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1da177e4 LT |
1 | /* Generate assembler source containing symbol information |
2 | * | |
3 | * Copyright 2002 by Kai Germaschewski | |
4 | * | |
5 | * This software may be used and distributed according to the terms | |
6 | * of the GNU General Public License, incorporated herein by reference. | |
7 | * | |
8 | * Usage: nm -n vmlinux | scripts/kallsyms [--all-symbols] > symbols.S | |
9 | * | |
10 | * ChangeLog: | |
11 | * | |
12 | * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com> | |
13 | * Changed the compression method from stem compression to "table lookup" | |
14 | * compression | |
15 | * | |
16 | * Table compression uses all the unused char codes on the symbols and | |
17 | * maps these to the most used substrings (tokens). For instance, it might | |
18 | * map char code 0xF7 to represent "write_" and then in every symbol where | |
19 | * "write_" appears it can be replaced by 0xF7, saving 5 bytes. | |
20 | * The used codes themselves are also placed in the table so that the | |
21 | * decompresion can work without "special cases". | |
22 | * Applied to kernel symbols, this usually produces a compression ratio | |
23 | * of about 50%. | |
24 | * | |
25 | */ | |
26 | ||
27 | #include <stdio.h> | |
28 | #include <stdlib.h> | |
29 | #include <string.h> | |
30 | #include <ctype.h> | |
31 | ||
32 | /* maximum token length used. It doesn't pay to increase it a lot, because | |
33 | * very long substrings probably don't repeat themselves too often. */ | |
34 | #define MAX_TOK_SIZE 11 | |
35 | #define KSYM_NAME_LEN 127 | |
36 | ||
37 | /* we use only a subset of the complete symbol table to gather the token count, | |
38 | * to speed up compression, at the expense of a little compression ratio */ | |
39 | #define WORKING_SET 1024 | |
40 | ||
41 | /* first find the best token only on the list of tokens that would profit more | |
42 | * than GOOD_BAD_THRESHOLD. Only if this list is empty go to the "bad" list. | |
43 | * Increasing this value will put less tokens on the "good" list, so the search | |
44 | * is faster. However, if the good list runs out of tokens, we must painfully | |
45 | * search the bad list. */ | |
46 | #define GOOD_BAD_THRESHOLD 10 | |
47 | ||
48 | /* token hash parameters */ | |
49 | #define HASH_BITS 18 | |
50 | #define HASH_TABLE_SIZE (1 << HASH_BITS) | |
51 | #define HASH_MASK (HASH_TABLE_SIZE - 1) | |
52 | #define HASH_BASE_OFFSET 2166136261U | |
53 | #define HASH_FOLD(a) ((a)&(HASH_MASK)) | |
54 | ||
55 | /* flags to mark symbols */ | |
56 | #define SYM_FLAG_VALID 1 | |
57 | #define SYM_FLAG_SAMPLED 2 | |
58 | ||
59 | struct sym_entry { | |
60 | unsigned long long addr; | |
61 | char type; | |
62 | unsigned char flags; | |
63 | unsigned char len; | |
64 | unsigned char *sym; | |
65 | }; | |
66 | ||
67 | ||
68 | static struct sym_entry *table; | |
69 | static int size, cnt; | |
70 | static unsigned long long _stext, _etext, _sinittext, _einittext; | |
71 | static int all_symbols = 0; | |
41f11a4f | 72 | static char symbol_prefix_char = '\0'; |
1da177e4 LT |
73 | |
74 | struct token { | |
75 | unsigned char data[MAX_TOK_SIZE]; | |
76 | unsigned char len; | |
77 | /* profit: the number of bytes that could be saved by inserting this | |
78 | * token into the table */ | |
79 | int profit; | |
80 | struct token *next; /* next token on the hash list */ | |
81 | struct token *right; /* next token on the good/bad list */ | |
