summaryrefslogtreecommitdiff
path: root/cord/cordxtra.c
blob: a5be10de58aed4ccd249f46ac036f0793d75d698 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
/*
 * Copyright (c) 1993-1994 by Xerox Corporation.  All rights reserved.
 *
 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
 * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
 *
 * Permission is hereby granted to use or copy this program
 * for any purpose,  provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is granted,
 * provided the above notices are retained, and a notice that the code was
 * modified is included with the above copyright notice.
 *
 * Author: Hans-J. Boehm (boehm@parc.xerox.com)
 */
/*
 * These are functions on cords that do not need to understand their
 * implementation.  They serve also serve as example client code for
 * cord_basics.
 */
/* Boehm, December 8, 1995 1:53 pm PST */
# include <stdio.h>
# include <string.h>
# include <stdlib.h>
# include <stdarg.h>
# include "cord.h"
# include "ec.h"
# define I_HIDE_POINTERS	/* So we get access to allocation lock.	*/
				/* We use this for lazy file reading, 	*/
				/* so that we remain independent 	*/
				/* of the threads primitives.		*/
# include "gc.h"

/* For now we assume that pointer reads and writes are atomic, 	*/
/* i.e. another thread always sees the state before or after	*/
/* a write.  This might be false on a Motorola M68K with	*/
/* pointers that are not 32-bit aligned.  But there probably	*/
/* aren't too many threads packages running on those.		*/
# define ATOMIC_WRITE(x,y) (x) = (y)
# define ATOMIC_READ(x) (*(x))

/* The standard says these are in stdio.h, but they aren't always: */
# ifndef SEEK_SET
#   define SEEK_SET 0
# endif
# ifndef SEEK_END
#   define SEEK_END 2
# endif

# define BUFSZ 2048	/* Size of stack allocated buffers when		*/
			/* we want large buffers.			*/

typedef void (* oom_fn)(void);

# define OUT_OF_MEMORY {  if (CORD_oom_fn != (oom_fn) 0) (*CORD_oom_fn)(); \
			  ABORT("Out of memory\n"); }
# define ABORT(msg) { fprintf(stderr, "%s\n", msg); abort(); }

CORD CORD_cat_char(CORD x, char c)
{
    register char * string;
    
    if (c == '\0') return(CORD_cat(x, CORD_nul(1)));
    string = GC_MALLOC_ATOMIC(2);
    if (string == 0) OUT_OF_MEMORY;
    string[0] = c;
    string[1] = '\0';
    return(CORD_cat_char_star(x, string, 1));
}

CORD CORD_catn(int nargs, ...)
{
    register CORD result = CORD_EMPTY;
    va_list args;
    register int i;

    va_start(args, nargs);
    for (i = 0; i < nargs; i++) {
        register CORD next = va_arg(args, CORD);
        result = CORD_cat(result, next);
    }
    va_end(args);
    return(result);
}

typedef struct {
	size_t len;
	size_t count;
	char * buf;
} CORD_fill_data;

int CORD_fill_proc(char c, void * client_data)
{
    register CORD_fill_data * d = (CORD_fill_data *)client_data;
    register size_t count = d -> count;
    
    (d -> buf)[count] = c;
    d -> count = ++count;
    if (count >= d -> len) {
    	return(1);
    } else {
    	return(0);
    }
}

int CORD_batched_fill_proc(const char * s, void * client_data)
{
    register CORD_fill_data * d = (CORD_fill_data *)client_data;
    register size_t count = d -> count;
    register size_t max = d -> len;
    register char * buf = d -> buf;
    register const char * t = s;
    
    while((buf[count] = *t++) != '\0') {
        count++;
        if (count >= max) {
            d -> count = count;
            return(1);
        }
    }
    d -> count = count;
    return(0);
}

