生成asm-offset

由於不善於在Makefile中調用shell的相關工具，因此關於asm-offsets.h中的產生的16進制數並不知如何作到。

所以本身寫了個腳本，能夠生成一樣的文件（再次造了輪子）。

參考：https://lkml.org/lkml/2001/10/6/3

#腳本offset.awk
1 /^->$/{printf("\n");next}                                                                                          
2 /^->.*/{sym = $1; val = $2; $1 = ""; $2 = ""; sub(/^\->/,"",sym);sub(/^\$/,"", val);printf("#define %-15s  %3d\t/* 0x%x\t%s */\n", sym, val, val, $0)}

 

 

//測試文件asm-offset.c
#include <stddef.h>

#ifndef offsetof                                                                                                   
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#endif

#define DEFINE(sym, val) \
    asm volatile("\n->" #sym " %0 " #val : : "i" (val))

#define BLANK() asm volatile("\n->" : : )

struct university
{
    int soochow;
    int seu;
    int tsing;
    int peking; 
    int nju;
    int sjtu;
};

int main(void)
{
    BLANK();
    DEFINE(SOOCHOW, offsetof(struct university, soochow));
    BLANK();
    DEFINE(SEU,     offsetof(struct university, seu));
    BLANK();
    DEFINE(TSING,   offsetof(struct university, tsing));
    BLANK();
    DEFINE(PEKING,  offsetof(struct university, peking));
    BLANK();
    DEFINE(NJU,     offsetof(struct university, nju));
    BLANK();
    DEFINE(SJTU,    offsetof(struct university, sjtu)); 
    BLANK();
}

 

使用：

1 gcc -S asm-offset.c; awk -f offset.awk asm-offset.s > asm-offset.h; rm asm-offset.s

輸出：

//asm-offset.h                                                                                                                   

#define SOOCHOW            0    /* 0x0    offsetof(struct university, soochow) */

#define SEU                4    /* 0x4    offsetof(struct university, seu) */

#define TSING              8    /* 0x8    offsetof(struct university, tsing) */

#define PEKING            12    /* 0xc    offsetof(struct university, peking) */

#define NJU               16    /* 0x10   offsetof(struct university, nju) */

#define SJTU              20    /* 0x14   offsetof(struct university, sjtu) */