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1.1 root 1: /* obstack.c - subroutines used implicitly by object stack macros
2: Copyright (C) 1988 Free Software Foundation, Inc.
3:
4: This program is free software; you can redistribute it and/or modify it
5: under the terms of the GNU General Public License as published by the
6: Free Software Foundation; either version 1, or (at your option) any
7: later version.
8:
9: This program is distributed in the hope that it will be useful,
10: but WITHOUT ANY WARRANTY; without even the implied warranty of
11: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12: GNU General Public License for more details.
13:
14: You should have received a copy of the GNU General Public License
15: along with this program; if not, write to the Free Software
16: Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
17:
18: #include "obstack.h"
19:
20: #ifdef __STDC__
21: #define POINTER void *
22: #else
23: #define POINTER char *
24: #endif
25:
26: /* Determine default alignment. */
27: struct fooalign {char x; double d;};
28: #define DEFAULT_ALIGNMENT ((char *)&((struct fooalign *) 0)->d - (char *)0)
29: /* If malloc were really smart, it would round addresses to DEFAULT_ALIGNMENT.
30: But in fact it might be less smart and round addresses to as much as
31: DEFAULT_ROUNDING. So we prepare for it to do that. */
32: union fooround {long x; double d;};
33: #define DEFAULT_ROUNDING (sizeof (union fooround))
34:
35: /* When we copy a long block of data, this is the unit to do it with.
36: On some machines, copying successive ints does not work;
37: in such a case, redefine COPYING_UNIT to `long' (if that works)
38: or `char' as a last resort. */
39: #ifndef COPYING_UNIT
40: #define COPYING_UNIT int
41: #endif
42:
43: /* The non-GNU-C macros copy the obstack into this global variable
44: to avoid multiple evaluation. */
45:
46: struct obstack *_obstack = 0;
47:
48: /* Initialize an obstack H for use. Specify chunk size SIZE (0 means default).
49: Objects start on multiples of ALIGNMENT (0 means use default).
50: CHUNKFUN is the function to use to allocate chunks,
51: and FREEFUN the function to free them. */
52:
53: void
54: _obstack_begin(
55: struct obstack *h,
56: int size,
57: int alignment,
58: void *(*chunkfun)(long n),
59: void (*freefun)() )
60: {
61: register struct _obstack_chunk* chunk; /* points to new chunk */
62:
63: if (alignment == 0)
64: alignment = DEFAULT_ALIGNMENT;
65: if (size == 0)
66: /* Default size is what GNU malloc can fit in a 4096-byte block. */
67: {
68: /* 12 is sizeof (mhead) and 4 is EXTRA from GNU malloc.
69: Use the values for range checking, because if range checking is off,
70: the extra bytes won't be missed terribly, but if range checking is on
71: and we used a larger request, a whole extra 4096 bytes would be
72: allocated.
73:
74: These number are irrelevant to the new GNU malloc. I suspect it is
75: less sensitive to the size of the request. */
76: int extra = ((((12 + DEFAULT_ROUNDING - 1) & ~(DEFAULT_ROUNDING - 1))
77: + 4 + DEFAULT_ROUNDING - 1)
78: & ~(DEFAULT_ROUNDING - 1));
79: size = 4096 - extra;
80: }
81:
82: h->chunkfun = (struct _obstack_chunk * (*)()) chunkfun;
83: h->freefun = freefun;
84: h->chunk_size = size;
85: h->alignment_mask = alignment - 1;
86:
87: chunk = h->chunk = (*h->chunkfun) (h->chunk_size);
88: h->next_free = h->object_base = chunk->contents;
89: h->chunk_limit = chunk->limit
90: = (char *) chunk + h->chunk_size;
91: chunk->prev = 0;
92: }
93:
94: /* Allocate a new current chunk for the obstack *H
95: on the assumption that LENGTH bytes need to be added
96: to the current object, or a new object of length LENGTH allocated.
97: Copies any partial object from the end of the old chunk
98: to the beginning of the new one. */
99:
100: void
101: _obstack_newchunk(
102: struct obstack *h,
103: int length)
104: {
105: register struct _obstack_chunk* old_chunk = h->chunk;
106: register struct _obstack_chunk* new_chunk;
107: register long new_size;
108: register int obj_size = h->next_free - h->object_base;
109: register int i;
110: int already;
111:
112: /* Compute size for new chunk. */
113: new_size = (obj_size + length) + (obj_size >> 3) + 100;
114: if (new_size < h->chunk_size)
115: new_size = h->chunk_size;
116:
117: /* Allocate and initialize the new chunk. */
118: new_chunk = h->chunk = (*h->chunkfun) (new_size);
119: new_chunk->prev = old_chunk;
120: new_chunk->limit = h->chunk_limit = (char *) new_chunk + new_size;
121:
122: /* Move the existing object to the new chunk.
123: Word at a time is fast and is safe if the object
124: is sufficiently aligned. */
125: if (h->alignment_mask + 1 >= DEFAULT_ALIGNMENT)
126: {
127: for (i = obj_size / sizeof (COPYING_UNIT) - 1;
128: i >= 0; i--)
129: ((COPYING_UNIT *)new_chunk->contents)[i]
130: = ((COPYING_UNIT *)h->object_base)[i];
131: /* We used to copy the odd few remaining bytes as one extra COPYING_UNIT,
132: but that can cross a page boundary on a machine
133: which does not do strict alignment for COPYING_UNITS. */
134: already = obj_size / sizeof (COPYING_UNIT) * sizeof (COPYING_UNIT);
135: }
136: else
137: already = 0;
138: /* Copy remaining bytes one by one. */
139: for (i = already; i < obj_size; i++)
140: new_chunk->contents[i] = h->object_base[i];
141:
142: h->object_base = new_chunk->contents;
143: h->next_free = h->object_base + obj_size;
144: }
145:
146: #ifdef DEBUG
147: /* Return nonzero if object OBJ has been allocated from obstack H.