/* Fill buf with len characters starting at i.  			*/
/* Assumes len characters are available.				*/ 
void CORD_fill_buf(CORD x, size_t i, size_t len, char * buf)
{
    CORD_fill_data fd;
    
    fd.len = len;
    fd.buf = buf;
    fd.count = 0;
    (void)CORD_iter5(x, i, CORD_fill_proc, CORD_batched_fill_proc, &fd);
}

int CORD_cmp(CORD x, CORD y)
{
    CORD_pos xpos;
    CORD_pos ypos;
    register size_t avail, yavail;
    
    if (y == CORD_EMPTY) return(x != CORD_EMPTY);
    if (x == CORD_EMPTY) return(-1);
    if (CORD_IS_STRING(y) && CORD_IS_STRING(x)) return(strcmp(x,y));
    CORD_set_pos(xpos, x, 0);
    CORD_set_pos(ypos, y, 0);
    for(;;) {
        if (!CORD_pos_valid(xpos)) {
            if (CORD_pos_valid(ypos)) {
            	return(-1);
            } else {
                return(0);
            }
        }
        if (!CORD_pos_valid(ypos)) {
            return(1);
        }
        if ((avail = CORD_pos_chars_left(xpos)) <= 0
            || (yavail = CORD_pos_chars_left(ypos)) <= 0) {
            register char xcurrent = CORD_pos_fetch(xpos);
            register char ycurrent = CORD_pos_fetch(ypos);
            if (xcurrent != ycurrent) return(xcurrent - ycurrent);
            CORD_next(xpos);
            CORD_next(ypos);
        } else {
            /* process as many characters as we can	*/
            register int result;
            
            if (avail > yavail) avail = yavail;
            result = strncmp(CORD_pos_cur_char_addr(xpos),
            		     CORD_pos_cur_char_addr(ypos), avail);
            if (result != 0) return(result);
            CORD_pos_advance(xpos, avail);
            CORD_pos_advance(ypos, avail);
        }
    }
}

int CORD_ncmp(CORD x, size_t x_start, CORD y, size_t y_start, size_t len)
{
    CORD_pos xpos;
    CORD_pos ypos;
    register size_t count;
    register long avail, yavail;
    
    CORD_set_pos(xpos, x, x_start);
    CORD_set_pos(ypos, y, y_start);
    for(count = 0; count < len;) {
        if (!CORD_pos_valid(xpos)) {
            if (CORD_pos_valid(ypos)) {
            	return(-1);
            } else {
                return(0);
            }
        }
        if (!CORD_pos_valid(ypos)) {
            return(1);
        }
        if ((avail = CORD_pos_chars_left(xpos)) <= 0
            || (yavail = CORD_pos_chars_left(ypos)) <= 0) {
            register char xcurrent = CORD_pos_fetch(xpos);
            register char ycurrent = CORD_pos_fetch(ypos);
            if (xcurrent != ycurrent) return(xcurrent - ycurrent);
            CORD_next(xpos);
            CORD_next(ypos);
            count++;
        } else {
            /* process as many characters as we can	*/
            register int result;
            
            if (avail > yavail) avail = yavail;
            count += avail;
            if (count > len) avail -= (count - len);
            result = strncmp(CORD_pos_cur_char_addr(xpos),
            		     CORD_pos_cur_char_addr(ypos), (size_t)avail);
            if (result != 0) return(result);
            CORD_pos_advance(xpos, (size_t)avail);
            CORD_pos_advance(ypos, (size_t)avail);
        }
    }
    return(0);
}

char * CORD_to_char_star(CORD x)
{
    register size_t len = CORD_len(x);
    char * result = GC_MALLOC_ATOMIC(len + 1);
    
    if (result == 0) OUT_OF_MEMORY;
    CORD_fill_buf(x, 0, len, result);
    result[len] = '\0';
    return(result);
}

CORD CORD_from_char_star(const char *s)
{
    char * result;
    size_t len = strlen(s);

    if (0 == len) return(CORD_EMPTY);
    result = GC_MALLOC_ATOMIC(len + 1);
    if (result == 0) OUT_OF_MEMORY;
    memcpy(result, s, len+1);
    return(result);
}

const char * CORD_to_const_char_star(CORD x)
{
    if (x == 0) return("");
    if (CORD_IS_STRING(x)) return((const char *)x);
    return(CORD_to_char_star(x));
}

char CORD_fetch(CORD x, size_t i)
{
    CORD_pos xpos;
    
