erl_term.h

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/* ``The contents of this file are subject to the Erlang Public License,
 * Version 1.1, (the "License"); you may not use this file except in
 * compliance with the License. You should have received a copy of the
 * Erlang Public License along with this software. If not, it can be
 * retrieved via the world wide web at http://www.erlang.org/.
 * 
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 * 
 * The Initial Developer of the Original Code is Ericsson Utvecklings AB.
 * Portions created by Ericsson are Copyright 1999, Ericsson Utvecklings
 * AB. All Rights Reserved.''
 * 
 *     $Id$
 */

#ifndef __ERL_TERM_H
#define __ERL_TERM_H

struct erl_node_; /* Declared in erl_node_tables.h */

/*
 * Defining ET_DEBUG to 1 causes all type-specific data access
 * macros to perform runtime type checking. This is very useful
 * during development but reduces performance, so ET_DEBUG should
 * be disabled during benchmarking or release.
 */
/* #define ET_DEBUG 1 */
#ifndef ET_DEBUG
#  ifdef DEBUG
#    define ET_DEBUG 1
#  else
#    define ET_DEBUG 0
#  endif
#endif

#if ET_DEBUG
#define _ET_DECLARE_CHECKED(TF,F,TX) extern TF checked_##F(TX,const char*,unsigned)
#define _ET_APPLY(F,X)	checked_##F(X,__FILE__,__LINE__)
#else
#define _ET_DECLARE_CHECKED(TF,F,TX)
#define _ET_APPLY(F,X)	_unchecked_##F(X)
#endif

#define _TAG_PRIMARY_SIZE	2
#define _TAG_PRIMARY_MASK	0x3
#define TAG_PRIMARY_HEADER	0x0
#define TAG_PRIMARY_LIST	0x1
#define TAG_PRIMARY_BOXED	0x2
#define TAG_PRIMARY_IMMED1	0x3

#define primary_tag(x)	((x) & _TAG_PRIMARY_MASK)

#define _TAG_IMMED1_SIZE	4
#define _TAG_IMMED1_MASK	0xF
#define _TAG_IMMED1_PID		((0x0 << _TAG_PRIMARY_SIZE) | TAG_PRIMARY_IMMED1)
#define _TAG_IMMED1_PORT	((0x1 << _TAG_PRIMARY_SIZE) | TAG_PRIMARY_IMMED1)
#define _TAG_IMMED1_IMMED2	((0x2 << _TAG_PRIMARY_SIZE) | TAG_PRIMARY_IMMED1)
#define _TAG_IMMED1_SMALL	((0x3 << _TAG_PRIMARY_SIZE) | TAG_PRIMARY_IMMED1)

#define _TAG_IMMED2_SIZE	6
#define _TAG_IMMED2_MASK	0x3F
#define _TAG_IMMED2_ATOM	((0x0 << _TAG_IMMED1_SIZE) | _TAG_IMMED1_IMMED2)
#define _TAG_IMMED2_CATCH	((0x1 << _TAG_IMMED1_SIZE) | _TAG_IMMED1_IMMED2)
#define _TAG_IMMED2_NIL		((0x3 << _TAG_IMMED1_SIZE) | _TAG_IMMED1_IMMED2)

