source/texk/web2c/texmfmem.h

   1 /* texmfmem.h: the memory_word type, which is too hard to translate
   2    automatically from Pascal.  We have to make sure the byte-swapping
   3    that the (un)dumping routines do suffices to put things in the right
   4    place in memory.
   5
   6    A memory_word can be broken up into a `twohalves' or a
   7    `fourquarters', and a `twohalves' can be further broken up.  Here is
   8    a picture.  ..._M = most significant byte, ..._L = least significant
   9    byte.
  10
  11    The halfword fields are four bytes if we are building a big TeX or MF;
  12    this leads to further complications:
  13
  14    BigEndian:
  15    twohalves.v:  RH_MM RH_ML RH_LM RH_LL LH_MM LH_ML LH_LM LH_LL
  16    twohalves.u:  ---------JUNK----------  B0         B1
  17    fourquarters:   B0    B1    B2    B3
  18
  19    LittleEndian:
  20    twohalves.v:  LH_LL LH_LM LH_ML LH_MM RH_LL RH_LM RH_ML RH_MM
  21    twohalves.u:  B1          B0
  22    fourquarters: ---------JUNK----------  B3    B2    B1    B0
  23
  24    I guess TeX and Metafont never refer to the B1 and B0 in the
  25    fourquarters structure as the B1 and B0 in the twohalves.u structure.
  26
  27    The B0 and B1 fields are declared short instead of quarterword,
  28    because they are used in character nodes to store a font number and a
  29    character.  If left as a quarterword (which is a single byte), we
  30    couldn't support more than 256 fonts. (If shorts aren't two bytes,
  31    this will lose.)
  32
  33    In the old four-byte memory structure (something more needs to be
  34    done to handle >256 fonts):
  35
  36    If BigEndian:
  37    twohalves.v:  RH_M  RH_L  LH_M  LH_L
  38    twohalves.u:  JNK1  JNK2    B0    B1
  39    fourquarters:   B0    B1    B2    B3
  40
  41    If LittleEndian:
  42    twohalves.v:  LH_L  LH_M  RH_L  RH_M
  43    twohalves.u:    B1    B0  JNK1  JNK2
  44    fourquarters:   B3    B2    B1    B0
  45
  46    In Aleph, quarterwords are two octets, so the picture becomes simpler:
  47
  48    BigEndian:
  49    twohalves.v:  RH_MM RH_ML RH_LM RH_LL LH_MM LH_ML LH_LM LH_LL
  50    twohalves.u:  ---------JUNK---------- ----B0----- ----B1-----
  51    fourquarters: ----B0----- ----B1----- ----B2----- ----B3-----
  52    twoints:      ---------CINT0--------- ---------CINT1---------
  53
  54    LittleEndian:
  55    twohalves.v:  LH_LL LH_LM LH_ML LH_MM RH_LL RH_LM RH_ML RH_MM
  56    twohalves.u:  ----B1----- ----B0-----
  57    fourquarters: ----B3----- ----B2----- ----B1----- ----B0-----
  58    twoints:      ---------CINT1--------- ---------CINT0---------
  59
  60    This file can't be part of texmf.h, because texmf.h gets included by
  61    {tex,mf,mp}d.h before the `halfword' etc. types are defined.  So we
  62    include it from the change file instead.