    CORD_set_pos(xpos, x, i);
    if (!CORD_pos_valid(xpos)) ABORT("bad index?");
    return(CORD_pos_fetch(xpos));
}


int CORD_put_proc(char c, void * client_data)
{
    register FILE * f = (FILE *)client_data;
    
    return(putc(c, f) == EOF);
}

int CORD_batched_put_proc(const char * s, void * client_data)
{
    register FILE * f = (FILE *)client_data;
    
    return(fputs(s, f) == EOF);
}
    

int CORD_put(CORD x, FILE * f)
{
    if (CORD_iter5(x, 0, CORD_put_proc, CORD_batched_put_proc, f)) {
        return(EOF);
    } else {
    	return(1);
    }
}

typedef struct {
    size_t pos;		/* Current position in the cord */
    char target;	/* Character we're looking for	*/
} chr_data;

int CORD_chr_proc(char c, void * client_data)
{
    register chr_data * d = (chr_data *)client_data;
    
    if (c == d -> target) return(1);
    (d -> pos) ++;
    return(0);
}

int CORD_rchr_proc(char c, void * client_data)
{
    register chr_data * d = (chr_data *)client_data;
    
    if (c == d -> target) return(1);
    (d -> pos) --;
    return(0);
}

int CORD_batched_chr_proc(const char *s, void * client_data)
{
    register chr_data * d = (chr_data *)client_data;
    register char * occ = strchr(s, d -> target);
    
    if (occ == 0) {
      	d -> pos += strlen(s);
      	return(0);
    } else {
    	d -> pos += occ - s;
    	return(1);
    }
}

size_t CORD_chr(CORD x, size_t i, int c)
{
    chr_data d;
    
    d.pos = i;
    d.target = c;
    if (CORD_iter5(x, i, CORD_chr_proc, CORD_batched_chr_proc, &d)) {
        return(d.pos);
    } else {
    	return(CORD_NOT_FOUND);
    }
}

size_t CORD_rchr(CORD x, size_t i, int c)
{
    chr_data d;
    
    d.pos = i;
    d.target = c;
    if (CORD_riter4(x, i, CORD_rchr_proc, &d)) {
        return(d.pos);
    } else {
    	return(CORD_NOT_FOUND);
    }
}

/* Find the first occurrence of s in x at position start or later.	*/
/* This uses an asymptotically poor algorithm, which should typically 	*/
/* perform acceptably.  We compare the first few characters directly,	*/
/* and call CORD_ncmp whenever there is a partial match.		*/
/* This has the advantage that we allocate very little, or not at all.	*/
/* It's very fast if there are few close misses.			*/
size_t CORD_str(CORD x, size_t start, CORD s)
{
    CORD_pos xpos;
    size_t xlen = CORD_len(x);
    size_t slen;
    register size_t start_len;
    const char * s_start;
    unsigned long s_buf = 0;	/* The first few characters of s	*/
    unsigned long x_buf = 0;	/* Start of candidate substring.	*/
    				/* Initialized only to make compilers	*/
    				/* happy.				*/
    unsigned long mask = 0;
    register size_t i;
    register size_t match_pos;
    
    if (s == CORD_EMPTY) return(start);
    if (CORD_IS_STRING(s)) {
        s_start = s;
        slen = strlen(s);
    } else {
        s_start = CORD_to_char_star(CORD_substr(s, 0, sizeof(unsigned long)));
        slen = CORD_len(s);
    }
    if (xlen < start || xlen - start < slen) return(CORD_NOT_FOUND);
    start_len = slen;
    if (start_len > sizeof(unsigned long)) start_len = sizeof(unsigned long);
    CORD_set_pos(xpos, x, start);
    for (i = 0; i < start_len; i++) {
        mask <<= 8;
        mask |= 0xff;
        s_buf <<= 8;
        s_buf |= s_start[i];
        x_buf <<= 8;
        x_buf |= CORD_pos_fetch(xpos);
        CORD_next(xpos);
    }
    for (match_pos = start; ; match_pos++) {
    	if ((x_buf & mask) == s_buf) {
    	    if (slen == start_len ||
    	     	CORD_ncmp(x, match_pos + start_len,
    	     	 	  s, start_len, slen - start_len) == 0) {
    	        return(match_pos);
    	    }
    	}
	if ( match_pos == xlen - slen ) {
	    return(CORD_NOT_FOUND);
	}
    	x_buf <<= 8;
        x_buf |= CORD_pos_fetch(xpos);
        CORD_next(xpos);
    }
}