82 | struct token *left; /* previous token on the good/bad list */ | |
83 | struct token *smaller; /* token that is less one letter than this one */ | |
84 | }; | |
85 | ||
86 | struct token bad_head, good_head; | |
87 | struct token *hash_table[HASH_TABLE_SIZE]; | |
88 | ||
89 | /* the table that holds the result of the compression */ | |
90 | unsigned char best_table[256][MAX_TOK_SIZE+1]; | |
91 | unsigned char best_table_len[256]; | |
92 | ||
93 | ||
94 | static void | |
95 | usage(void) | |
96 | { | |
41f11a4f | 97 | fprintf(stderr, "Usage: kallsyms [--all-symbols] [--symbol-prefix=<prefix char>] < in.map > out.S\n"); |
1da177e4 LT |
98 | exit(1); |
99 | } | |
100 | ||
101 | /* | |
102 | * This ignores the intensely annoying "mapping symbols" found | |
103 | * in ARM ELF files: $a, $t and $d. | |
104 | */ | |
105 | static inline int | |
106 | is_arm_mapping_symbol(const char *str) | |
107 | { | |
108 | return str[0] == '$' && strchr("atd", str[1]) | |
109 | && (str[2] == '\0' || str[2] == '.'); | |
110 | } | |
111 | ||
112 | static int | |
113 | read_symbol(FILE *in, struct sym_entry *s) | |
114 | { | |
115 | char str[500]; | |
41f11a4f | 116 | char *sym; |
1da177e4 LT |
117 | int rc; |
118 | ||
119 | rc = fscanf(in, "%llx %c %499s\n", &s->addr, &s->type, str); | |
120 | if (rc != 3) { | |
121 | if (rc != EOF) { | |
122 | /* skip line */ | |
123 | fgets(str, 500, in); | |
124 | } | |
125 | return -1; | |
126 | } | |
127 | ||
41f11a4f YS |
128 | sym = str; |
129 | /* skip prefix char */ | |
130 | if (symbol_prefix_char && str[0] == symbol_prefix_char) | |
131 | sym++; | |
132 | ||
1da177e4 | 133 | /* Ignore most absolute/undefined (?) symbols. */ |
41f11a4f | 134 | if (strcmp(sym, "_stext") == 0) |
1da177e4 | 135 | _stext = s->addr; |
41f11a4f | 136 | else if (strcmp(sym, "_etext") == 0) |
1da177e4 | 137 | _etext = s->addr; |
41f11a4f | 138 | else if (strcmp(sym, "_sinittext") == 0) |
1da177e4 | 139 | _sinittext = s->addr; |
41f11a4f | 140 | else if (strcmp(sym, "_einittext") == 0) |
1da177e4 LT |
141 | _einittext = s->addr; |
142 | else if (toupper(s->type) == 'A') | |
143 | { | |
144 | /* Keep these useful absolute symbols */ | |
41f11a4f YS |
145 | if (strcmp(sym, "__kernel_syscall_via_break") && |
146 | strcmp(sym, "__kernel_syscall_via_epc") && | |
147 | strcmp(sym, "__kernel_sigtramp") && | |
148 | strcmp(sym, "__gp")) | |
1da177e4 LT |
149 | return -1; |
150 | ||
151 | } | |
152 | else if (toupper(s->type) == 'U' || | |
41f11a4f | 153 | is_arm_mapping_symbol(sym)) |
1da177e4 LT |
154 | return -1; |
155 | ||
156 | /* include the type field in the symbol name, so that it gets | |
157 | * compressed together */ | |
158 | s->len = strlen(str) + 1; | |
159 | s->sym = (char *) malloc(s->len + 1); | |
160 | strcpy(s->sym + 1, str); | |
161 | s->sym[0] = s->type; | |
162 | ||
163 | return 0; | |
164 | } | |
165 | ||
166 | static int | |
167 | symbol_valid(struct sym_entry *s) | |
168 | { | |
169 | /* Symbols which vary between passes. Passes 1 and 2 must have | |
170 | * identical symbol lists. The kallsyms_* symbols below are only added | |
171 | * after pass 1, they would be included in pass 2 when --all-symbols is | |
172 | * specified so exclude them to get a stable symbol list. | |
173 | */ | |
174 | static char *special_symbols[] = { | |
175 | "kallsyms_addresses", | |
176 | "kallsyms_num_syms", | |
177 | "kallsyms_names", | |
178 | "kallsyms_markers", | |
179 | "kallsyms_token_table", | |
