pd.if.org Git - pdclib/blob - includes/stdarg.h

   1 /* ----------------------------------------------------------------------------
   2  * $Id$
   3  * ----------------------------------------------------------------------------
   4  * Public Domain C Library - http://pdclib.sourceforge.net
   5  * This code is Public Domain. Use, modify, and redistribute at will.
   6  * ----------------------------------------------------------------------------
   7  * Variable arguments
   8  * ----------------------------------------------------------------------------
   9  * This header is part of a freestanding implementation
  10  * --------------------------------------------------------------------------*/
  11
  12 #ifndef _STDARG_H
  13 #define _STDARG_H _STDARG_H
  14
  15 /* TODO: This code was contributed by Michael Moody, who added:
  16  * "As always with my code it's not guaranteed bug-free (In fact I know for a
  17  * fact it won't work properly on certain archs)."
  18  * Code assumes that:
  19  * - arguments are passed on the stack;
  20  * - arguments are alligned to pointer size.
  21  */
  22
  23 /* ----------------------------------------------------------------------------
  24  * TYPEDEFS
  25  * --------------------------------------------------------------------------*/
  26
  27 typedef char * va_list;
  28
  29 /* ----------------------------------------------------------------------------
  30  * MACROS
  31  * --------------------------------------------------------------------------*/
  32
  33 /** Returns the size of 'type' rounded up to the nearest multiple of the size
  34  * of a pointer. This macro is just here for clarity.
  35  */
  36 #define __va_round(type)                                                      \
  37    (                                                                          \
  38       (sizeof(type) + sizeof(void *) - 1) & ~(sizeof(void *) - 1)             \
  39    )
  40
  41 /** Initialises ap for use by va_arg by setting ap to point at the first
  42  * argument in the ellipsis. parmN is the last known parameter in the function
  43  * definition (ie the one before the ellipsis).
  44  */
  45 #define va_start(ap, parmN)                                                   \
  46    (                                                                          \
  47       (ap) = (char *)&parmN + (__va_round(parmN))                               \
  48       ,                                                                       \
  49       (void)0                                                                 \
  50    )
  51
  52 /** Returns the next argument, assumed variable type is 'type', in the
  53  * ellipsis.
  54  */
  55 #define va_arg(ap, type)                                                      \
  56    (                                                                          \
  57       (ap) += (__va_round(type))                                              \
  58       ,                                                                       \
  59       (*(type*)((ap) - (__va_round(type))))                                   \
  60    )
  61
  62 /** Cleans up ap.
  63  */
  64 #define va_end(ap)                                                            \
  65    (                                                                          \
  66       (ap) = (void *)0                                                        \
  67       ,                                                                       \
  68       (void)0                                                                 \
  69    )
  70
  71 /** Makes the va_list dest be a copy of the va_list src.
  72  */
  73 #define va_copy(dest, src)                                                    \
  74    (                                                                          \
  75       (dest) = (src)                                                          \
  76       ,                                                                       \
  77       (void)0                                                                 \
  78    )
  79
  80 #endif /* _STDARG_H */