1 /******************************************************************************
2 *
3 * Copyright (C) 2015 The Android Open Source Project
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at:
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 *****************************************************************************
18 * Originally developed and contributed by Ittiam Systems Pvt. Ltd, Bangalore
19 */
20 /*****************************************************************************/
21 /* */
22 /* File Name : impeg2d_bitstream.c */
23 /* */
24 /* Description : This file contains all the necessary examples to */
25 /* establish a consistent use of Ittiam C coding */
26 /* standards (based on Indian Hill C Standards) */
27 /* */
28 /* List of Functions : <List the functions defined in this file> */
29 /* */
30 /* Issues / Problems : None */
31 /* */
32 /* Revision History : */
33 /* */
34 /* DD MM YYYY Author(s) Changes (Describe the changes made) */
35 /* 10 01 2005 Ittiam Draft */
36 /* */
37 /*****************************************************************************/
38 #include <stdlib.h>
39
40 #include "iv_datatypedef.h"
41 #include "impeg2_defs.h"
42 #include "impeg2_platform_macros.h"
43 #include "impeg2_macros.h"
44 #include "impeg2d_bitstream.h"
45
46 #define BIT(val,bit) (UWORD16)(((val) >> (bit)) & 0x1)
47 /******************************************************************************
48 *
49 * Function Name : impeg2d_bit_stream_init
50 *
51 * Description : This is a Bitstream initialising function.
52 * Arguments :
53 * stream : Pointer to the Bitstream.
54 * byteBuf : Address of the buffer
55 * size : Size of the buffer in bytes
56 *
57 * Values Returned : None
58 *******************************************************************************/
impeg2d_bit_stream_init(stream_t * ps_stream,UWORD8 * pu1_byte_buf,UWORD32 u4_max_offset)59 void impeg2d_bit_stream_init(stream_t *ps_stream,
60 UWORD8 *pu1_byte_buf,
61 UWORD32 u4_max_offset)
62 {
63 UWORD8 *pu1_byte_buff;
64 UWORD32 *pu4_word_buf;
65 size_t u4_byte_addr;
66 UWORD32 u4_temp1,u4_temp2;
67
68 /* Set parameters of the stream structure.Associate the structure with
69 the file */
70 ps_stream->pv_bs_buf = pu1_byte_buf;
71 ps_stream->u4_offset = 0;
72
73 /* Take care of unaligned address and create
74 nearest greater aligned address */
75 pu1_byte_buff = (UWORD8 *)pu1_byte_buf;
76 u4_byte_addr = (size_t)pu1_byte_buff;
77
78 if((u4_byte_addr & 3) == 1)
79 {
80 u4_temp1 = ((UWORD32)(*pu1_byte_buff++)) << 8;
81 u4_temp1 += ((UWORD32)(*pu1_byte_buff++)) << 16;
82 u4_temp1 += ((UWORD32)(*pu1_byte_buff++)) << 24;
83
84 pu4_word_buf = (UWORD32 *)pu1_byte_buff;
85
86 ps_stream->u4_offset = 8;
87 }
88 else if((u4_byte_addr & 3) == 2)
89 {
90 u4_temp1 = ((UWORD32)(*pu1_byte_buff++)) << 16;
91 u4_temp1 += ((UWORD32)(*pu1_byte_buff++)) << 24;
92
93 pu4_word_buf = (UWORD32 *)pu1_byte_buff;
94
95 ps_stream->u4_offset = 16;
96 }
97 else if((u4_byte_addr & 3) == 3)
98 {
99 u4_temp1 = (((UWORD32)(*pu1_byte_buff++)) << 24);
100
101 pu4_word_buf = (UWORD32 *)pu1_byte_buff;
102
103 ps_stream->u4_offset = 24;
104 }
105 else
106 {
107 pu4_word_buf = (UWORD32 *)pu1_byte_buff;
108
109 u4_temp1 = *pu4_word_buf++;
110 ps_stream->u4_offset = 0;
111 }
112
113 /* convert the endian ness from Little endian to Big endian so that bits
114 are in proper order from MSB to LSB */
115 CONV_LE_TO_BE(u4_temp2,u4_temp1)
116
117 /* Read One more word for buf nxt */
118 u4_temp1 = *pu4_word_buf++;
119 ps_stream->u4_buf = u4_temp2;
120
121 CONV_LE_TO_BE(u4_temp2,u4_temp1)
122
123 ps_stream->u4_buf_nxt = u4_temp2;
124
125 ps_stream->pu4_buf_aligned = pu4_word_buf;
126
127
128 ps_stream->u4_max_offset = (u4_max_offset << 3) + ps_stream->u4_offset;
129
130 return;
131 }
132
133
134
135 /******************************************************************************
136 *
137 * Function Name : impeg2d_bit_stream_get_bit
138 *
139 * Description : This is a Bitstream processing function. It reads the
140 * bit currently pointed by the bit pointer in the buffer and
141 * advances the pointer by one.