void CORD_ec_flush_buf(CORD_ec x)
{
    register size_t len = x[0].ec_bufptr - x[0].ec_buf;
    char * s;

    if (len == 0) return;
    s = GC_MALLOC_ATOMIC(len+1);
    memcpy(s, x[0].ec_buf, len);
    s[len] = '\0';
    x[0].ec_cord = CORD_cat_char_star(x[0].ec_cord, s, len);
    x[0].ec_bufptr = x[0].ec_buf;
}

void CORD_ec_append_cord(CORD_ec x, CORD s)
{
    CORD_ec_flush_buf(x);
    x[0].ec_cord = CORD_cat(x[0].ec_cord, s);
}

/*ARGSUSED*/
char CORD_nul_func(size_t i, void * client_data)
{
    return((char)(unsigned long)client_data);
}


CORD CORD_chars(char c, size_t i)
{
    return(CORD_from_fn(CORD_nul_func, (void *)(unsigned long)c, i));
}

CORD CORD_from_file_eager(FILE * f)
{
    register int c;
    CORD_ec ecord;
    
    CORD_ec_init(ecord);
    for(;;) {
        c = getc(f);
        if (c == 0) {
          /* Append the right number of NULs	*/
          /* Note that any string of NULs is rpresented in 4 words,	*/
          /* independent of its length.					*/
            register size_t count = 1;
            
            CORD_ec_flush_buf(ecord);
            while ((c = getc(f)) == 0) count++;
            ecord[0].ec_cord = CORD_cat(ecord[0].ec_cord, CORD_nul(count));
        }
        if (c == EOF) break;
        CORD_ec_append(ecord, c);
    }
    (void) fclose(f);
    return(CORD_balance(CORD_ec_to_cord(ecord)));
}

/* The state maintained for a lazily read file consists primarily	*/
/* of a large direct-mapped cache of previously read values.		*/
/* We could rely more on stdio buffering.  That would have 2		*/
/* disadvantages:							*/
/*  	1) Empirically, not all fseek implementations preserve the	*/
/*	   buffer whenever they could.					*/
/*	2) It would fail if 2 different sections of a long cord		*/
/*	   were being read alternately.					*/
/* We do use the stdio buffer for read ahead.				*/
/* To guarantee thread safety in the presence of atomic pointer		*/
/* writes, cache lines are always replaced, and never modified in	*/
/* place.								*/

# define LOG_CACHE_SZ 14
# define CACHE_SZ (1 << LOG_CACHE_SZ)
# define LOG_LINE_SZ 9
# define LINE_SZ (1 << LOG_LINE_SZ)

typedef struct {
    size_t tag;
    char data[LINE_SZ];
    	/* data[i%LINE_SZ] = ith char in file if tag = i/LINE_SZ	*/
} cache_line;

typedef struct {
    FILE * lf_file;
    size_t lf_current;	/* Current file pointer value */
    cache_line * volatile lf_cache[CACHE_SZ/LINE_SZ];
} lf_state;

# define MOD_CACHE_SZ(n) ((n) & (CACHE_SZ - 1))
# define DIV_CACHE_SZ(n) ((n) >> LOG_CACHE_SZ)
# define MOD_LINE_SZ(n) ((n) & (LINE_SZ - 1))
# define DIV_LINE_SZ(n) ((n) >> LOG_LINE_SZ)
# define LINE_START(n) ((n) & ~(LINE_SZ - 1))

typedef struct {
    lf_state * state;
    size_t file_pos;	/* Position of needed character. */
    cache_line * new_cache;
} refill_data;

