【提要】本篇《C語言宏定義技巧【1】》特別爲需要語言編程學習的朋友收集整理的，僅供參考。內容如下：
1、防止一個頭文件被重複包含
#ifndef COMDEF_H
#define COMDEF_H
//頭文件內容
#endif
2、重新定義一些類型，防止由於各種平臺和編譯器的不同，而產生的類型字節數差異，方便移植。
typedef unsigned char boolean; /* Boolean value type. */
typedef unsigned long int uint32; /* Unsigned 32 bit value */
typedef unsigned short uint16; /* Unsigned 16 bit value */
typedef unsigned char uint8; /* Unsigned 8 bit value */
typedef signed long int int32; /* Signed 32 bit value */
typedef signed short int16; /* Signed 16 bit value */
typedef signed char int8; /* Signed 8 bit value */
//下面的不建議使用
typedef unsigned char byte; /* Unsigned 8 bit value type. */
typedef unsigned short Word; /* Unsinged 16 bit value type. */
typedef unsigned long dword; /* Unsigned 32 bit value type. */
typedef unsigned char uint1; /* Unsigned 8 bit value type. */
typedef unsigned short uint2; /* Unsigned 16 bit value type. */
typedef unsigned long uint4; /* Unsigned 32 bit value type. */
typedef signed char int1; /* Signed 8 bit value type. */
typedef signed short int2; /* Signed 16 bit value type. */
typedef long int int4; /* Signed 32 bit value type. */
typedef signed long sint31; /* Signed 32 bit value */
typedef signed short sint15; /* Signed 16 bit value */
typedef signed char sint7; /* Signed 8 bit value */
3、得到指定地址上的一個字節或字
#define MEM_B( x ) ( *( (byte *) (x) ) )
#define MEM_W( x ) ( *( (word *) (x) ) )
4、求最大值和最小值
#define MAX( x, y ) ( ((x) > (y)) ? (x) : (y) )
#define MIN( x, y ) ( ((x) < (y)) ? (x) : (y) )
5、得到一個field在結構體(struct)中的偏移量
#define FPOS( type, field )
/*lint -e545 */ ( (dword) &(( type *) 0)-> field ) /*lint +e545 */
6、得到一個結構體中field所佔用的.字節數
#define FSIZ( type, field ) sizeof( ((type *) 0)->field )
7、按照LSB格式把兩個字節轉化爲一個Word
#define FLIPW( ray ) ( (((word) (ray)[0]) * 256) + (ray)[1] )
8、按照LSB格式把一個Word轉化爲兩個字節
#define FLOPW( ray, val )
(ray)[0] = ((val) / 256);
(ray)[1] = ((val) & 0xFF)
9、得到一個變量的地址(word寬度)
#define B_PTR( var ) ( (byte *) (void *) &(var) )
#define W_PTR( var ) ( (word *) (void *) &(var) )
10、得到一個字的高位和低位字節
#define WORD_LO(xxx) ((byte) ((word)(xxx) & 255))
#define WORD_HI(xxx) ((byte) ((word)(xxx) >> 8))
11、返回一個比X大的最接近的8的倍數
#define RND8( x ) ((((x) + 7) / 8 ) * 8 )
 
