-/* classes: h_files */
-
-#ifndef TAGSH
-#define TAGSH
-/* Copyright (C) 1995, 96, 97, 98, 99, 2000 Free Software Foundation, Inc.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2, or (at your option)
- * any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this software; see the file COPYING. If not, write to
- * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
- * Boston, MA 02111-1307 USA
- *
- * As a special exception, the Free Software Foundation gives permission
- * for additional uses of the text contained in its release of GUILE.
- *
- * The exception is that, if you link the GUILE library with other files
- * to produce an executable, this does not by itself cause the
- * resulting executable to be covered by the GNU General Public License.
- * Your use of that executable is in no way restricted on account of
- * linking the GUILE library code into it.
- *
- * This exception does not however invalidate any other reasons why
- * the executable file might be covered by the GNU General Public License.
- *
- * This exception applies only to the code released by the
- * Free Software Foundation under the name GUILE. If you copy
- * code from other Free Software Foundation releases into a copy of
- * GUILE, as the General Public License permits, the exception does
- * not apply to the code that you add in this way. To avoid misleading
- * anyone as to the status of such modified files, you must delete
- * this exception notice from them.
- *
- * If you write modifications of your own for GUILE, it is your choice
- * whether to permit this exception to apply to your modifications.
- * If you do not wish that, delete this exception notice. */
-
-/* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
- gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
-
-\f
-
-/** This file defines the format of SCM values and cons pairs.
- ** It is here that tag bits are assigned for various purposes.
- **/
-
-\f
-
-/* #define SCM_STRICT_TYPING */
-/* #define SCM_VOIDP_TEST */
-
-/* In the beginning was the Word:
- */
-typedef long scm_bits_t;
-
-/* But as external interface, we use SCM, which may, according to the desired
- * level of type checking, be defined in several ways:
- */
-#if defined (SCM_STRICT_TYPING)
-/* Use this for _compile time_ type checking only, since the compiled result
- * will be quite inefficient. The right way to make use of this mode is to do
- * a 'make clean' of your project, 'make all CFLAGS=-DSCM_STRICT_TYPING', fix
- * your errors, and then do 'make clean; make all'.
-*/
- typedef union { struct { scm_bits_t n; } n; } SCM;
- static SCM scm_pack(scm_bits_t b) { SCM s; s.n.n = b; return s; }
- #define SCM_UNPACK(x) ((x).n.n)
- #define SCM_PACK(x) (scm_pack ((scm_bits_t) (x)))
-#elif defined (SCM_VOIDP_TEST)
-/* This is the default, which provides an intermediate level of compile time
- * type checking while still resulting in very efficient code.
- */
- typedef void * SCM;
- #define SCM_UNPACK(x) ((scm_bits_t) (x))
- #define SCM_PACK(x) ((SCM) (x))
-#else
-/* This should be used as a fall back solution for machines on which casting
- * to a pointer may lead to loss of bit information, e. g. in the three least
- * significant bits.
- */
- typedef scm_bits_t SCM;
- #define SCM_UNPACK(x) (x)
- #define SCM_PACK(x) ((scm_bits_t) (x))
-#endif
-
-
-/* SCM values can not be compared by using the operator ==. Use the following
- * macro instead, which is the equivalent of the scheme predicate 'eq?'.
- */
-#define SCM_EQ_P(x, y) (SCM_UNPACK (x) == SCM_UNPACK (y))
-
-
-/* SCM_UNPACK_CAR is a convenience for treating the CAR of X as a word */
-#define SCM_UNPACK_CAR(x) SCM_UNPACK (SCM_CAR (x))
-
-\f
-
-/* SCM variables can contain:
- *
- * Non-objects -- meaning that the tag-related macros don't apply to them
- * in the usual way.
- *
- * Immediates -- meaning that the variable contains an entire Scheme object.
- *
- * Non-immediates -- meaning that the variable holds a (possibly
- * tagged) pointer into the cons pair heap.
- *
- * Non-objects are distinguished from other values by careful coding
- * only (i.e., programmers must keep track of any SCM variables they
- * create that don't contain ordinary scheme values).
- *
- * All immediates and non-immediates must have a 0 in bit 0. Only
- * non-object values can have a 1 in bit 0. In some cases, bit 0 of a
- * word in the heap is used for the GC tag so during garbage
- * collection, that bit might be 1 even in an immediate or
- * non-immediate value. In other cases, bit 0 of a word in the heap
- * is used to tag a pointer to a GLOC (VM global variable address) or
- * the header of a struct. But whenever an SCM variable holds a
- * normal Scheme value, bit 0 is 0.
- *
- * Immediates and non-immediates are distinguished by bits two and four.
- * Immediate values must have a 1 in at least one of those bits. Does
- * this (or any other detail of tagging) seem arbitrary? Try changing it!
- * (Not always impossible but it is fair to say that many details of tags
- * are mutually dependent). */
-
-#define SCM_IMP(x) (6 & SCM_UNPACK (x))
-#define SCM_NIMP(x) (!SCM_IMP (x))
-
-/* Here is a summary of tagging in SCM values as they might occur in
- * SCM variables or in the heap.
- *
- * low bits meaning
- *
- *
- * 0 Most objects except...
- * 1 ...glocs and structs (this tag valid only in a SCM_CAR or
- * in the header of a struct's data).
- *
- * 00 heap addresses and many immediates (not integers)
- * 01 glocs/structs, some tc7_ codes
- * 10 immediate integers
- * 11 various tc7_ codes including, tc16_ codes.
- *
- *
- * 000 heap address
- * 001 glocs/structs
- * 010 integer
- * 011 closure
- * 100 immediates
- * 101 tc7_
- * 110 integer
- * 111 tc7_
- *
- *
- * 100 --- IMMEDIATES
- *
- * Looking at the seven final bits of an immediate:
- *
- * 0000-100 short instruction
- * 0001-100 short instruction
- * 0010-100 short instruction
- * 0011-100 short instruction
- * 0100-100 short instruction
- * 0101-100 short instruction
- * 0110-100 various immediates and long instructions
- * 0111-100 short instruction
- * 1000-100 short instruction
- * 1001-100 short instruction
- * 1010-100 short instruction
- * 1011-100 short instruction
- * 1100-100 short instruction
- * 1101-100 short instruction
- * 1110-100 immediate characters
- * 1111-100 ilocs
- *
- * Some of the 0110100 immediates are long instructions (they dispatch
- * in two steps compared to one step for a short instruction).
- * The two steps are, (1) dispatch on 7 bits to the long instruction
- * handler, (2) dispatch on 7 additional bits.
- *
- * One way to think of it is that there are 128 short instructions,
- * with the 13 immediates above being some of the most interesting.
- *
- * Also noteworthy are the groups of 16 7-bit instructions implied by
- * some of the 3-bit tags. For example, closure references consist
- * of an 8-bit aligned address tagged with 011. There are 16 identical 7-bit
- * instructions, all ending 011, which are invoked by evaluating closures.
- *
- * In other words, if you hand the evaluator a closure, the evaluator
- * treats the closure as a graph of virtual machine instructions.
