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2da572c9 DS |
1 | /* |
2 | * 842 Software Compression | |
3 | * | |
4 | * Copyright (C) 2015 Dan Streetman, IBM Corp | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * See 842.h for details of the 842 compressed format. | |
17 | */ | |
18 | ||
19 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
20 | #define MODULE_NAME "842_compress" | |
21 | ||
22 | #include <linux/hashtable.h> | |
23 | ||
24 | #include "842.h" | |
25 | #include "842_debugfs.h" | |
26 | ||
27 | #define SW842_HASHTABLE8_BITS (10) | |
28 | #define SW842_HASHTABLE4_BITS (11) | |
29 | #define SW842_HASHTABLE2_BITS (10) | |
30 | ||
31 | /* By default, we allow compressing input buffers of any length, but we must | |
32 | * use the non-standard "short data" template so the decompressor can correctly | |
33 | * reproduce the uncompressed data buffer at the right length. However the | |
34 | * hardware 842 compressor will not recognize the "short data" template, and | |
35 | * will fail to decompress any compressed buffer containing it (I have no idea | |
36 | * why anyone would want to use software to compress and hardware to decompress | |
37 | * but that's beside the point). This parameter forces the compression | |
38 | * function to simply reject any input buffer that isn't a multiple of 8 bytes | |
39 | * long, instead of using the "short data" template, so that all compressed | |
40 | * buffers produced by this function will be decompressable by the 842 hardware | |
41 | * decompressor. Unless you have a specific need for that, leave this disabled | |
42 | * so that any length buffer can be compressed. | |
43 | */ | |
44 | static bool sw842_strict; | |
45 | module_param_named(strict, sw842_strict, bool, 0644); | |
46 | ||
47 | static u8 comp_ops[OPS_MAX][5] = { /* params size in bits */ | |
48 | { I8, N0, N0, N0, 0x19 }, /* 8 */ | |
49 | { I4, I4, N0, N0, 0x18 }, /* 18 */ | |
50 | { I4, I2, I2, N0, 0x17 }, /* 25 */ | |
51 | { I2, I2, I4, N0, 0x13 }, /* 25 */ | |
52 | { I2, I2, I2, I2, 0x12 }, /* 32 */ | |
53 | { I4, I2, D2, N0, 0x16 }, /* 33 */ | |
54 | { I4, D2, I2, N0, 0x15 }, /* 33 */ | |
55 | { I2, D2, I4, N0, 0x0e }, /* 33 */ | |
56 | { D2, I2, I4, N0, 0x09 }, /* 33 */ | |
57 | { I2, I2, I2, D2, 0x11 }, /* 40 */ | |
58 | { I2, I2, D2, I2, 0x10 }, /* 40 */ | |
59 | { I2, D2, I2, I2, 0x0d }, /* 40 */ | |
60 | { D2, I2, I2, I2, 0x08 }, /* 40 */ | |
61 | { I4, D4, N0, N0, 0x14 }, /* 41 */ | |
62 | { D4, I4, N0, N0, 0x04 }, /* 41 */ | |
63 | { I2, I2, D4, N0, 0x0f }, /* 48 */ | |
64 | { I2, D2, I2, D2, 0x0c }, /* 48 */ | |
65 | { I2, D4, I2, N0, 0x0b }, /* 48 */ | |
66 | { D2, I2, I2, D2, 0x07 }, /* 48 */ | |
67 | { D2, I2, D2, I2, 0x06 }, /* 48 */ | |
68 | { D4, I2, I2, N0, 0x03 }, /* 48 */ | |
69 | { I2, D2, D4, N0, 0x0a }, /* 56 */ | |
70 | { D2, I2, D4, N0, 0x05 }, /* 56 */ | |
71 | { D4, I2, D2, N0, 0x02 }, /* 56 */ | |
72 | { D4, D2, I2, N0, 0x01 }, /* 56 */ | |
73 | { D8, N0, N0, N0, 0x00 }, /* 64 */ | |
74 | }; | |
75 | ||
76 | struct sw842_hlist_node8 { | |
77 | struct hlist_node node; | |
78 | u64 data; | |
79 | u8 index; | |
80 | }; | |
81 | ||
82 | struct sw842_hlist_node4 { | |
83 | struct hlist_node node; | |
84 | u32 data; | |
85 | u16 index; | |
