| |
| /*! |
| ************************************************************************************* |
| * \file biaridecod.c |
| * |
| * \brief |
| * binary arithmetic decoder routines |
| * \date |
| * 21. Oct 2000 |
| * \author |
| * Main contributors (see contributors.h for copyright, address and affiliation details) |
| * - Detlev Marpe <marpe@hhi.de> |
| * - Gabi Blaettermann <blaetter@hhi.de> |
| ************************************************************************************* |
| */ |
| |
| #include <stdlib.h> |
| |
| #include "global.h" |
| #include "memalloc.h" |
| |
| extern int symbolCount; |
| |
| int binCount = 0; |
| |
| #define Dbuffer (dep->Dbuffer) |
| #define Dbits_to_go (dep->Dbits_to_go) |
| #define Dcodestrm (dep->Dcodestrm) |
| #define Dcodestrm_len (dep->Dcodestrm_len) |
| |
| #define B_BITS 10 // Number of bits to represent the whole coding interval |
| #define HALF (1 << (B_BITS-1)) |
| #define QUARTER (1 << (B_BITS-2)) |
| |
| /* Range table for LPS */ |
| const byte rLPS_table_64x4[64][4]= |
| { |
| { 128, 176, 208, 240}, |
| { 128, 167, 197, 227}, |
| { 128, 158, 187, 216}, |
| { 123, 150, 178, 205}, |
| { 116, 142, 169, 195}, |
| { 111, 135, 160, 185}, |
| { 105, 128, 152, 175}, |
| { 100, 122, 144, 166}, |
| { 95, 116, 137, 158}, |
| { 90, 110, 130, 150}, |
| { 85, 104, 123, 142}, |
| { 81, 99, 117, 135}, |
| { 77, 94, 111, 128}, |
| { 73, 89, 105, 122}, |
| { 69, 85, 100, 116}, |
| { 66, 80, 95, 110}, |
| { 62, 76, 90, 104}, |
| { 59, 72, 86, 99}, |
| { 56, 69, 81, 94}, |
| { 53, 65, 77, 89}, |
| { 51, 62, 73, 85}, |
| { 48, 59, 69, 80}, |
| { 46, 56, 66, 76}, |
| { 43, 53, 63, 72}, |
| { 41, 50, 59, 69}, |
| { 39, 48, 56, 65}, |
| { 37, 45, 54, 62}, |
| { 35, 43, 51, 59}, |
| { 33, 41, 48, 56}, |
| { 32, 39, 46, 53}, |
| { 30, 37, 43, 50}, |
| { 29, 35, 41, 48}, |
| { 27, 33, 39, 45}, |
| { 26, 31, 37, 43}, |
| { 24, 30, 35, 41}, |
| { 23, 28, 33, 39}, |
| { 22, 27, 32, 37}, |
| { 21, 26, 30, 35}, |
| { 20, 24, 29, 33}, |
| { 19, 23, 27, 31}, |
| { 18, 22, 26, 30}, |
| { 17, 21, 25, 28}, |
| { 16, 20, 23, 27}, |
| { 15, 19, 22, 25}, |
| { 14, 18, 21, 24}, |
| { 14, 17, 20, 23}, |
| { 13, 16, 19, 22}, |
| { 12, 15, 18, 21}, |
| { 12, 14, 17, 20}, |
| { 11, 14, 16, 19}, |
| { 11, 13, 15, 18}, |
| { 10, 12, 15, 17}, |
| { 10, 12, 14, 16}, |
| { 9, 11, 13, 15}, |
| { 9, 11, 12, 14}, |
| { 8, 10, 12, 14}, |
| { 8, 9, 11, 13}, |
| { 7, 9, 11, 12}, |
| { 7, 9, 10, 12}, |
| { 7, 8, 10, 11}, |
| { 6, 8, 9, 11}, |
| { 6, 7, 9, 10}, |
| { 6, 7, 8, 9}, |
| { 2, 2, 2, 2} |
| }; |
| |
| |
| |
| const unsigned short AC_next_state_MPS_64[64] = |
| { |
| 1,2,3,4,5,6,7,8,9,10, |
| 11,12,13,14,15,16,17,18,19,20, |
| 21,22,23,24,25,26,27,28,29,30, |
| 31,32,33,34,35,36,37,38,39,40, |
| 41,42,43,44,45,46,47,48,49,50, |
| 51,52,53,54,55,56,57,58,59,60, |
| 61,62,62,63 |
| }; |
| |
| |
| const unsigned short AC_next_state_LPS_64[64] = |
| { |
| 0, 0, 1, 2, 2, 4, 4, 5, 6, 7, |
| 8, 9, 9,11,11,12,13,13,15,15, |
| 16,16,18,18,19,19,21,21,22,22, |
| 23,24,24,25,26,26,27,27,28,29, |
| 29,30,30,30,31,32,32,33,33,33, |
| 34,34,35,35,35,36,36,36,37,37, |
| 37,38,38,63 |
| }; |
| |
| /************************************************************************ |
| * M a c r o s |
| ************************************************************************ |
| */ |
| |
| #define get_byte(){ \ |
