-/* classes: h_files */
-
-#ifndef TAGSH
-#define TAGSH
-/* Copyright (C) 1995,1996, 1997 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. */
-\f
-
-/** This file defines the format of SCM values and cons pairs.
- ** It is here that tag bits are assigned for various purposes.
- **/
-
-\f
-
-/* In the beginning was the Word:
- */
-typedef long SCM;
-
-
-
-/* Cray machines have pointers that are incremented once for each word,
- * rather than each byte, the 3 most significant bits encode the byte
- * within the word. The following macros deal with this by storing the
- * native Cray pointers like the ones that looks like scm expects. This
- * is done for any pointers that might appear in the car of a scm_cell, pointers
- * to scm_vector elts, functions, &c are not munged.
- */
-#ifdef _UNICOS
-# define SCM2PTR(x) ((int)(x) >> 3)
-# define PTR2SCM(x) (((SCM)(x)) << 3)
-# define SCM_POINTERS_MUNGED
-#else
-# define SCM2PTR(x) (x)
-# define PTR2SCM(x) ((SCM)(x))
-#endif /* def _UNICOS */
-
-\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 & (int)(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_NCONSP(x) (1 & (int)SCM_CAR(x))
-#define SCM_CONSP(x) (!SCM_NCONSP(x))
-
-
-/* SCM_ECONSP should be used instead of SCM_CONSP at places where GLOCS
- * can be expected to occur.
- */
-#define SCM_ECONSP(x) (SCM_CONSP (x) \
- || (SCM_TYP3(x) == 1 \
- && SCM_CDR (SCM_CAR (x) - 1) != 0))
-#define SCM_NECONSP(x) (SCM_NCONSP(x) \
- && (SCM_TYP3(x) != 1 \
- || SCM_CDR (SCM_CAR (x) - 1) == 0))
-
-\f
-
-#define SCM_CELLP(x) (!SCM_NCELLP(x))
-#define SCM_NCELLP(x) ((sizeof(scm_cell)-1) & (int)(x))
-
-/* See numbers.h for macros relating to immediate integers.
- */
-
-#define SCM_ITAG3(x) (7 & (int)x)
-#define SCM_TYP3(x) (7 & (int)SCM_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) ((int)SCM_CAR(x) & 0x7f)
-#define SCM_TYP7S(x) ((int)SCM_CAR(x) & (0x7f & ~2))
-
-
-#define SCM_TYP16(x) (0xffff & (int)SCM_CAR(x))
-#define SCM_TYP16S(x) (0xfeff & (int)SCM_CAR(x))
-#define SCM_GCTYP16(x) (0xff7f & (int)SCM_CAR(x))
-
-
-
-/* Testing and Changing GC Marks in Various Standard Positions
- */
-#define SCM_GCMARKP(x) (1 & (int)SCM_CDR(x))
-#define SCM_GC8MARKP(x) (0x80 & (int)SCM_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
-
-/* 29 and 31 are free! */
-
-/* Many of the following should be turned
- * into structs or smobs. We need back some
- * of these 7 bit tags!
- */
-#define scm_tc7_uvect 37
-#define scm_tc7_lvector 39
-#define scm_tc7_fvect 45
-#define scm_tc7_dvect 47
-#define scm_tc7_cvect 53
-#define scm_tc7_svect 55
-#define scm_tc7_contin 61
-#define scm_tc7_cclo 63
-#define scm_tc7_rpsubr 69
-#define scm_tc7_bvect 71
-#define scm_tc7_byvect 77
-#define scm_tc7_ivect 79
-#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 four.
- * These must agree with the init function in ports.c
- */
-#define scm_tc7_port 125
-
-/* fports and pipes form an intended TYP16S equivelancy
- * group (similar to a tc7 "couple".
- */
-#define scm_tc16_fport (scm_tc7_port + 0*256L)
-#define scm_tc16_pipe (scm_tc7_port + 1*256L)
-
-#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 127
-
-/* The 1st smob type:
- */
-#define scm_tc16_flo 0x017f
-#define scm_tc_flo 0x017fL
-
-/* Some option bits begeinning at bit 16 of scm_tc16_flo:
- */
-#define SCM_REAL_PART (1L<<16)
-#define SCM_IMAG_PART (2L<<16)
-#define scm_tc_dblr (scm_tc16_flo|SCM_REAL_PART)
-#define scm_tc_dblc (scm_tc16_flo|SCM_REAL_PART|SCM_IMAG_PART)
-
-
-/* Smob types 2 and 3:
- */
-#define scm_tc16_bigpos 0x027f
-#define scm_tc16_bigneg 0x037f
-
-
-\f
-/* {Immediate Values}
- */
-
-enum scm_tags
-{
- scm_tc8_char = 0xf4,
- scm_tc8_iloc = 0xfc
-};
-
-#define SCM_ITAG8(X) ((int)(X) & 0xff)
-#define SCM_MAKE_ITAG8(X, TAG) (((X)<<8) + TAG)
-#define SCM_ITAG8_DATA(X) ((X)>>8)
-
-
-\f
-/* Immediate Symbols, Special Symbols, Flags (various constants).
