1 /**************************************************************************
2 *
3 * Copyright 2011 Christian König.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27
28 /*
29 * Functions for fast bitwise access to multiple probably unaligned input buffers
30 */
31
32 #ifndef vl_vlc_h
33 #define vl_vlc_h
34
35 #include "pipe/p_compiler.h"
36
37 #include "util/u_math.h"
38 #include "util/u_pointer.h"
39 #include "util/u_debug.h"
40
41 struct vl_vlc
42 {
43 uint64_t buffer;
44 signed invalid_bits;
45 const uint8_t *data;
46 const uint8_t *end;
47
48 const void *const *inputs;
49 const unsigned *sizes;
50 unsigned bytes_left;
51 };
52
53 struct vl_vlc_entry
54 {
55 int8_t length;
56 int8_t value;
57 };
58
59 struct vl_vlc_compressed
60 {
61 uint16_t bitcode;
62 struct vl_vlc_entry entry;
63 };
64
65 /**
66 * initalize and decompress a lookup table
67 */
68 static inline void
vl_vlc_init_table(struct vl_vlc_entry * dst,unsigned dst_size,const struct vl_vlc_compressed * src,unsigned src_size)69 vl_vlc_init_table(struct vl_vlc_entry *dst, unsigned dst_size, const struct vl_vlc_compressed *src, unsigned src_size)
70 {
71 unsigned i, bits = util_logbase2(dst_size);
72
73 assert(dst && dst_size);
74 assert(src && src_size);
75
76 for (i=0;i<dst_size;++i) {
77 dst[i].length = 0;
78 dst[i].value = 0;
79 }
80
81 for(; src_size > 0; --src_size, ++src) {
82 for(i = 0; i < (1u << (bits - src->entry.length)); ++i)
83 dst[src->bitcode >> (16 - bits) | i] = src->entry;
84 }
85 }
86
87 /**
88 * switch over to next input buffer
89 */
90 static inline void
vl_vlc_next_input(struct vl_vlc * vlc)91 vl_vlc_next_input(struct vl_vlc *vlc)
92 {
93 unsigned len = vlc->sizes[0];
94
95 assert(vlc);
96 assert(vlc->bytes_left);
97
98 if (len < vlc->bytes_left)
99 vlc->bytes_left -= len;
100 else {
101 len = vlc->bytes_left;
102 vlc->bytes_left = 0;
103 }
104
105 vlc->data = vlc->inputs[0];
106 vlc->end = vlc->data + len;
107
108 ++vlc->inputs;
109 ++vlc->sizes;
110 }
111
112 /**
113 * align the data pointer to the next dword
114 */
115 static inline void
vl_vlc_align_data_ptr(struct vl_vlc * vlc)116 vl_vlc_align_data_ptr(struct vl_vlc *vlc)
117 {
118 /* align the data pointer */
119 while (vlc->data != vlc->end && pointer_to_uintptr(vlc->data) & 3) {
120 vlc->buffer |= (uint64_t)*vlc->data << (24 + vlc->invalid_bits);
121 ++vlc->data;
122 vlc->invalid_bits -= 8;
123 }
124 }
125
126 /**
127 * fill the bit buffer, so that at least 32 bits are valid
128 */
129 static inline void
vl_vlc_fillbits(struct vl_vlc * vlc)130 vl_vlc_fillbits(struct vl_vlc *vlc)
131 {
132 assert(vlc);
133
134 /* as long as the buffer needs to be filled */
135 while (vlc->invalid_bits > 0) {
136 unsigned bytes_left = vlc->end - vlc->data;
137
138 /* if this input is depleted */
139 if (bytes_left == 0) {
140
141 if (vlc->bytes_left) {
142 /* go on to next input */
143 vl_vlc_next_input(vlc);
144 vl_vlc_align_data_ptr(vlc);
145 } else
146 /* or give up since we don't have anymore inputs */
147 return;
148
149 } else if (bytes_left >= 4) {
150
151 /* enough bytes in buffer, read in a whole dword */
152 uint64_t value = *(const uint32_t*)vlc->data;