| Dbuffer = Dcodestrm[(*Dcodestrm_len)++];\ |
| Dbits_to_go = 7; \ |
| } |
| |
| |
| /************************************************************************ |
| ************************************************************************ |
| init / exit decoder |
| ************************************************************************ |
| ************************************************************************/ |
| |
| |
| /*! |
| ************************************************************************ |
| * \brief |
| * Allocates memory for the DecodingEnvironment struct |
| * \return DecodingContextPtr |
| * allocates memory |
| ************************************************************************ |
| */ |
| DecodingEnvironmentPtr arideco_create_decoding_environment() |
| { |
| DecodingEnvironmentPtr dep; |
| |
| if ((dep = calloc(1,sizeof(DecodingEnvironment))) == NULL) |
| no_mem_exit("arideco_create_decoding_environment: dep"); |
| return dep; |
| } |
| |
| |
| /*! |
| *********************************************************************** |
| * \brief |
| * Frees memory of the DecodingEnvironment struct |
| *********************************************************************** |
| */ |
| void arideco_delete_decoding_environment(DecodingEnvironmentPtr dep) |
| { |
| if (dep == NULL) |
| { |
| snprintf(errortext, ET_SIZE, "Error freeing dep (NULL pointer)"); |
| error (errortext, 200); |
| } |
| else |
| free(dep); |
| } |
| |
| |
| /*! |
| ************************************************************************ |
| * \brief |
| * Initializes the DecodingEnvironment for the arithmetic coder |
| ************************************************************************ |
| */ |
| void arideco_start_decoding(DecodingEnvironmentPtr dep, unsigned char *cpixcode, |
| int firstbyte, int *cpixcode_len, int slice_type ) |
| { |
| |
| int value = 0; |
| |
| Dcodestrm = cpixcode; |
| Dcodestrm_len = cpixcode_len; |
| *Dcodestrm_len = firstbyte; |
| |
| { |
| int i; |
| Dbits_to_go = 0; |
| for (i = 0; i < B_BITS -1 ; i++) // insertion of redundant bit |
| { |
| if (--Dbits_to_go < 0) |
| get_byte(); |
| value = (value<<1) | ((Dbuffer >> Dbits_to_go) & 0x01); |
| } |
| } |
| dep->Drange = HALF-2; |
| dep->Dvalue = value; |
| } |
| |
| |
| /*! |
| ************************************************************************ |
| * \brief |
| * arideco_bits_read |
| ************************************************************************ |
| */ |
| int arideco_bits_read(DecodingEnvironmentPtr dep) |
| { |
| return 8 * ((*Dcodestrm_len)-1) + (8 - Dbits_to_go) - 16; |
| } |
| |
| |
| /*! |
| ************************************************************************ |
| * \brief |
| * arideco_done_decoding(): |
| ************************************************************************ |
| */ |
| void arideco_done_decoding(DecodingEnvironmentPtr dep) |
| { |
| (*Dcodestrm_len)++; |
| } |
| |
| |
| |
| /*! |
| ************************************************************************ |
| * \brief |
| * biari_decode_symbol(): |
| * \return |
| * the decoded symbol |
| ************************************************************************ |
| */ |
| unsigned int biari_decode_symbol(DecodingEnvironmentPtr dep, BiContextTypePtr bi_ct ) |
| { |
| register unsigned int bit = bi_ct->MPS; |
| register unsigned int value = dep->Dvalue; |
