stdarg.h

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#ifndef __STDARG_H__
#define __STDARG_H__
 
 
#ifdef __cplusplus
extern "C"
{
#endif
 
 
    /*
     * __clang__ is deliberately *not* tested above. mainline's
     * <linux/stdarg.h> forwards here, so whichever type is typedef'd
     * below is the one every drm source sees -- and the two drm users
     * want opposite things from it. drm_print.c needs the builtins
     * (clang's va_start rejects a hand-rolled pointer), and
     * KernelAA64/Drivers/uart.c:129 needs the flat one, because
     * `va_list args = ((va_list)reg_save_area + 8)` only compiles when
     * va_list is a pointer it can cast and add to.
     *
     * XEClib's userspace copy of this header
     * (Libs/XEClib/includes/stdarg.h) *has* moved arm-64 to the builtins,
     * with a note naming the forwarded-va_list cases the pointer walk gets
     * wrong. When this side follows it, the thing that has to change is
     * uart.c's register-save-area walk -- not this typedef back and forth.
     */
#ifdef __GNUC__
    typedef __builtin_va_list va_list;
#else
    /* va list parameter list */
    typedef unsigned char* va_list;
#endif
 
 
    /* width of stack == width of int */
#define STACKITEM   int64_t
 
    /* round up width of objects pushed on stack. The expression before the
    & ensures that we get 0 for objects of size 0. */
#define VA_SIZE(TYPE)                   \
    ((sizeof(TYPE)+sizeof(STACKITEM)-1) \
    & ~(sizeof(STACKITEM)-1))
 
#if defined(ARCH_X64) || defined(__x86_64__)
    /* &(LASTARG) points to the LEFTMOST argument of the function call
    (before the ...) */
#define va_start(AP, LASTARG)   \
    (AP = ((va_list)&(LASTARG)+VA_SIZE(LASTARG)))
 
    /* nothing for va_end */
#define va_end(AP)
 
#define va_arg(AP, TYPE)    \
    (AP += VA_SIZE(TYPE), *((TYPE *)(AP - VA_SIZE(TYPE))))
#elif defined(ARCH_ARM64) || defined(__aarch64__)
#ifdef __GNUC__
#define va_start(ap, last) __builtin_va_start(ap, last)
#define va_arg(ap, type) __builtin_va_arg(ap, type)
#define va_end(ap) __builtin_va_end(ap)
#else
#define va_start(ap,last) \
     ((ap) = (va_list)(&(last)) + 8)
 
#define va_arg(ap,T) \
     (*(T*)((ap) += 8, (ap) - 8))
 
#define va_end(ap) \
     ((ap) = (va_list)0)
#endif
#endif
 
#ifdef __cplusplus
}
#endif
 
 
#endif