180 | "kallsyms_token_index", | |
181 | ||
182 | /* Exclude linker generated symbols which vary between passes */ | |
183 | "_SDA_BASE_", /* ppc */ | |
184 | "_SDA2_BASE_", /* ppc */ | |
185 | NULL }; | |
186 | int i; | |
41f11a4f YS |
187 | int offset = 1; |
188 | ||
189 | /* skip prefix char */ | |
190 | if (symbol_prefix_char && *(s->sym + 1) == symbol_prefix_char) | |
191 | offset++; | |
1da177e4 LT |
192 | |
193 | /* if --all-symbols is not specified, then symbols outside the text | |
194 | * and inittext sections are discarded */ | |
195 | if (!all_symbols) { | |
196 | if ((s->addr < _stext || s->addr > _etext) | |
197 | && (s->addr < _sinittext || s->addr > _einittext)) | |
198 | return 0; | |
199 | /* Corner case. Discard any symbols with the same value as | |
200 | * _etext or _einittext, they can move between pass 1 and 2 | |
201 | * when the kallsyms data is added. If these symbols move then | |
202 | * they may get dropped in pass 2, which breaks the kallsyms | |
203 | * rules. | |
204 | */ | |
41f11a4f YS |
205 | if ((s->addr == _etext && strcmp(s->sym + offset, "_etext")) || |
206 | (s->addr == _einittext && strcmp(s->sym + offset, "_einittext"))) | |
1da177e4 LT |
207 | return 0; |
208 | } | |
209 | ||
210 | /* Exclude symbols which vary between passes. */ | |
41f11a4f | 211 | if (strstr(s->sym + offset, "_compiled.")) |
1da177e4 LT |
212 | return 0; |
213 | ||
214 | for (i = 0; special_symbols[i]; i++) | |
41f11a4f | 215 | if( strcmp(s->sym + offset, special_symbols[i]) == 0 ) |
1da177e4 LT |
216 | return 0; |
217 | ||
218 | return 1; | |
219 | } | |
220 | ||
221 | static void | |
222 | read_map(FILE *in) | |
223 | { | |
224 | while (!feof(in)) { | |
225 | if (cnt >= size) { | |
226 | size += 10000; | |
227 | table = realloc(table, sizeof(*table) * size); | |
228 | if (!table) { | |
229 | fprintf(stderr, "out of memory\n"); | |
230 | exit (1); | |
231 | } | |
232 | } | |
233 | if (read_symbol(in, &table[cnt]) == 0) | |
234 | cnt++; | |
235 | } | |
236 | } | |
237 | ||
238 | static void output_label(char *label) | |
239 | { | |
41f11a4f YS |
240 | if (symbol_prefix_char) |
241 | printf(".globl %c%s\n", symbol_prefix_char, label); | |
242 | else | |
243 | printf(".globl %s\n", label); | |
1da177e4 | 244 | printf("\tALGN\n"); |
41f11a4f YS |
245 | if (symbol_prefix_char) |
246 | printf("%c%s:\n", symbol_prefix_char, label); | |
247 | else | |
248 | printf("%s:\n", label); | |
1da177e4 LT |
249 | } |
250 | ||
251 | /* uncompress a compressed symbol. When this function is called, the best table | |
252 | * might still be compressed itself, so the function needs to be recursive */ | |
253 | static int expand_symbol(unsigned char *data, int len, char *result) | |
254 | { | |
255 | int c, rlen, total=0; | |
256 | ||
257 | while (len) { | |
258 | c = *data; | |
259 | /* if the table holds a single char that is the same as the one | |
260 | * we are looking for, then end the search */ | |
261 | if (best_table[c][0]==c && best_table_len[c]==1) { | |
262 | *result++ = c; | |
263 | total++; | |
264 | } else { | |
265 | /* if not, recurse and expand */ | |
266 | rlen = expand_symbol(best_table[c], best_table_len[c], result); | |
267 | total += rlen; | |
268 | result += rlen; | |
269 | } | |
270 | data++; | |
271 | len--; | |
272 | } | |
273 | *result=0; | |
274 | ||
275 | return total; | |
276 | } | |
277 | ||
278 | static void | |
279 | write_src(void) | |
280 | { | |
