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/*
* Copyright 1997, University Corporation for Atmospheric Research
* See netcdf/COPYRIGHT file for copying and redistribution conditions.
*/
/* $Id: onstack.h,v 1.1 2005/07/15 21:56:39 andy Exp $ */
#ifndef _ONSTACK_H_
#define _ONSTACK_H_
/* include after ncconfig.h */
/**
* This file provides definitions which allow us to
* "allocate" arrays on the stack where possible.
* (Where not possible, malloc and free are used.)
*
* The macro ALLOC_ONSTACK(name, type, nelems) is used to declare
* an array of 'type' named 'name' which is 'nelems' long.
* FREE_ONSTACK(name) is placed at the end of the scope of 'name'
* to call 'free' if necessary.
*
* The macro ALLOC_ONSTACK wraps a call to alloca() on most systems.
*/
#if HAVE_ALLOCA
/*
* Implementation based on alloca()
*/
#if defined(__GNUC__)
# if !defined(alloca)
# define alloca __builtin_alloca
# endif
#else
# if HAVE_ALLOCA_H
# include <alloca.h>
# elif defined(_AIX)
# pragma alloca
# endif /* HAVE_ALLOCA_H */
#endif /* __GNUC__ */
# if !defined(ALLOCA_ARG_T)
# define ALLOCA_ARG_T int /* the usual type of the alloca argument */
# endif
# define ALLOC_ONSTACK(name, type, nelems) \
type *const name = (type *) alloca((ALLOCA_ARG_T)((nelems) * sizeof(type)))
# define FREE_ONSTACK(name)
#elif defined(_CRAYC) && !__cplusplus && __STDC__ > 1
/*
* Cray C allows sizing of arrays with non-constant values.
*/
# define ALLOC_ONSTACK(name, type, nelems) \
type name[nelems]
# define FREE_ONSTACK(name)
#else
/*
* Default implementation. When all else fails, use malloc/free.
*/
# define ALLOC_ONSTACK(name, type, nelems) \
type *const name = (type *) malloc((nelems) * sizeof(type))
# define FREE_ONSTACK(name) \
free(name)
#endif
#endif /* _ONSTACK_H_ */
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