- * A closure is a pair with a pointer to the body of the procedure
- * in the CDR and a pointer to the environment of the closure in the CAR.
- * The environment pointer is tagged 011 which implies that the least
- * significant 7 bits of the environment pointer also happen to be
- * a virtual machine instruction we could call "SELF" (for self-evaluating
- * object).
- *
- * A less trivial example are the 16 instructions ending 000. If those
- * bits tag the CAR of a pair, then evidently the pair is an ordinary
- * cons pair and should be evaluated as a procedure application. The sixteen,
- * 7-bit 000 instructions are all "NORMAL-APPLY" (Things get trickier.
- * For example, if the CAR of a procedure application is a symbol, the NORMAL-APPLY
- * instruction will, as a side effect, overwrite that CAR with a new instruction
- * that contains a cached address for the variable named by the symbol.)
- *
- * Here is a summary of tags in the CAR of a non-immediate:
- *
- * HEAP CELL: G=gc_mark; 1 during mark, 0 other times.
- *
- * cons ..........SCM car..............0 ...........SCM cdr.............G
- * gloc ..........SCM vcell..........001 ...........SCM cdr.............G
- * struct ..........void * type........001 ...........void * data.........G
- * closure ..........SCM code...........011 ...........SCM env.............G
- * tc7 .........long length....Gxxxx1S1 ..........void *data............
- *
- *
- *
- * 101 & 111 --- tc7_ types
- *
- * tc7_tags are 7 bit tags ending in 1x1. These tags
- * occur only in the CAR of heap cells, and have the
- * handy property that all bits of the CAR above the
- * bottom eight can be used to store a length, thus
- * saving a word in the body itself. Thus, we use them
- * for strings, symbols, and vectors (among other
- * things).
- *
- * SCM_LENGTH returns the bits in "length" (see the diagram).
- * SCM_CHARS returns the data cast to "char *"
- * SCM_CDR returns the data cast to "SCM"
- * TYP7(X) returns bits 0...6 of SCM_CAR (X)
- *
- * For the interpretation of SCM_LENGTH and SCM_CHARS
- * that applies to a particular type, see the header file
- * for that type.
- *
- * Sometimes we choose the bottom seven bits carefully,
- * so that the 2-valued bit (called S bit) can be masked
- * off to reveal a common type.
- *
- * TYP7S(X) returns TYP7, but masking out the option bit S.
- *
- * For example, all strings have 0010 in the 'xxxx' bits
- * in the diagram above, the S bit says whether it's a
- * substring.
- *
- * for example:
- * S
- * scm_tc7_string = G0010101
- * scm_tc7_substring = G0010111
- *
- * TYP7S turns both string tags into tc7_string; thus,
- * testing TYP7S against tc7_string is a quick way to
- * test for any kind of string, shared or unshared.
- *
- * Some TC7 types are subdivided into 256 subtypes giving
- * rise to the macros:
- *
- * TYP16
- * TYP16S
- * GCTYP16
- *
- * TYP16S functions similarly wrt to TYP16 as TYP7S to TYP7,
- * but a different option bit is used (bit 2 for TYP7S,
- * bit 8 for TYP16S).
- * */
-
-
-
-\f
-/* {Non-immediate values.}
- *
- * If X is non-immediate, it is necessary to look at SCM_CAR (X) to
- * figure out Xs type. X may be a cons pair, in which case the value
- * SCM_CAR (x) will be either an immediate or non-immediate value. X
- * may be something other than a cons pair, in which case the value
- * SCM_CAR (x) will be a non-object value.
- *
- * All immediates and non-immediates have a 0 in bit 0. We
- * additionally preserve the invariant that all non-object values
- * stored in the SCM_CAR of a non-immediate object have a 1 in bit 1:
- */
-
-#define SCM_SLOPPY_NCONSP(x) (1 & SCM_UNPACK_CAR (x))
-#define SCM_SLOPPY_CONSP(x) (!SCM_SLOPPY_NCONSP (x))
-
-#define SCM_NCONSP(x) (SCM_IMP (x) || SCM_SLOPPY_NCONSP (x))
-#define SCM_CONSP(x) (SCM_NIMP (x) && SCM_SLOPPY_CONSP (x))
-
-
-/* SCM_ECONSP should be used instead of SCM_CONSP at places where GLOCS
- * can be expected to occur.
- */
-#define SCM_ECONSP(x) \
- (SCM_NIMP (x) \
- && (SCM_SLOPPY_CONSP (x) \
- || (SCM_TYP3 (x) == 1 \
- && (SCM_CDR ((SCM) SCM_STRUCT_VTABLE_DATA (x)) \
- != (SCM) 0))))
-#define SCM_NECONSP(x) \
- (SCM_IMP (x) \
- || (SCM_SLOPPY_NCONSP (x) \
- && (SCM_TYP3 (x) != 1 \
- || (SCM_CDR ((SCM) SCM_STRUCT_VTABLE_DATA (x)) \
- == (SCM) 0))))
-
-\f
-
-#define SCM_CELLP(x) (!SCM_NCELLP (x))
-#define SCM_NCELLP(x) ((sizeof (scm_cell) - 1) & SCM_UNPACK (x))
-
-#define SCM_DOUBLE_CELLP(x) (!SCM_NDOUBLE_CELLP (x))
-#define SCM_NDOUBLE_CELLP(x) ((2 * sizeof (scm_cell) - 1) & SCM_UNPACK (x))
-
-/* See numbers.h for macros relating to immediate integers.
- */
-
-#define SCM_ITAG3(x) (7 & SCM_UNPACK (x))
-#define SCM_TYP3(x) (7 & SCM_UNPACK_CAR (x))
-#define scm_tc3_cons 0
-#define scm_tc3_cons_gloc 1
-#define scm_tc3_int_1 2
-#define scm_tc3_closure 3
-#define scm_tc3_imm24 4
-#define scm_tc3_tc7_1 5
-#define scm_tc3_int_2 6
-#define scm_tc3_tc7_2 7
-
-
-/*
- * Do not change the three bit tags.
- */
-
-
-#define SCM_TYP7(x) (0x7f & SCM_UNPACK_CAR (x))
-#define SCM_TYP7S(x) ((0x7f & ~2) & SCM_UNPACK_CAR (x))
-
-
-#define SCM_TYP16(x) (0xffff & SCM_UNPACK_CAR (x))
-#define SCM_TYP16S(x) (0xfeff & SCM_UNPACK_CAR (x))
-#define SCM_GCTYP16(x) (0xff7f & SCM_UNPACK_CAR (x))
-
-
-
-/* Testing and Changing GC Marks in Various Standard Positions
- */
-#define SCM_GCCDR(x) SCM_PACK(~1L & SCM_UNPACK (SCM_CDR (x)))
-#define SCM_GCMARKP(x) (1 & SCM_UNPACK (SCM_CDR (x)))
-#define SCM_GC8MARKP(x) (0x80 & SCM_UNPACK_CAR (x))
-#define SCM_SETGCMARK(x) SCM_SETOR_CDR (x, 1)
-#define SCM_CLRGCMARK(x) SCM_SETAND_CDR (x, ~1L)
-#define SCM_SETGC8MARK(x) SCM_SETOR_CAR (x, 0x80)
-#define SCM_CLRGC8MARK(x) SCM_SETAND_CAR (x, ~0x80L)
-
-
-\f
-
-/* couple */
-#define scm_tc7_ssymbol 5
-#define scm_tc7_msymbol 7
-
-/* couple */
-#define scm_tc7_vector 13
-#define scm_tc7_wvect 15
-
-/* couple */
-#define scm_tc7_string 21
-#define scm_tc7_substring 23
-
-/* Many of the following should be turned
- * into structs or smobs. We need back some
- * of these 7 bit tags!
