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1 /* Fundamental definitions for XEmacs Lisp interpreter -- non-union objects.
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2 Copyright (C) 1985, 1986, 1987, 1992, 1993 Free Software Foundation, Inc.
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3
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4 This file is part of XEmacs.
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5
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6 XEmacs is free software; you can redistribute it and/or modify it
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7 under the terms of the GNU General Public License as published by the
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8 Free Software Foundation; either version 2, or (at your option) any
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9 later version.
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10
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11 XEmacs is distributed in the hope that it will be useful, but WITHOUT
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12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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14 for more details.
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15
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16 You should have received a copy of the GNU General Public License
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17 along with XEmacs; see the file COPYING. If not, write to
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18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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19 Boston, MA 02111-1307, USA. */
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20
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21 /* Synched up with: FSF 19.30. Split out from lisp.h. */
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207
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22 /* This file has diverged greatly from FSF Emacs. Syncing is no
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23 longer desired or possible */
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0
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24
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207
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25 /*
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26 * Format of a non-union-type Lisp Object
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27 *
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28 * For the USE_MINIMAL_TAGBITS implementation:
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29 *
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30 * 3 2 1 0
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31 * bit 10987654321098765432109876543210
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32 * --------------------------------
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33 * VVVVVVVVVVVVVVVVVVVVVVVVVVVVVVTT
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34 *
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35 * For the non-USE_MINIMAL_TAGBITS implementation:
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36 *
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37 * 3 2 1 0
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38 * bit 10987654321098765432109876543210
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39 * --------------------------------
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40 * TTTMVVVVVVVVVVVVVVVVVVVVVVVVVVVV
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41 *
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42 * V = value bits
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43 * T = type bits
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44 * M = mark bits
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45 *
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46 * For integral Lisp types, i.e. integers and characters, the value
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47 * bits are the Lisp object.
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48 *
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49 * The object is obtained by masking off the type and mark
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50 * bits. In the USE_MINIMAL_TAGBITS implementation, bit 1 is
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51 * used as a value bit by splitting the Lisp integer type into
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52 * two subtypes, Lisp_Type_Int_Even and Lisp_Type_Int_Odd. By
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53 * this trickery we get 31 bits for integers instead of 30.
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54 *
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55 * In the non-USE_MINIMAL_TAGBITS world, Lisp integers are 28
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56 * bits, or more properly (LONGBITS - GCTYPEBITS - 1) bits.
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57 *
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58 * For non-integral types, the value bits of Lisp_Object contain a
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59 * pointer to structure containing the object. The pointer is
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60 * obtained by masking off the type and mark bits.
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61 *
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62 * In the USE_MINIMAL_TAGBITS implementation, all
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63 * pointer-based types are coalesced under a single type called
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64 * Lisp_Type_Record. The type bits for this type are required
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65 * by the implementation to be 00, just like the least
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66 * significant bits of word-aligned struct pointers on 32-bit
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67 * hardware. Because of this, Lisp_Object pointers don't have
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68 * to be masked and are full-sized.
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69 *
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70 * In the non-USE_MINIMAL_TAGBITS implementation, the type and
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71 * mark bits must be masked off and pointers are limited to 28
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72 * bits (really LONGBITS - GCTYPEBITS - 1 bits).
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73 */
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74
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207
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75 #ifdef USE_MINIMAL_TAGBITS
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76 # define Qzero Lisp_Type_Int_Even
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77 # define VALMASK (((1L << (VALBITS)) - 1L) << (GCTYPEBITS))
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78 #else
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79 # define Qzero Lisp_Type_Int
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80 # define VALMASK ((1L << (VALBITS)) - 1L)
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81 # define GCTYPEMASK ((1L << (GCTYPEBITS)) - 1L)
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82 #endif
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0
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83
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84 typedef EMACS_INT Lisp_Object;
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85
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207
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86 #define Qnull_pointer 0
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87
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207
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88 /*
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89 * There are no mark bits in the USE_MINIMAL_TAGBITS implementation.
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90 * Integers and characters don't need to be marked. All other types
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91 * are lrecord-based, which means they get marked by incrementing
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92 * their ->implementation pointer.
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93 */
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94 #if GCMARKBITS > 0
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95 /*
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96 * XMARKBIT accesses the markbit. Markbits are used only in particular
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97 * slots of particular structure types. Other markbits are always
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98 * zero. Outside of garbage collection, all mark bits are always zero.
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99 */
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100 # define MARKBIT (1UL << (VALBITS))
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101 # define XMARKBIT(a) ((a) & (MARKBIT))
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102
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103 # define XMARK(a) ((void) ((a) |= (MARKBIT)))
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104 # define XUNMARK(a) ((void) ((a) &= (~(MARKBIT))))
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105 #endif
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106
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207
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107 /*
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108 * Extract the type bits from a Lisp_Object. If using USE_MINIMAL_TAGBITS,
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109 * the least significant two bits are the type bits. Otherwise the
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110 * most significant GCTYPEBITS bits are the type bits.
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111 *
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112 * In the non-USE_MINIMAL_TAGBITS case, one needs to override this
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113 * if there must be high bits set in data space. Masking the bits
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114 * (doing the result of the below & ((1 << (GCTYPEBITS)) - 1) would
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115 * work on all machines, but would penalize machines which don't
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116 * need it)
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117 */
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118 #ifdef USE_MINIMAL_TAGBITS
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119 # define XTYPE(a) ((enum Lisp_Type) (((EMACS_UINT)(a)) & ~(VALMASK)))
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120 #else
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121 # define XTYPE(a) ((enum Lisp_Type) (((EMACS_UINT)(a)) >> ((VALBITS) + 1)))
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122 #endif
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123
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207
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124 /*
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125 * This applies only to the non-USE_MINIMAL_TAGBITS Lisp_Object.