281 | int i, k, off, valid; | |
282 | unsigned int best_idx[256]; | |
283 | unsigned int *markers; | |
284 | char buf[KSYM_NAME_LEN+1]; | |
285 | ||
286 | printf("#include <asm/types.h>\n"); | |
287 | printf("#if BITS_PER_LONG == 64\n"); | |
288 | printf("#define PTR .quad\n"); | |
289 | printf("#define ALGN .align 8\n"); | |
290 | printf("#else\n"); | |
291 | printf("#define PTR .long\n"); | |
292 | printf("#define ALGN .align 4\n"); | |
293 | printf("#endif\n"); | |
294 | ||
295 | printf(".data\n"); | |
296 | ||
297 | output_label("kallsyms_addresses"); | |
298 | valid = 0; | |
299 | for (i = 0; i < cnt; i++) { | |
300 | if (table[i].flags & SYM_FLAG_VALID) { | |
301 | printf("\tPTR\t%#llx\n", table[i].addr); | |
302 | valid++; | |
303 | } | |
304 | } | |
305 | printf("\n"); | |
306 | ||
307 | output_label("kallsyms_num_syms"); | |
308 | printf("\tPTR\t%d\n", valid); | |
309 | printf("\n"); | |
310 | ||
311 | /* table of offset markers, that give the offset in the compressed stream | |
312 | * every 256 symbols */ | |
313 | markers = (unsigned int *) malloc(sizeof(unsigned int)*((valid + 255) / 256)); | |
314 | ||
315 | output_label("kallsyms_names"); | |
316 | valid = 0; | |
317 | off = 0; | |
318 | for (i = 0; i < cnt; i++) { | |
319 | ||
320 | if (!table[i].flags & SYM_FLAG_VALID) | |
321 | continue; | |
322 | ||
323 | if ((valid & 0xFF) == 0) | |
324 | markers[valid >> 8] = off; | |
325 | ||
326 | printf("\t.byte 0x%02x", table[i].len); | |
327 | for (k = 0; k < table[i].len; k++) | |
328 | printf(", 0x%02x", table[i].sym[k]); | |
329 | printf("\n"); | |
330 | ||
331 | off += table[i].len + 1; | |
332 | valid++; | |
333 | } | |
334 | printf("\n"); | |
335 | ||
336 | output_label("kallsyms_markers"); | |
337 | for (i = 0; i < ((valid + 255) >> 8); i++) | |
338 | printf("\tPTR\t%d\n", markers[i]); | |
339 | printf("\n"); | |
340 | ||
341 | free(markers); | |
342 | ||
343 | output_label("kallsyms_token_table"); | |
344 | off = 0; | |
345 | for (i = 0; i < 256; i++) { | |
346 | best_idx[i] = off; | |
347 | expand_symbol(best_table[i],best_table_len[i],buf); | |
348 | printf("\t.asciz\t\"%s\"\n", buf); | |
349 | off += strlen(buf) + 1; | |
350 | } | |
351 | printf("\n"); | |
352 | ||
353 | output_label("kallsyms_token_index"); | |
354 | for (i = 0; i < 256; i++) | |
355 | printf("\t.short\t%d\n", best_idx[i]); | |
356 | printf("\n"); | |
357 | } | |
358 | ||
359 | ||
360 | /* table lookup compression functions */ | |
361 | ||
362 | static inline unsigned int rehash_token(unsigned int hash, unsigned char data) | |
363 | { | |
364 | return ((hash * 16777619) ^ data); | |
365 | } | |
366 | ||
367 | static unsigned int hash_token(unsigned char *data, int len) | |
368 | { | |
369 | unsigned int hash=HASH_BASE_OFFSET; | |
370 | int i; | |
371 | ||
372 | for (i = 0; i < len; i++) | |
373 | hash = rehash_token(hash, data[i]); | |
374 | ||
375 | return HASH_FOLD(hash); | |
376 | } | |
377 | ||
378 | /* find a token given its data and hash value */ | |
379 | static struct token *find_token_hash(unsigned char *data, int len, unsigned int hash) | |
380 | { | |
381 | struct token *ptr; | |
382 | ||
383 | ptr = hash_table[hash]; | |
384 | ||
385 | while (ptr) { | |
386 | if ((ptr->len == len) && (memcmp(ptr->data, data, len) == 0)) | |
387 | return ptr; | |
388 | ptr=ptr->next; | |
389 | } | |
390 | ||
391 | return NULL; | |
392 | } | |
393 | ||
394 | static inline void insert_token_in_group(struct token *head, struct token *ptr) | |
