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 TUNGSTEN GRAPHICS 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
41struct vl_vlc
42{
43   uint64_t buffer;
44   signed invalid_bits;
45   const uint8_t *data;
46   const uint8_t *end;
47
48   unsigned          num_inputs;
49   const void *const *inputs;
50   const unsigned    *sizes;
51   unsigned          bytes_left;
52};
53
54struct vl_vlc_entry
55{
56   int8_t length;
57   int8_t value;
58};
59
60struct vl_vlc_compressed
61{
62   uint16_t bitcode;
63   struct vl_vlc_entry entry;
64};
65
66/**
67 * initalize and decompress a lookup table
68 */
69static INLINE void
70vl_vlc_init_table(struct vl_vlc_entry *dst, unsigned dst_size, const struct vl_vlc_compressed *src, unsigned src_size)
71{
72   unsigned i, bits = util_logbase2(dst_size);
73
74   assert(dst && dst_size);
75   assert(src && src_size);
76
77   for (i=0;i<dst_size;++i) {
78      dst[i].length = 0;
79      dst[i].value = 0;
80   }
81
82   for(; src_size > 0; --src_size, ++src) {
83      for(i=0; i<(1 << (bits - src->entry.length)); ++i)
84         dst[src->bitcode >> (16 - bits) | i] = src->entry;
85   }
86}
87
88/**
89 * switch over to next input buffer
90 */
91static INLINE void
92vl_vlc_next_input(struct vl_vlc *vlc)
93{
94   const uint8_t* data = vlc->inputs[0];
95   unsigned len = vlc->sizes[0];
96
97   assert(vlc);
98   assert(vlc->num_inputs);
99
100   vlc->bytes_left -= len;
101
102   /* align the data pointer */
103   while (len && pointer_to_uintptr(data) & 3) {
104      vlc->buffer |= (uint64_t)*data << (24 + vlc->invalid_bits);
105      ++data;
106      --len;
107      vlc->invalid_bits -= 8;
108   }
109   vlc->data = data;
110   vlc->end = data + len;
111
112   --vlc->num_inputs;
113   ++vlc->inputs;
114   ++vlc->sizes;
115}
116
117/**
118 * fill the bit buffer, so that at least 32 bits are valid
119 */
120static INLINE void
121vl_vlc_fillbits(struct vl_vlc *vlc)
122{
123   assert(vlc);
124
125   /* as long as the buffer needs to be filled */
126   while (vlc->invalid_bits > 0) {
127      unsigned bytes_left = vlc->end - vlc->data;
128
129      /* if this input is depleted */
130      if (bytes_left == 0) {
131
132         if (vlc->num_inputs)
133            /* go on to next input */
134            vl_vlc_next_input(vlc);
135         else
136            /* or give up since we don't have anymore inputs */
137            return;
138
139      } else if (bytes_left >= 4) {
140
141         /* enough bytes in buffer, read in a whole dword */
142         uint64_t value = *(const uint32_t*)vlc->data;
143
144#ifndef PIPE_ARCH_BIG_ENDIAN
145         value = util_bswap32(value);
146#endif
147
148         vlc->buffer |= value << vlc->invalid_bits;
149         vlc->data += 4;
150         vlc->invalid_bits -= 32;
151
152         /* buffer is now definitely filled up avoid the loop test */
153         break;
154
155      } else while (vlc->data < vlc->end) {
156
157         /* not enough bytes left in buffer, read single bytes */
158         vlc->buffer |= (uint64_t)*vlc->data << (24 + vlc->invalid_bits);
159         ++vlc->data;
160         vlc->invalid_bits -= 8;
161      }
162   }
163}
164
165/**
166 * initialize vlc structure and start reading from first input buffer
167 */
168static INLINE void
169vl_vlc_init(struct vl_vlc *vlc, unsigned num_inputs,
170            const void *const *inputs, const unsigned *sizes)
171{
172   unsigned i;
173
174   assert(vlc);
175   assert(num_inputs);
176
177   vlc->buffer = 0;
178   vlc->invalid_bits = 32;
179   vlc->num_inputs = num_inputs;
180   vlc->inputs = inputs;
181   vlc->sizes = sizes;
182   vlc->bytes_left = 0;
183
184   for (i = 0; i < num_inputs; ++i)
185      vlc->bytes_left += sizes[i];
186
187   vl_vlc_next_input(vlc);
188   vl_vlc_fillbits(vlc);
189   vl_vlc_fillbits(vlc);
190}
191
192/**
193 * number of bits still valid in bit buffer
194 */
195static INLINE unsigned
196vl_vlc_valid_bits(struct vl_vlc *vlc)
197{
198   return 32 - vlc->invalid_bits;
199}
200
201/**
202 * number of bits left over all inbut buffers
203 */
204static INLINE unsigned
205vl_vlc_bits_left(struct vl_vlc *vlc)
206{
207   signed bytes_left = vlc->end - vlc->data;
208   bytes_left += vlc->bytes_left;
209   return bytes_left * 8 + vl_vlc_valid_bits(vlc);
210}
211
212/**
213 * get num_bits from bit buffer without removing them
214 */
215static INLINE unsigned
216vl_vlc_peekbits(struct vl_vlc *vlc, unsigned num_bits)
217{
218   assert(vl_vlc_valid_bits(vlc) >= num_bits || vlc->data >= vlc->end);
219   return vlc->buffer >> (64 - num_bits);
220}
221
222/**
223 * remove num_bits from bit buffer
224 */
225static INLINE void
226vl_vlc_eatbits(struct vl_vlc *vlc, unsigned num_bits)
227{
228   assert(vl_vlc_valid_bits(vlc) >= num_bits);
229
230   vlc->buffer <<= num_bits;
231   vlc->invalid_bits += num_bits;
232}
233
234/**
235 * get num_bits from bit buffer with removing them
236 */
237static INLINE unsigned
238vl_vlc_get_uimsbf(struct vl_vlc *vlc, unsigned num_bits)
239{
240   unsigned value;
241
242   assert(vl_vlc_valid_bits(vlc) >= num_bits);
243
244   value = vlc->buffer >> (64 - num_bits);
245   vl_vlc_eatbits(vlc, num_bits);
246
247   return value;
248}
249
250/**
251 * treat num_bits as signed value and remove them from bit buffer
252 */
253static INLINE signed
254vl_vlc_get_simsbf(struct vl_vlc *vlc, unsigned num_bits)
255{
256   signed value;
257
258   assert(vl_vlc_valid_bits(vlc) >= num_bits);
259
260   value = ((int64_t)vlc->buffer) >> (64 - num_bits);
261   vl_vlc_eatbits(vlc, num_bits);
262
263   return value;
264}
265
266/**
267 * lookup a value and length in a decompressed table
268 */
269static INLINE int8_t
270vl_vlc_get_vlclbf(struct vl_vlc *vlc, const struct vl_vlc_entry *tbl, unsigned num_bits)
271{
272   tbl += vl_vlc_peekbits(vlc, num_bits);
273   vl_vlc_eatbits(vlc, tbl->length);
274   return tbl->value;
275}
276
277#endif /* vl_vlc_h */
278