/** set to 1 if a is TOS when evaluting a op b. */
typedef struct {
    char sub;
    char lsh;
    char rsh;
    char mod;
    char div;
    char lt;
    char le;
    char gt;
    char ge;
} rhs_first;

typedef struct {
    unsigned char max_unaligned_load;
    /* Stack specific functions */
    int depth;
    Node (*recalcNode)(Node temp, Node cse);
    int (*makeVirtual)(Symbol p);
    void* reserved2;
    /* The following functions are used by LBURG code-generator */
    void (*_label)(Node);
    int (*_rule)(void*, int);
    short **_nts;
    void (*_kids)(Node, int, Node*);
    char **_string;
    char **_templates;
    char *_isinstruction;
    char **_ntname;
    void (*emit2)(Node);
    /* Swap nodes for various binary ops. rhs.xx == 1 means rhs of xx is evaluated first. */
    rhs_first rhs;
} Xinterface;

typedef struct {
    int offset;
    unsigned freemask[2];
} Env;

#define LBURG_MAX SHRT_MAX

enum { VREG  =(44<<4) };
enum { STACK =(45<<4) };
//enum { TUCK  =(46<<4) };
enum { COPY  =(47<<4) };
enum { NOOP  =(48<<4) };

typedef struct {
    unsigned listed:1;
    unsigned registered:1;
    unsigned emitted:1;
    unsigned copy:1;
    unsigned duplicate:1;
    unsigned defn:1;
    unsigned mayrecalc:1;
    unsigned dead:1;
    void *state;
    short inst;
    int e_depth;
    int l_depth;
    /** For root nodes this links all roots within a basic block. 
      * For leaf register nodes this links all usages and definitions within a basic block. */
    Node prev, next;
    /** Points to the next use of the same variable within the same basic block */
    Node nextUse;
    /** Availble for use within optimisation stages */
    int scratch;
} Xnode;

typedef struct {
    char *name;
    /** Memory frame offset for the local variable represented by this Symbol */
    int offset;
    /** Corresponds to the index of this Symbol in the global list local_variable_list */
    int uniqueID;
    /** Availble for use within optimisation stages */
    int scratch;
//    unsigned spilled:1;
//    unsigned allocated:1;
    unsigned branchTemp:1;
} Xsymbol;

extern int offset;
extern int maxoffset;
extern int framesize;
/** The number of variables allocated within this function, useful upper limit for set sizes */
extern int local_variable_count;

extern int getEDepth(Node n);
extern int getLDepth(Node n);
extern int getDelve(Node n);
extern void setDelve(Node n, int delve);

extern void printTree(Node n, FILE* file);
extern void stackemit(Node forest);

extern void prettytree(Node n);
extern void backendflags(int argc, char** argv);
extern void write_log(char* format, ...);
extern FILE* logfile;
extern void makeTemporary(Symbol p);
extern Symbol localVariableSymbol(int n);
extern void  verify(char* name);
extern Node stackParameters(Symbol caller[], Symbol callee[]);
extern void mkauto(Symbol p);
extern int range(Node p, int lo, int hi);
extern int getEDepth(Node n);
extern int getTotalDepth(Node n);
extern int getDelve(Node n);
extern void setDelve(Node n, int delve);
extern void optimise(void);
#define getTempIndex(n) (n->syms[0]->x.uniqueID)

#define LOG(x) if (logfile) write_log x