/*
 * HEADER representation:
 *
 *	aaaaaaaaaaaaaaaaaaaaaaaaaatttt00	arity:26, tag:4
 *
 * HEADER tags:
 *
 *	0000	ARITYVAL
 *      0001    BINARY_AGGREGATE                |
 *	001x	BIGNUM with sign bit		|
 *	0100	REF				|
 *	0101	FUN				| THINGS
 *	0110	FLONUM				|
 *      0111    EXPORT                          |
 *	1000	REFC_BINARY	|		|
 *	1001	HEAP_BINARY	| BINARIES	|
 *	1010	SUB_BINARY	|		|
 *      1011    Not used
 *      1100    EXTERNAL_PID  |                 |
 *      1101    EXTERNAL_PORT | EXTERNAL THINGS |
 *      1110    EXTERNAL_REF  |                 |
 *      1111    Not used
 *
 * COMMENTS:
 *
 * - The tag is zero for arityval and non-zero for thing headers.
 * - A single bit differentiates between positive and negative bignums.
 * - If more tags are needed, the REF and and EXTERNAL_REF tags could probably
 *   be combined to one tag.
 *
 * XXX: globally replace XXX_SUBTAG with TAG_HEADER_XXX
 */
#define ARITYVAL_SUBTAG		(0x0 << _TAG_PRIMARY_SIZE) /* TUPLE */
#define BIN_MATCHSTATE_SUBTAG	(0x1 << _TAG_PRIMARY_SIZE) 
#define POS_BIG_SUBTAG		(0x2 << _TAG_PRIMARY_SIZE) /* BIG: tags 2&3 */
#define NEG_BIG_SUBTAG		(0x3 << _TAG_PRIMARY_SIZE) /* BIG: tags 2&3 */
#define _BIG_SIGN_BIT		(0x1 << _TAG_PRIMARY_SIZE)
#define REF_SUBTAG		(0x4 << _TAG_PRIMARY_SIZE) /* REF */
#define FUN_SUBTAG		(0x5 << _TAG_PRIMARY_SIZE) /* FUN */
#define FLOAT_SUBTAG		(0x6 << _TAG_PRIMARY_SIZE) /* FLOAT */
#define EXPORT_SUBTAG	(0x7 << _TAG_PRIMARY_SIZE) /* FLOAT */
#define _BINARY_XXX_MASK	(0x3 << _TAG_PRIMARY_SIZE)
#define REFC_BINARY_SUBTAG	(0x8 << _TAG_PRIMARY_SIZE) /* BINARY */
#define HEAP_BINARY_SUBTAG	(0x9 << _TAG_PRIMARY_SIZE) /* BINARY */
#define SUB_BINARY_SUBTAG	(0xA << _TAG_PRIMARY_SIZE) /* BINARY */
#define EXTERNAL_PID_SUBTAG	(0xC << _TAG_PRIMARY_SIZE) /* EXTERNAL_PID */
#define EXTERNAL_PORT_SUBTAG	(0xD << _TAG_PRIMARY_SIZE) /* EXTERNAL_PORT */
#define EXTERNAL_REF_SUBTAG	(0xE << _TAG_PRIMARY_SIZE) /* EXTERNAL_REF */


#define _TAG_HEADER_ARITYVAL	(TAG_PRIMARY_HEADER|ARITYVAL_SUBTAG)
#define _TAG_HEADER_FUN		(TAG_PRIMARY_HEADER|FUN_SUBTAG)
#define _TAG_HEADER_POS_BIG	(TAG_PRIMARY_HEADER|POS_BIG_SUBTAG)
#define _TAG_HEADER_NEG_BIG	(TAG_PRIMARY_HEADER|NEG_BIG_SUBTAG)
#define _TAG_HEADER_FLOAT	(TAG_PRIMARY_HEADER|FLOAT_SUBTAG)
#define _TAG_HEADER_EXPORT	(TAG_PRIMARY_HEADER|EXPORT_SUBTAG)
#define _TAG_HEADER_REF		(TAG_PRIMARY_HEADER|REF_SUBTAG)
#define _TAG_HEADER_REFC_BIN	(TAG_PRIMARY_HEADER|REFC_BINARY_SUBTAG)
#define _TAG_HEADER_HEAP_BIN	(TAG_PRIMARY_HEADER|HEAP_BINARY_SUBTAG)
#define _TAG_HEADER_SUB_BIN	(TAG_PRIMARY_HEADER|SUB_BINARY_SUBTAG)
#define _TAG_HEADER_EXTERNAL_PID  (TAG_PRIMARY_HEADER|EXTERNAL_PID_SUBTAG)
#define _TAG_HEADER_EXTERNAL_PORT (TAG_PRIMARY_HEADER|EXTERNAL_PORT_SUBTAG)
#define _TAG_HEADER_EXTERNAL_REF  (TAG_PRIMARY_HEADER|EXTERNAL_REF_SUBTAG)
#define _TAG_HEADER_BIN_MATCHSTATE (TAG_PRIMARY_HEADER|BIN_MATCHSTATE_SUBTAG)


#define _TAG_HEADER_MASK	0x3F
#define _HEADER_SUBTAG_MASK	0x3C	/* 4 bits for subtag */
#define _HEADER_ARITY_OFFS	6

#define header_is_transparent(x) \
 (((x) & (_HEADER_SUBTAG_MASK)) == ARITYVAL_SUBTAG)
#define header_is_arityval(x)	(((x) & _HEADER_SUBTAG_MASK) == ARITYVAL_SUBTAG)
#define header_is_thing(x)	(!header_is_transparent((x)))
#define header_is_bin_matchstate(x)	((((x) & (_HEADER_SUBTAG_MASK)) == BIN_MATCHSTATE_SUBTAG))