395 | { | |
396 | ptr->right = head->right; | |
397 | ptr->right->left = ptr; | |
398 | head->right = ptr; | |
399 | ptr->left = head; | |
400 | } | |
401 | ||
402 | static inline void remove_token_from_group(struct token *ptr) | |
403 | { | |
404 | ptr->left->right = ptr->right; | |
405 | ptr->right->left = ptr->left; | |
406 | } | |
407 | ||
408 | ||
409 | /* build the counts for all the tokens that start with "data", and have lenghts | |
410 | * from 2 to "len" */ | |
411 | static void learn_token(unsigned char *data, int len) | |
412 | { | |
413 | struct token *ptr,*last_ptr; | |
414 | int i, newprofit; | |
415 | unsigned int hash = HASH_BASE_OFFSET; | |
416 | unsigned int hashes[MAX_TOK_SIZE + 1]; | |
417 | ||
418 | if (len > MAX_TOK_SIZE) | |
419 | len = MAX_TOK_SIZE; | |
420 | ||
421 | /* calculate and store the hash values for all the sub-tokens */ | |
422 | hash = rehash_token(hash, data[0]); | |
423 | for (i = 2; i <= len; i++) { | |
424 | hash = rehash_token(hash, data[i-1]); | |
425 | hashes[i] = HASH_FOLD(hash); | |
426 | } | |
427 | ||
428 | last_ptr = NULL; | |
429 | ptr = NULL; | |
430 | ||
431 | for (i = len; i >= 2; i--) { | |
432 | hash = hashes[i]; | |
433 | ||
434 | if (!ptr) ptr = find_token_hash(data, i, hash); | |
435 | ||
436 | if (!ptr) { | |
437 | /* create a new token entry */ | |
438 | ptr = (struct token *) malloc(sizeof(*ptr)); | |
439 | ||
440 | memcpy(ptr->data, data, i); | |
441 | ptr->len = i; | |
442 | ||
443 | /* when we create an entry, it's profit is 0 because | |
444 | * we also take into account the size of the token on | |
445 | * the compressed table. We then subtract GOOD_BAD_THRESHOLD | |
446 | * so that the test to see if this token belongs to | |
447 | * the good or bad list, is a comparison to zero */ | |
448 | ptr->profit = -GOOD_BAD_THRESHOLD; | |
449 | ||
450 | ptr->next = hash_table[hash]; | |
451 | hash_table[hash] = ptr; | |
452 | ||
453 | insert_token_in_group(&bad_head, ptr); | |
454 | ||
455 | ptr->smaller = NULL; | |
456 | } else { | |
457 | newprofit = ptr->profit + (ptr->len - 1); | |
458 | /* check to see if this token needs to be moved to a | |
459 | * different list */ | |
460 | if((ptr->profit < 0) && (newprofit >= 0)) { | |
461 | remove_token_from_group(ptr); | |
462 | insert_token_in_group(&good_head,ptr); | |
463 | } | |
464 | ptr->profit = newprofit; | |
465 | } | |
466 | ||
467 | if (last_ptr) last_ptr->smaller = ptr; | |
468 | last_ptr = ptr; | |
469 | ||
470 | ptr = ptr->smaller; | |
471 | } | |
472 | } | |
473 | ||
474 | /* decrease the counts for all the tokens that start with "data", and have lenghts | |
475 | * from 2 to "len". This function is much simpler than learn_token because we have | |
476 | * more guarantees (tho tokens exist, the ->smaller pointer is set, etc.) | |
477 | * The two separate functions exist only because of compression performance */ | |
478 | static void forget_token(unsigned char *data, int len) | |
479 | { | |
480 | struct token *ptr; | |
481 | int i, newprofit; | |
482 | unsigned int hash=0; | |
483 | ||
484 | if (len > MAX_TOK_SIZE) len = MAX_TOK_SIZE; | |
485 | ||
486 | hash = hash_token(data, len); | |
487 | ptr = find_token_hash(data, len, hash); | |
488 | ||
489 | for (i = len; i >= 2; i--) { | |
490 | ||
491 | newprofit = ptr->profit - (ptr->len - 1); | |
492 | if ((ptr->profit >= 0) && (newprofit < 0)) { | |
493 | remove_token_from_group(ptr); | |
