1,从https://github.com/vlm/asn1c 下载最新版的asn1c的源码；
2，打开Linux系统，将asn1c源码解压，找到INSTALL.md文件，根据INSTALL.md文件步骤安装即可；
3，将下述内容的asn文件保存为Rectangle.asn文件（假设所在文件夹目录为../RectangleTest,./目录为asn1c安装目录asn1c-master）
RectangleTest DEFINITIONS ::= BEGIN
Rectangle ::= SEQUENCE {
height INTEGER, -- Height of the rectangle
width INTEGER -- Width of the rectangle
}
END
4，编译asn文件
5，生成的C文件在RectangleTest目录中
6，将下述代码保存为main.c文件，
1 #include <stdio.h> 2 #include <sys/types.h> 3 #include <Rectangle.h> /* Rectangle ASN.1 type */ 4 /* Write the encoded output into some FILE stream. */ 5 static int write_out(const void *buffer, size_t size, void *app_key) { 6 FILE *out_fp = app_key; 7 size_t wrote = fwrite(buffer, 1, size, out_fp); 8 return (wrote == size) ? 0 : -1; 9 } 10 int main(int ac, char **av) { 11 Rectangle_t *rectangle; /* Type to encode */ 12 asn_enc_rval_t ec; /* Encoder return value */ 13 /* Allocate the Rectangle_t */ 14 rectangle = calloc(1, sizeof(Rectangle_t)); /* not malloc! */ 15 if(!rectangle) { 16 perror("calloc() failed "); 17 exit(1); 18 } 19 /* Initialize the Rectangle members */ 20 rectangle->height = 42; /* any random value */ 21 rectangle->width = 23; /* any random value */ 22 /* BER encode the data if filename is given */ 23 if(ac < 2) { 24 fprintf(stderr," specify filename for BER output "); 25 } else { 26 const char *filename = av[1]; 27 FILE *fp = fopen(filename, "wb"); /* for BER output */ 28 if(!fp) { 29 perror(filename); 30 exit(1); 31 } 32 /* Encode the Rectangle type as BER (DER) */ 33 ec = der_encode(&asn_DEF_Rectangle, rectangle, write_out, fp); 34 fclose(fp); 35 if(ec.encoded == -1) { 36 fprintf(stderr, "”Could not encode Rectangle (at %s) ”", 37 ec.failed_type ? ec.failed_type->name : "unknown"); 38 exit(1); 39 } else { 40 fprintf(stderr, "”Created %s with BER encoded Rectangle ”", filename); 41 } 42 } 43 /* Also print the constructed Rectangle XER encoded (XML) */ 44 xer_fprint(stdout, &asn_DEF_Rectangle, rectangle); 45 return 0; /* Encoding finished successfully */ 46 }
7.输入gcc -I. -o rencode *.c ，生成recode文件
8，执行./recode，结果如下：