- */
-#define scm_tc7_pws 31
-#define scm_tc7_lvector 39
-
-#ifdef HAVE_ARRAYS
-#define scm_tc7_llvect 29
-#define scm_tc7_uvect 37
-#define scm_tc7_fvect 45
-#define scm_tc7_dvect 47
-#define scm_tc7_cvect 53
-#define scm_tc7_svect 55
-#define scm_tc7_bvect 71
-#define scm_tc7_byvect 77
-#define scm_tc7_ivect 79
-#endif
-
-#define scm_tc7_contin 61
-#define scm_tc7_cclo 63
-#define scm_tc7_rpsubr 69
-#define scm_tc7_subr_0 85
-#define scm_tc7_subr_1 87
-#define scm_tc7_cxr 93
-#define scm_tc7_subr_3 95
-#define scm_tc7_subr_2 101
-#define scm_tc7_asubr 103
-#define scm_tc7_subr_1o 109
-#define scm_tc7_subr_2o 111
-#define scm_tc7_lsubr_2 117
-#define scm_tc7_lsubr 119
-
-
-/* There are 256 port subtypes. Here are the first few.
- * These must agree with the init function in ports.c
- */
-#define scm_tc7_port 125
-
-#define scm_tc16_fport (scm_tc7_port + 0 * 256L)
-/* scm_tc16_pipe was here. */
-#define scm_tc16_strport (scm_tc7_port + 2 * 256L)
-#define scm_tc16_sfport (scm_tc7_port + 3 * 256L)
-
-
-/* There are 256 smob subtypes. Here are the first four.
- */
-
-#define scm_tc7_smob 127 /* DO NOT CHANGE [**] */
-
-/* [**] If you change scm_tc7_smob, you must also change
- * the places it is hard coded in this file and possibly others.
- */
-
-
-/* scm_tc_free_cell is also the 0th smob type. We place this
- * in free cells to tell the conservative marker not to trace it.
- */
-#define scm_tc_free_cell 0x007f
-
-/* Smob type 1 (note the dependency on the predicate SCM_NUMP)
- */
-#define scm_tc16_big 0x017f
-
-/* Smob types 2 and 3:
- */
-#define scm_tc16_real 0x027f
-#define scm_tc16_complex 0x037f
-
-/* The following four macros are now deprecated: */
-#define scm_tc16_flo scm_tc16_real
-#define scm_tc_flo 0x017fL
-#define scm_tc_dblr scm_tc16_real
-#define scm_tc_dblc scm_tc16_complex
-
-/* Smob type 4 allocated, but not initialized cells;
- this is required to prevent the gc from hosing your cells if
- you have to allocate while creating the cell*/
-#define scm_tc16_allocated 0x047f
-
-\f
-/* {Immediate Values}
- */
-
-enum scm_tags
-{
- scm_tc8_char = 0xf4,
- scm_tc8_iloc = 0xfc
-};
-
-#define SCM_ITAG8(X) (SCM_UNPACK (X) & 0xff)
-#define SCM_MAKE_ITAG8(X, TAG) SCM_PACK (((X) << 8) + TAG)
-#define SCM_ITAG8_DATA(X) (SCM_UNPACK (X) >> 8)
-
-
-\f
-/* Immediate Symbols, Special Symbols, Flags (various constants).
- */
-
-/* SCM_ISYMP tests for ISPCSYM and ISYM */
-#define SCM_ISYMP(n) ((0x187 & SCM_UNPACK (n)) == 4)
-
-/* SCM_IFLAGP tests for ISPCSYM, ISYM and IFLAG */
-#define SCM_IFLAGP(n) ((0x87 & SCM_UNPACK (n)) == 4)
-#define SCM_ISYMNUM(n) (SCM_UNPACK (n) >> 9)
-#define SCM_ISYMCHARS(n) (scm_isymnames[SCM_ISYMNUM (n)])
-#define SCM_MAKSPCSYM(n) SCM_PACK (((n) << 9) + ((n) << 3) + 4L)
-#define SCM_MAKISYM(n) SCM_PACK (((n) << 9) + 0x74L)
-#define SCM_MAKIFLAG(n) SCM_PACK (((n) << 9) + 0x174L)
-
-extern char *scm_isymnames[]; /* defined in print.c */
-
-/* This table must agree with the declarations
- * in repl.c: {Names of immediate symbols}.
- *
- * These are used only in eval but their values
- * have to be allocated here.
- *
- */
-
-#define SCM_IM_AND SCM_MAKSPCSYM (0)
-#define SCM_IM_BEGIN SCM_MAKSPCSYM (1)
-#define SCM_IM_CASE SCM_MAKSPCSYM (2)
-#define SCM_IM_COND SCM_MAKSPCSYM (3)
-#define SCM_IM_DO SCM_MAKSPCSYM (4)
-#define SCM_IM_IF SCM_MAKSPCSYM (5)
-#define SCM_IM_LAMBDA SCM_MAKSPCSYM (6)
-#define SCM_IM_LET SCM_MAKSPCSYM (7)
-#define SCM_IM_LETSTAR SCM_MAKSPCSYM (8)
-#define SCM_IM_LETREC SCM_MAKSPCSYM (9)
-#define SCM_IM_OR SCM_MAKSPCSYM (10)
-#define SCM_IM_QUOTE SCM_MAKSPCSYM (11)
-#define SCM_IM_SET_X SCM_MAKSPCSYM (12)
-#define SCM_IM_DEFINE SCM_MAKSPCSYM (13)
-#define SCM_IM_APPLY SCM_MAKISYM (14)
-#define SCM_IM_CONT SCM_MAKISYM (15)
-#define SCM_BOOL_F SCM_MAKIFLAG (16)
-#define SCM_BOOL_T SCM_MAKIFLAG (17)
-#define SCM_UNDEFINED SCM_MAKIFLAG (18)
-#define SCM_EOF_VAL SCM_MAKIFLAG (19)
-#define SCM_EOL SCM_MAKIFLAG (20)
-#define SCM_UNSPECIFIED SCM_MAKIFLAG (21)
-#define SCM_IM_DISPATCH SCM_MAKISYM (22)
-#define SCM_IM_SLOT_REF SCM_MAKISYM (23)
-#define SCM_IM_SLOT_SET_X SCM_MAKISYM (24)
-
-/* Multi-language support */
-
-#define SCM_IM_NIL_COND SCM_MAKISYM (25)
-#define SCM_IM_NIL_IFY SCM_MAKISYM (26)
-#define SCM_IM_T_IFY SCM_MAKISYM (27)
-#define SCM_IM_0_COND SCM_MAKISYM (28)
-#define SCM_IM_0_IFY SCM_MAKISYM (29)
-#define SCM_IM_1_IFY SCM_MAKISYM (30)
-#define SCM_IM_BIND SCM_MAKISYM (31)
-
-#define SCM_IM_DELAY SCM_MAKISYM (32)
-
-/* When a variable is unbound this is marked by the SCM_UNDEFINED
- * value. The following is an unbound value which can be handled on
- * the Scheme level, i.e., it can be stored in and retrieved from a
- * Scheme variable. This value is only intended to mark an unbound
- * slot in GOOPS. It is needed now, but we should probably rewrite
- * the code which handles this value in C so that SCM_UNDEFINED can be
- * used instead. It is not ideal to let this kind of unique and
- * strange values loose on the Scheme level.
