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1.1 root 1: static char *sccsid = "@(#)tree.c 1.1 (Berkeley) 3/2/81";
2: /* Copyright (c) 1979 Regents of the University of California */
3: #
4: /*
5: * pi - Pascal interpreter code translator
6: *
7: * Charles Haley, Bill Joy UCB
8: * Version 1.1 February 1978
9: *
10: *
11: * pxp - Pascal execution profiler
12: *
13: * Bill Joy UCB
14: * Version 1.1 February 1978
15: */
16:
17: #include "0.h"
18:
19: /*
20: * TREE SPACE DECLARATIONS
21: */
22: struct tr {
23: int *tr_low;
24: int *tr_high;
25: } ttab[MAXTREE], *tract;
26:
27: /*
28: * The variable space is the
29: * absolute base of the tree segments.
30: * (exactly the same as ttab[0].tr_low)
31: * Spacep is maintained to point at the
32: * beginning of the next tree slot to
33: * be allocated for use by the grammar.
34: * Spacep is used "extern" by the semantic
35: * actions in pas.y.
36: * The variable tract is maintained to point
37: * at the tree segment out of which we are
38: * allocating (the active segment).
39: */
40: int *space, *spacep;
41:
42: /*
43: * TREENMAX is the maximum width
44: * in words that any tree node
45: * due to the way in which the parser uses
46: * the pointer spacep.
47: */
48: #define TREENMAX 6
49:
50: int trspace[ITREE];
51: int *space = trspace;
52: int *spacep = trspace;
53: struct tr *tract = ttab;
54:
55: /*
56: * Inittree allocates the first tree slot
57: * and sets up the first segment descriptor.
58: * A lot of this work is actually done statically
59: * above.
60: */
61: inittree()
62: {
63:
64: ttab[0].tr_low = space;
65: ttab[0].tr_high = &space[ITREE];
66: }
67:
68: /*
69: * Tree builds the nodes in the
70: * parse tree. It is rarely called
71: * directly, rather calls are made
72: * to tree[12345] which supplies the
73: * first argument to save space in
74: * the code. Tree also guarantees
75: * that spacep points to the beginning
76: * of the next slot it will return,
77: * a property required by the parser
78: * which was always true before we
79: * segmented the tree space.
80: */
81: int *tree(cnt, a)
82: int cnt;
83: {
84: register int *p, *q;
85: register int i;
86:
87: i = cnt;
88: p = spacep;
89: q = &a;
90: do
91: *p++ = *q++;
92: while (--i);
93: q = spacep;
94: spacep = p;
95: if (p+TREENMAX >= tract->tr_high)
96: /*
97: * this peek-ahead should
98: * save a great number of calls
99: * to tralloc.
100: */
101: tralloc(TREENMAX);
102: return (q);
103: }
104:
105: /*
106: * Tralloc preallocates enough
107: * space in the tree to allow
108: * the grammar to use the variable
109: * spacep, as it did before the
110: * tree was segmented.
111: */
112: tralloc(howmuch)
113: {
114: register char *cp;
115: register i;
116:
117: if (spacep + howmuch >= tract->tr_high) {
118: i = TRINC;
119: cp = malloc(i * sizeof ( int ));
120: if (cp == -1) {
121: yerror("Ran out of memory (tralloc)");
122: pexit(DIED);
123: }
124: spacep = cp;
125: tract++;
126: if (tract >= &ttab[MAXTREE]) {
127: yerror("Ran out of tree tables");
128: pexit(DIED);
129: }
130: tract->tr_low = cp;
131: tract->tr_high = tract->tr_low+i;
132: }
133: }
134:
135: extern int yylacnt;
136: extern bottled;
137: #ifdef PXP
138: #endif
139: /*
140: * Free up the tree segments
141: * at the end of a block.
142: * If there is scanner lookahead,
143: * i.e. if yylacnt != 0 or there is bottled output, then we
144: * cannot free the tree space.
145: * This happens only when errors
146: * occur and the forward move extends
147: * across "units".
148: */
149: trfree()
150: {
151:
152: if (yylacnt != 0 || bottled != NIL)
153: return;
154: #ifdef PXP
155: if (needtree())
156: return;
157: #endif
158: spacep = space;
159: while (tract->tr_low > spacep || tract->tr_high <= spacep) {
160: free(tract->tr_low);
161: tract->tr_low = NIL;
162: tract->tr_high = NIL;
163: tract--;
164: if (tract < ttab)
165: panic("ttab");
166: }
167: #ifdef PXP
168: packtree();
169: #endif
170: }
171:
172: /*
173: * Copystr copies a token from
174: * the "token" buffer into the
175: * tree space.
176: */
177: copystr(token)
178: register char *token;
179: {
180: register char *cp;
181: register int i;
182:
183: i = (strlen(token) + sizeof ( int )) & ~( ( sizeof ( int ) ) - 1 );
184: tralloc(i / sizeof ( int ));
185: strcpy(spacep, token);
186: cp = spacep;
187: spacep = cp + i;
188: tralloc(TREENMAX);
189: return (cp);
190: }
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