#ifndef _VAR_H
#define _VAR_H

#include "reg.h"
#include "mem.h"

/*
  Variables (or function/procedure) including symbol information are store in the heap
  The heap segment is a symbol table, too.
  The heap is the upper region of the data memory.
*/

/*
  +----------+ size -1
  |  data+n  |
  |  ..      |
  |  data    | <- addr
  |  length  |
  | name[]   | <- top
  ...
  +----------+ 0  
*/

typedef enum {
  MVAR    = 'V',    // numeric variable or array on the heap    var x,y,z
#if HAS_FUNC > 0
  MVARLOC = 'v',    // numeric variable or array on the stack   var* x,y,z : func (a,b,c) { }
#endif
  MCONST  = 'C',    // constant value
  MFUNC   = 'F',    // user defined function reference
  MPROC   = 'P',    // user defined procedure reference
  MSTRING = 'S',    // string variable
  MEVENT  = 'E',    // user defined events, duplicate, but needed because events table need name string stolen from here!
  MANY    = '*'     // any pattern for heap look-up
} var_type;

#ifndef VARPADDING
#define VARPADDING 1
#endif

typedef struct __attribute__((packed)) {
  char      name[MAXNAMELEN+1+HAS_LOCK+VARPADDING];
  var_type  type;
  index_t   length;   // data length, for proc length is code size, scalar=1, array > 1
  number_t  data;
} var_t;

#define var_s   sizeof(var_t)
// data as an array
#define VARDATA(v,index) ((number_t*)&v->data)[index]

#if HAS_LOCK>0
/*
  variable lock is stored at the end of the name field
*/
#define LOCKDATA(v) v->name[MAXNAMELEN+1] 
#endif

#if HAS_FUNC > 0
  #define VARLOCLEVEL(x) ((index_t)x&1)
  #define VARLOCINDEX(x) ((index_t)x>>1)
  // encode variable address: addr>=0 is heap, addr < -1 is stack
  #define VARADDRESS(var,addr) var->type==MVARLOC?-(VARLOCINDEX(var->data))-2:addr
#endif


/*
  Dual use: Allocates variable on heap or resolves address if exists already (and type and length is conforming)
*/

address_t Allocate(mem_t *M, reg_t *R, char *name, var_type type, index_t length, var_t **v);
void HeapInit();

#endif