- */
-#define SCM_UNBOUND SCM_MAKIFLAG (33)
-
-#define SCM_UNBNDP(x) (SCM_EQ_P ((x), SCM_UNDEFINED))
-
-\f
-
-/* Dispatching aids: */
-
-
-/* For cons pairs with immediate values in the CAR
- */
-
-#define scm_tcs_cons_imcar 2:case 4:case 6:case 10:\
- case 12:case 14:case 18:case 20:\
- case 22:case 26:case 28:case 30:\
- case 34:case 36:case 38:case 42:\
- case 44:case 46:case 50:case 52:\
- case 54:case 58:case 60:case 62:\
- case 66:case 68:case 70:case 74:\
- case 76:case 78:case 82:case 84:\
- case 86:case 90:case 92:case 94:\
- case 98:case 100:case 102:case 106:\
- case 108:case 110:case 114:case 116:\
- case 118:case 122:case 124:case 126
-
-/* For cons pairs with non-immediate values in the SCM_CAR
- */
-#define scm_tcs_cons_nimcar 0:case 8:case 16:case 24:\
- case 32:case 40:case 48:case 56:\
- case 64:case 72:case 80:case 88:\
- case 96:case 104:case 112:case 120
-
-/* A CONS_GLOC occurs in code. It's CAR is a pointer to the
- * CDR of a variable. The low order bits of the CAR are 001.
- * The CDR of the gloc is the code continuation.
- */
-#define scm_tcs_cons_gloc 1:case 9:case 17:case 25:\
- case 33:case 41:case 49:case 57:\
- case 65:case 73:case 81:case 89:\
- case 97:case 105:case 113:case 121
-
-#define scm_tcs_closures 3:case 11:case 19:case 27:\
- case 35:case 43:case 51:case 59:\
- case 67:case 75:case 83:case 91:\
- case 99:case 107:case 115:case 123
-
-#define scm_tcs_subrs scm_tc7_asubr:case scm_tc7_subr_0:case scm_tc7_subr_1:case scm_tc7_cxr:\
- case scm_tc7_subr_3:case scm_tc7_subr_2:case scm_tc7_rpsubr:case scm_tc7_subr_1o:\
- case scm_tc7_subr_2o:case scm_tc7_lsubr_2:case scm_tc7_lsubr
-
-#define scm_tcs_symbols scm_tc7_ssymbol:case scm_tc7_msymbol
-
-#endif /* TAGSH */
-
-/*
- Local Variables:
- c-file-style: "gnu"
- End:
-*/
+/* classes: h_files */
+
+#ifndef SCM_TAGS_H
+#define SCM_TAGS_H
+
+/* Copyright (C) 1995,1996,1997,1998,1999,2000,2001,2002,2003,2004
+ * Free Software Foundation, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+\f
+
+/** This file defines the format of SCM values and cons pairs.
+ ** It is here that tag bits are assigned for various purposes.
+ **/
+
+/* picks up scmconfig.h too */
+#include "libguile/__scm.h"
+
+#if HAVE_INTTYPES_H
+# include <inttypes.h> /* for INTPTR_MAX and friends */
+#else
+# if HAVE_STDINT_H
+# include <stdint.h> /* for INTPTR_MAX and friends */
+# endif
+#endif
+
+\f
+
+/* In the beginning was the Word:
+ *
+ * For the representation of scheme objects and their handling, Guile provides
+ * two types: scm_t_bits and SCM.
+ *
+ * - scm_t_bits values can hold bit patterns of non-objects and objects:
+ *
+ * Non-objects -- in this case the value may not be changed into a SCM value
+ * in any way.
+ *
+ * Objects -- in this case the value may be changed into a SCM value using
+ * the SCM_PACK macro.
+ *
+ * - SCM values can hold proper scheme objects only. They can be changed into
+ * a scm_t_bits value using the SCM_UNPACK macro.
+ *
+ * When working in the domain of scm_t_bits values, programmers must keep
+ * track of any scm_t_bits value they create that is not a proper scheme
+ * object. This makes sure that in the domain of SCM values developers can
+ * rely on the fact that they are dealing with proper scheme objects only.
+ * Thus, the distinction between scm_t_bits and SCM values helps to identify
+ * those parts of the code where special care has to be taken not to create
+ * bad SCM values.
+ */
+
+/* For dealing with the bit level representation of scheme objects we define
+ * scm_t_bits:
+ */
+/* On Solaris 7 and 8, /usr/include/sys/int_limits.h defines
+ INTPTR_MAX and UINTPTR_MAX to empty, INTPTR_MIN is not defined.
+ To avoid uintptr_t and intptr_t in this case we require
+ UINTPTR_MAX-0 != 0 etc. */
+#if SCM_SIZEOF_INTPTR_T != 0 && defined(INTPTR_MAX) && defined(INTPTR_MIN) \
+ && INTPTR_MAX-0 != 0 && INTPTR_MIN-0 != 0 \
+ && SCM_SIZEOF_UINTPTR_T != 0 && defined(UINTPTR_MAX) && UINTPTR_MAX-0 != 0
+
+typedef intptr_t scm_t_signed_bits;
+#define SCM_T_SIGNED_BITS_MAX INTPTR_MAX
+#define SCM_T_SIGNED_BITS_MIN INTPTR_MIN
+typedef uintptr_t scm_t_bits;
+#define SIZEOF_SCM_T_BITS SCM_SIZEOF_UINTPTR_T
+#define SCM_T_BITS_MAX UINTPTR_MAX
+
+#else
+
+typedef signed long scm_t_signed_bits;
+#define SCM_T_SIGNED_BITS_MAX LONG_MAX
+#define SCM_T_SIGNED_BITS_MIN LONG_MIN
+typedef unsigned long scm_t_bits;
+#define SIZEOF_SCM_T_BITS SCM_SIZEOF_UNSIGNED_LONG
+#define SCM_T_BITS_MAX ULONG_MAX
+
+#endif
+
+/* But as external interface, we define SCM, which may, according to the
+ * desired level of type checking, be defined in several ways:
+ */
+#if (SCM_DEBUG_TYPING_STRICTNESS == 2)
+ typedef union { struct { scm_t_bits n; } n; } SCM;
+ static SCM scm_pack(scm_t_bits b) { SCM s; s.n.n = b; return s; }
+# define SCM_UNPACK(x) ((x).n.n)
+# define SCM_PACK(x) (scm_pack ((scm_t_bits) (x)))
+#elif (SCM_DEBUG_TYPING_STRICTNESS == 1)
+/* This is the default, which provides an intermediate level of compile time
+ * type checking while still resulting in very efficient code.