/* Executed with allocation lock. */
static char refill_cache(client_data)
refill_data * client_data;
{
    register lf_state * state = client_data -> state;
    register size_t file_pos = client_data -> file_pos;
    FILE *f = state -> lf_file;
    size_t line_start = LINE_START(file_pos);
    size_t line_no = DIV_LINE_SZ(MOD_CACHE_SZ(file_pos));
    cache_line * new_cache = client_data -> new_cache;
    
    if (line_start != state -> lf_current
        && fseek(f, line_start, SEEK_SET) != 0) {
    	    ABORT("fseek failed");
    }
    if (fread(new_cache -> data, sizeof(char), LINE_SZ, f)
    	<= file_pos - line_start) {
    	ABORT("fread failed");
    }
    new_cache -> tag = DIV_LINE_SZ(file_pos);
    /* Store barrier goes here. */
    ATOMIC_WRITE(state -> lf_cache[line_no], new_cache);
    state -> lf_current = line_start + LINE_SZ;
    return(new_cache->data[MOD_LINE_SZ(file_pos)]);
}

char CORD_lf_func(size_t i, void * client_data)
{
    register lf_state * state = (lf_state *)client_data;
    register cache_line * volatile * cl_addr =
		&(state -> lf_cache[DIV_LINE_SZ(MOD_CACHE_SZ(i))]);
    register cache_line * cl = (cache_line *)ATOMIC_READ(cl_addr);
    
    if (cl == 0 || cl -> tag != DIV_LINE_SZ(i)) {
    	/* Cache miss */
    	refill_data rd;
    	
        rd.state = state;
        rd.file_pos =  i;
        rd.new_cache = GC_NEW_ATOMIC(cache_line);
        if (rd.new_cache == 0) OUT_OF_MEMORY;
        return((char)(GC_word)
        	  GC_call_with_alloc_lock((GC_fn_type) refill_cache, &rd));
    }
    return(cl -> data[MOD_LINE_SZ(i)]);
}    

/*ARGSUSED*/
void CORD_lf_close_proc(void * obj, void * client_data)  
{
    if (fclose(((lf_state *)obj) -> lf_file) != 0) {
    	ABORT("CORD_lf_close_proc: fclose failed");
    }
}			

CORD CORD_from_file_lazy_inner(FILE * f, size_t len)
{
    register lf_state * state = GC_NEW(lf_state);
    register int i;
    
    if (state == 0) OUT_OF_MEMORY;
    if (len != 0) {
	/* Dummy read to force buffer allocation.  	*/
	/* This greatly increases the probability	*/
	/* of avoiding deadlock if buffer allocation	*/
	/* is redirected to GC_malloc and the		*/
	/* world is multithreaded.			*/
	char buf[1];

	(void) fread(buf, 1, 1, f); 
	rewind(f);
    }
    state -> lf_file = f;
    for (i = 0; i < CACHE_SZ/LINE_SZ; i++) {
        state -> lf_cache[i] = 0;
    }
    state -> lf_current = 0;
    GC_REGISTER_FINALIZER(state, CORD_lf_close_proc, 0, 0, 0);
    return(CORD_from_fn(CORD_lf_func, state, len));
}

CORD CORD_from_file_lazy(FILE * f)
{
    register long len;
    
    if (fseek(f, 0l, SEEK_END) != 0) {
        ABORT("Bad fd argument - fseek failed");
    }
    if ((len = ftell(f)) < 0) {
        ABORT("Bad fd argument - ftell failed");
    }
    rewind(f);
    return(CORD_from_file_lazy_inner(f, (size_t)len));
}

# define LAZY_THRESHOLD (128*1024 + 1)

CORD CORD_from_file(FILE * f)
{
    register long len;
    
    if (fseek(f, 0l, SEEK_END) != 0) {
        ABORT("Bad fd argument - fseek failed");
    }
    if ((len = ftell(f)) < 0) {
        ABORT("Bad fd argument - ftell failed");
    }
    rewind(f);
    if (len < LAZY_THRESHOLD) {
        return(CORD_from_file_eager(f));
    } else {
        return(CORD_from_file_lazy_inner(f, (size_t)len));
    }
}