![[BACK]](/cvsweb/icons/back.gif){kind=icon}
Return to obstack.h CVS log ![[TXT]](/cvsweb/icons/text.gif){kind=icon}
![[DIR]](/cvsweb/icons/dir.gif){kind=icon}
Up to [Apple XNU] / GNUtools / cctools / as|
Return to obstack.h CVS log | Up to [Apple XNU] / GNUtools / cctools / as |
1.1 root 1: /* obstack.h - 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: /* Summary:
19:
20: All the apparent functions defined here are macros. The idea
21: is that you would use these pre-tested macros to solve a
22: very specific set of problems, and they would run fast.
23: Caution: no side-effects in arguments please!! They may be
24: evaluated MANY times!!
25:
26: These macros operate a stack of objects. Each object starts life
27: small, and may grow to maturity. (Consider building a word syllable
28: by syllable.) An object can move while it is growing. Once it has
29: been "finished" it never changes address again. So the "top of the
30: stack" is typically an immature growing object, while the rest of the
31: stack is of mature, fixed size and fixed address objects.
32:
33: These routines grab large chunks of memory, using a function you
34: supply, called `obstack_chunk_alloc'. On occasion, they free chunks,
35: by calling `obstack_chunk_free'. You must define them and declare
36: them before using any obstack macros.
37:
38: Each independent stack is represented by a `struct obstack'.
39: Each of the obstack macros expects a pointer to such a structure
40: as the first argument.
41:
42: One motivation for this package is the problem of growing char strings
43: in symbol tables. Unless you are "fascist pig with a read-only mind"
44: [Gosper's immortal quote from HAKMEM item 154, out of context] you
45: would not like to put any arbitrary upper limit on the length of your
46: symbols.
47:
48: In practice this often means you will build many short symbols and a
49: few long symbols. At the time you are reading a symbol you don't know
50: how long it is. One traditional method is to read a symbol into a
51: buffer, realloc()ating the buffer every time you try to read a symbol
52: that is longer than the buffer. This is beaut, but you still will
53: want to copy the symbol from the buffer to a more permanent
54: symbol-table entry say about half the time.
55:
56: With obstacks, you can work differently. Use one obstack for all symbol
57: names. As you read a symbol, grow the name in the obstack gradually.
58: When the name is complete, finalize it. Then, if the symbol exists already,
59: free the newly read name.
60:
61: The way we do this is to take a large chunk, allocating memory from
62: low addresses. When you want to build a symbol in the chunk you just
63: add chars above the current "high water mark" in the chunk. When you
64: have finished adding chars, because you got to the end of the symbol,
65: you know how long the chars are, and you can create a new object.
66: Mostly the chars will not burst over the highest address of the chunk,
67: because you would typically expect a chunk to be (say) 100 times as
68: long as an average object.
69:
70: In case that isn't clear, when we have enough chars to make up
71: the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
72: so we just point to it where it lies. No moving of chars is
73: needed and this is the second win: potentially long strings need
74: never be explicitly shuffled. Once an object is formed, it does not
75: change its address during its lifetime.
76:
77: When the chars burst over a chunk boundary, we allocate a larger
78: chunk, and then copy the partly formed object from the end of the old
79: chunk to the beginning of the new larger chunk. We then carry on
80: accreting characters to the end of the object as we normally would.
81:
82: A special macro is provided to add a single char at a time to a
83: growing object. This allows the use of register variables, which
84: break the ordinary 'growth' macro.
85:
86: Summary:
87: We allocate large chunks.
88: We carve out one object at a time from the current chunk.
89: Once carved, an object never moves.
90: We are free to append data of any size to the currently
91: growing object.
92: Exactly one object is growing in an obstack at any one time.
93: You can run one obstack per control block.
94: You may have as many control blocks as you dare.
95: Because of the way we do it, you can `unwind' a obstack
96: back to a previous state. (You may remove objects much
97: as you would with a stack.)