+ */
+ typedef struct scm_unused_struct * SCM;
+
+/*
+ The 0?: constructions makes sure that the code is never executed,
+ and that there is no performance hit. However, the alternative is
+ compiled, and does generate a warning when used with the wrong
+ pointer type.
+ */
+# define SCM_UNPACK(x) ((scm_t_bits) (0? (*(SCM*)0=(x)): x))
+
+/*
+ There is no typechecking on SCM_PACK, since all kinds of types
+ (unsigned long, void*) go in SCM_PACK
+ */
+# define SCM_PACK(x) ((SCM) (x))
+
+#else
+/* This should be used as a fall back solution for machines on which casting
+ * to a pointer may lead to loss of bit information, e. g. in the three least
+ * significant bits.
+ */
+ typedef scm_t_bits SCM;
+# define SCM_UNPACK(x) (x)
+# define SCM_PACK(x) ((SCM) (x))
+#endif
+
+
+/* SCM values can not be compared by using the operator ==. Use the following
+ * macro instead, which is the equivalent of the scheme predicate 'eq?'.
+ */
+#define scm_is_eq(x, y) (SCM_UNPACK (x) == SCM_UNPACK (y))
+
+\f
+
+/* Representation of scheme objects:
+ *
+ * Guile's type system is designed to work on systems where scm_t_bits and SCM
+ * variables consist of at least 32 bits. The objects that a SCM variable can
+ * represent belong to one of the following two major categories:
+ *
+ * - Immediates -- meaning that the SCM variable contains an entire Scheme
+ * object. That means, all the object's data (including the type tagging
+ * information that is required to identify the object's type) must fit into
+ * 32 bits.
+ *
+ * - Non-immediates -- meaning that the SCM variable holds a pointer into the
+ * heap of cells (see below). On systems where a pointer needs more than 32
+ * bits this means that scm_t_bits and SCM variables need to be large enough
+ * to hold such pointers. In contrast to immediates, the object's data of
+ * a non-immediate can consume arbitrary amounts of memory: The heap cell
+ * being pointed to consists of at least two scm_t_bits variables and thus
+ * can be used to hold pointers to malloc'ed memory of any size.
+ *
+ * The 'heap' is the memory area that is under control of Guile's garbage
+ * collector. It holds 'single-cells' or 'double-cells', which consist of
+ * either two or four scm_t_bits variables, respectively. It is guaranteed
+ * that the address of a cell on the heap is 8-byte aligned. That is, since
+ * non-immediates hold a cell address, the three least significant bits of a
+ * non-immediate can be used to store additional information. The bits are
+ * used to store information about the object's type and thus are called
+ * tc3-bits, where tc stands for type-code.
+ *
+ * For a given SCM value, the distinction whether it holds an immediate or
+ * non-immediate object is based on the tc3-bits (see above) of its scm_t_bits
+ * equivalent: If the tc3-bits equal #b000, then the SCM value holds a
+ * non-immediate, and the scm_t_bits variable's value is just the pointer to
+ * the heap cell.
+ *
+ * Summarized, the data of a scheme object that is represented by a SCM
+ * variable consists of a) the SCM variable itself, b) in case of
+ * non-immediates the data of the single-cell or double-cell the SCM object
+ * points to, c) in case of non-immediates potentially additional data outside
+ * of the heap (like for example malloc'ed data), and d) in case of
+ * non-immediates potentially additional data inside of the heap, since data
+ * stored in b) and c) may hold references to other cells.
+ *
+ *
+ * Immediates
+ *
+ * Operations on immediate objects can typically be processed faster than on
+ * non-immediates. The reason is that the object's data can be extracted
+ * directly from the SCM variable (or rather a corresponding scm_t_bits
+ * variable), instead of having to perform additional memory accesses to
+ * obtain the object's data from the heap. In order to get the best possible
+ * performance frequently used data types should be realized as immediates.
+ * This is, as has been mentioned above, only possible if the objects can be
+ * represented with 32 bits (including type tagging).
+ *
+ * In Guile, the following data types and special objects are realized as
+ * immediates: booleans, characters, small integers (see below), the empty
+ * list, the end of file object, the 'unspecified' object (which is delivered
+ * as a return value by functions for which the return value is unspecified),
+ * a 'nil' object used in the elisp-compatibility mode and certain other
+ * 'special' objects which are only used internally in Guile.
+ *
+ * Integers in Guile can be arbitrarily large. On the other hand, integers
+ * are one of the most frequently used data types. Especially integers with
+ * less than 32 bits are commonly used. Thus, internally and transparently
+ * for application code guile distinguishes between small and large integers.
+ * Whether an integer is a large or a small integer depends on the number of
+ * bits needed to represent its value. Small integers are those which can be
+ * represented as immediates. Since they don't require more than a fixed
+ * number of bits for their representation, they are also known as 'fixnums'.
+ *
+ * The tc3-combinations #b010 and #b110 are used to represent small integers,
+ * which allows to use the most significant bit of the tc3-bits to be part of
+ * the integer value being represented. This means that all integers with up
+ * to 30 bits (including one bit for the sign) can be represented as
+ * immediates. On systems where SCM and scm_t_bits variables hold more than
+ * 32 bits, the amount of bits usable for small integers will even be larger.
+ * The tc3-code #b100 is shared among booleans, characters and the other
+ * special objects listed above.
+ *
+ *
+ * Non-Immediates
+ *
+ * All object types not mentioned above in the list of immedate objects are
+ * represented as non-immediates. Whether a non-immediate scheme object is
+ * represented by a single-cell or a double-cell depends on the object's type,
+ * namely on the set of attributes that have to be stored with objects of that
+ * type. Every non-immediate type is allowed to define its own layout and
+ * interpretation of the data stored in its cell (with some restrictions, see
+ * below).
+ *
+ * One of the design goals of guile's type system is to make it possible to
+ * store a scheme pair with as little memory usage as possible. The minimum
+ * amount of memory that is required to store two scheme objects (car and cdr
+ * of a pair) is the amount of memory required by two scm_t_bits or SCM
+ * variables. Therefore pairs in guile are stored in single-cells.
+ *
+ * Another design goal for the type system is to store procedure objects
+ * created by lambda expresssions (closures) and class instances (goops
+ * objects) with as little memory usage as possible. Closures are represented
+ * by a reference to the function code and a reference to the closure's
+ * environment. Class instances are represented by a reference to the
+ * instance's class definition and a reference to the instance's data. Thus,
+ * closures as well as class instances also can be stored in single-cells.
+ *
+ * Certain other non-immediate types also store their data in single-cells.