  63 */
  64
  65 /* Aleph is sufficiently different to separate the definition. */
  66 #if !defined(Aleph) && !defined(epTeX) && !defined(eupTeX) && !defined(upTeX)
  67
  68 typedef union
  69 {
  70   struct
  71   {
  72 #ifdef WORDS_BIGENDIAN
  73     halfword RH, LH;
  74 #else
  75     halfword LH, RH;
  76 #endif
  77   } v;
  78
  79   struct
  80   { /* Make B0,B1 overlap the most significant bytes of LH.  */
  81 #ifdef WORDS_BIGENDIAN
  82     halfword junk;
  83     short B0, B1;
  84 #else /* not WORDS_BIGENDIAN */
  85   /* If 32-bit memory words, have to do something.  */
  86 #if defined (SMALLTeX) || defined (SMALLMF) || defined (SMALLMP)
  87     fixme
  88 #else
  89     short B1, B0;
  90 #endif /* big memory words */
  91 #endif /* LittleEndian */
  92   } u;
  93 } twohalves;
  94
  95 typedef struct
  96 {
  97   struct
  98   {
  99 #ifdef WORDS_BIGENDIAN
 100     quarterword B0, B1, B2, B3;
 101 #else
 102     quarterword B3, B2, B1, B0;
 103 #endif
 104   } u;
 105 } fourquarters;
 106
 107 typedef union
 108 {
 109 #ifdef TeX
 110   glueratio gr;
 111   twohalves hh;
 112 #else
 113   twohalves hhfield;
 114 #endif
 115 #ifdef XeTeX
 116   voidpointer ptr;
 117 #endif
 118 #ifdef WORDS_BIGENDIAN
 119   integer cint;
 120   fourquarters qqqq;
 121 #else /* not WORDS_BIGENDIAN */
 122   struct
 123   {
 124 #if defined (TeX) && !defined (SMALLTeX) || defined (MF) && !defined (SMALLMF) || defined (MP) && !defined (SMALLMP)
 125     halfword junk;
 126 #endif /* big {TeX,MF,MP} */
 127     integer CINT;
 128   } u;
 129
 130   struct
 131   {
 132 #ifndef XeTeX
 133 #if defined (TeX) && !defined (SMALLTeX) || defined (MF) && !defined (SMALLMF) || defined (MP) && !defined (SMALLMP)
 134     halfword junk;
 135 #endif /* big {TeX,MF,MP} */
 136 #endif
 137     fourquarters QQQQ;
 138   } v;
 139 #endif /* not WORDS_BIGENDIAN */
 140 } memoryword;
 141
 142
 143 /* fmemory_word for font_list; needs to be only four bytes.  This saves
 144    significant space in the .fmt files. (Not true in XeTeX, actually!) */
 145 typedef union
 146 {
 147 #ifdef WORDS_BIGENDIAN
 148   integer cint;
 149   fourquarters qqqq;
 150 #else /* not WORDS_BIGENDIAN */
 151   struct
 152   {
 153 #ifdef XeTeX
 154     halfword junk; /* quarterword is really 16 bits in XeTeX, so integer does not fill the union */
 155 #endif
 156     integer CINT;
 157   } u;
 158
 159   struct
 160   {
 161     fourquarters QQQQ;
 162   } v;
 163 #endif /* not WORDS_BIGENDIAN */
 164 } fmemoryword;
 165
 166 /* To keep the original structure accesses working, we must go through
 167    the extra names C forced us to introduce.  */
 168 #define b0 u.B0
 169 #define b1 u.B1
 170 #define b2 u.B2
 171 #define b3 u.B3
 172
 173 #define rh v.RH
 174 #define lhfield v.LH
 175
 176 #ifndef WORDS_BIGENDIAN
 177 #define cint u.CINT
 178 #endif
 179
 180 #ifndef WORDS_BIGENDIAN
 181 #define qqqq v.QQQQ
 182 #endif
 183
 184 #else /* Aleph || epTeX || eupTeX || upTeX */
 185
 186 typedef union
 187 {
 188   struct
 189   {
 190 #ifdef WORDS_BIGENDIAN
 191     halfword RH, LH;
 192 #else
 193     halfword LH, RH;
 194 #endif
 195   } v;
 196
 197   struct
 198   { /* Make B0,B1 overlap the most significant bytes of LH.  */
 199 #ifdef WORDS_BIGENDIAN
 200     halfword junk;
 201     quarterword B0, B1;
 202 #else /* not WORDS_BIGENDIAN */
 203   /* If 32-bit memory words, have to do something.  */
 204 #if defined (SMALLTeX) || defined (SMALLMF) || defined (SMALLMP)
 205     fixme
 206 #else
 207     quarterword B1, B0;
 208 #endif /* big memory words */
 209 #endif /* LittleEndian */
 210   } u;
 211 } twohalves;
 212
 213 typedef struct
 214 {
 215   struct
 216   {
 217 #ifdef WORDS_BIGENDIAN
 218     quarterword B0, B1, B2, B3;
 219 #else
 220     quarterword B3, B2, B1, B0;
 221 #endif
 222   } u;
 223 } fourquarters;
 224
 225 typedef struct
 226 {
 227 #ifdef WORDS_BIGENDIAN
 228   integer CINT0, CINT1;
 229 #else
 230   integer CINT1, CINT0;
 231 #endif
 232 } twoints;
 233
 234 typedef struct
 235 {
 236   glueratio GLUE;
 237 } glues;
 238
 239 typedef union
 240 {
 241   twohalves hh;
 242   fourquarters qqqq;
 243   twoints ii;
 244   glues gg;
 245 } memoryword;
 246
 247 #define b0 u.B0
 248 #define b1 u.B1
 249 #define b2 u.B2
 250 #define b3 u.B3
 251
 252 #define rh v.RH
 253 #define lhfield v.LH
 254
 255 #define cint ii.CINT0
 256 #define cint1 ii.CINT1
 257
 258 #define gr gg.GLUE
 259
 260 #endif /* Aleph || epTeX || eupTeX || upTeX */