# define I_INSTR_MASK		0x1f	/* instruction mask */

# define I_PUSH_ZERO		 0
# define I_PUSH_ONE		 1
# define I_PUSH_INT1		 2	/* 1 signed */
# define I_PUSH_INT4		 3	/* 4 signed */
# define I_PUSH_FLOAT		 4	/* 6 unsigned */
# define I_PUSH_STRING		 5	/* 1 unsigned */
# define I_PUSH_NEAR_STRING	 6	/* 1 unsigned, 1 unsigned */
# define I_PUSH_FAR_STRING	 7	/* 1 unsigned, 2 unsigned */
# define I_PUSH_LOCAL		 8	/* 1 signed */
# define I_PUSH_GLOBAL		 9	/* 1 unsigned */
# define I_PUSH_FAR_GLOBAL	10	/* 1 unsigned, 1 unsigned */
# define I_PUSH_LOCAL_LVAL	11	/* 1 signed */
# define I_PUSH_GLOBAL_LVAL	12	/* 1 unsigned */
# define I_PUSH_FAR_GLOBAL_LVAL	13	/* 1 unsigned, 1 unsigned */
# define I_INDEX		14
# define I_INDEX_LVAL		15
# define I_AGGREGATE		16	/* 1 unsigned, 2 unsigned */
# define I_SPREAD		17	/* 1 signed */
# define I_CAST			18	/* 1 unsigned */
# define I_FETCH		19
# define I_STORE		20
# define I_JUMP			21	/* 2 unsigned */
# define I_JUMP_ZERO		22	/* 2 unsigned */
# define I_JUMP_NONZERO		23	/* 2 unsigned */
# define I_SWITCH		24	/* n */
# define I_CALL_KFUNC		25	/* 1 unsigned (+ 1 unsigned) */
# define I_CALL_AFUNC		26	/* 1 unsigned, 1 unsigned */
# define I_CALL_DFUNC		27	/* 1 unsigned, 1 unsigned, 1 unsigned */
# define I_CALL_FUNC		28	/* 2 unsigned, 1 unsigned */
# define I_CATCH		29	/* 2 unsigned */
# define I_RLIMITS		30
# define I_RETURN		31

# define I_LINE_MASK		0xc0	/* line add bits */
# define I_POP_BIT		0x20	/* pop 1 after instruction */
# define I_TYPE_BIT		I_POP_BIT /* lvalue typechecks assignment */
# define I_LINE_SHIFT		6


# define FETCH1S(pc)	SCHAR(*(pc)++)
# define FETCH1U(pc)	UCHAR(*(pc)++)
# define FETCH2S(pc, v)	((short) (v = *(pc)++ << 8, v |= UCHAR(*(pc)++)))
# define FETCH2U(pc, v)	((unsigned short) (v = *(pc)++ << 8, \
					   v |= UCHAR(*(pc)++)))
# define FETCH3S(pc, v)	((Int) (v = *(pc)++ << 8, \
				v |= UCHAR(*(pc)++), v <<= 8, \
				v |= UCHAR(*(pc)++)))
# define FETCH3U(pc, v)	((Uint) (v = UCHAR(*(pc)++) << 8, \
				 v |= UCHAR(*(pc)++), v <<= 8, \
				 v |= UCHAR(*(pc)++)))
# define FETCH4S(pc, v)	((Int) (v = *(pc)++ << 8, \
				v |= UCHAR(*(pc)++), v <<= 8, \
				v |= UCHAR(*(pc)++), v <<= 8, \
				v |= UCHAR(*(pc)++)))
# define FETCH4U(pc, v)	((Uint) (v = *(pc)++ << 8, \
				 v |= UCHAR(*(pc)++), v <<= 8, \
				 v |= UCHAR(*(pc)++), v <<= 8, \
				 v |= UCHAR(*(pc)++)))


# define T_TYPE		0x0f	/* type mask */
# define T_INVALID	0x00
# define T_INT		0x01
# define T_FLOAT	0x02
# define T_STRING	0x03
# define T_OBJECT	0x04
# define T_ARRAY	0x05	/* value type only */
# define T_MAPPING	0x06
# define T_RESERVED	0x07	/* reserved for add-on packages */
# define T_MIXED	0x08	/* declaration type only */
# define T_VOID		0x09	/* function return type only */
# define T_LVALUE	0x0a	/* address of a value */
# define T_SLVALUE	0x0b	/* indexed string lvalue */
# define T_ALVALUE	0x0c	/* indexed array lvalue */
# define T_MLVALUE	0x0d	/* indexed mapping lvalue */
# define T_SALVALUE	0x0e	/* indexed string indexed array lvalue */
# define T_SMLVALUE	0x0f	/* indexed string indexed mapping lvalue */

# define T_ELLIPSIS	0x10	/* or'ed with declaration type */

# define T_REF		0xe0	/* reference count mask */
# define REFSHIFT	5

# define T_ARITHMETIC(t) ((t) <= T_FLOAT)
# define T_ARITHSTR(t)	((t) <= T_STRING)
# define T_INDEXED(t)	((t) >= T_ARRAY)	/* only T_ARRAY and T_MAPPING */