+ * By design decision, the heap is split into areas for single-cells and
+ * double-cells, but not into areas for single-cells-holding-pairs and areas
+ * for single-cells-holding-non-pairs. Any single-cell on the heap therefore
+ * can hold pairs (consisting of two scm_t_bits variables representing two
+ * scheme objects - the car and cdr of the pair) and non-pairs (consisting of
+ * two scm_t_bits variables that hold bit patterns as defined by the layout of
+ * the corresponding object's type).
+ *
+ *
+ * Garbage collection
+ *
+ * During garbage collection, unreachable cells on the heap will be freed.
+ * That is, the garbage collector will detect cells which have no SCM variable
+ * pointing towards them. In order to properly release all memory belonging
+ * to the object to which a cell belongs, the gc needs to be able to interpret
+ * the cell contents in the correct way. That means that the gc needs to be
+ * able to determine the object type associated with a cell only from the cell
+ * itself.
+ *
+ * Consequently, if the gc detects an unreachable single-cell, those two
+ * scm_t_bits variables must provide enough information to determine whether
+ * they belong to a pair (i. e. both scm_t_bits variables represent valid
+ * scheme objects), to a closure, a class instance or if they belong to any
+ * other non-immediate. Guile's type system is designed to make it possible
+ * to determine a the type to which a cell belongs in the majority of cases
+ * from the cell's first scm_t_bits variable. (Given a SCM variable X holding
+ * a non-immediate object, the macro SCM_CELL_TYPE(X) will deliver the
+ * corresponding cell's first scm_t_bits variable.)
+ *
+ * If the cell holds a scheme pair, then we already know that the first
+ * scm_t_bits variable of the cell will hold a scheme object with one of the
+ * following tc3-codes: #b000 (non-immediate), #b010 (small integer), #b100
+ * (small integer), #b110 (non-integer immediate). All these tc3-codes have
+ * in common, that their least significant bit is #b0. This fact is used by
+ * the garbage collector to identify cells that hold pairs. The remaining
+ * tc3-codes are assigned as follows: #b001 (class instance or, more
+ * precisely, a struct, of which a class instance is a special case), #b011
+ * (closure), #b101/#b111 (all remaining non-immediate types).
+ *
+ *
+ * Summary of type codes of scheme objects (SCM variables)
+ *
+ * Here is a summary of tagging bits as they might occur in a scheme object.
+ * The notation is as follows: tc stands for type code as before, tc<n> with n
+ * being a number indicates a type code formed by the n least significant bits
+ * of the SCM variables corresponding scm_t_bits value.
+ *
+ * Note that (as has been explained above) tc1==1 can only occur in the first
+ * scm_t_bits variable of a cell belonging to a non-immediate object that is
+ * not a pair. For an explanation of the tc tags with tc1==1, see the next
+ * section with the summary of the type codes on the heap.
+ *
+ * tc1:
+ * 0: For scheme objects, tc1==0 must be fulfilled.
+ * (1: This can never be the case for a scheme object.)
+ *
+ * tc2:
+ * 00: Either a non-immediate or some non-integer immediate
+ * (01: This can never be the case for a scheme object.)
+ * 10: Small integer
+ * (11: This can never be the case for a scheme object.)
+ *
+ * tc3:
+ * 000: a non-immediate object (pair, closure, class instance etc.)
+ * (001: This can never be the case for a scheme object.)
+ * 010: an even small integer (least significant bit is 0).
+ * (011: This can never be the case for a scheme object.)
+ * 100: Non-integer immediate
+ * (101: This can never be the case for a scheme object.)
+ * 110: an odd small integer (least significant bit is 1).
+ * (111: This can never be the case for a scheme object.)
+ *
+ * The remaining bits of the non-immediate objects form the pointer to the
+ * heap cell. The remaining bits of the small integers form the integer's
+ * value and sign. Thus, the only scheme objects for which a further
+ * subdivision is of interest are the ones with tc3==100.
+ *
+ * tc8 (for objects with tc3==100):
+ * 00000-100: special objects ('flags')
+ * 00001-100: characters
+ * 00010-100: evaluator byte codes ('isyms')
+ * 00011-100: evaluator byte codes ('ilocs')
+ *
+ *
+ * Summary of type codes on the heap
+ *
+ * Here is a summary of tagging in scm_t_bits values as they might occur in
+ * the first scm_t_bits variable of a heap cell.
+ *
+ * tc1:
+ * 0: the cell belongs to a pair.
+ * 1: the cell belongs to a non-pair.
+ *
+ * tc2:
+ * 00: the cell belongs to a pair with no short integer in its car.
+ * 01: the cell belongs to a non-pair (struct or some other non-immediate).
+ * 10: the cell belongs to a pair with a short integer in its car.
+ * 11: the cell belongs to a non-pair (closure or some other non-immediate).
+ *
+ * tc3:
+ * 000: the cell belongs to a pair with a non-immediate in its car.
+ * 001: the cell belongs to a struct
+ * 010: the cell belongs to a pair with an even short integer in its car.
+ * 011: the cell belongs to a closure
+ * 100: the cell belongs to a pair with a non-integer immediate in its car.
+ * 101: the cell belongs to some other non-immediate.
+ * 110: the cell belongs to a pair with an odd short integer in its car.
+ * 111: the cell belongs to some other non-immediate.
+ *
+ * tc7 (for tc3==1x1):
+ * See below for the list of types. Note the special case of scm_tc7_vector
+ * and scm_tc7_wvect: vectors and weak vectors are treated the same in many
+ * cases. Thus, their tc7-codes are chosen to only differ in one bit. This
+ * makes it possible to check an object at the same time for being a vector
+ * or a weak vector by comparing its tc7 code with that bit masked (using
+ * the TYP7S macro). Three more special tc7-codes are of interest:
+ * numbers, ports and smobs in fact each represent collections of types,
+ * which are subdivided using tc16-codes.
+ *
+ * tc16 (for tc7==scm_tc7_smob):
+ * The largest part of the space of smob types is not subdivided in a
+ * predefined way, since smobs can be added arbitrarily by user C code.
+ * However, while Guile also defines a number of smob types throughout,
+ * there is one smob type, namely scm_tc_free_cell, for which Guile assumes
+ * that it is declared first and thus gets a known-in-advance tc16-code.
+ * The reason of requiring a fixed tc16-code for this type is performance.
+ */
+
+\f
+
+/* Checking if a SCM variable holds an immediate or a non-immediate object:
+ * This check can either be performed by checking for tc3==000 or tc3==00x,
+ * since for a SCM variable it is known that tc1==0. */
+#define SCM_IMP(x) (6 & SCM_UNPACK (x))
+#define SCM_NIMP(x) (!SCM_IMP (x))
+
+/* Checking if a SCM variable holds an immediate integer: See numbers.h for
+ * the definition of the following macros: SCM_I_FIXNUM_BIT,
+ * SCM_MOST_POSITIVE_FIXNUM, SCM_I_INUMP, SCM_I_MAKINUM, SCM_I_INUM. */
+
+/* Checking if a SCM variable holds a pair (for historical reasons, in Guile
+ * also known as a cons-cell): This is done by first checking that the SCM
+ * variable holds a non-immediate, and second, by checking that tc1==0 holds
+ * for the SCM_CELL_TYPE of the SCM variable.
