X-Git-Url: https://git.llucax.com/z.facultad/75.06/jacu.git/blobdiff_plain/35fa025326ae9e6ab219b9016861dc1cedece945..21619014c9bbc135c3fa731e376f6aed0ade0b75:/src/ppmc/range.c?ds=sidebyside diff --git a/src/ppmc/range.c b/src/ppmc/range.c index f734e62..168ddc2 100644 --- a/src/ppmc/range.c +++ b/src/ppmc/range.c @@ -1,212 +1,212 @@ /* - Copyright (C) Arturo San Emeterio Campos 1999. All rights reserved. - Permission is granted to make verbatim copies of this file for private - use only. There is ABSOLUTELY NO WARRANTY. Use it at your OWN RISK. + Copyright (C) Arturo San Emeterio Campos 1999. All rights reserved. + Permission is granted to make verbatim copies of this file for private + use only. There is ABSOLUTELY NO WARRANTY. Use it at your OWN RISK. - This file is: "range.c" - Email: arturo@arturocampos.com - Web: http://www.arturocampos.com + This file is: "range.c" +Email: arturo@arturocampos.com +Web: http://www.arturocampos.com - This module contains the routines of both the range coder and decoder. +This module contains the routines of both the range coder and decoder. - The range coder works internally in 32 bits, and uses bytes as symbols. - Also the end of message symbol is used. So z=257. +The range coder works internally in 32 bits, and uses bytes as symbols. +Also the end of message symbol is used. So z=257. - Both input and output use rc_file as the file stream. Of course we can't - code and decode at the same time. All the input or output comes from the - same file, no matter what range coder structure are we using. The modules - here provided don't manage the io except for reading and writing, they - don't open nor close the files. The reading and writing is done via - putc and getc. +Both input and output use rc_file as the file stream. Of course we can't +code and decode at the same time. All the input or output comes from the +same file, no matter what range coder structure are we using. The modules +here provided don't manage the io except for reading and writing, they +don't open nor close the files. The reading and writing is done via +putc and getc. */ #include "range.h" #include /* - Inits the range coder state. Must be called before encoding any symbol. - It uses a magic number 0xB3 as the first byte outputted. - -rangecoder *rc, the range coder to be used. + Inits the range coder state. Must be called before encoding any symbol. + It uses a magic number 0xB3 as the first byte outputted. + -rangecoder *rc, the range coder to be used. - Shoulde be called like that: - range_coder_init(&o0_rc_state,file_output); -*/ + Shoulde be called like that: + range_coder_init(&o0_rc_state,file_output); + */ void range_coder_init(rangecoder *rc, FILE *stream) { - rc_file=stream; - rc->low=0; //define state - rc->range=0x80000000; - rc->byte_buffer=0xB3; //magic number - rc->help=0; //temp value + rc_file=stream; + rc->low=0; //define state + rc->range=0x80000000; + rc->byte_buffer=0xB3; //magic number + rc->help=0; //temp value } /* - Encodes a symbol. - -rangecoder *rc, the range coder to be used. - -unsigned long tot_f, the maximum cumulative frequency - -unsigned long lt_f, the cumulative probabilty of the symbol - -unsigned long sy_f, the probability of the symbol -*/ + Encodes a symbol. + -rangecoder *rc, the range coder to be used. + -unsigned long tot_f, the maximum cumulative frequency + -unsigned long lt_f, the cumulative probabilty of the symbol + -unsigned long sy_f, the probability of the symbol + */ void range_coder_encode(rangecoder *rc,unsigned long tot_f, unsigned long lt_f,unsigned long sy_f) { - unsigned long temp, r; + unsigned long temp, r; - range_coder_renormalize(rc); //&rc? + range_coder_renormalize(rc); //&rc? - r=rc->range/tot_f; - temp=r*lt_f; - if(lt_f+sy_frange=r*sy_f; - else - rc->range-=temp; - rc->low+=temp; + r=rc->range/tot_f; + temp=r*lt_f; + if(lt_f+sy_frange=r*sy_f; + else + rc->range-=temp; + rc->low+=temp; } /* - Renormalizes the state when coding. - -rangecoder *rc, the range coder to be used. -*/ + Renormalizes the state when coding. + -rangecoder *rc, the range coder to be used. + */ void range_coder_renormalize(rangecoder *rc) { - while(rc->range<=(unsigned long)0x00800000) - { - if(rc->low<(unsigned long)0x7F800000) - { - putc(rc->byte_buffer,rc_file); - for(;rc->help;rc->help--) - putc(0xFF,rc_file); - rc->byte_buffer=(unsigned char)(rc->low>>23); - } - else - { - if(rc->low&(unsigned long)0x80000000) - { - putc(rc->byte_buffer+1,rc_file); - for(;rc->help;rc->help--) - putc(0x00,rc_file); - rc->byte_buffer=(unsigned char)(rc->low>>23); - } - else - rc->help++; - } - rc->range<<=8; - rc->low=(rc->low<<8)&(unsigned long)(0x7FFFFFFF); - } + while(rc->range<=(unsigned long)0x00800000) + { + if(rc->low<(unsigned long)0x7F800000) + { + putc(rc->byte_buffer,rc_file); + for(;rc->help;rc->help--) + putc(0xFF,rc_file); + rc->byte_buffer=(unsigned char)(rc->low>>23); + } + else + { + if(rc->low&(unsigned long)0x80000000) + { + putc(rc->byte_buffer+1,rc_file); + for(;rc->help;rc->help--) + putc(0x00,rc_file); + rc->byte_buffer=(unsigned char)(rc->low>>23); + } + else + rc->help++; + } + rc->range<<=8; + rc->low=(rc->low<<8)&(unsigned long)(0x7FFFFFFF); + } } /* - Flushes the encoder. Must be called when the coding is done. - -rangecoder *rc, the range coder to be used. + Flushes the encoder. Must be called when the coding is done. + -rangecoder *rc, the range coder to be used. - Shoulde be called like that: - range_coder_flush(&o0_rc_state); -*/ + Shoulde be called like that: + range_coder_flush(&o0_rc_state); + */ void range_coder_flush(rangecoder *rc) { - unsigned long tmp; - - range_coder_renormalize(rc); - tmp = rc->low >> 23; - if (tmp > 0xff) - { - putc(rc->byte_buffer+1,rc_file); - for(; rc->help; rc->help--) - putc(0,rc_file); - } - else - { - putc(rc->byte_buffer,rc_file); - for(; rc->help; rc->help--) - putc(0xff,rc_file); - } - - putc(tmp & 0xff,rc_file); - putc((tmp = rc->low >> (23-8)) & 0xff,rc_file); + unsigned long tmp; + + range_coder_renormalize(rc); + tmp = rc->low >> 23; + if (tmp > 0xff) + { + putc(rc->byte_buffer+1,rc_file); + for(; rc->help; rc->help--) + putc(0,rc_file); + } + else + { + putc(rc->byte_buffer,rc_file); + for(; rc->help; rc->help--) + putc(0xff,rc_file); + } + + putc(tmp & 0xff,rc_file); + putc((tmp = rc->low >> (23-8)) & 0xff,rc_file); } /* - Inits the range decoder state. Also checks for the magic number, and - quits in case it isn't the first, so be careful. - -rangecoder *rc, the range coder to be used. -*/ + Inits the range decoder state. Also checks for the magic number, and + quits in case it isn't the first, so be careful. + -rangecoder *rc, the range coder to be used. + */ void range_decoder_init(rangecoder *rc, FILE *stream) { - unsigned int _rd_c; - - rc_file=stream; - if((_rd_c=getc(rc_file))!=0xB3) - { - printf("\nThis is not range coded data. Magic number not found. Exiting."); - exit(1); - } - rc->byte_buffer=getc(rc_file); - rc->low=rc->byte_buffer>>1; - rc->range=0x80; + unsigned int _rd_c; + + rc_file=stream; + if((_rd_c=getc(rc_file))!=0xB3) + { + printf("\nThis is not range coded data. Magic number not found. Exiting."); + exit(1); + } + rc->byte_buffer=getc(rc_file); + rc->low=rc->byte_buffer>>1; + rc->range=0x80; } /* - Decode a symbol, get its cumulative probability. - Input: - -rangecoder *rc, the range coder to be used. - -unsigned long tot_f, the maximum cumulative probability - Output: - -unsigned long, cumulative probability of the current symbol - Should be called like that: - current_cump=range_decoder_decode(&o0_rc_state,o0_tot_f); + Decode a symbol, get its cumulative probability. +Input: +-rangecoder *rc, the range coder to be used. +-unsigned long tot_f, the maximum cumulative probability +Output: +-unsigned long, cumulative probability of the current symbol +Should be called like that: +current_cump=range_decoder_decode(&o0_rc_state,o0_tot_f); */ unsigned long range_decoder_decode(rangecoder *rc, unsigned long tot_f) { - unsigned long temp; - - range_decoder_renormalize(rc); - rc->help=rc->range/tot_f; - temp=rc->low/rc->help; - if(temp>=tot_f) - return tot_f-1; - else - return temp; + unsigned long temp; + + range_decoder_renormalize(rc); + rc->help=rc->range/tot_f; + temp=rc->low/rc->help; + if(temp>=tot_f) + return tot_f-1; + else + return temp; } /* - Updates the state so next symbol can be decoded. - Input: - -rangecoder *rc, the range coder to be used. - -unsigned long tot_f, the maximum cumulative probability - -unsigned long lt_f, the cumulative probabilty of the symbol - -unsigned long sy_f, the probability of the symbol + Updates the state so next symbol can be decoded. +Input: +-rangecoder *rc, the range coder to be used. +-unsigned long tot_f, the maximum cumulative probability +-unsigned long lt_f, the cumulative probabilty of the symbol +-unsigned long sy_f, the probability of the symbol */ void range_decoder_update(rangecoder *rc, unsigned long tot_f, unsigned long lt_f,unsigned long sy_f) { - unsigned long temp; - - temp=rc->help*lt_f; - rc->low-=temp; - if(lt_f+sy_frange=rc->help*sy_f; - else - rc->range-=temp; + unsigned long temp; + + temp=rc->help*lt_f; + rc->low-=temp; + if(lt_f+sy_frange=rc->help*sy_f; + else + rc->range-=temp; } /* - Renormalizes the state while decoding. - -rangecoder *rc, the range coder to be used. -*/ + Renormalizes the state while decoding. + -rangecoder *rc, the range coder to be used. + */ void range_decoder_renormalize(rangecoder *rc) { - while(rc->range<=0x00800000) - { - rc->low=(rc->low<<8)|((rc->byte_buffer<<7)&0xFF); - rc->byte_buffer=getc(rc_file); - rc->low |= rc->byte_buffer >> (1); - rc->range<<=8; - } + while(rc->range<=0x00800000) + { + rc->low=(rc->low<<8)|((rc->byte_buffer<<7)&0xFF); + rc->byte_buffer=getc(rc_file); + rc->low |= rc->byte_buffer >> (1); + rc->range<<=8; + } }