alloca.h File Reference

defines the alloca() function More...

#include <nlibc.h>
#include <stddef.h>

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Defines
#define	alloca(SIZE)   __builtin_alloca(SIZE)
Functions
void *	alloca (size_t)

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Detailed Description

defines the alloca() function

Id

alloca.h,v 2.3 2005/10/27 20:04:44 morinl Exp

Definition in file alloca.h.

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Define Documentation

#define alloca (  SIZE   )     __builtin_alloca(SIZE)

Definition at line 59 of file alloca.h. Referenced by stringexpand().

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Function Documentation

alloca (  size_t   )

NAME alloca - memory allocator SYNOPSIS #include <alloca.h> void *alloca(size_t size); DESCRIPTION The alloca function allocates size bytes of space in the stack frame of the caller. This temporary space is automatically freed when the function that called alloca returns to its caller. RETURN VALUE The alloca function returns a pointer to the beginning of the allocated space. If the allocation causes stack over­ flow, program behaviour is undefined. CONFORMING TO There is evidence that the alloca function appeared in 32v, pwb, pwb.2, 3bsd, and 4bsd. There is a man page for it in BSD 4.3. This function is not in POSIX or SUSv3. NOTES The fact that the code is inlined, means that it is impossible to take the address of this function, or to change its behaviour by linking with a different library. BUGS On many systems (inluding apeNEXT) alloca cannot be used inside the list of arguments of a function call, because the stack space reserved by alloca would appear on the stack in the middle of the space for the function arguments. The inlined code consists of a few instructions adjusting the stack pointer and does not check for stack overflow. Thus, there is no NULL error return. IMPLEMENTATION for apeNEXT: done. No stack checking yet. The parameter size MUST be in bytes AND take alignments into account. See sizeof_aligned().

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