+*/
+
+#define SCM_I_CONSP(x) (!SCM_IMP (x) && ((1 & SCM_CELL_TYPE (x)) == 0))
+
+\f
+
+/* Definitions for tc2: */
+
+#define scm_tc2_int 2
+
+
+/* Definitions for tc3: */
+
+#define SCM_ITAG3(x) (7 & SCM_UNPACK (x))
+#define SCM_TYP3(x) (7 & SCM_CELL_TYPE (x))
+
+#define scm_tc3_cons 0
+#define scm_tc3_struct 1
+#define scm_tc3_int_1 (scm_tc2_int + 0)
+#define scm_tc3_closure 3
+#define scm_tc3_imm24 4
+#define scm_tc3_tc7_1 5
+#define scm_tc3_int_2 (scm_tc2_int + 4)
+#define scm_tc3_tc7_2 7
+
+
+/* Definitions for tc7: */
+
+#define SCM_ITAG7(x) (127 & SCM_UNPACK (x))
+#define SCM_TYP7(x) (0x7f & SCM_CELL_TYPE (x))
+#define SCM_TYP7S(x) ((0x7f & ~2) & SCM_CELL_TYPE (x))
+
+#define scm_tc7_symbol 5
+#define scm_tc7_variable 7
+
+/* couple */
+#define scm_tc7_vector 13
+#define scm_tc7_wvect 15
+
+#define scm_tc7_string 21
+#define scm_tc7_number 23
+#define scm_tc7_stringbuf 39
+
+/* Many of the following should be turned
+ * into structs or smobs. We need back some
+ * of these 7 bit tags! */
+
+#define scm_tc7_pws 31
+
+#define scm_tc7_unused_1 29
+#define scm_tc7_unused_2 37
+#define scm_tc7_unused_3 45
+#define scm_tc7_unused_4 47
+#define scm_tc7_unused_5 53
+#define scm_tc7_unused_6 55
+#define scm_tc7_unused_7 71
+#define scm_tc7_unused_8 77
+#define scm_tc7_unused_9 79
+
+#define scm_tc7_dsubr 61
+#define scm_tc7_cclo 63
+#define scm_tc7_rpsubr 69
+#define scm_tc7_subr_0 85
+#define scm_tc7_subr_1 87
+#define scm_tc7_cxr 93
+#define scm_tc7_subr_3 95
+#define scm_tc7_subr_2 101
+#define scm_tc7_asubr 103
+#define scm_tc7_subr_1o 109
+#define scm_tc7_subr_2o 111
+#define scm_tc7_lsubr_2 117
+#define scm_tc7_lsubr 119
+
+/* There are 256 port subtypes. */
+#define scm_tc7_port 125
+
+/* There are 256 smob subtypes. [**] If you change scm_tc7_smob, you must
+ * also change the places it is hard coded in this file and possibly others.
+ * Dirk:FIXME:: Any hard coded reference to scm_tc7_smob must be replaced by a
+ * symbolic reference. */
+#define scm_tc7_smob 127 /* DO NOT CHANGE [**] */
+
+
+/* Definitions for tc16: */
+#define SCM_TYP16(x) (0xffff & SCM_CELL_TYPE (x))
+#define SCM_TYP16_PREDICATE(tag, x) (!SCM_IMP (x) && SCM_TYP16 (x) == (tag))
+
+
+/* Here is the first smob subtype. */
+
+/* scm_tc_free_cell is the 0th smob type. We place this in free cells to tell
+ * the conservative marker not to trace it. */
+#define scm_tc_free_cell (scm_tc7_smob + 0 * 256L)
+
+\f
+
+/* {Immediate Values}
+ */
+
+enum scm_tc8_tags
+{
+ scm_tc8_flag = scm_tc3_imm24 + 0x00, /* special objects ('flags') */
+ scm_tc8_char = scm_tc3_imm24 + 0x08, /* characters */
+ scm_tc8_isym = scm_tc3_imm24 + 0x10, /* evaluator byte codes ('isyms') */
+ scm_tc8_iloc = scm_tc3_imm24 + 0x18 /* evaluator byte codes ('ilocs') */
+};
+
+#define SCM_ITAG8(X) (SCM_UNPACK (X) & 0xff)
+#define SCM_MAKE_ITAG8(X, TAG) SCM_PACK (((X) << 8) + TAG)
+#define SCM_ITAG8_DATA(X) (SCM_UNPACK (X) >> 8)
+
+\f
+
+/* Flags (special objects). The indices of the flags must agree with the
+ * declarations in print.c: iflagnames. */
+
+#define SCM_IFLAGP(n) (SCM_ITAG8 (n) == scm_tc8_flag)
+#define SCM_MAKIFLAG(n) SCM_MAKE_ITAG8 ((n), scm_tc8_flag)
+#define SCM_IFLAGNUM(n) (SCM_ITAG8_DATA (n))
+
+#define SCM_BOOL_F SCM_MAKIFLAG (0)
+#define SCM_BOOL_T SCM_MAKIFLAG (1)
+#define SCM_UNDEFINED SCM_MAKIFLAG (2)
+#define SCM_EOF_VAL SCM_MAKIFLAG (3)
+#define SCM_EOL SCM_MAKIFLAG (4)
+#define SCM_UNSPECIFIED SCM_MAKIFLAG (5)
+
+/* When a variable is unbound this is marked by the SCM_UNDEFINED
+ * value. The following is an unbound value which can be handled on
+ * the Scheme level, i.e., it can be stored in and retrieved from a
+ * Scheme variable. This value is only intended to mark an unbound
+ * slot in GOOPS. It is needed now, but we should probably rewrite
+ * the code which handles this value in C so that SCM_UNDEFINED can be
+ * used instead. It is not ideal to let this kind of unique and
+ * strange values loose on the Scheme level. */
+#define SCM_UNBOUND SCM_MAKIFLAG (6)
+
+/* The Elisp nil value. */
+#define SCM_ELISP_NIL SCM_MAKIFLAG (7)
+
+
+#define SCM_UNBNDP(x) (scm_is_eq ((x), SCM_UNDEFINED))
+
+\f
+
+/* Evaluator byte codes ('immediate symbols'). These constants are used only
+ * in eval but their values have to be allocated here. The indices of the
+ * SCM_IM_ symbols must agree with the declarations in print.c:
+ * scm_isymnames. */
+
+#define SCM_ISYMP(n) (SCM_ITAG8 (n) == scm_tc8_isym)
+#define SCM_MAKISYM(n) SCM_MAKE_ITAG8 ((n), scm_tc8_isym)
+
+#define SCM_IM_AND SCM_MAKISYM (0)
+#define SCM_IM_BEGIN SCM_MAKISYM (1)