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126 *
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127 * In the past, during garbage collection, XGCTYPE needed to be used
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128 * for extracting types so that the mark bit was ignored. XGCTYPE
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129 * did and exatr & operation to remove the mark bit. But the mark
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130 * bit has been since moved so that the type bits could be extracted
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131 * with a single shift operation, making XGCTYPE no more expensive
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132 * than XTYPE, so the two operations are now equivalent.
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133 */
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134 #ifndef XGCTYPE
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135 # define XGCTYPE(a) XTYPE(a)
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136 #endif
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137
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138 #define EQ(x,y) ((x) == (y))
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139
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207
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140 #ifdef USE_MINIMAL_TAGBITS
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141 # define GC_EQ(x,y) EQ(x,y)
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142 #else
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143 # define GC_EQ(x,y) (XGCTYPE (x) == XGCTYPE (y) && XPNTR (x) == XPNTR (y))
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144 #endif
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145
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207
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146 /*
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147 * Extract the value of a Lisp_Object as a signed integer.
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148 *
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149 * The right shifts below are non-portable because >> is allowed to
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150 * sign extend or not signed extend signed integers depending on the
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151 * compiler implementors preference. But this right-shifting of
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152 * signed ints has been here forever, so the apparently reality is
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153 * that all compilers of any consequence do sign extension, which is
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154 * what is needed here.
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155 */
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156 #ifndef XREALINT /* Some machines need to do this differently. */
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157 # ifdef USE_MINIMAL_TAGBITS
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158 # define XREALINT(a) ((a) >> (LONGBITS-VALBITS-1))
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159 # else
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160 # define XREALINT(a) (((a) << (LONGBITS-VALBITS)) >> (LONGBITS-VALBITS))
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161 # endif
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162 #endif
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163
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207
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164 /*
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165 * Extract the pointer value bits of a pointer based type.
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166 */
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167 #ifdef USE_MINIMAL_TAGBITS
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168 # define XPNTRVAL(a) (a) /* This depends on Lisp_Type_Record == 0 */
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169 # define XCHARVAL(a) ((a) >> (LONGBITS-VALBITS))
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170 #else
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171 # define XPNTRVAL(a) ((a) & VALMASK)
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172 # define XCHARVAL(a) XPNTRVAL(a)
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173 #endif
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174
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185
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175 #ifdef HAVE_SHM
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176 /* In this representation, data is found in two widely separated segments. */
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177 extern int pure_size;
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178 # define XPNTR(a) \
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179 (XPNTRVAL (a) | (XPNTRVAL (a) > pure_size ? DATA_SEG_BITS : PURE_SEG_BITS))
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180 # else /* not HAVE_SHM */
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181 # ifdef DATA_SEG_BITS
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182 /* This case is used for the rt-pc.
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183 In the diffs I was given, it checked for ptr = 0
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184 and did not adjust it in that case.
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185 But I don't think that zero should ever be found
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185
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186 in a Lisp object whose data type says it points to something. */
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207
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187 # define XPNTR(a) (XPNTRVAL (a) | DATA_SEG_BITS)
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188 # else
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189 # define XPNTR(a) XPNTRVAL (a)
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190 # endif
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185
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191 #endif /* not HAVE_SHM */
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192
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207
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193 #ifdef USE_MINIMAL_TAGBITS
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194
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207
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195 /* XSETINT depends on Lisp_Type_Int_Even == 1 and Lisp_Type_Int_Odd == 3 */
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196 # define XSETINT(var, value) \
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197 ((void) ((var) = ((value) << (LONGBITS-VALBITS-1)) + 1))
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198 # define XSETCHAR(var, value) \
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199 ((void) ((var) = ((value) << (LONGBITS-VALBITS)) + Lisp_Type_Char))
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200 # define XSETOBJ(var, type_tag, value) \
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201 ((void) ((var) = ((EMACS_UINT) (value))))
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202
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207
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203 #else
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204
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207
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205 # define XSETINT(a, b) XSETOBJ (a, Lisp_Type_Int, b)
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206 # define XSETCHAR(var, value) XSETOBJ (var, Lisp_Type_Char, value)
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207 # define XSETOBJ(var, type_tag, value) \
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208 ((void) ((var) = (((EMACS_UINT) (type_tag) << ((VALBITS) + 1)) \
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209 + ((EMACS_INT) (value) & VALMASK))))
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210 #endif
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211
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212 /* Use this for turning a (void *) into a Lisp_Object, as when the
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213 Lisp_Object is passed into a toolkit callback function */
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185
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214 #define VOID_TO_LISP(larg,varg) ((void) ((larg) = ((Lisp_Object) (varg))))
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215 #define CVOID_TO_LISP VOID_TO_LISP
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216
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185
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217 /* Use this for turning a Lisp_Object into a (void *), as when the
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218 Lisp_Object is passed into a toolkit callback function */
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219 #define LISP_TO_VOID(larg) ((void *) (larg))
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220 #define LISP_TO_CVOID(varg) ((CONST void *) (larg))
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221
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222 /* Convert a Lisp_Object into something that can't be used as an
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223 lvalue. Useful for type-checking. */
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224 #define NON_LVALUE(larg) ((larg) + 0)
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