153
154 #if !UTIL_ARCH_BIG_ENDIAN
155 value = util_bswap32(value);
156 #endif
157
158 vlc->buffer |= value << vlc->invalid_bits;
159 vlc->data += 4;
160 vlc->invalid_bits -= 32;
161
162 /* buffer is now definitely filled up avoid the loop test */
163 break;
164
165 } else while (vlc->data < vlc->end) {
166
167 /* not enough bytes left in buffer, read single bytes */
168 vlc->buffer |= (uint64_t)*vlc->data << (24 + vlc->invalid_bits);
169 ++vlc->data;
170 vlc->invalid_bits -= 8;
171 }
172 }
173 }
174
175 /**
176 * initialize vlc structure and start reading from first input buffer
177 */
178 static inline void
vl_vlc_init(struct vl_vlc * vlc,unsigned num_inputs,const void * const * inputs,const unsigned * sizes)179 vl_vlc_init(struct vl_vlc *vlc, unsigned num_inputs,
180 const void *const *inputs, const unsigned *sizes)
181 {
182 unsigned i;
183
184 assert(vlc);
185 assert(num_inputs);
186
187 vlc->buffer = 0;
188 vlc->invalid_bits = 32;
189 vlc->inputs = inputs;
190 vlc->sizes = sizes;
191 vlc->bytes_left = 0;
192
193 for (i = 0; i < num_inputs; ++i)
194 vlc->bytes_left += sizes[i];
195
196 if (vlc->bytes_left) {
197 vl_vlc_next_input(vlc);
198 vl_vlc_align_data_ptr(vlc);
199 vl_vlc_fillbits(vlc);
200 }
201 }
202
203 /**
204 * number of bits still valid in bit buffer
205 */
206 static inline unsigned
vl_vlc_valid_bits(struct vl_vlc * vlc)207 vl_vlc_valid_bits(struct vl_vlc *vlc)
208 {
209 return 32 - vlc->invalid_bits;
210 }
211
212 /**
213 * number of bits left over all inbut buffers
214 */
215 static inline unsigned
vl_vlc_bits_left(struct vl_vlc * vlc)216 vl_vlc_bits_left(struct vl_vlc *vlc)
217 {
218 signed bytes_left = vlc->end - vlc->data;
219 bytes_left += vlc->bytes_left;
220 return bytes_left * 8 + vl_vlc_valid_bits(vlc);
221 }
222
223 /**
224 * get num_bits from bit buffer without removing them
225 */
226 static inline unsigned
vl_vlc_peekbits(struct vl_vlc * vlc,unsigned num_bits)227 vl_vlc_peekbits(struct vl_vlc *vlc, unsigned num_bits)
228 {
229 assert(vl_vlc_valid_bits(vlc) >= num_bits || vlc->data >= vlc->end);
230 return vlc->buffer >> (64 - num_bits);
231 }
232
233 /**
234 * remove num_bits from bit buffer
235 */
236 static inline void
vl_vlc_eatbits(struct vl_vlc * vlc,unsigned num_bits)237 vl_vlc_eatbits(struct vl_vlc *vlc, unsigned num_bits)
238 {
239 assert(vl_vlc_valid_bits(vlc) >= num_bits);
240
241 vlc->buffer <<= num_bits;
242 vlc->invalid_bits += num_bits;
243 }
244
245 /**
246 * get num_bits from bit buffer with removing them
247 */
248 static inline unsigned
vl_vlc_get_uimsbf(struct vl_vlc * vlc,unsigned num_bits)249 vl_vlc_get_uimsbf(struct vl_vlc *vlc, unsigned num_bits)
250 {
251 unsigned value;
252
253 assert(vl_vlc_valid_bits(vlc) >= num_bits);
254
255 value = vlc->buffer >> (64 - num_bits);
256 vl_vlc_eatbits(vlc, num_bits);
257
258 return value;
259 }
260
261 /**
262 * treat num_bits as signed value and remove them from bit buffer
263 */
264 static inline signed
vl_vlc_get_simsbf(struct vl_vlc * vlc,unsigned num_bits)265 vl_vlc_get_simsbf(struct vl_vlc *vlc, unsigned num_bits)
266 {
267 signed value;
268