| register unsigned int range = dep->Drange; |
| register unsigned int rLPS = (unsigned int) rLPS_table_64x4[bi_ct->state][(range>>6) & 0x03]; |
| |
| #if (2==TRACE) |
| fprintf(p_trace, "%d 0x%04x %d %d\n", binCount++, dep->Drange, bi_ct->state, bi_ct->MPS ); |
| #endif |
| |
| range -= rLPS; |
| |
| if (value < range) /* MPS */ |
| bi_ct->state = AC_next_state_MPS_64[bi_ct->state]; // next state |
| else /* LPS */ |
| { |
| value -= range; |
| range = rLPS; |
| bit = !bit; |
| if (!bi_ct->state) // switch meaning of MPS if necessary |
| bi_ct->MPS ^= 0x01; |
| bi_ct->state = AC_next_state_LPS_64[bi_ct->state]; // next state |
| } |
| |
| while (range < QUARTER) |
| { |
| /* Double range */ |
| range <<= 1; |
| if (--Dbits_to_go < 0) |
| get_byte(); |
| /* Shift in next bit and add to value */ |
| value = (value << 1) | ((Dbuffer >> Dbits_to_go) & 0x01); |
| |
| } |
| |
| dep->Drange = range; |
| dep->Dvalue = value; |
| |
| return(bit); |
| } |
| |
| |
| /*! |
| ************************************************************************ |
| * \brief |
| * biari_decode_symbol_eq_prob(): |
| * \return |
| * the decoded symbol |
| ************************************************************************ |
| */ |
| unsigned int biari_decode_symbol_eq_prob(DecodingEnvironmentPtr dep) |
| { |
| register unsigned int bit = 0; |
| register unsigned int value = (dep->Dvalue<<1); |
| |
| #if TRACE |
| // fprintf(p_trace, "%d 0x%04x\n", binCount++, dep->Drange ); |
| #endif |
| |
| if (--Dbits_to_go < 0) |
| get_byte(); |
| /* Shift in next bit and add to value */ |
| value |= (Dbuffer >> Dbits_to_go) & 0x01; |
| if (value >= dep->Drange) |
| { |
| bit = 1; |
| value -= dep->Drange; |
| } |
| |
| dep->Dvalue = value; |
| |
| return(bit); |
| } |
| |
| /*! |
| ************************************************************************ |
| * \brief |
| * biari_decode_symbol_final(): |
| * \return |
| * the decoded symbol |
| ************************************************************************ |
| */ |
| unsigned int biari_decode_final(DecodingEnvironmentPtr dep) |
| { |
| register unsigned int value = dep->Dvalue; |
| register unsigned int range = dep->Drange - 2; |
| |
| #if (2==TRACE) |
| fprintf(p_trace, "%d 0x%04x\n", binCount++, dep->Drange ); |
| #endif |
| |
| if (value >= range) |
| { |
| return 1; |
| } |
| else |
| { |
| while (range < QUARTER) |
| { |
| /* Double range */ |
| range <<= 1; |
| if (--Dbits_to_go < 0) |
| get_byte(); |
| /* Shift in next bit and add to value */ |
| value = (value << 1) | ((Dbuffer >> Dbits_to_go) & 0x01); |
| } |
| dep->Dvalue = value; |
| dep->Drange = range; |
| return 0; |
| } |
| } |
| |
| |
| |
| /*! |
| ************************************************************************ |
| * \brief |
| * Initializes a given context with some pre-defined probability state |
| ************************************************************************ |
| */ |
| void biari_init_context (struct img_par* img, BiContextTypePtr ctx, const int* ini) |
| { |
| int pstate; |
| |
| pstate = ((ini[0]* imax(0,img->qp) )>>4) + ini[1]; |
| pstate = iClip3(1, 126, pstate); |
| |
| if ( pstate >= 64 ) |
| { |
| ctx->state = (unsigned short) (pstate - 64); |
| ctx->MPS = 1; |
| } |
| else |
| { |
| ctx->state = (unsigned short) (63 - pstate); |
| ctx->MPS = 0; |
| } |
| } |
| |