86 | }; | |
87 | ||
88 | struct sw842_hlist_node2 { | |
89 | struct hlist_node node; | |
90 | u16 data; | |
91 | u8 index; | |
92 | }; | |
93 | ||
94 | #define INDEX_NOT_FOUND (-1) | |
95 | #define INDEX_NOT_CHECKED (-2) | |
96 | ||
97 | struct sw842_param { | |
98 | u8 *in; | |
99 | u8 *instart; | |
100 | u64 ilen; | |
101 | u8 *out; | |
102 | u64 olen; | |
103 | u8 bit; | |
104 | u64 data8[1]; | |
105 | u32 data4[2]; | |
106 | u16 data2[4]; | |
107 | int index8[1]; | |
108 | int index4[2]; | |
109 | int index2[4]; | |
110 | DECLARE_HASHTABLE(htable8, SW842_HASHTABLE8_BITS); | |
111 | DECLARE_HASHTABLE(htable4, SW842_HASHTABLE4_BITS); | |
112 | DECLARE_HASHTABLE(htable2, SW842_HASHTABLE2_BITS); | |
113 | struct sw842_hlist_node8 node8[1 << I8_BITS]; | |
114 | struct sw842_hlist_node4 node4[1 << I4_BITS]; | |
115 | struct sw842_hlist_node2 node2[1 << I2_BITS]; | |
116 | }; | |
117 | ||
118 | #define get_input_data(p, o, b) \ | |
119 | be##b##_to_cpu(get_unaligned((__be##b *)((p)->in + (o)))) | |
120 | ||
121 | #define init_hashtable_nodes(p, b) do { \ | |
122 | int _i; \ | |
123 | hash_init((p)->htable##b); \ | |
124 | for (_i = 0; _i < ARRAY_SIZE((p)->node##b); _i++) { \ | |
125 | (p)->node##b[_i].index = _i; \ | |
126 | (p)->node##b[_i].data = 0; \ | |
127 | INIT_HLIST_NODE(&(p)->node##b[_i].node); \ | |
128 | } \ | |
129 | } while (0) | |
130 | ||
131 | #define find_index(p, b, n) ({ \ | |
132 | struct sw842_hlist_node##b *_n; \ | |
133 | p->index##b[n] = INDEX_NOT_FOUND; \ | |
134 | hash_for_each_possible(p->htable##b, _n, node, p->data##b[n]) { \ | |
135 | if (p->data##b[n] == _n->data) { \ | |
136 | p->index##b[n] = _n->index; \ | |
137 | break; \ | |
138 | } \ | |
139 | } \ | |
140 | p->index##b[n] >= 0; \ | |
141 | }) | |
142 | ||
143 | #define check_index(p, b, n) \ | |
144 | ((p)->index##b[n] == INDEX_NOT_CHECKED \ | |
145 | ? find_index(p, b, n) \ | |
146 | : (p)->index##b[n] >= 0) | |
147 | ||
148 | #define replace_hash(p, b, i, d) do { \ | |
149 | struct sw842_hlist_node##b *_n = &(p)->node##b[(i)+(d)]; \ | |
150 | hash_del(&_n->node); \ | |
151 | _n->data = (p)->data##b[d]; \ | |
152 | pr_debug("add hash index%x %x pos %x data %lx\n", b, \ | |
153 | (unsigned int)_n->index, \ | |
154 | (unsigned int)((p)->in - (p)->instart), \ | |
155 | (unsigned long)_n->data); \ | |
156 | hash_add((p)->htable##b, &_n->node, _n->data); \ | |
157 | } while (0) | |
158 | ||
159 | static u8 bmask[8] = { 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe }; | |
160 | ||
161 | static int add_bits(struct sw842_param *p, u64 d, u8 n); | |
162 | ||
163 | static int __split_add_bits(struct sw842_param *p, u64 d, u8 n, u8 s) | |
164 | { | |
165 | int ret; | |
166 | ||
167 | if (n <= s) | |
168 | return -EINVAL; | |
169 | ||
170 | ret = add_bits(p, d >> s, n - s); | |
171 | if (ret) | |
172 | return ret; | |
173 | return add_bits(p, d & GENMASK_ULL(s - 1, 0), s); | |
174 | } | |
175 | ||
176 | static int add_bits(struct sw842_param *p, u64 d, u8 n) | |
177 | { | |
178 | int b = p->bit, bits = b + n, s = round_up(bits, 8) - bits; | |
179 | u64 o; | |
180 | u8 *out = p->out; | |
181 | ||
182 | pr_debug("add %u bits %lx\n", (unsigned char)n, (unsigned long)d); | |
183 | ||
184 | if (n > 64) | |
185 | return -EINVAL; | |
