#include <stdio.h>
#include <string.h>

// the function trace stack is a simple linked list of 
// pointers to function identifiers
// the head of the list is the op of the stack
struct TRACE_NODE_STRUCT {
  char* floc;                      // ptr to function identifier
  struct TRACE_NODE_STRUCT* next;  // ptr to next frama
};
typedef struct TRACE_NODE_STRUCT TRACE_NODE;
static TRACE_NODE* TRACETop = NULL;       // ptr to the top of the stack



/* function PUSH_TRACE ---------------------------------------------- */
void PUSH_TRACE(char* p)          // push p on the stack
{
  TRACE_NODE* tnode;
  static char glob[]="global";

  if (TRACETop==NULL) {
    // initialize the stack with "global" identifier

    TRACETop=(TRACE_NODE*) malloc(sizeof(TRACE_NODE));

    // no recovery needed if allocation failed, this is only
    // used in debugging, not in production
    if (TRACETop==NULL) { 
      printf("PUSH_TRACE: memory allocation error\n");
      exit(1);   
    }

    TRACETop->floc = glob;
    TRACETop->next=NULL;
  }
  // now create the node for p

  tnode = (TRACE_NODE*) malloc(sizeof(TRACE_NODE));

  // no recovery needed if allocation failed, this is only
  // used in debugging, not in production
  if (tnode==NULL) {
    printf("PUSH_TRACE: memory allocation error\n");
    exit(1);
  }

  tnode->floc=p;
  tnode->next = TRACETop;  // insert fnode as the first in the list
  TRACETop=tnode;          // point TRACETop to the first node

}/*end PUSH_TRACE*/




/* function POP_TRACE ---------------------------------------------- */
void POP_TRACE()    // remove the op of the stack
{
  TRACE_NODE* tnode;
  tnode = TRACETop;
  TRACETop = tnode->next;
  free(tnode);

}/*end POP_TRACE*/



/* report `depth' top entries from the stack in the form
   fun1:fun2:fun3:....:funk  meaning fun1 called from fun2
   that was called from fun3 ... that was called from funk
   where k = depth
   The calling path may be up to 100 characters, if longer
   it is truncated  */

/* function REPORT_TRACE ---------------------------------------------- */
char* REPORT_TRACE(int depth)
{
  int i, length, j;
  TRACE_NODE* tnode;
  static char buf[100];
 
  if (TRACETop==NULL) {     // stack not initialized yet, so we are
    strcpy(buf,"global");   // still in the `global' area
    return buf;
  }

  /* peek at the depth top entries on the stactk, but do not
     go over 100 chars and do not go over the bottom of the
     stack */

  sprintf(buf,"%s",TRACETop->floc);
  length = strlen(buf);                  // length of the string so far
  for(i=1, tnode=TRACETop->next; 
                        tnode!=NULL && i < depth; 
                                  i++,tnode=tnode->next) {
    j = strlen(tnode->floc);             // length of what we want to add
    if (length+j+1 < 100) {              // total length is ok
      sprintf(buf+length,":%s",tnode->floc);
      length += j+1;
    }else                                // it would be too long
      break;
  }
  return buf;
}