- */
-
-/* SCM_ISYMP tests for ISPCSYM and ISYM */
-#define SCM_ISYMP(n) ((0x187 & (int)(n))==4)
-
-/* SCM_IFLAGP tests for ISPCSYM, ISYM and IFLAG */
-#define SCM_IFLAGP(n) ((0x87 & (int)(n))==4)
-#define SCM_ISYMNUM(n) ((int)((n)>>9))
-#define SCM_ISYMCHARS(n) (scm_isymnames[SCM_ISYMNUM(n)])
-#define SCM_MAKSPCSYM(n) (((n)<<9)+((n)<<3)+4L)
-#define SCM_MAKISYM(n) (((n)<<9)+0x74L)
-#define SCM_MAKIFLAG(n) (((n)<<9)+0x174L)
-
-/* 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 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_UNBNDP(x) (SCM_UNDEFINED==(x))
-
-\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
-
-#define scm_tcs_bignums scm_tc16_bigpos:case scm_tc16_bigneg
-
-#endif /* TAGSH */
+/* classes: h_files */
+
+#ifndef SCM_TAGS_H
+#define SCM_TAGS_H
+
+/* Copyright (C) 1995,1996,1997,1998,1999,2000,2001,2002,2003 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
+
+/* In the beginning was the Word:
+ */
+/* 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 use 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;
+# define SCM_UNPACK(x) ((scm_t_bits) (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_t_bits SCM;
+# define SCM_UNPACK(x) (x)
+# define SCM_PACK(x) ((scm_t_bits) (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))
+
+\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 pointers to cells of non-immediates have a 0 in
+ * bit 0. All non-immediates that are not pairs have a 1 in bit 0 of
+ * the first word of their cell. This is how pairs are distinguished
+ * from other non-immediates; a pair can have a immediate in its car
+ * (thus a 0 in bit 0), or a pointer to the cell of a non-immediate
+ * (again, this pointer has a 0 in bit 0).
+ *
+ * Immediates and non-immediates are distinguished by bits 1 and 2.
+ * Immediate values must have a 1 in at least one of those bits.
+ * Consequently, a pointer to a cell of a non-immediate must have
+ * zeros in bits 1 and 2. Together with the requirement from above
+ * that bit 0 must also be zero, this means that pointers to cells of
+ * non-immediates must have their three low bits all zero. This in
+ * turn means that cells must be aligned on a 8 byte boundary, which
+ * is just right for two 32bit numbers (surprise, surprise). 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 ... structs (this tag is valid only in the header
+ * of a struct's data, as with all odd tags).
+ *
+ * 00 heap addresses and many immediates (not integers)
+ * 01 structs, some tc7_ codes
+ * 10 immediate integers
+ * 11 various tc7_ codes including, tc16_ codes.
+ *
+ *
+ * 000 heap address
+ * 001 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 short instruction
+ * 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, various immediates and long instructions
+ * 1111-100 ilocs
+ *
+ * Some of the 1110100 immediates are long instructions (they dispatch in
+ * three steps compared to one step for a short instruction). The three steps
+ * are, (1) dispatch on 7 bits to the long instruction handler, (2) check, if
+ * the immediate indicates a long instruction (rather than a character or
+ * other immediate) (3) dispatch on the 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-byte 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:
+ *
+ * cons ..........SCM car..............0 ...........SCM cdr.............0
+ * struct ..........void * type........001 ...........void * data.........0
+ * closure ..........SCM code...........011 ...........SCM env.............0
+ * tc7 ......24.bits of data...0xxxx1S1 ..........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 some data, thus
+ * saving a word in the body itself. Thus, we use them
+ * for strings and vectors (among other things).
+ *
+ * TYP7(X) returns bits 0...6 of CELL_TYPE (X)
+ *
+ * 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.
+ *
+ * Some TC7 types are subdivided into 256 subtypes giving
+ * rise to the macros:
+ *
+ * TYP16
+ * TYP16S
+ *
+ * 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_CONSP(x) (!SCM_IMP (x) && ((1 & SCM_CELL_TYPE (x)) == 0))
+#define SCM_NCONSP(x) (!SCM_CONSP (x))
+
+\f
+
+/* See numbers.h for macros relating to immediate integers.
+ */
+
+#define scm_tc2_int 2
+
+#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
+
+
+/*
+ * Do not change the three bit tags.
+ */
+
+
+#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_TYP16(x) (0xffff & SCM_CELL_TYPE (x))
+#define SCM_TYP16S(x) (0xfeff & SCM_CELL_TYPE (x))
+
+#define SCM_TYP16_PREDICATE(tag, x) (!SCM_IMP (x) && SCM_TYP16 (x) == (tag))
+
+\f
+
+#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
+/* free 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
+
+#if SCM_HAVE_ARRAYS
+#define scm_tc7_llvect 29
+#define scm_tc7_uvect 37
+/* free 39 */
+#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_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 [**] */
+
+
+/* Here are the first four smob subtypes.
+ */
+
+/* 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)
+
+/* Smob type 1 to 3 (note the dependency on the predicate SCM_NUMP)
+ */
+#define scm_tc16_big (scm_tc7_smob + 1 * 256L)
+#define scm_tc16_real (scm_tc7_smob + 2 * 256L)
+#define scm_tc16_complex (scm_tc7_smob + 3 * 256L)
+
+\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)
+
+SCM_API 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_BIND SCM_MAKISYM (26)
+
+#define SCM_IM_DELAY SCM_MAKISYM (27)
+#define SCM_IM_FUTURE SCM_MAKISYM (28)
+#define SCM_IM_CALL_WITH_VALUES SCM_MAKISYM (29)
+
+/* 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 (30)
+
+#define SCM_UNBNDP(x) (SCM_EQ_P ((x), SCM_UNDEFINED))
+
+/* The Elisp nil value. */
+#define SCM_ELISP_NIL SCM_MAKIFLAG (31)
+
+\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:
+*/
HCoop / bpt / guile.git / blobdiff