186 | ||
187 | /* split this up if writing to > 8 bytes (i.e. n == 64 && p->bit > 0), | |
188 | * or if we're at the end of the output buffer and would write past end | |
189 | */ | |
190 | if (bits > 64) | |
191 | return __split_add_bits(p, d, n, 32); | |
192 | else if (p->olen < 8 && bits > 32 && bits <= 56) | |
193 | return __split_add_bits(p, d, n, 16); | |
194 | else if (p->olen < 4 && bits > 16 && bits <= 24) | |
195 | return __split_add_bits(p, d, n, 8); | |
196 | ||
197 | if (DIV_ROUND_UP(bits, 8) > p->olen) | |
198 | return -ENOSPC; | |
199 | ||
200 | o = *out & bmask[b]; | |
201 | d <<= s; | |
202 | ||
203 | if (bits <= 8) | |
204 | *out = o | d; | |
205 | else if (bits <= 16) | |
206 | put_unaligned(cpu_to_be16(o << 8 | d), (__be16 *)out); | |
207 | else if (bits <= 24) | |
208 | put_unaligned(cpu_to_be32(o << 24 | d << 8), (__be32 *)out); | |
209 | else if (bits <= 32) | |
210 | put_unaligned(cpu_to_be32(o << 24 | d), (__be32 *)out); | |
211 | else if (bits <= 40) | |
212 | put_unaligned(cpu_to_be64(o << 56 | d << 24), (__be64 *)out); | |
213 | else if (bits <= 48) | |
214 | put_unaligned(cpu_to_be64(o << 56 | d << 16), (__be64 *)out); | |
215 | else if (bits <= 56) | |
216 | put_unaligned(cpu_to_be64(o << 56 | d << 8), (__be64 *)out); | |
217 | else | |
218 | put_unaligned(cpu_to_be64(o << 56 | d), (__be64 *)out); | |
219 | ||
220 | p->bit += n; | |
221 | ||
222 | if (p->bit > 7) { | |
223 | p->out += p->bit / 8; | |
224 | p->olen -= p->bit / 8; | |
225 | p->bit %= 8; | |
226 | } | |
227 | ||
228 | return 0; | |
229 | } | |
230 | ||
231 | static int add_template(struct sw842_param *p, u8 c) | |
232 | { | |
233 | int ret, i, b = 0; | |
234 | u8 *t = comp_ops[c]; | |
235 | bool inv = false; | |
236 | ||
237 | if (c >= OPS_MAX) | |
238 | return -EINVAL; | |
239 | ||
240 | pr_debug("template %x\n", t[4]); | |
241 | ||
242 | ret = add_bits(p, t[4], OP_BITS); | |
243 | if (ret) | |
244 | return ret; | |
245 | ||
246 | for (i = 0; i < 4; i++) { | |
247 | pr_debug("op %x\n", t[i]); | |
248 | ||
249 | switch (t[i] & OP_AMOUNT) { | |
250 | case OP_AMOUNT_8: | |
251 | if (b) | |
252 | inv = true; | |
253 | else if (t[i] & OP_ACTION_INDEX) | |
254 | ret = add_bits(p, p->index8[0], I8_BITS); | |
255 | else if (t[i] & OP_ACTION_DATA) | |
256 | ret = add_bits(p, p->data8[0], 64); | |
257 | else | |
258 | inv = true; | |
259 | break; | |
260 | case OP_AMOUNT_4: | |
261 | if (b == 2 && t[i] & OP_ACTION_DATA) | |
262 | ret = add_bits(p, get_input_data(p, 2, 32), 32); | |
263 | else if (b != 0 && b != 4) | |
264 | inv = true; | |
265 | else if (t[i] & OP_ACTION_INDEX) | |
266 | ret = add_bits(p, p->index4[b >> 2], I4_BITS); | |
267 | else if (t[i] & OP_ACTION_DATA) | |
268 | ret = add_bits(p, p->data4[b >> 2], 32); | |
269 | else | |
270 | inv = true; | |
271 | break; | |
272 | case OP_AMOUNT_2: | |
273 | if (b != 0 && b != 2 && b != 4 && b != 6) | |
274 | inv = true; | |
275 | if (t[i] & OP_ACTION_INDEX) | |
276 | ret = add_bits(p, p->index2[b >> 1], I2_BITS); | |
277 | else if (t[i] & OP_ACTION_DATA) | |
278 | ret = add_bits(p, p->data2[b >> 1], 16); | |
279 | else | |
280 | inv = true; | |
281 | break; | |
282 | case OP_AMOUNT_0: | |
283 | inv = (b != 8) || !(t[i] & OP_ACTION_NOOP); | |
