stdarg.h源代码

  1 /*
  2  * stdarg.h
  3  *
  4  * Provides facilities for stepping through a list of function arguments of
  5  * an unknown number and type.
  6  *
  7  * NOTE: Gcc should provide stdarg.h, and I believe their version will work
  8  *       with crtdll. If necessary I think you can replace this with the GCC
  9  *       stdarg.h.
 10  *
 11  * Note that the type used in va_arg is supposed to match the actual type
 12  * *after default promotions*. Thus, va_arg (..., short) is not valid.
 13  *
 14  * This file is part of the Mingw32 package.
 15  *
 16  * Contributors:
 17  *  Created by Colin Peters <colin@bird.fu.is.saga-u.ac.jp>
 18  *
 19  *  THIS SOFTWARE IS NOT COPYRIGHTED
 20  *
 21  *  This source code is offered for use in the public domain. You may
 22  *  use, modify or distribute it freely.
 23  *
 24  *  This code is distributed in the hope that it will be useful but
 25  *  WITHOUT ANY WARRANTY. ALL WARRANTIES, EXPRESS OR IMPLIED ARE HEREBY
 26  *  DISCLAMED. This includes but is not limited to warranties of
 27  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 28  *
 29  * $Revision: 1.2 $
 30  * $Author: noer $
 31  * $Date: 1998/10/10 00:51:16 $
 32  *
 33  */
 34 
 35 #ifndef _STDARG_H_
 36 #define _STDARG_H_
 37 
 38 /*
 39  * Don't do any of this stuff for the resource compiler.
 40  */
 41 #ifndef RC_INVOKED
 42 
 43 /* 
 44  * I was told that Win NT likes this.
 45  */
 46 #ifndef _VA_LIST_DEFINED
 47 #define _VA_LIST_DEFINED
 48 #endif
 49 
 50 #ifndef    _VA_LIST
 51 #define _VA_LIST
 52 typedef char* va_list;
 53 #endif
 54 
 55 
 56 /*
 57  * Amount of space required in an argument list (ie. the stack) for an
 58  * argument of type t.
 59  */
 60 #define __va_argsiz(t)    \
 61     (((sizeof(t) + sizeof(int) - 1) / sizeof(int)) * sizeof(int))
 62 
 63 
 64 /*
 65  * Start variable argument list processing by setting AP to point to the
 66  * argument after pN.
 67  */
 68 #ifdef    __GNUC__
 69 /*
 70  * In GNU the stack is not necessarily arranged very neatly in order to
 71  * pack shorts and such into a smaller argument list. Fortunately a
 72  * neatly arranged version is available through the use of __builtin_next_arg.
 73  */
 74 #define va_start(ap, pN)    \
 75     ((ap) = ((va_list) __builtin_next_arg(pN)))
 76 #else
 77 /*
 78  * For a simple minded compiler this should work (it works in GNU too for
 79  * vararg lists that don't follow shorts and such).
 80  */
 81 #define va_start(ap, pN)    \
 82     ((ap) = ((va_list) (&pN) + __va_argsiz(pN)))
 83 #endif
 84 
 85 
 86 /*
 87  * End processing of variable argument list. In this case we do nothing.
 88  */
 89 #define va_end(ap)    ((void)0)
 90 
 91 
 92 /*
 93  * Increment ap to the next argument in the list while returing a
 94  * pointer to what ap pointed to first, which is of type t.
 95  *
 96  * We cast to void* and then to t* because this avoids a warning about
 97  * increasing the alignment requirement.
 98  */
 99 
100 #define va_arg(ap, t)                    \
101      (((ap) = (ap) + __va_argsiz(t)),        \
102       *((t*) (void*) ((ap) - __va_argsiz(t))))
103 
104 #endif /* Not RC_INVOKED */
105 
106 #endif /* not _STDARG_H_ */