# define TYPENAMES	{ "invalid", "int", "float", "string", "object", \
			  "array", "mapping", "reserved", "mixed", "void" }

struct _value_ {
    char type;			/* value type */
    bool modified;		/* dirty bit */
    uindex oindex;		/* index in object table */
    union {
	Int number;		/* number */
	Uint objcnt;		/* object creation count */
	string *string;		/* string */
	array *array;		/* array or mapping */
	value *lval;		/* lvalue: variable */
    } u;
};

# define VFLT_GET(v, f)	((f).high = (v)->oindex, (f).low = (v)->u.objcnt)
# define VFLT_PUT(v, f)	((v)->oindex = (f).high, (v)->u.objcnt = (f).low)
# define VFLT_ISZERO(v)	FLT_ISZERO((v)->oindex, (v)->u.objcnt)
# define VFLT_ISONE(v)	FLT_ISONE((v)->oindex, (v)->u.objcnt)
# define VFLT_ONE(v)	FLT_ONE((v)->oindex, (v)->u.objcnt)
# define VFLT_ABS(v)	FLT_ABS((v)->oindex, (v)->u.objcnt)
# define VFLT_NEG(v)	FLT_NEG((v)->oindex, (v)->u.objcnt)
# define VFLT_HASH(v)	((v)->oindex ^ (v)->u.objcnt)

# define DESTRUCTED(v)	(otable[(v)->oindex].count != (v)->u.objcnt)


# define C_PRIVATE	0x01
# define C_STATIC	0x02
# define C_NOMASK	0x04
# define C_VARARGS	0x08
# define C_ATOMIC	0x10
# define C_TYPECHECKED	0x20
# define C_COMPILED	0x40
# define C_UNDEFINED	0x80


struct _frame_ {
    frame *prev;		/* previous stack frame */
    object *obj;		/* current object */
    control *ctrl;		/* object control block */
    dataspace *data;		/* dataspace of current object */
    control *p_ctrl;		/* program control block */
    unsigned short p_index;	/* program index */
    unsigned short nargs;	/* # arguments */
    bool external;		/* TRUE if it's an external call */
    bool sos;			/* stack on stack */
    uindex foffset;		/* program function offset */
    struct _dfuncdef_ *func;	/* current function */
    char *prog;			/* start of program */
    char *pc;			/* program counter */
    value *stack;		/* local value stack */
    value *sp;			/* stack pointer */
    value *ilvp;		/* indexed lvalue pointer */
    value *argp;		/* argument pointer (previous sp) */
    value *fp;			/* frame pointer (at end of local stack) */
    value *prev_ilvp;		/* previous indexed lvalue pointer */
    string *lvstr;		/* last indexed lvalue string */
    Int depth;			/* stack depth */
    Int maxdepth;		/* max stack depth */
    Int ticks;			/* ticks left */
    bool nodepth;		/* no stack depth checking */
    bool noticks;		/* no ticks checking */
    short rli;			/* rlimits stack index */
};


extern void		i_init		P((char*));
extern void		i_ref_value	P((value*));
extern void		i_del_value	P((value*));
extern void		i_copy		P((value*, value*, unsigned int));
extern void		i_grow_stack	P((frame*, int));
extern void		i_push_value	P((frame*, value*));
extern void		i_pop		P((frame*, int));
extern void		i_odest		P((frame*, object*));
extern void		i_string	P((frame*, int, unsigned int));
extern void		i_aggregate	P((frame*, unsigned int));
extern void		i_map_aggregate	P((frame*, unsigned int));
extern int		i_spread	P((frame*, int, int));
extern void		i_global	P((frame*, int, int));
extern void		i_global_lvalue	P((frame*, int, int, int));
extern void		i_index		P((frame*));
extern void		i_index_lvalue	P((frame*, int));
extern char	       *i_typename	P((unsigned int));
extern void		i_cast		P((value*, unsigned int));
extern void		i_fetch		P((frame*));
extern void		i_store		P((frame*, value*, value*));
extern Int		i_get_depth	P((frame*));
extern Int		i_get_ticks	P((frame*));
extern int		i_set_rlimits	P((frame*, Int, Int));
extern int		i_get_rllevel	P((frame*));
extern void		i_set_rllevel	P((frame*, int));
extern frame	       *i_set_sp	P((frame*, value*));
extern object	       *i_prev_object	P((frame*, int));
extern char	       *i_prev_program	P((frame*, int));
extern void		i_typecheck	P((frame*, char*, char*, char*, int,
					   int));
extern void		i_catcherr	P((frame*, Int));
extern void		i_funcall	P((frame*, object*, int, int, int));
extern bool		i_call		P((frame*, object*, char*, unsigned int,
					   int, int));
extern bool		i_call_tracei	P((frame*, Int, value*));
extern array	       *i_call_trace	P((frame*));
extern bool		i_call_critical	P((frame*, char*, int, int));
extern void		i_runtime_error	P((frame*, Int));
extern void		i_clear		P((void));

extern frame *cframe;
extern value zero_value, zero_float;

# define i_add_ticks(f, t)	((f)->ticks -= (t))