#define _CPMASK		0x3

/* immediate object access methods */
#define is_immed(x)		(((x) & _TAG_PRIMARY_MASK) == TAG_PRIMARY_IMMED1)
#define is_not_immed(x)		(!is_immed((x)))
#define IS_CONST(x)		is_immed((x))
#define is_not_both_immed(x,y)	is_not_immed(((x)&(y)))

/* boxed object access methods */
#define _is_aligned(x)		(((Uint)(x) & 0x3) == 0)
#define _unchecked_make_boxed(x)	((Uint)(x) + TAG_PRIMARY_BOXED)
_ET_DECLARE_CHECKED(Eterm,make_boxed,Eterm*);
#define make_boxed(x)		_ET_APPLY(make_boxed,(x))
#if 1
#define _is_not_boxed(x)	((x) & (_TAG_PRIMARY_MASK-TAG_PRIMARY_BOXED))
#define _unchecked_is_boxed(x)	(!_is_not_boxed((x)))
_ET_DECLARE_CHECKED(int,is_boxed,Eterm);
#define is_boxed(x)		_ET_APPLY(is_boxed,(x))
#else
#define is_boxed(x)		(((x) & _TAG_PRIMARY_MASK) == TAG_PRIMARY_BOXED)
#endif
#define _unchecked_boxed_val(x) ((Eterm*)((x) - TAG_PRIMARY_BOXED))
_ET_DECLARE_CHECKED(Eterm*,boxed_val,Eterm);
#define boxed_val(x)		_ET_APPLY(boxed_val,(x))

/* cons cell ("list") access methods */
#define _unchecked_make_list(x)	((Uint)(x) + TAG_PRIMARY_LIST)
_ET_DECLARE_CHECKED(Eterm,make_list,Eterm*);
#define make_list(x)		_ET_APPLY(make_list,(x))
#if 1
#define _unchecked_is_not_list(x) ((x) & (_TAG_PRIMARY_MASK-TAG_PRIMARY_LIST))
_ET_DECLARE_CHECKED(int,is_not_list,Eterm);
#define is_not_list(x)		_ET_APPLY(is_not_list,(x))
#define is_list(x)		(!is_not_list((x)))
#else
#define is_list(x)		(((x) & _TAG_PRIMARY_MASK) == TAG_PRIMARY_LIST)
#define is_not_list(x)		(!is_list((x)))
#endif
#define _unchecked_list_val(x)	((Eterm*)((x) - TAG_PRIMARY_LIST))
_ET_DECLARE_CHECKED(Eterm*,list_val,Eterm);
#define list_val(x)		_ET_APPLY(list_val,(x))

#define CONS(hp, car, cdr) \
        (CAR(hp)=(car), CDR(hp)=(cdr), make_list(hp))

#define CAR(x)  ((x)[0])
#define CDR(x)  ((x)[1])

/* generic tagged pointer (boxed or list) access methods */
#define _unchecked_ptr_val(x)	((Eterm*)((x) & ~((Uint) 0x3)))
#define ptr_val(x)		_unchecked_ptr_val((x))	/*XXX*/
#define _unchecked_offset_ptr(x,offs)	((x)+((offs)*sizeof(Eterm)))
#define offset_ptr(x,offs)	_unchecked_offset_ptr(x,offs)	/*XXX*/

/* fixnum ("small") access methods */
#if defined(ARCH_64)
#define SMALL_BITS	(64-4)
#define SMALL_DIGITS	(17)
#else
#define SMALL_BITS	(28)
#define SMALL_DIGITS	(8)
#endif
#define MAX_SMALL	((1L << (SMALL_BITS-1))-1)
#define MIN_SMALL	(-(1L << (SMALL_BITS-1)))
#define make_small(x)	(((Uint)(x) << _TAG_IMMED1_SIZE) + _TAG_IMMED1_SMALL)
#define is_small(x)	(((x) & _TAG_IMMED1_MASK) == _TAG_IMMED1_SMALL)
#define is_not_small(x)	(!is_small((x)))
#define is_byte(x)	(((x) & ((~(Uint)0 << (_TAG_IMMED1_SIZE+8)) + _TAG_IMMED1_MASK)) == _TAG_IMMED1_SMALL)
#define is_valid_bit_size(x) (((Sint)(x)) >= 0 && ((x) & 0x7F) == _TAG_IMMED1_SMALL)
#define is_not_valid_bit_size(x) (!is_valid_bit_size((x)))
#define MY_IS_SSMALL(x) (((Uint) (((x) >> (SMALL_BITS-1)) + 1)) < 2)
#define _unchecked_unsigned_val(x)	((x) >> _TAG_IMMED1_SIZE)
_ET_DECLARE_CHECKED(Uint,unsigned_val,Eterm);
#define unsigned_val(x)	_ET_APPLY(unsigned_val,(x))
#define _unchecked_signed_val(x)	((Sint)(x) >> _TAG_IMMED1_SIZE)
_ET_DECLARE_CHECKED(Sint,signed_val,Eterm);
#define signed_val(x)	_ET_APPLY(signed_val,(x))