98: */
99:
100:
101: /* Don't do the contents of this file more than once. */
102:
103: #ifndef __OBSTACKS__
104: #define __OBSTACKS__
105:
106: #define obstack_chunk_alloc xmalloc
107: #define obstack_chunk_free xfree
108:
109: /* We use subtraction of (char *)0 instead of casting to int
110: because on word-addressable machines a simple cast to int
111: may ignore the byte-within-word field of the pointer. */
112:
113: #ifndef __PTR_TO_INT
114: #define __PTR_TO_INT(P) ((P) - (char *)0)
115: #endif
116:
117: #ifndef __INT_TO_PTR
118: #define __INT_TO_PTR(P) ((P) + (char *)0)
119: #endif
120:
121: struct _obstack_chunk /* Lives at front of each chunk. */
122: {
123: char *limit; /* 1 past end of this chunk */
124: struct _obstack_chunk *prev; /* address of prior chunk or NULL */
125: char contents[4]; /* objects begin here */
126: };
127:
128: struct obstack /* control current object in current chunk */
129: {
130: long chunk_size; /* preferred size to allocate chunks in */
131: struct _obstack_chunk* chunk; /* address of current struct obstack_chunk */
132: char *object_base; /* address of object we are building */
133: char *next_free; /* where to add next char to current object */
134: char *chunk_limit; /* address of char after current chunk */
135: int temp; /* Temporary for some macros. */
136: int alignment_mask; /* Mask of alignment for each object. */
137: struct _obstack_chunk *(*chunkfun) (); /* User's fcn to allocate a chunk. */
138: void (*freefun) (); /* User's function to free a chunk. */
139: };
140:
141: #ifdef __STDC__
142:
143: /* Do the function-declarations after the structs
144: but before defining the macros. */
145:
146: void obstack_init (struct obstack *obstack);
147:
148: void * obstack_alloc (struct obstack *obstack, int size);
149:
150: void * obstack_copy (struct obstack *obstack, void *address, int size);
151: void * obstack_copy0 (struct obstack *obstack, void *address, int size);
152:
153: void obstack_free (struct obstack *obstack, void *block);
154:
155: void obstack_blank (struct obstack *obstack, int size);
156:
157: void obstack_grow (struct obstack *obstack, void *data, int size);
158: void obstack_grow0 (struct obstack *obstack, void *data, int size);
159:
160: void obstack_1grow (struct obstack *obstack, int data_char);
161: void obstack_ptr_grow (struct obstack *obstack, void *data);
162: void obstack_int_grow (struct obstack *obstack, int data);
163:
164: void * obstack_finish (struct obstack *obstack);
165:
166: int obstack_object_size (struct obstack *obstack);
167:
168: int obstack_room (struct obstack *obstack);
169: void obstack_1grow_fast (struct obstack *obstack, int data_char);
170: void obstack_ptr_grow_fast (struct obstack *obstack, void *data);
171: void obstack_int_grow_fast (struct obstack *obstack, int data);
172: void obstack_blank_fast (struct obstack *obstack, int size);
173:
174: void * obstack_base (struct obstack *obstack);
175: void * obstack_next_free (struct obstack *obstack);
176: int obstack_alignment_mask (struct obstack *obstack);
177: int obstack_chunk_size (struct obstack *obstack);
178:
179: void _obstack_begin (struct obstack *h, int size, int alignment,
180: void * (*chunkfun)(long n), void (*freefun)());
181: void _obstack_newchunk (struct obstack *h, int length);
182: #endif /* __STDC__ */
183:
184: /* Non-ANSI C cannot really support alternative functions for these macros,
185: so we do not declare them. */
186:
187: /* Pointer to beginning of object being allocated or to be allocated next.
188: Note that this might not be the final address of the object
189: because a new chunk might be needed to hold the final size. */
190:
191: #define obstack_base(h) ((h)->object_base)
192:
193: /* Size for allocating ordinary chunks. */
194:
195: #define obstack_chunk_size(h) ((h)->chunk_size)
196:
197: /* Pointer to next byte not yet allocated in current chunk. */
198:
199: #define obstack_next_free(h) ((h)->next_free)
200:
201: /* Mask specifying low bits that should be clear in address of an object. */
202:
203: #define obstack_alignment_mask(h) ((h)->alignment_mask)
204:
205: #define obstack_init(h) \
206: _obstack_begin ((h), 0, 0, obstack_chunk_alloc, obstack_chunk_free)
207:
208: #define obstack_begin(h, size) \
209: _obstack_begin ((h), (size), 0, obstack_chunk_alloc, obstack_chunk_free)
210:
211: #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)
212:
213: #define obstack_blank_fast(h,n) ((h)->next_free += (n))
214:
215: #if defined (__GNUC__) && defined (__STDC__)
216:
217: /* For GNU C, if not -traditional,
218: we can define these macros to compute all args only once
219: without using a global variable.