284 | break; | |
285 | default: | |
286 | inv = true; | |
287 | break; | |
288 | } | |
289 | ||
290 | if (ret) | |
291 | return ret; | |
292 | ||
293 | if (inv) { | |
294 | pr_err("Invalid templ %x op %d : %x %x %x %x\n", | |
295 | c, i, t[0], t[1], t[2], t[3]); | |
296 | return -EINVAL; | |
297 | } | |
298 | ||
299 | b += t[i] & OP_AMOUNT; | |
300 | } | |
301 | ||
302 | if (b != 8) { | |
303 | pr_err("Invalid template %x len %x : %x %x %x %x\n", | |
304 | c, b, t[0], t[1], t[2], t[3]); | |
305 | return -EINVAL; | |
306 | } | |
307 | ||
308 | if (sw842_template_counts) | |
309 | atomic_inc(&template_count[t[4]]); | |
310 | ||
311 | return 0; | |
312 | } | |
313 | ||
314 | static int add_repeat_template(struct sw842_param *p, u8 r) | |
315 | { | |
316 | int ret; | |
317 | ||
318 | /* repeat param is 0-based */ | |
319 | if (!r || --r > REPEAT_BITS_MAX) | |
320 | return -EINVAL; | |
321 | ||
322 | ret = add_bits(p, OP_REPEAT, OP_BITS); | |
323 | if (ret) | |
324 | return ret; | |
325 | ||
326 | ret = add_bits(p, r, REPEAT_BITS); | |
327 | if (ret) | |
328 | return ret; | |
329 | ||
330 | if (sw842_template_counts) | |
331 | atomic_inc(&template_repeat_count); | |
332 | ||
333 | return 0; | |
334 | } | |
335 | ||
336 | static int add_short_data_template(struct sw842_param *p, u8 b) | |
337 | { | |
338 | int ret, i; | |
339 | ||
340 | if (!b || b > SHORT_DATA_BITS_MAX) | |
341 | return -EINVAL; | |
342 | ||
343 | ret = add_bits(p, OP_SHORT_DATA, OP_BITS); | |
344 | if (ret) | |
345 | return ret; | |
346 | ||
347 | ret = add_bits(p, b, SHORT_DATA_BITS); | |
348 | if (ret) | |
349 | return ret; | |
350 | ||
351 | for (i = 0; i < b; i++) { | |
352 | ret = add_bits(p, p->in[i], 8); | |
353 | if (ret) | |
354 | return ret; | |
355 | } | |
356 | ||
357 | if (sw842_template_counts) | |
358 | atomic_inc(&template_short_data_count); | |
359 | ||
360 | return 0; | |
361 | } | |
362 | ||
363 | static int add_zeros_template(struct sw842_param *p) | |
364 | { | |
365 | int ret = add_bits(p, OP_ZEROS, OP_BITS); | |
366 | ||
367 | if (ret) | |
368 | return ret; | |
369 | ||
370 | if (sw842_template_counts) | |
371 | atomic_inc(&template_zeros_count); | |
372 | ||
373 | return 0; | |
374 | } | |
375 | ||
376 | static int add_end_template(struct sw842_param *p) | |
377 | { | |
378 | int ret = add_bits(p, OP_END, OP_BITS); | |
379 | ||
380 | if (ret) | |
381 | return ret; | |
382 | ||
383 | if (sw842_template_counts) | |
384 | atomic_inc(&template_end_count); | |
385 | ||
386 | return 0; | |
387 | } | |
388 | ||
389 | static bool check_template(struct sw842_param *p, u8 c) | |
390 | { | |
391 | u8 *t = comp_ops[c]; | |
392 | int i, match, b = 0; | |
393 | ||
394 | if (c >= OPS_MAX) | |
395 | return false; | |
396 | ||
397 | for (i = 0; i < 4; i++) { | |
398 | if (t[i] & OP_ACTION_INDEX) { | |
399 | if (t[i] & OP_AMOUNT_2) | |
400 | match = check_index(p, 2, b >> 1); | |
401 | else if (t[i] & OP_AMOUNT_4) | |
402 | match = check_index(p, 4, b >> 2); | |
403 | else if (t[i] & OP_AMOUNT_8) | |
404 | match = check_index(p, 8, 0); | |
405 | else | |
406 | return false; | |
407 | if (!match) | |
408 | return false; | |
409 | } | |
410 | ||
411 | b += t[i] & OP_AMOUNT; | |
412 | } | |
413 | ||
414 | return true; | |