142 * Arguments :
143 * stream : Pointer to the Bitstream.
144 *
145 * Values Returned : The bit read(0/1)
146 *******************************************************************************/
impeg2d_bit_stream_get_bit(stream_t * ps_stream)147 INLINE UWORD8 impeg2d_bit_stream_get_bit(stream_t *ps_stream)
148 {
149 UWORD32 u4_bit,u4_offset,u4_temp;
150 UWORD32 u4_curr_bit;
151
152 u4_offset = ps_stream->u4_offset;
153 u4_curr_bit = u4_offset & 0x1F;
154 u4_bit = ps_stream->u4_buf;
155
156 /* Move the current bit read from the current word to the
157 least significant bit positions of 'c'.*/
158 u4_bit >>= BITS_IN_INT - u4_curr_bit - 1;
159
160 u4_offset++;
161
162 /* If the last bit of the last word of the buffer has been read update
163 the currrent buf with next, and read next buf from bit stream buffer */
164 if (u4_curr_bit == 31)
165 {
166 ps_stream->u4_buf = ps_stream->u4_buf_nxt;
167
168 if (ps_stream->u4_offset < ps_stream->u4_max_offset)
169 {
170 u4_temp = *(ps_stream->pu4_buf_aligned)++;
171 CONV_LE_TO_BE(ps_stream->u4_buf_nxt,u4_temp)
172 }
173 }
174 ps_stream->u4_offset = u4_offset;
175
176 return (u4_bit & 0x1);
177 }
178 /******************************************************************************
179 *
180 * Function Name : impeg2d_bit_stream_flush
181 *
182 * Description : This is a Bitstream processing function. It
183 * advances the bit and byte pointers appropriately
184 *
185 * Arguments :
186 * ctxt : Pointer to the Bitstream.
187 * numBits : No of bits to be read
188 *
189 * Values Returned : None
190 *******************************************************************************/
impeg2d_bit_stream_flush(void * pv_ctxt,UWORD32 u4_no_of_bits)191 INLINE void impeg2d_bit_stream_flush(void* pv_ctxt, UWORD32 u4_no_of_bits)
192 {
193 stream_t *ps_stream = (stream_t *)pv_ctxt;
194
195
196 if (ps_stream->u4_offset <= ps_stream->u4_max_offset)
197 {
198 /* We have to flush the bytes even if the offset is equal to the maximum
199 * offset. This will ensure that a stream with an error exactly at the
200 * offset will not get stuck in an infinite loop - If we do not flush
201 * these bytes, then we keep feeding the erroneous bits.
202 */
203 FLUSH_BITS(ps_stream->u4_offset,ps_stream->u4_buf,ps_stream->u4_buf_nxt,u4_no_of_bits,ps_stream->pu4_buf_aligned)
204 }
205 return;
206 }
207 /******************************************************************************
208 *
209 * Function Name : impeg2d_bit_stream_flush_to_byte_boundary
210 *
211 * Description : This is a Bitstream processing function.It advances
212 * the bit and byte pointers to next byte boundary
213 *
214 * Arguments :
215 * stream : Pointer to the Bitstream.
216 * NoOfBits : No of bits to be read
217 *
218 * Values Returned : The bits read (upto 32 bits maximum) starting from the
219 * least significant bit and going towards most significant
220 * bit in the order of their occurence.
221 *******************************************************************************/
impeg2d_bit_stream_flush_to_byte_boundary(void * pv_ctxt)222 INLINE void impeg2d_bit_stream_flush_to_byte_boundary(void* pv_ctxt)
223 {
224 UWORD8 u1_bit_offset;
225 stream_t *ps_stream = (stream_t *)pv_ctxt;
226
227 u1_bit_offset = (ps_stream->u4_offset) & 0x7;
228
229
230 /* if it is not byte aligned make it byte aligned*/
231 if(u1_bit_offset != 0)
232 {
233 impeg2d_bit_stream_flush(ps_stream,(8 - u1_bit_offset));
234 }
235
236
237
238 }
239
240
241 /******************************************************************************
242 *
243 * Function Name : ibits_next
244 *
245 * Description : This is a Bitstream processing function.It gets the
246 * specified number of bits from the buffer without
247 * altering the current pointers. It is used mainly to
248 * check for some specific pattern of bits like start
249 * code. This is equivalent to next_bits() function
250 * defined in MPEG-4 Visual Standard Definition of functions
251 *
252 * Arguments :
253 * ctxt : Pointer to the Bitstream.