#if _TAG_IMMED1_SMALL == 0x0F
#define is_both_small(x,y) (((x) & (y) & _TAG_IMMED1_MASK) == _TAG_IMMED1_SMALL)
#elif _TAG_IMMED1_SMALL == 0x00
#define is_both_small(x,y) ((((x)|(y)) & _TAG_IMMED1_MASK) == _TAG_IMMED1_SMALL)
#else
#define is_both_small(x,y) (is_small(x) && is_small(y))
#endif

/* NIL access methods */
#define NIL		((~((Uint) 0) << _TAG_IMMED2_SIZE) | _TAG_IMMED2_NIL)
#define is_nil(x)	((x) == NIL)
#define is_not_nil(x)	((x) != NIL)

#define MAX_ATOM_INDEX (~(~((Uint) 0) << (sizeof(Uint)*8 - _TAG_IMMED2_SIZE)))

/* atom access methods */
#define make_atom(x)	(((x) << _TAG_IMMED2_SIZE) + _TAG_IMMED2_ATOM)
#define is_atom(x)	(((x) & _TAG_IMMED2_MASK) == _TAG_IMMED2_ATOM)
#define is_not_atom(x)	(!is_atom(x))
#define _unchecked_atom_val(x)	((x) >> _TAG_IMMED2_SIZE)
_ET_DECLARE_CHECKED(Uint,atom_val,Eterm);
#define atom_val(x)	_ET_APPLY(atom_val,(x))

/* header (arityval or thing) access methods */
#define _make_header(sz,tag)	(((sz) << _HEADER_ARITY_OFFS) + (tag))
#define is_header(x)	(((x) & _TAG_PRIMARY_MASK) == TAG_PRIMARY_HEADER)
#define _unchecked_header_arity(x)	((x) >> _HEADER_ARITY_OFFS)
_ET_DECLARE_CHECKED(Uint,header_arity,Eterm);
#define header_arity(x)	_ET_APPLY(header_arity,(x))

/* arityval access methods */
#define make_arityval(sz)	_make_header((sz),_TAG_HEADER_ARITYVAL)
#define is_arity_value(x)	(((x) & _TAG_HEADER_MASK) == _TAG_HEADER_ARITYVAL)
#define is_not_arity_value(x)	(!is_arity_value((x)))
#define _unchecked_arityval(x)	_unchecked_header_arity((x))
_ET_DECLARE_CHECKED(Uint,arityval,Eterm);
#define arityval(x)		_ET_APPLY(arityval,(x))

/* thing access methods */
#define is_thing(x)	(is_header((x)) && header_is_thing((x)))
#define _unchecked_thing_arityval(x)	_unchecked_header_arity((x))
_ET_DECLARE_CHECKED(Uint,thing_arityval,Eterm);
#define thing_arityval(x)	_ET_APPLY(thing_arityval,(x))
#define _unchecked_thing_subtag(x)	((x) & _HEADER_SUBTAG_MASK)
_ET_DECLARE_CHECKED(Uint,thing_subtag,Eterm);
#define thing_subtag(x)		_ET_APPLY(thing_subtag,(x))