415 | } | |
416 | ||
417 | static void get_next_data(struct sw842_param *p) | |
418 | { | |
419 | p->data8[0] = get_input_data(p, 0, 64); | |
420 | p->data4[0] = get_input_data(p, 0, 32); | |
421 | p->data4[1] = get_input_data(p, 4, 32); | |
422 | p->data2[0] = get_input_data(p, 0, 16); | |
423 | p->data2[1] = get_input_data(p, 2, 16); | |
424 | p->data2[2] = get_input_data(p, 4, 16); | |
425 | p->data2[3] = get_input_data(p, 6, 16); | |
426 | } | |
427 | ||
428 | /* update the hashtable entries. | |
429 | * only call this after finding/adding the current template | |
430 | * the dataN fields for the current 8 byte block must be already updated | |
431 | */ | |
432 | static void update_hashtables(struct sw842_param *p) | |
433 | { | |
434 | u64 pos = p->in - p->instart; | |
435 | u64 n8 = (pos >> 3) % (1 << I8_BITS); | |
436 | u64 n4 = (pos >> 2) % (1 << I4_BITS); | |
437 | u64 n2 = (pos >> 1) % (1 << I2_BITS); | |
438 | ||
439 | replace_hash(p, 8, n8, 0); | |
440 | replace_hash(p, 4, n4, 0); | |
441 | replace_hash(p, 4, n4, 1); | |
442 | replace_hash(p, 2, n2, 0); | |
443 | replace_hash(p, 2, n2, 1); | |
444 | replace_hash(p, 2, n2, 2); | |
445 | replace_hash(p, 2, n2, 3); | |
446 | } | |
447 | ||
448 | /* find the next template to use, and add it | |
449 | * the p->dataN fields must already be set for the current 8 byte block | |
450 | */ | |
451 | static int process_next(struct sw842_param *p) | |
452 | { | |
453 | int ret, i; | |
454 | ||
455 | p->index8[0] = INDEX_NOT_CHECKED; | |
456 | p->index4[0] = INDEX_NOT_CHECKED; | |
457 | p->index4[1] = INDEX_NOT_CHECKED; | |
458 | p->index2[0] = INDEX_NOT_CHECKED; | |
459 | p->index2[1] = INDEX_NOT_CHECKED; | |
460 | p->index2[2] = INDEX_NOT_CHECKED; | |
461 | p->index2[3] = INDEX_NOT_CHECKED; | |
462 | ||
463 | /* check up to OPS_MAX - 1; last op is our fallback */ | |
464 | for (i = 0; i < OPS_MAX - 1; i++) { | |
465 | if (check_template(p, i)) | |
466 | break; | |
467 | } | |
468 | ||
469 | ret = add_template(p, i); | |
470 | if (ret) | |
471 | return ret; | |
472 | ||
473 | return 0; | |
474 | } | |
475 | ||
476 | /** | |
477 | * sw842_compress | |
478 | * | |
479 | * Compress the uncompressed buffer of length @ilen at @in to the output buffer | |
480 | * @out, using no more than @olen bytes, using the 842 compression format. | |
481 | * | |
482 | * Returns: 0 on success, error on failure. The @olen parameter | |
483 | * will contain the number of output bytes written on success, or | |
484 | * 0 on error. | |
485 | */ | |
486 | int sw842_compress(const u8 *in, unsigned int ilen, | |
487 | u8 *out, unsigned int *olen, void *wmem) | |
488 | { | |
489 | struct sw842_param *p = (struct sw842_param *)wmem; | |
490 | int ret; | |
491 | u64 last, next, pad, total; | |
492 | u8 repeat_count = 0; | |
493 | ||
494 | BUILD_BUG_ON(sizeof(*p) > SW842_MEM_COMPRESS); | |
495 | ||
496 | init_hashtable_nodes(p, 8); | |
497 | init_hashtable_nodes(p, 4); | |
498 | init_hashtable_nodes(p, 2); | |
499 | ||
500 | p->in = (u8 *)in; | |
501 | p->instart = p->in; | |
502 | p->ilen = ilen; | |
503 | p->out = out; | |
504 | p->olen = *olen; | |
505 | p->bit = 0; | |
506 | ||
507 | total = p->olen; | |
508 | ||
509 | *olen = 0; | |
510 | ||