254 * numBits : No of bits to be read
255 *
256 * Values Returned : The bits read (upto 32 bits maximum) starting from the
257 * least significant bit and going towards most significant
258 * bit in the order of their occurence.
259 *******************************************************************************/
impeg2d_bit_stream_nxt(stream_t * ps_stream,WORD32 i4_no_of_bits)260 INLINE UWORD32 impeg2d_bit_stream_nxt( stream_t *ps_stream, WORD32 i4_no_of_bits)
261 {
262 UWORD32 u4_bits,u4_offset,u4_temp;
263 UWORD8 u4_bit_ptr;
264
265 ASSERT(i4_no_of_bits > 0);
266
267 u4_offset = ps_stream->u4_offset;
268 u4_bit_ptr = u4_offset & 0x1F;
269 u4_bits = ps_stream->u4_buf << u4_bit_ptr;
270
271 u4_bit_ptr += i4_no_of_bits;
272 if(32 < u4_bit_ptr)
273 {
274 /* Read bits from the next word if necessary */
275 u4_temp = ps_stream->u4_buf_nxt;
276 u4_bit_ptr &= (BITS_IN_INT - 1);
277
278 u4_temp = (u4_temp >> (BITS_IN_INT - u4_bit_ptr));
279
280 /* u4_temp consists of bits,if any that had to be read from the next word
281 of the buffer.The bits read from both the words are concatenated and
282 moved to the least significant positions of 'u4_bits'*/
283 u4_bits = (u4_bits >> (32 - i4_no_of_bits)) | u4_temp;
284 }
285 else
286 {
287 u4_bits = (u4_bits >> (32 - i4_no_of_bits));
288 }
289
290 return (u4_bits);
291 }
292 /******************************************************************************
293 *
294 * Function Name : impeg2d_bit_stream_get
295 *
296 * Description : This is a Bitstream processing function. It reads a
297 * specified number of bits from the current bit
298 * position and advances the bit and byte pointers
299 * appropriately
300 * Arguments :
301 * ctxt : Pointer to the Bitstream.
302 * numBits : No of bits to be read
303 *
304 * Values Returned : The bits read (upto 32 bits maximum) starting from the
305 * least significant bit and going towards most significant
306 * bit in the order of their occurence.
307 *******************************************************************************/
308
impeg2d_bit_stream_get(void * pv_ctxt,UWORD32 u4_num_bits)309 INLINE UWORD32 impeg2d_bit_stream_get(void* pv_ctxt, UWORD32 u4_num_bits)
310 {
311 UWORD32 u4_next_bits = impeg2d_bit_stream_nxt(pv_ctxt, u4_num_bits);
312 impeg2d_bit_stream_flush(pv_ctxt, u4_num_bits);
313 return(u4_next_bits);
314 }
315
316
317
318 /******************************************************************************
319 *
320 * Function Name : impeg2d_bit_stream_num_bits_read
321 *
322 * Description : This is a Bitstream processing function. It reads a
323 * specified number of bits from the current bit
324 * position and advances the bit and byte pointers
325 * appropriately
326 * Arguments :
327 * ctxt : Pointer to the Bitstream.
328 * numBits : No of bits to be read
329 *
330 * Values Returned : The bits read (upto 16 bits maximum) starting from the
331 * least significant bit and going towards most significant
332 * bit in the order of their occurence.
333 *******************************************************************************/
impeg2d_bit_stream_num_bits_read(void * pv_ctxt)334 INLINE UWORD32 impeg2d_bit_stream_num_bits_read(void* pv_ctxt)
335 {
336 stream_t *u4_no_of_bitsstream = (stream_t *)pv_ctxt;
337 size_t u4_temp;
338 UWORD32 u4_bits_read;
339 u4_temp = (size_t)(u4_no_of_bitsstream->pv_bs_buf);
340 u4_temp &= 0x3;
341 u4_bits_read = (u4_no_of_bitsstream->u4_offset - (u4_temp << 3));
342
343 return(u4_bits_read);
344
345 }
346
347
348