标签:soft amp copy rpo x86 reserve ssi spl ons
standrad parameter
该头文件包含了一个变量类型和3个宏
变量类型
va_list
#ifndef _VA_LIST_DEFINED #ifdef _M_ALPHA typedef struct { char *a0; /* pointer to first homed integer argument */ int offset; /* byte offset of next parameter */ } va_list; #else typedef char * va_list; #endif
它通常是一个字符型指针
宏
va_start ( va_list valist , int num )
用于初始化va_list型的变量,从左到右获取num个参数。
va_arg ( valist valist , type )
以type型返回当前valist指向的参数,然后让valist所指的地址向后移动sizeof(type)个字节
就相当于返回type型的一个参数,然后valist指向下一个参数
va_end ( va_list valist )
让va_list型的变量指向NULL
就相当于释放了va_list
头文件
1 /*** 2 *stdarg.h - defines ANSI-style macros for variable argument functions 3 * 4 * Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved. 5 * 6 *Purpose: 7 * This file defines ANSI-style macros for accessing arguments 8 * of functions which take a variable number of arguments. 9 * [ANSI] 10 * 11 * [Public] 12 * 13 ****/ 14 15 #if _MSC_VER > 1000 16 #pragma once 17 #endif 18 19 #ifndef _INC_STDARG 20 #define _INC_STDARG 21 22 #if !defined(_WIN32) && !defined(_MAC) 23 #error ERROR: Only Mac or Win32 targets supported! 24 #endif 25 26 27 #ifdef _MSC_VER 28 /* 29 * Currently, all MS C compilers for Win32 platforms default to 8 byte 30 * alignment. 31 */ 32 #pragma pack(push,8) 33 #endif /* _MSC_VER */ 34 35 #ifdef __cplusplus 36 extern "C" { 37 #endif 38 39 40 41 #ifndef _VA_LIST_DEFINED 42 #ifdef _M_ALPHA 43 typedef struct { 44 char *a0; /* pointer to first homed integer argument */ 45 int offset; /* byte offset of next parameter */ 46 } va_list; 47 #else 48 typedef char * va_list; 49 #endif 50 #define _VA_LIST_DEFINED 51 #endif 52 53 #ifdef _M_IX86 54 55 56 #define _INTSIZEOF(n) ( (sizeof(n) + sizeof(int) - 1) & ~(sizeof(int) - 1) ) 57 58 #define va_start(ap,v) ( ap = (va_list)&v + _INTSIZEOF(v) ) 59 #define va_arg(ap,t) ( *(t *)((ap += _INTSIZEOF(t)) - _INTSIZEOF(t)) ) 60 #define va_end(ap) ( ap = (va_list)0 ) 61 62 #elif defined(_M_MRX000) 63 64 65 /* Use these types and definitions if generating code for MIPS */ 66 67 #define va_start(ap,v) ap = (va_list)&v + sizeof(v) 68 #define va_end(list) 69 #define va_arg(list, mode) ((mode *)(list = 70 (char *) ((((int)list + (__builtin_alignof(mode)<=4?3:7)) & 71 (__builtin_alignof(mode)<=4?-4:-8))+sizeof(mode))))[-1] 72 73 /* +++++++++++++++++++++++++++++++++++++++++++ 74 Because of parameter passing conventions in C: 75 use mode=int for char, and short types 76 use mode=double for float types 77 use a pointer for array types 78 +++++++++++++++++++++++++++++++++++++++++++ */ 79 80 81 #elif defined(_M_ALPHA) 82 83 84 /* Use these types and definitions if generating code for ALPHA */ 85 86 /* 87 * The Alpha compiler supports two builtin functions that are used to 88 * implement stdarg/varargs. The __builtin_va_start function is used 89 * by va_start to initialize the data structure that locates the next 90 * argument. The __builtin_isfloat function is used by va_arg to pick 91 * which part of the home area a given register argument is stored in. 92 * The home area is where up to six integer and/or six floating point 93 * register arguments are stored down (so they can also be referenced 94 * by a pointer like any arguments passed on the stack). 95 */ 96 97 extern void * __builtin_va_start(va_list, ...); 98 99 #ifdef _CFRONT 100 #define __builtin_isfloat(a) __builtin_alignof(a) 101 #endif 102 103 #define va_start(list, v) __builtin_va_start(list, v, 1) 104 #define va_end(list) 105 #define va_arg(list, mode) 106 ( *( ((list).offset += ((int)sizeof(mode) + 7) & -8) , 107 (mode *)((list).a0 + (list).offset - 108 ((__builtin_isfloat(mode) && (list).offset <= (6 * 8)) ? 109 (6 * 8) + 8 : ((int)sizeof(mode) + 7) & -8) 110 ) 111 ) 112 ) 113 114 #elif defined(_M_PPC) 115 116 /* Microsoft C8 front end (used in Motorola Merged compiler) */ 117 /* bytes that a type occupies in the argument list */ 118 #define _INTSIZEOF(n) ( (sizeof(n) + sizeof(int) - 1) & ~(sizeof(int) - 1) ) 119 /* return ‘ap‘ adjusted for type ‘t‘ in arglist */ 120 #define _ALIGNIT(ap,t) 121 ((((int)(ap))+(sizeof(t)<8?3:7)) & (sizeof(t)<8?~3:~7)) 122 123 #define va_start(ap,v) ( ap = (va_list)&v + _INTSIZEOF(v) ) 124 #define va_arg(ap,t) ( *(t *)((ap = (char *) (_ALIGNIT(ap, t) + _INTSIZEOF(t))) - _INTSIZEOF(t)) ) 125 #define va_end(ap) ( ap = (va_list)0 ) 126 127 #elif defined(_M_M68K) 128 #define _INTSIZEOF(n) ( (sizeof(n) + sizeof(int) - 1) & ~(sizeof(int) - 1) ) 129 130 #define va_start(ap,v) ( ap = (va_list)&v + (sizeof(v) < sizeof(int) ? sizeof(v) : _INTSIZEOF(v)) ) 131 #define va_arg(ap,t) ( *(t *)((ap += _INTSIZEOF(t)) - _INTSIZEOF(t)) ) 132 #define va_end(ap) ( ap = (va_list)0 ) 133 134 #elif defined(_M_MPPC) 135 #define _INTSIZEOF(n) ( (sizeof(n) + sizeof(int) - 1) & ~(sizeof(int) - 1) ) 136 137 #define va_start(ap,v) ( ap = (va_list)&v + _INTSIZEOF(v) ) 138 #define va_arg(ap,t) ( *(t *)((ap += _INTSIZEOF(t)) - _INTSIZEOF(t)) ) 139 #define va_end(ap) ( ap = (va_list)0 ) 140 141 #else 142 143 /* A guess at the proper definitions for other platforms */ 144 145 #define _INTSIZEOF(n) ( (sizeof(n) + sizeof(int) - 1) & ~(sizeof(int) - 1) ) 146 147 #define va_start(ap,v) ( ap = (va_list)&v + _INTSIZEOF(v) ) 148 #define va_arg(ap,t) ( *(t *)((ap += _INTSIZEOF(t)) - _INTSIZEOF(t)) ) 149 #define va_end(ap) ( ap = (va_list)0 ) 150 151 152 #endif 153 154 155 #ifdef __cplusplus 156 } 157 #endif 158 159 #ifdef _MSC_VER 160 #pragma pack(pop) 161 #endif /* _MSC_VER */ 162 163 #endif /* _INC_STDARG */
标签:soft amp copy rpo x86 reserve ssi spl ons
原文地址:https://www.cnblogs.com/jawide/p/10825684.html