511 | /* if using strict mode, we can only compress a multiple of 8 */ | |
512 | if (sw842_strict && (ilen % 8)) { | |
513 | pr_err("Using strict mode, can't compress len %d\n", ilen); | |
514 | return -EINVAL; | |
515 | } | |
516 | ||
517 | /* let's compress at least 8 bytes, mkay? */ | |
518 | if (unlikely(ilen < 8)) | |
519 | goto skip_comp; | |
520 | ||
521 | /* make initial 'last' different so we don't match the first time */ | |
522 | last = ~get_unaligned((u64 *)p->in); | |
523 | ||
524 | while (p->ilen > 7) { | |
525 | next = get_unaligned((u64 *)p->in); | |
526 | ||
527 | /* must get the next data, as we need to update the hashtable | |
528 | * entries with the new data every time | |
529 | */ | |
530 | get_next_data(p); | |
531 | ||
532 | /* we don't care about endianness in last or next; | |
533 | * we're just comparing 8 bytes to another 8 bytes, | |
534 | * they're both the same endianness | |
535 | */ | |
536 | if (next == last) { | |
537 | /* repeat count bits are 0-based, so we stop at +1 */ | |
538 | if (++repeat_count <= REPEAT_BITS_MAX) | |
539 | goto repeat; | |
540 | } | |
541 | if (repeat_count) { | |
542 | ret = add_repeat_template(p, repeat_count); | |
543 | repeat_count = 0; | |
544 | if (next == last) /* reached max repeat bits */ | |
545 | goto repeat; | |
546 | } | |
547 | ||
548 | if (next == 0) | |
549 | ret = add_zeros_template(p); | |
550 | else | |
551 | ret = process_next(p); | |
552 | ||
553 | if (ret) | |
554 | return ret; | |
555 | ||
556 | repeat: | |
557 | last = next; | |
558 | update_hashtables(p); | |
559 | p->in += 8; | |
560 | p->ilen -= 8; | |
561 | } | |
562 | ||
563 | if (repeat_count) { | |
564 | ret = add_repeat_template(p, repeat_count); | |
565 | if (ret) | |
566 | return ret; | |
567 | } | |
568 | ||
569 | skip_comp: | |
570 | if (p->ilen > 0) { | |
571 | ret = add_short_data_template(p, p->ilen); | |
572 | if (ret) | |
573 | return ret; | |
574 | ||
575 | p->in += p->ilen; | |
576 | p->ilen = 0; | |
577 | } | |
578 | ||
579 | ret = add_end_template(p); | |
580 | if (ret) | |
581 | return ret; | |
582 | ||
583 | if (p->bit) { | |
584 | p->out++; | |
585 | p->olen--; | |
586 | p->bit = 0; | |
587 | } | |
588 | ||
589 | /* pad compressed length to multiple of 8 */ | |
590 | pad = (8 - ((total - p->olen) % 8)) % 8; | |
591 | if (pad) { | |
592 | if (pad > p->olen) /* we were so close! */ | |
593 | return -ENOSPC; | |
594 | memset(p->out, 0, pad); | |
595 | p->out += pad; | |
596 | p->olen -= pad; | |
597 | } | |
598 | ||
599 | if (unlikely((total - p->olen) > UINT_MAX)) | |
600 | return -ENOSPC; | |
601 | ||
602 | *olen = total - p->olen; | |
603 | ||
604 | return 0; | |
605 | } | |
606 | EXPORT_SYMBOL_GPL(sw842_compress); | |
607 | ||
608 | static int __init sw842_init(void) | |
609 | { | |
610 | if (sw842_template_counts) | |
611 | sw842_debugfs_create(); | |
612 | ||
613 | return 0; | |
614 | } | |
615 | module_init(sw842_init); | |
616 | ||
617 | static void __exit sw842_exit(void) | |
618 | { | |
619 | if (sw842_template_counts) | |
620 | sw842_debugfs_remove(); | |
621 | } | |
622 | module_exit(sw842_exit); | |
623 | ||
624 | MODULE_LICENSE("GPL"); | |
625 | MODULE_DESCRIPTION("Software 842 Compressor"); | |
626 | MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>"); |