220: Also, we can avoid using the `temp' slot, to make faster code. */
221:
222: #define obstack_object_size(OBSTACK) \
223: ({ struct obstack *__o = (OBSTACK); \
224: (unsigned) (__o->next_free - __o->object_base); })
225:
226: #define obstack_room(OBSTACK) \
227: ({ struct obstack *__o = (OBSTACK); \
228: (unsigned) (__o->chunk_limit - __o->next_free); })
229:
230: #define obstack_grow(OBSTACK,where,length) \
231: ({ struct obstack *__o = (OBSTACK); \
232: int __len = (length); \
233: ((__o->next_free + __len > __o->chunk_limit) \
234: ? _obstack_newchunk (__o, __len) : 0); \
235: bcopy (where, __o->next_free, __len); \
236: __o->next_free += __len; \
237: (void) 0; })
238:
239: #define obstack_grow0(OBSTACK,where,length) \
240: ({ struct obstack *__o = (OBSTACK); \
241: int __len = (length); \
242: ((__o->next_free + __len + 1 > __o->chunk_limit) \
243: ? _obstack_newchunk (__o, __len + 1) : 0), \
244: bcopy (where, __o->next_free, __len), \
245: __o->next_free += __len, \
246: *(__o->next_free)++ = 0; \
247: (void) 0; })
248:
249: #define obstack_1grow(OBSTACK,datum) \
250: ({ struct obstack *__o = (OBSTACK); \
251: ((__o->next_free + 1 > __o->chunk_limit) \
252: ? _obstack_newchunk (__o, 1) : 0), \
253: *(__o->next_free)++ = (datum); \
254: (void) 0; })
255:
256: /* These assume that the obstack alignment is good enough for pointers or ints,
257: and that the data added so far to the current object
258: shares that much alignment. */
259:
260: #define obstack_ptr_grow(OBSTACK,datum) \
261: ({ struct obstack *__o = (OBSTACK); \
262: ((__o->next_free + sizeof (void *) > __o->chunk_limit) \
263: ? _obstack_newchunk (__o, sizeof (void *)) : 0), \
264: *((void **)__o->next_free)++ = ((void *)datum); \
265: (void) 0; })
266:
267: #define obstack_int_grow(OBSTACK,datum) \
268: ({ struct obstack *__o = (OBSTACK); \
269: ((__o->next_free + sizeof (int) > __o->chunk_limit) \
270: ? _obstack_newchunk (__o, sizeof (int)) : 0), \
271: *((int *)__o->next_free)++ = ((int)datum); \
272: (void) 0; })
273:
274: #define obstack_ptr_grow_fast(h,aptr) (*((void **)(h)->next_free)++ = (void *)aptr)
275: #define obstack_int_grow_fast(h,aint) (*((int *)(h)->next_free)++ = (int)aint)
276:
277: #define obstack_blank(OBSTACK,length) \
278: ({ struct obstack *__o = (OBSTACK); \
279: int __len = (length); \
280: ((__o->next_free + __len > __o->chunk_limit) \
281: ? _obstack_newchunk (__o, __len) : 0); \
282: __o->next_free += __len; \
283: (void) 0; })
284:
285: #define obstack_alloc(OBSTACK,length) \
286: ({ struct obstack *__h = (OBSTACK); \
287: obstack_blank (__h, (length)); \
288: obstack_finish (__h); })
289:
290: #define obstack_copy(OBSTACK,where,length) \
291: ({ struct obstack *__h = (OBSTACK); \
292: obstack_grow (__h, (where), (length)); \
293: obstack_finish (__h); })
294:
295: #define obstack_copy0(OBSTACK,where,length) \
296: ({ struct obstack *__h = (OBSTACK); \
297: obstack_grow0 (__h, (where), (length)); \
298: obstack_finish (__h); })
299:
300: #define obstack_finish(OBSTACK) \
301: ({ struct obstack *__o = (OBSTACK); \
302: void *value = (void *) __o->object_base; \
303: __o->next_free \
304: = __INT_TO_PTR ((__PTR_TO_INT (__o->next_free)+__o->alignment_mask)\
305: & ~ (__o->alignment_mask)); \
306: ((__o->next_free - (char *)__o->chunk \
307: > __o->chunk_limit - (char *)__o->chunk) \
308: ? (__o->next_free = __o->chunk_limit) : 0); \
309: __o->object_base = __o->next_free; \
310: value; })
311:
312: #define obstack_free(OBSTACK, OBJ) \
313: ({ struct obstack *__o = (OBSTACK); \
314: void *__obj = (OBJ); \