148: This is here for debugging.
149: If you use it in a program, you are probably losing. */
150:
151: static
152: int
153: _obstack_allocated_p(
154: struct obstack *h,
155: POINTER obj)
156: {
157: register struct _obstack_chunk* lp; /* below addr of any objects in this chunk */
158: register struct _obstack_chunk* plp; /* point to previous chunk if any */
159:
160: lp = (h)->chunk;
161: while (lp != 0 && ((POINTER)lp > obj || (POINTER)(lp)->limit < obj))
162: {
163: plp = lp -> prev;
164: lp = plp;
165: }
166: return lp != 0;
167: }
168: #endif /* DEBUG */
169:
170: /* Free objects in obstack H, including OBJ and everything allocate
171: more recently than OBJ. If OBJ is zero, free everything in H. */
172: #undef obstack_free
173: void
174: obstack_free(
175: struct obstack *h,
176: POINTER obj)
177: {
178: register struct _obstack_chunk* lp; /* below addr of any objects in this chunk */
179: register struct _obstack_chunk* plp; /* point to previous chunk if any */
180:
181: lp = (h)->chunk;
182: /* We use >= because there cannot be an object at the beginning of a chunk.
183: But there can be an empty object at that address
184: at the end of another chunk. */
185: while (lp != 0 && ((POINTER)lp >= obj || (POINTER)(lp)->limit < obj))
186: {
187: plp = lp -> prev;
188: (*h->freefun) (lp);
189: lp = plp;
190: }
191: if (lp)
192: {
193: (h)->object_base = (h)->next_free = (char *)(obj);
194: (h)->chunk_limit = lp->limit;
195: (h)->chunk = lp;
196: }
197: else if (obj != 0)
198: /* obj is not in any of the chunks! */
199: abort ();
200: }
201:
202:
203: #if 0
204: /* These are now turned off because the applications do not use it
205: and it uses bcopy via obstack_grow, which causes trouble on sysV. */
206:
207: /* Now define the functional versions of the obstack macros.
208: Define them to simply use the corresponding macros to do the job. */
209:
210: #ifdef __STDC__
211: /* These function definitions do not work with non-ANSI preprocessors;
212: they won't pass through the macro names in parentheses. */
213:
214: /* The function names appear in parentheses in order to prevent
215: the macro-definitions of the names from being expanded there. */
216:
217: POINTER (obstack_base) (obstack)
218: struct obstack *obstack;
219: {
220: return obstack_base (obstack);
221: }
222:
223: POINTER (obstack_next_free) (obstack)
224: struct obstack *obstack;
225: {
226: return obstack_next_free (obstack);
227: }
228:
229: int (obstack_object_size) (obstack)
230: struct obstack *obstack;
231: {
232: return obstack_object_size (obstack);
233: }
234:
235: int (obstack_room) (obstack)
236: struct obstack *obstack;
237: {
238: return obstack_room (obstack);
239: }
240:
241: void (obstack_grow) (obstack, pointer, length)
242: struct obstack *obstack;
243: POINTER pointer;
244: int length;
245: {
246: obstack_grow (obstack, pointer, length);
247: }
248:
249: void (obstack_grow0) (obstack, pointer, length)
250: struct obstack *obstack;
251: POINTER pointer;
252: int length;
253: {
254: obstack_grow0 (obstack, pointer, length);
255: }
256:
257: void (obstack_1grow) (obstack, character)
258: struct obstack *obstack;
259: int character;
260: {
261: obstack_1grow (obstack, character);
262: }
263:
264: void (obstack_blank) (obstack, length)
265: struct obstack *obstack;
266: int length;
267: {
268: obstack_blank (obstack, length);
269: }
270:
271: void (obstack_1grow_fast) (obstack, character)
272: struct obstack *obstack;
273: int character;
274: {
275: obstack_1grow_fast (obstack, character);
276: }
277:
278: void (obstack_blank_fast) (obstack, length)
279: struct obstack *obstack;
280: int length;
281: {
282: obstack_blank_fast (obstack, length);
283: }
284:
285: POINTER (obstack_finish) (obstack)
286: struct obstack *obstack;
287: {
288: return obstack_finish (obstack);
289: }
290:
291: POINTER (obstack_alloc) (obstack, length)
292: struct obstack *obstack;
293: int length;
294: {
295: return obstack_alloc (obstack, length);
296: }
297:
298: POINTER (obstack_copy) (obstack, pointer, length)
299: struct obstack *obstack;
300: POINTER pointer;
301: int length;
302: {
303: return obstack_copy (obstack, pointer, length);
304: }
305:
306: POINTER (obstack_copy0) (obstack, pointer, length)
307: struct obstack *obstack;
308: POINTER pointer;
309: int length;
310: {
311: return obstack_copy0 (obstack, pointer, length);
312: }
313:
314: #endif /* __STDC__ */
315:
316: #endif /* 0 */
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