEOF(X) ((int)(sizeof(X)))
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#else
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# define SIZEOF(X) ((long)sizeof(X))
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#endif
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#endif
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