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 *******************************************************************************/ 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 *******************************************************************************/ 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 *******************************************************************************/ 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 if ((ps_stream->u4_offset + 64) < ps_stream->u4_max_offset) 195 { 196 FLUSH_BITS(ps_stream->u4_offset,ps_stream->u4_buf,ps_stream->u4_buf_nxt,u4_no_of_bits,ps_stream->pu4_buf_aligned) 197 } 198 else 199 { 200 UWORD32 u4_temp; 201 202 if (((ps_stream->u4_offset & 0x1f) + u4_no_of_bits) >= 32) 203 { 204 ps_stream->u4_buf = ps_stream->u4_buf_nxt; 205 ps_stream->u4_buf_nxt = 0; 206 } 207 ps_stream->u4_offset += u4_no_of_bits; 208 } 209 return; 210 } 211 /****************************************************************************** 212 * 213 * Function Name : impeg2d_bit_stream_flush_to_byte_boundary 214 * 215 * Description : This is a Bitstream processing function.It advances 216 * the bit and byte pointers to next byte boundary 217 * 218 * Arguments : 219 * stream : Pointer to the Bitstream. 220 * NoOfBits : No of bits to be read 221 * 222 * Values Returned : The bits read (upto 32 bits maximum) starting from the 223 * least significant bit and going towards most significant 224 * bit in the order of their occurence. 225 *******************************************************************************/ 226 INLINE void impeg2d_bit_stream_flush_to_byte_boundary(void* pv_ctxt) 227 { 228 UWORD8 u1_bit_offset; 229 stream_t *ps_stream = (stream_t *)pv_ctxt; 230 231 u1_bit_offset = (ps_stream->u4_offset) & 0x7; 232 233 234 /* if it is not byte aligned make it byte aligned*/ 235 if(u1_bit_offset != 0) 236 { 237 impeg2d_bit_stream_flush(ps_stream,(8 - u1_bit_offset)); 238 } 239 240 241 242 } 243 244 245 /****************************************************************************** 246 * 247 * Function Name : ibits_next 248 * 249 * Description : This is a Bitstream processing function.It gets the 250 * specified number of bits from the buffer without 251 * altering the current pointers. It is used mainly to 252 * check for some specific pattern of bits like start 253 * code. This is equivalent to next_bits() function 254 * defined in MPEG-4 Visual Standard Definition of functions 255 * 256 * Arguments : 257 * ctxt : Pointer to the Bitstream. 258 * numBits : No of bits to be read 259 * 260 * Values Returned : The bits read (upto 32 bits maximum) starting from the 261 * least significant bit and going towards most significant 262 * bit in the order of their occurence. 263 *******************************************************************************/ 264 INLINE UWORD32 impeg2d_bit_stream_nxt( stream_t *ps_stream, WORD32 i4_no_of_bits) 265 { 266 UWORD32 u4_bits,u4_offset,u4_temp; 267 UWORD8 u4_bit_ptr; 268 269 ASSERT(i4_no_of_bits > 0); 270 271 u4_offset = ps_stream->u4_offset; 272 u4_bit_ptr = u4_offset & 0x1F; 273 u4_bits = ps_stream->u4_buf << u4_bit_ptr; 274 275 u4_bit_ptr += i4_no_of_bits; 276 if(32 < u4_bit_ptr) 277 { 278 /* Read bits from the next word if necessary */ 279 u4_temp = ps_stream->u4_buf_nxt; 280 u4_bit_ptr &= (BITS_IN_INT - 1); 281 282 u4_temp = (u4_temp >> (BITS_IN_INT - u4_bit_ptr)); 283 284 /* u4_temp consists of bits,if any that had to be read from the next word 285 of the buffer.The bits read from both the words are concatenated and 286 moved to the least significant positions of 'u4_bits'*/ 287 u4_bits = (u4_bits >> (32 - i4_no_of_bits)) | u4_temp; 288 } 289 else 290 { 291 u4_bits = (u4_bits >> (32 - i4_no_of_bits)); 292 } 293 294 return (u4_bits); 295 } 296 /****************************************************************************** 297 * 298 * Function Name : impeg2d_bit_stream_get 299 * 300 * Description : This is a Bitstream processing function. It reads a 301 * specified number of bits from the current bit 302 * position and advances the bit and byte pointers 303 * appropriately 304 * Arguments : 305 * ctxt : Pointer to the Bitstream. 306 * numBits : No of bits to be read 307 * 308 * Values Returned : The bits read (upto 32 bits maximum) starting from the 309 * least significant bit and going towards most significant 310 * bit in the order of their occurence. 311 *******************************************************************************/ 312 313 INLINE UWORD32 impeg2d_bit_stream_get(void* pv_ctxt, UWORD32 u4_num_bits) 314 { 315 UWORD32 u4_next_bits = impeg2d_bit_stream_nxt(pv_ctxt, u4_num_bits); 316 impeg2d_bit_stream_flush(pv_ctxt, u4_num_bits); 317 return(u4_next_bits); 318 } 319 320 321 322 /****************************************************************************** 323 * 324 * Function Name : impeg2d_bit_stream_num_bits_read 325 * 326 * Description : This is a Bitstream processing function. It reads a 327 * specified number of bits from the current bit 328 * position and advances the bit and byte pointers 329 * appropriately 330 * Arguments : 331 * ctxt : Pointer to the Bitstream. 332 * numBits : No of bits to be read 333 * 334 * Values Returned : The bits read (upto 16 bits maximum) starting from the 335 * least significant bit and going towards most significant 336 * bit in the order of their occurence. 337 *******************************************************************************/ 338 INLINE UWORD32 impeg2d_bit_stream_num_bits_read(void* pv_ctxt) 339 { 340 stream_t *u4_no_of_bitsstream = (stream_t *)pv_ctxt; 341 size_t u4_temp; 342 UWORD32 u4_bits_read; 343 u4_temp = (size_t)(u4_no_of_bitsstream->pv_bs_buf); 344 u4_temp &= 0x3; 345 u4_bits_read = (u4_no_of_bitsstream->u4_offset - (u4_temp << 3)); 346 347 return(u4_bits_read); 348 349 } 350 351 352
