109 lines
1.7 KiB
C
109 lines
1.7 KiB
C
/**************************************************************************
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*
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* FILE universal.c
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* Copyright (c) 2015 Daniel Kahlin <daniel@kahlin.net>
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* Written by Daniel Kahlin <daniel@kahlin.net>
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*
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* DESCRIPTION
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* universal encodings
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*
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******/
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#include <stdio.h>
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#include "bitfunc.h"
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#include "universal.h"
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#include "global.h"
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/**************************************************************************
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*
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* NAME cost_unary, write_unary, read_unary
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*
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******/
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int cost_unary(int v, int lim)
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{
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if (v == lim-1) {
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return v;
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}
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return v+1;
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}
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void write_unary(BitWriteState *bws, int v, int lim, int pol)
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{
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uint32_t mask = pol ? 0xfffffff : 0;
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int endbit = pol ? 0 : 1;
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bitwr_write(bws, mask, v);
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if (v < lim-1) {
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bitwr_write(bws, endbit, 1);
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}
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}
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int read_unary(BitReadState *brs, int lim, int pol)
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{
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int n = 0;
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while (bitrd_read(brs, 1) == pol) {
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n++;
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if (n == lim-1) {
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break;
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}
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}
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return n;
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}
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/**************************************************************************
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*
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* NAME cost_eliasgamma, write_eliasgamma, read_eliasgamma
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*
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******/
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int cost_eliasgamma(int v)
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{
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int n;
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/* find first 1 */
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for (n = 31; n >= 0; n--) {
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if ( (v>>n) & 0x01)
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break;
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}
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return n + n+1;
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}
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void write_eliasgamma(BitWriteState *bws, int v)
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{
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int n;
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/* find first 1 */
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for (n = 31; n >= 0; n--) {
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if ( (v>>n) & 0x01)
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break;
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}
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bitwr_write(bws, 0, n);
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bitwr_write(bws, v, n+1);
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}
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int read_eliasgamma(BitReadState *brs)
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{
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int v;
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int n = 0;
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while (bitrd_read(brs, 1) == 0) {
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n++;
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}
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if (n == 16) {
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/* short cut to end marker */
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return 0x10000;
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}
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v = bitrd_read(brs, n);
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v |= 1<<n;
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return v;
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}
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/* eof */
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