269 assert(vl_vlc_valid_bits(vlc) >= num_bits);
270
271 value = ((int64_t)vlc->buffer) >> (64 - num_bits);
272 vl_vlc_eatbits(vlc, num_bits);
273
274 return value;
275 }
276
277 /**
278 * lookup a value and length in a decompressed table
279 */
280 static inline int8_t
vl_vlc_get_vlclbf(struct vl_vlc * vlc,const struct vl_vlc_entry * tbl,unsigned num_bits)281 vl_vlc_get_vlclbf(struct vl_vlc *vlc, const struct vl_vlc_entry *tbl, unsigned num_bits)
282 {
283 tbl += vl_vlc_peekbits(vlc, num_bits);
284 vl_vlc_eatbits(vlc, tbl->length);
285 return tbl->value;
286 }
287
288 /**
289 * fast forward search for a specific byte value
290 */
291 static inline boolean
vl_vlc_search_byte(struct vl_vlc * vlc,unsigned num_bits,uint8_t value)292 vl_vlc_search_byte(struct vl_vlc *vlc, unsigned num_bits, uint8_t value)
293 {
294 /* make sure we are on a byte boundary */
295 assert((vl_vlc_valid_bits(vlc) % 8) == 0);
296 assert(num_bits == ~0u || (num_bits % 8) == 0);
297
298 /* deplete the bit buffer */
299 while (vl_vlc_valid_bits(vlc) > 0) {
300
301 if (vl_vlc_peekbits(vlc, 8) == value) {
302 vl_vlc_fillbits(vlc);
303 return TRUE;
304 }
305
306 vl_vlc_eatbits(vlc, 8);
307
308 if (num_bits != ~0u) {
309 num_bits -= 8;
310 if (num_bits == 0)
311 return FALSE;
312 }
313 }
314
315 /* deplete the byte buffers */
316 while (1) {
317
318 /* if this input is depleted */
319 if (vlc->data == vlc->end) {
320 if (vlc->bytes_left)
321 /* go on to next input */
322 vl_vlc_next_input(vlc);
323 else
324 /* or give up since we don't have anymore inputs */
325 return FALSE;
326 }
327
328 if (*vlc->data == value) {
329 vl_vlc_align_data_ptr(vlc);
330 vl_vlc_fillbits(vlc);
331 return TRUE;
332 }
333
334 ++vlc->data;
335 if (num_bits != ~0u) {
336 num_bits -= 8;
337 if (num_bits == 0) {
338 vl_vlc_align_data_ptr(vlc);
339 return FALSE;
340 }
341 }
342 }
343 }
344
345 /**
346 * remove num_bits bits starting at pos from the bitbuffer
347 */
348 static inline void
vl_vlc_removebits(struct vl_vlc * vlc,unsigned pos,unsigned num_bits)349 vl_vlc_removebits(struct vl_vlc *vlc, unsigned pos, unsigned num_bits)
350 {
351 uint64_t lo = (vlc->buffer & (~0UL >> (pos + num_bits))) << num_bits;
352 uint64_t hi = (vlc->buffer & (~0UL << (64 - pos)));
353 vlc->buffer = lo | hi;
354 vlc->invalid_bits += num_bits;
355 }
356
357 /**
358 * limit the number of bits left for fetching
359 */
360 static inline void
vl_vlc_limit(struct vl_vlc * vlc,unsigned bits_left)361 vl_vlc_limit(struct vl_vlc *vlc, unsigned bits_left)
362 {
363 assert(bits_left <= vl_vlc_bits_left(vlc));
364
365 vl_vlc_fillbits(vlc);
366 if (bits_left < vl_vlc_valid_bits(vlc)) {
367 vlc->invalid_bits = 32 - bits_left;
368 vlc->buffer &= ~0L << (vlc->invalid_bits + 32);
369 vlc->end = vlc->data;
370 vlc->bytes_left = 0;
371 } else {
372 assert((bits_left - vl_vlc_valid_bits(vlc)) % 8 == 0);
373 vlc->bytes_left = (bits_left - vl_vlc_valid_bits(vlc)) / 8;
374 if (vlc->bytes_left < (vlc->end - vlc->data)) {
375 vlc->end = vlc->data + vlc->bytes_left;
376 vlc->bytes_left = 0;
377 } else
378 vlc->bytes_left -= vlc->end - vlc->data;
379 }
380 }
381
382 #endif /* vl_vlc_h */
383