315: if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
316: __o->next_free = __o->object_base = __obj; \
317: else (obstack_free) (__o, __obj); })
318:
319: #else /* not __GNUC__ or not __STDC__ */
320:
321: #define obstack_object_size(h) \
322: (unsigned) ((h)->next_free - (h)->object_base)
323:
324: #define obstack_room(h) \
325: (unsigned) ((h)->chunk_limit - (h)->next_free)
326:
327: #define obstack_grow(h,where,length) \
328: ( (h)->temp = (length), \
329: (((h)->next_free + (h)->temp > (h)->chunk_limit) \
330: ? _obstack_newchunk ((h), (h)->temp) : 0), \
331: bcopy (where, (h)->next_free, (h)->temp), \
332: (h)->next_free += (h)->temp)
333:
334: #define obstack_grow0(h,where,length) \
335: ( (h)->temp = (length), \
336: (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \
337: ? _obstack_newchunk ((h), (h)->temp + 1) : 0), \
338: bcopy (where, (h)->next_free, (h)->temp), \
339: (h)->next_free += (h)->temp, \
340: *((h)->next_free)++ = 0)
341:
342: #define obstack_1grow(h,datum) \
343: ( (((h)->next_free + 1 > (h)->chunk_limit) \
344: ? _obstack_newchunk ((h), 1) : 0), \
345: *((h)->next_free)++ = (datum))
346:
347: #define obstack_ptr_grow(h,datum) \
348: ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
349: ? _obstack_newchunk ((h), sizeof (char *)) : 0), \
350: *((char **)(h)->next_free)++ = ((char *)datum))
351:
352: #define obstack_int_grow(h,datum) \
353: ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
354: ? _obstack_newchunk ((h), sizeof (int)) : 0), \
355: *((int *)(h)->next_free)++ = ((int)datum))
356:
357: #define obstack_ptr_grow_fast(h,aptr) (*((char **)(h)->next_free)++ = (char *)aptr)
358: #define obstack_int_grow_fast(h,aint) (*((int *)(h)->next_free)++ = (int)aint)
359:
360: #define obstack_blank(h,length) \
361: ( (h)->temp = (length), \
362: (((h)->next_free + (h)->temp > (h)->chunk_limit) \
363: ? _obstack_newchunk ((h), (h)->temp) : 0), \
364: (h)->next_free += (h)->temp)
365:
366: #define obstack_alloc(h,length) \
367: (obstack_blank ((h), (length)), obstack_finish ((h)))
368:
369: #define obstack_copy(h,where,length) \
370: (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
371:
372: #define obstack_copy0(h,where,length) \
373: (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
374:
375: #define obstack_finish(h) \
376: ( (h)->temp = __PTR_TO_INT ((h)->object_base), \
377: (h)->next_free \
378: = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
379: & ~ ((h)->alignment_mask)), \
380: (((h)->next_free - (char *)(h)->chunk \
381: > (h)->chunk_limit - (char *)(h)->chunk) \
382: ? ((h)->next_free = (h)->chunk_limit) : 0), \
383: (h)->object_base = (h)->next_free, \
384: __INT_TO_PTR ((h)->temp))
385:
386: #ifdef __STDC__
387: #define obstack_free(h,obj) \
388: ( (h)->temp = (char *)(obj) - (char *) (h)->chunk, \
389: (((h)->temp >= 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
390: ? (int) ((h)->next_free = (h)->object_base \
391: = (h)->temp + (char *) (h)->chunk) \
392: : ((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0)))
393: #else
394: #define obstack_free(h,obj) \
395: ( (h)->temp = (char *)(obj) - (char *) (h)->chunk, \
396: (((h)->temp >= 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
397: ? (int) ((h)->next_free = (h)->object_base \
398: = (h)->temp + (char *) (h)->chunk) \
399: : (int) _obstack_free ((h), (h)->temp + (char *) (h)->chunk)))
400: #endif
401:
402: #endif /* not __GNUC__ or not __STDC__ */
403:
404: #endif /* not __OBSTACKS__ */
405:
This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.