string.c

用于汇编领域的,运用于OS的MAIN函数.基于硬件基础的源代码

// string utility routines
int findloc(char *buf, char c){
// return the first appearing location of c in buf
// return -1 if no c in buf
   int i;
   for(i=0;;i++){
      if (buf[i]==c) return i;
	  if (buf[i]==0) return -1; // end of string
   }
}

void substr(char *buf, char *dest, int beg, int end){
// copy buf[beg] to buf[end] into dest. make it a string
   int i,j;
   for(i=0,j=beg;j<=end;i++,j++)
      dest[i]=buf[j];
   dest[i]=0;
}

void write_substr(char *buf, char *dest, int beg, int end){
// copy buf into dest[beg]..dest[end]. 
   int i,j;
   for(i=0,j=beg;j<=end;i++,j++)
      dest[j]=buf[i];
}

void copystr(char *buf, char *dest){
   int i;
   for(i=0;;i++){
	  dest[i]=buf[i];
      if (buf[i]==0) return;
   }
}

void strcpy(char *dest, char *buf){
   copystr(buf, dest); // for compatibility
}
void strncpy(char *dest, char *buf, int len){
   int i;
   for(i=0;i<len;i++){
	  dest[i]=buf[i];
   }
}

int strlen(char *buf){
   int i;
   for(i=0;;i++)
      if (buf[i]==0) return i;
}

int strcmp(char *s1, char *s2){
// return 0 if same; otherwise return -1
   int i,n1,n2;
   n1=strlen(s1); n2=strlen(s2);
   if (n1!=n2) return -1;
   for(i=0;i<n1;i++)
      if (s1[i]!=s2[i]) return -1;
   return 0;
}

int strncmp(char *s1, char *s2, int len){
// return 0 if same; otherwise return -1
   int i;
   for(i=0;i<len;i++)
      if (s1[i]!=s2[i]) return -1;
   return 0;
}
int get_next_tok(char *buf, char *dest, char c){
// get substr (delimiter c) in buf to dest
// if there is no delimiter in buf, everything is considered
// as a substr, so put but into dest in this case, and return
// 1 to indicate we didn't find the delimiter
   int x;
   x=findloc(buf,c);  // the next appearance of c in buf
   if (x==-1){ // token is the whole string in buf
      copystr(buf, dest);
	  return 1; // dest is the leaf of the path
   }
   else if (x==0) // token is buf[0]
      substr(buf, dest, 0, 0);      
   else //buf[0] to buf[x-1] is the token
      substr(buf, dest, 0, x-1);
   // we found delimiter
   return 0; // normal case

}