494 | insert_token_in_group(&bad_head, ptr); | |
495 | } | |
496 | ptr->profit=newprofit; | |
497 | ||
498 | ptr=ptr->smaller; | |
499 | } | |
500 | } | |
501 | ||
502 | /* count all the possible tokens in a symbol */ | |
503 | static void learn_symbol(unsigned char *symbol, int len) | |
504 | { | |
505 | int i; | |
506 | ||
507 | for (i = 0; i < len - 1; i++) | |
508 | learn_token(symbol + i, len - i); | |
509 | } | |
510 | ||
511 | /* decrease the count for all the possible tokens in a symbol */ | |
512 | static void forget_symbol(unsigned char *symbol, int len) | |
513 | { | |
514 | int i; | |
515 | ||
516 | for (i = 0; i < len - 1; i++) | |
517 | forget_token(symbol + i, len - i); | |
518 | } | |
519 | ||
520 | /* set all the symbol flags and do the initial token count */ | |
521 | static void build_initial_tok_table(void) | |
522 | { | |
523 | int i, use_it, valid; | |
524 | ||
525 | valid = 0; | |
526 | for (i = 0; i < cnt; i++) { | |
527 | table[i].flags = 0; | |
528 | if ( symbol_valid(&table[i]) ) { | |
529 | table[i].flags |= SYM_FLAG_VALID; | |
530 | valid++; | |
531 | } | |
532 | } | |
533 | ||
534 | use_it = 0; | |
535 | for (i = 0; i < cnt; i++) { | |
536 | ||
537 | /* subsample the available symbols. This method is almost like | |
538 | * a Bresenham's algorithm to get uniformly distributed samples | |
539 | * across the symbol table */ | |
540 | if (table[i].flags & SYM_FLAG_VALID) { | |
541 | ||
542 | use_it += WORKING_SET; | |
543 | ||
544 | if (use_it >= valid) { | |
545 | table[i].flags |= SYM_FLAG_SAMPLED; | |
546 | use_it -= valid; | |
547 | } | |
548 | } | |
549 | if (table[i].flags & SYM_FLAG_SAMPLED) | |
550 | learn_symbol(table[i].sym, table[i].len); | |
551 | } | |
552 | } | |
553 | ||
554 | /* replace a given token in all the valid symbols. Use the sampled symbols | |
555 | * to update the counts */ | |
556 | static void compress_symbols(unsigned char *str, int tlen, int idx) | |
557 | { | |
558 | int i, len, learn, size; | |
559 | unsigned char *p; | |
560 | ||
561 | for (i = 0; i < cnt; i++) { | |
562 | ||
563 | if (!(table[i].flags & SYM_FLAG_VALID)) continue; | |
564 | ||
565 | len = table[i].len; | |
566 | learn = 0; | |
567 | p = table[i].sym; | |
568 | ||
569 | do { | |
570 | /* find the token on the symbol */ | |
571 | p = (unsigned char *) strstr((char *) p, (char *) str); | |
572 | if (!p) break; | |
573 | ||
574 | if (!learn) { | |
575 | /* if this symbol was used to count, decrease it */ | |
576 | if (table[i].flags & SYM_FLAG_SAMPLED) | |
577 | forget_symbol(table[i].sym, len); | |
578 | learn = 1; | |
579 | } | |
580 | ||
581 | *p = idx; | |
582 | size = (len - (p - table[i].sym)) - tlen + 1; | |
583 | memmove(p + 1, p + tlen, size); | |
584 | p++; | |
585 | len -= tlen - 1; | |
586 | ||
587 | } while (size >= tlen); | |
588 | ||
589 | if(learn) { | |
590 | table[i].len = len; | |
591 | /* if this symbol was used to count, learn it again */ | |
592 | if(table[i].flags & SYM_FLAG_SAMPLED) | |
593 | learn_symbol(table[i].sym, len); | |
594 | } | |
595 | } | |
596 | } | |
597 | ||
598 | /* search the token with the maximum profit */ | |
599 | static struct token *find_best_token(void) | |
600 | { | |
601 | struct token *ptr,*best,*head; | |
602 | int bestprofit; | |
603 | ||
604 | bestprofit=-10000; | |
605 | ||
606 | /* failsafe: if the "good" list is empty search from the "bad" list */ | |
607 | if(good_head.right == &good_head) head = &bad_head; | |