+#define SCM_IM_CASE SCM_MAKISYM (2)
+#define SCM_IM_COND SCM_MAKISYM (3)
+#define SCM_IM_DO SCM_MAKISYM (4)
+#define SCM_IM_IF SCM_MAKISYM (5)
+#define SCM_IM_LAMBDA SCM_MAKISYM (6)
+#define SCM_IM_LET SCM_MAKISYM (7)
+#define SCM_IM_LETSTAR SCM_MAKISYM (8)
+#define SCM_IM_LETREC SCM_MAKISYM (9)
+#define SCM_IM_OR SCM_MAKISYM (10)
+#define SCM_IM_QUOTE SCM_MAKISYM (11)
+#define SCM_IM_SET_X SCM_MAKISYM (12)
+#define SCM_IM_DEFINE SCM_MAKISYM (13)
+#define SCM_IM_APPLY SCM_MAKISYM (14)
+#define SCM_IM_CONT SCM_MAKISYM (15)
+#define SCM_IM_DISPATCH SCM_MAKISYM (16)
+#define SCM_IM_SLOT_REF SCM_MAKISYM (17)
+#define SCM_IM_SLOT_SET_X SCM_MAKISYM (18)
+#define SCM_IM_DELAY SCM_MAKISYM (19)
+#define SCM_IM_FUTURE SCM_MAKISYM (20)
+#define SCM_IM_CALL_WITH_VALUES SCM_MAKISYM (21)
+#define SCM_IM_ELSE SCM_MAKISYM (22)
+#define SCM_IM_ARROW SCM_MAKISYM (23)
+#define SCM_IM_NIL_COND SCM_MAKISYM (24) /* Multi-language support */
+#define SCM_IM_BIND SCM_MAKISYM (25) /* Multi-language support */
+
+\f
+
+/* Dispatching aids:
+
+ When switching on SCM_TYP7 of a SCM value, use these fake case
+ labels to catch types that use fewer than 7 bits for tagging. */
+
+/* For cons pairs with immediate values in the CAR
+ */
+
+#define scm_tcs_cons_imcar \
+ scm_tc2_int + 0: case scm_tc2_int + 4: case scm_tc3_imm24 + 0:\
+ case scm_tc2_int + 8: case scm_tc2_int + 12: case scm_tc3_imm24 + 8:\
+ case scm_tc2_int + 16: case scm_tc2_int + 20: case scm_tc3_imm24 + 16:\
+ case scm_tc2_int + 24: case scm_tc2_int + 28: case scm_tc3_imm24 + 24:\
+ case scm_tc2_int + 32: case scm_tc2_int + 36: case scm_tc3_imm24 + 32:\
+ case scm_tc2_int + 40: case scm_tc2_int + 44: case scm_tc3_imm24 + 40:\
+ case scm_tc2_int + 48: case scm_tc2_int + 52: case scm_tc3_imm24 + 48:\
+ case scm_tc2_int + 56: case scm_tc2_int + 60: case scm_tc3_imm24 + 56:\
+ case scm_tc2_int + 64: case scm_tc2_int + 68: case scm_tc3_imm24 + 64:\
+ case scm_tc2_int + 72: case scm_tc2_int + 76: case scm_tc3_imm24 + 72:\
+ case scm_tc2_int + 80: case scm_tc2_int + 84: case scm_tc3_imm24 + 80:\
+ case scm_tc2_int + 88: case scm_tc2_int + 92: case scm_tc3_imm24 + 88:\
+ case scm_tc2_int + 96: case scm_tc2_int + 100: case scm_tc3_imm24 + 96:\
+ case scm_tc2_int + 104: case scm_tc2_int + 108: case scm_tc3_imm24 + 104:\
+ case scm_tc2_int + 112: case scm_tc2_int + 116: case scm_tc3_imm24 + 112:\
+ case scm_tc2_int + 120: case scm_tc2_int + 124: case scm_tc3_imm24 + 120
+
+/* For cons pairs with non-immediate values in the SCM_CAR
+ */
+#define scm_tcs_cons_nimcar \
+ scm_tc3_cons + 0:\
+ case scm_tc3_cons + 8:\
+ case scm_tc3_cons + 16:\
+ case scm_tc3_cons + 24:\
+ case scm_tc3_cons + 32:\
+ case scm_tc3_cons + 40:\
+ case scm_tc3_cons + 48:\
+ case scm_tc3_cons + 56:\
+ case scm_tc3_cons + 64:\
+ case scm_tc3_cons + 72:\
+ case scm_tc3_cons + 80:\
+ case scm_tc3_cons + 88:\
+ case scm_tc3_cons + 96:\
+ case scm_tc3_cons + 104:\
+ case scm_tc3_cons + 112:\
+ case scm_tc3_cons + 120
+
+/* For structs
+ */
+#define scm_tcs_struct \
+ scm_tc3_struct + 0:\
+ case scm_tc3_struct + 8:\
+ case scm_tc3_struct + 16:\
+ case scm_tc3_struct + 24:\
+ case scm_tc3_struct + 32:\
+ case scm_tc3_struct + 40:\
+ case scm_tc3_struct + 48:\
+ case scm_tc3_struct + 56:\
+ case scm_tc3_struct + 64:\
+ case scm_tc3_struct + 72:\
+ case scm_tc3_struct + 80:\
+ case scm_tc3_struct + 88:\
+ case scm_tc3_struct + 96:\
+ case scm_tc3_struct + 104:\
+ case scm_tc3_struct + 112:\
+ case scm_tc3_struct + 120
+
+/* For closures
+ */
+#define scm_tcs_closures \
+ scm_tc3_closure + 0:\
+ case scm_tc3_closure + 8:\
+ case scm_tc3_closure + 16:\
+ case scm_tc3_closure + 24:\
+ case scm_tc3_closure + 32:\
+ case scm_tc3_closure + 40:\
+ case scm_tc3_closure + 48:\
+ case scm_tc3_closure + 56:\
+ case scm_tc3_closure + 64:\
+ case scm_tc3_closure + 72:\
+ case scm_tc3_closure + 80:\
+ case scm_tc3_closure + 88:\
+ case scm_tc3_closure + 96:\
+ case scm_tc3_closure + 104:\
+ case scm_tc3_closure + 112:\
+ case scm_tc3_closure + 120
+
+/* For subrs
+ */
+#define scm_tcs_subrs \
+ scm_tc7_asubr:\
+ case scm_tc7_subr_0:\
+ case scm_tc7_subr_1:\
+ case scm_tc7_dsubr:\
+ case scm_tc7_cxr:\
+ case scm_tc7_subr_3:\
+ case scm_tc7_subr_2:\
+ case scm_tc7_rpsubr:\
+ case scm_tc7_subr_1o:\
+ case scm_tc7_subr_2o:\
+ case scm_tc7_lsubr_2:\
+ case scm_tc7_lsubr
+
+\f
+
+#if (SCM_ENABLE_DEPRECATED == 1)
+
+#define SCM_CELLP(x) (((sizeof (scm_t_cell) - 1) & SCM_UNPACK (x)) == 0)
+#define SCM_NCELLP(x) (!SCM_CELLP (x))
+
+#endif
+
+#endif /* SCM_TAGS_H */
+
+/*
+ Local Variables:
+ c-file-style: "gnu"
+ End:
+*/