/*
 * Magic non-value object.
 * Used as function return error and "absent value" indicator
 * in the original runtime system. The new runtime system also
 * uses it as forwarding marker for CONS cells.
 *
 * This value is 0 in the original runtime system, which unfortunately
 * promotes sloppy programming practices. It also prevents some useful
 * tag assignment schemes, e.g. using a 2-bit tag 00 for FIXNUM.
 *
 * To help find code which makes unwarranted assumptions about zero,
 * we now use a non-zero bit-pattern in debug mode.
 */
#if ET_DEBUG
#define THE_NON_VALUE	_make_header(0,_TAG_HEADER_FLOAT)
#else
#define THE_NON_VALUE	(0)
#endif
#define is_non_value(x)	((x) == THE_NON_VALUE)
#define is_value(x)	((x) != THE_NON_VALUE)

/* binary object access methods */
#define is_binary_header(x)	(((x) & (_TAG_HEADER_MASK-_BINARY_XXX_MASK)) == _TAG_HEADER_REFC_BIN)
#define make_binary(x)	make_boxed((Eterm*)(x))
#define is_binary(x)	(is_boxed((x)) && is_binary_header(*boxed_val((x))))
#define is_not_binary(x) (!is_binary((x)))
#define _unchecked_binary_val(x) _unchecked_boxed_val((x))
_ET_DECLARE_CHECKED(Eterm*,binary_val,Eterm);
#define binary_val(x)	_ET_APPLY(binary_val,(x))

/* process binaries stuff (special case of binaries) */
#define HEADER_PROC_BIN	_make_header(PROC_BIN_SIZE-1,_TAG_HEADER_REFC_BIN)

/* fun & export objects */
#define is_any_fun(x)   (is_fun((x)) || is_export((x)))
#define is_not_any_fun(x) (!is_any_fun((x)))

/* fun objects */
#define HEADER_FUN		_make_header(ERL_FUN_SIZE-2,_TAG_HEADER_FUN)
#define is_fun_header(x)	((x) == HEADER_FUN)
#define make_fun(x)		make_boxed((Eterm*)(x))
#define is_fun(x)		(is_boxed((x)) && is_fun_header(*boxed_val((x))))
#define is_not_fun(x)		(!is_fun((x)))
#define _unchecked_fun_val(x)   _unchecked_boxed_val((x))
_ET_DECLARE_CHECKED(Eterm*,fun_val,Eterm);
#define fun_val(x)		_ET_APPLY(fun_val,(x))

/* export access methods */
#define make_export(x)	 make_boxed((x))
#define is_export(x)     (is_boxed((x)) && is_export_header(*boxed_val((x))))
#define is_not_export(x) (!is_export((x)))
#define _unchecked_export_val(x)   _unchecked_boxed_val(x)
_ET_DECLARE_CHECKED(Eterm*,export_val,Eterm);
#define export_val(x)	_ET_APPLY(export_val,(x))
#define is_export_header(x)	((x) == HEADER_EXPORT)
#define HEADER_EXPORT   _make_header(1,_TAG_HEADER_EXPORT)

/* bignum access methods */
#define make_pos_bignum_header(sz)	_make_header((sz),_TAG_HEADER_POS_BIG)
#define make_neg_bignum_header(sz)	_make_header((sz),_TAG_HEADER_NEG_BIG)
#define _is_bignum_header(x)	(((x) & (_TAG_HEADER_MASK-_BIG_SIGN_BIT)) == _TAG_HEADER_POS_BIG)
#define _unchecked_bignum_header_is_neg(x)	((x) & _BIG_SIGN_BIT)
_ET_DECLARE_CHECKED(int,bignum_header_is_neg,Eterm);
#define bignum_header_is_neg(x)	_ET_APPLY(bignum_header_is_neg,(x))
#define _unchecked_bignum_header_neg(x)	((x) | _BIG_SIGN_BIT)
_ET_DECLARE_CHECKED(Eterm,bignum_header_neg,Eterm);
#define bignum_header_neg(x)	_ET_APPLY(bignum_header_neg,(x))
#define _unchecked_bignum_header_arity(x)	_unchecked_header_arity((x))
_ET_DECLARE_CHECKED(Uint,bignum_header_arity,Eterm);
#define bignum_header_arity(x)	_ET_APPLY(bignum_header_arity,(x))
#define BIG_ARITY_MAX		((1 << 19)-1)
#define make_big(x)	make_boxed((x))
#define is_big(x)	(is_boxed((x)) && _is_bignum_header(*boxed_val((x))))
#define is_not_big(x)	(!is_big((x)))
#define _unchecked_big_val(x)	_unchecked_boxed_val((x))
_ET_DECLARE_CHECKED(Eterm*,big_val,Eterm);
#define big_val(x)		_ET_APPLY(big_val,(x))