608 | else head = &good_head; | |
609 | ||
610 | ptr = head->right; | |
611 | best = NULL; | |
612 | while (ptr != head) { | |
613 | if (ptr->profit > bestprofit) { | |
614 | bestprofit = ptr->profit; | |
615 | best = ptr; | |
616 | } | |
617 | ptr = ptr->right; | |
618 | } | |
619 | ||
620 | return best; | |
621 | } | |
622 | ||
623 | /* this is the core of the algorithm: calculate the "best" table */ | |
624 | static void optimize_result(void) | |
625 | { | |
626 | struct token *best; | |
627 | int i; | |
628 | ||
629 | /* using the '\0' symbol last allows compress_symbols to use standard | |
630 | * fast string functions */ | |
631 | for (i = 255; i >= 0; i--) { | |
632 | ||
633 | /* if this table slot is empty (it is not used by an actual | |
634 | * original char code */ | |
635 | if (!best_table_len[i]) { | |
636 | ||
637 | /* find the token with the breates profit value */ | |
638 | best = find_best_token(); | |
639 | ||
640 | /* place it in the "best" table */ | |
641 | best_table_len[i] = best->len; | |
642 | memcpy(best_table[i], best->data, best_table_len[i]); | |
643 | /* zero terminate the token so that we can use strstr | |
644 | in compress_symbols */ | |
645 | best_table[i][best_table_len[i]]='\0'; | |
646 | ||
647 | /* replace this token in all the valid symbols */ | |
648 | compress_symbols(best_table[i], best_table_len[i], i); | |
649 | } | |
650 | } | |
651 | } | |
652 | ||
653 | /* start by placing the symbols that are actually used on the table */ | |
654 | static void insert_real_symbols_in_table(void) | |
655 | { | |
656 | int i, j, c; | |
657 | ||
658 | memset(best_table, 0, sizeof(best_table)); | |
659 | memset(best_table_len, 0, sizeof(best_table_len)); | |
660 | ||
661 | for (i = 0; i < cnt; i++) { | |
662 | if (table[i].flags & SYM_FLAG_VALID) { | |
663 | for (j = 0; j < table[i].len; j++) { | |
664 | c = table[i].sym[j]; | |
665 | best_table[c][0]=c; | |
666 | best_table_len[c]=1; | |
667 | } | |
668 | } | |
669 | } | |
670 | } | |
671 | ||
672 | static void optimize_token_table(void) | |
673 | { | |
674 | memset(hash_table, 0, sizeof(hash_table)); | |
675 | ||
676 | good_head.left = &good_head; | |
677 | good_head.right = &good_head; | |
678 | ||
679 | bad_head.left = &bad_head; | |
680 | bad_head.right = &bad_head; | |
681 | ||
682 | build_initial_tok_table(); | |
683 | ||
684 | insert_real_symbols_in_table(); | |
685 | ||
41f11a4f YS |
686 | /* When valid symbol is not registered, exit to error */ |
687 | if (good_head.left == good_head.right && | |
688 | bad_head.left == bad_head.right) { | |
689 | fprintf(stderr, "No valid symbol.\n"); | |
690 | exit(1); | |
691 | } | |
692 | ||
1da177e4 LT |
693 | optimize_result(); |
694 | } | |
695 | ||
696 | ||
697 | int | |
698 | main(int argc, char **argv) | |
699 | { | |
41f11a4f YS |
700 | if (argc >= 2) { |
701 | int i; | |
702 | for (i = 1; i < argc; i++) { | |
703 | if(strcmp(argv[i], "--all-symbols") == 0) | |
704 | all_symbols = 1; | |
705 | else if (strncmp(argv[i], "--symbol-prefix=", 16) == 0) { | |
706 | char *p = &argv[i][16]; | |
707 | /* skip quote */ | |
708 | if ((*p == '"' && *(p+2) == '"') || (*p == '\'' && *(p+2) == '\'')) | |
709 | p++; | |
710 | symbol_prefix_char = *p; | |
711 | } else | |
712 | usage(); | |
713 | } | |
714 | } else if (argc != 1) | |
1da177e4 LT |
715 | usage(); |
716 | ||
717 | read_map(stdin); | |
718 | optimize_token_table(); | |
719 | write_src(); | |
720 | ||
721 | return 0; | |
722 | } |