2.11BSD#431 - /usr/src/ucb/PORT/pascal/src/tree.c

   1: /*
   2:  * Copyright (c) 1980 Regents of the University of California.
   3:  * All rights reserved.  The Berkeley software License Agreement
   4:  * specifies the terms and conditions for redistribution.
   5:  */
   6: 
   7: #ifndef lint
   8: static char sccsid[] = "@(#)tree.c	5.1 (Berkeley) 6/5/85";
   9: #endif not lint
  10: 
  11: #include "whoami.h"
  12: #include "0.h"
  13: 
  14: /*
  15:  * TREE SPACE DECLARATIONS
  16:  */
  17: struct tr {
  18:     int *tr_low;
  19:     int *tr_high;
  20: } ttab[MAXTREE], *tract;
  21: 
  22: /*
  23:  * The variable space is the
  24:  * absolute base of the tree segments.
  25:  * (exactly the same as ttab[0].tr_low)
  26:  * Spacep is maintained to point at the
  27:  * beginning of the next tree slot to
  28:  * be allocated for use by the grammar.
  29:  * Spacep is used "extern" by the semantic
  30:  * actions in pas.y.
  31:  * The variable tract is maintained to point
  32:  * at the tree segment out of which we are
  33:  * allocating (the active segment).
  34:  */
  35: int *space, *spacep;
  36: 
  37: /*
  38:  * TREENMAX is the maximum width
  39:  * in words that any tree node
  40:  * due to the way in which the parser uses
  41:  * the pointer spacep.
  42:  */
  43: #define TREENMAX    6
  44: 
  45: int trspace[ITREE];
  46: int *space  = trspace;
  47: int *spacep = trspace;
  48: struct  tr *tract   = ttab;
  49: 
  50: /*
  51:  * Inittree allocates the first tree slot
  52:  * and sets up the first segment descriptor.
  53:  * A lot of this work is actually done statically
  54:  * above.
  55:  */
  56: inittree()
  57: {
  58: 
  59:     ttab[0].tr_low = space;
  60:     ttab[0].tr_high = &space[ITREE];
  61: }
  62: 
  63: /*
  64:  * Tree builds the nodes in the
  65:  * parse tree. It is rarely called
  66:  * directly, rather calls are made
  67:  * to tree[12345] which supplies the
  68:  * first argument to save space in
  69:  * the code. Tree also guarantees
  70:  * that spacep points to the beginning
  71:  * of the next slot it will return,
  72:  * a property required by the parser
  73:  * which was always true before we
  74:  * segmented the tree space.
  75:  */
  76: /*VARARGS1*/
  77: struct tnode *
  78: tree(cnt, a)
  79:     int cnt;
  80: {
  81:     register int *p, *q;
  82:     register int i;
  83: 
  84:     i = cnt;
  85:     p = spacep;
  86:     q = &a;
  87:     do
  88:         *p++ = *q++;
  89:     while (--i);
  90:     q = spacep;
  91:     spacep = p;
  92:     if (p+TREENMAX >= tract->tr_high)
  93:         /*
  94: 		 * this peek-ahead should
  95: 		 * save a great number of calls
  96: 		 * to tralloc.
  97: 		 */
  98:         tralloc(TREENMAX);
  99:     return ((struct tnode *) q);
 100: }
 101: 
 102: /*
 103:  * Tralloc preallocates enough
 104:  * space in the tree to allow
 105:  * the grammar to use the variable
 106:  * spacep, as it did before the
 107:  * tree was segmented.
 108:  */
 109: tralloc(howmuch)
 110: {
 111:     register char *cp;
 112:     register i;
 113: 
 114:     if (spacep + howmuch >= tract->tr_high) {
 115:         i = TRINC;
 116:         cp = malloc((unsigned) (i * sizeof ( int )));
 117:         if (cp == 0) {
 118:             yerror("Ran out of memory (tralloc)");
 119:             pexit(DIED);
 120:         }
 121:         spacep = (int *) cp;
 122:         tract++;
 123:         if (tract >= &ttab[MAXTREE]) {
 124:             yerror("Ran out of tree tables");
 125:             pexit(DIED);
 126:         }
 127:         tract->tr_low = (int *) cp;
 128:         tract->tr_high = tract->tr_low+i;
 129:     }
 130: }
 131: 
 132: extern  int yylacnt;
 133: extern  struct B *bottled;
 134: #ifdef PXP
 135: #endif
 136: /*
 137:  * Free up the tree segments
 138:  * at the end of a block.
 139:  * If there is scanner lookahead,
 140:  * i.e. if yylacnt != 0 or there is bottled output, then we
 141:  * cannot free the tree space.
 142:  * This happens only when errors
 143:  * occur and the forward move extends
 144:  * across "units".
 145:  */
 146: trfree()
 147: {
 148: 
 149:     if (yylacnt != 0 || bottled != NIL)
 150:         return;
 151: #ifdef PXP
 152:     if (needtree())
 153:         return;
 154: #endif
 155:     spacep = space;
 156:     while (tract->tr_low > spacep || tract->tr_high <= spacep) {
 157:         free((char *) tract->tr_low);
 158:         tract->tr_low = NIL;
 159:         tract->tr_high = NIL;
 160:         tract--;
 161:         if (tract < ttab)
 162:             panic("ttab");
 163:     }
 164: #ifdef PXP
 165:     packtree();
 166: #endif
 167: }
 168: 
 169: /*
 170:  * Copystr copies a token from
 171:  * the "token" buffer into the
 172:  * tree space.
 173:  */
 174: copystr(token)
 175:     register char *token;
 176: {
 177:     register char *cp;
 178:     register int i;
 179: 
 180:     i = (strlen(token) + sizeof ( int )) & ~( ( sizeof ( int ) ) - 1 );
 181:     tralloc(i / sizeof ( int ));
 182:     (void) pstrcpy((char *) spacep, token);
 183:     cp = (char *) spacep;
 184:     spacep = ((int *) cp + i);
 185:     tralloc(TREENMAX);
 186:     return ((int) cp);
 187: }

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