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-rw-r--r--media/libtheora/lib/bitpack.c114
1 files changed, 114 insertions, 0 deletions
diff --git a/media/libtheora/lib/bitpack.c b/media/libtheora/lib/bitpack.c
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+++ b/media/libtheora/lib/bitpack.c
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+/********************************************************************
+ * *
+ * THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE. *
+ * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS *
+ * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
+ * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. *
+ * *
+ * THE OggTheora SOURCE CODE IS (C) COPYRIGHT 1994-2009 *
+ * by the Xiph.Org Foundation and contributors http://www.xiph.org/ *
+ * *
+ ********************************************************************
+
+ function: packing variable sized words into an octet stream
+ last mod: $Id$
+
+ ********************************************************************/
+#include <string.h>
+#include <stdlib.h>
+#include "bitpack.h"
+
+/*We're 'MSb' endian; if we write a word but read individual bits,
+ then we'll read the MSb first.*/
+
+void oc_pack_readinit(oc_pack_buf *_b,unsigned char *_buf,long _bytes){
+ memset(_b,0,sizeof(*_b));
+ _b->ptr=_buf;
+ _b->stop=_buf+_bytes;
+}
+
+static oc_pb_window oc_pack_refill(oc_pack_buf *_b,int _bits){
+ const unsigned char *ptr;
+ const unsigned char *stop;
+ oc_pb_window window;
+ int available;
+ unsigned shift;
+ stop=_b->stop;
+ ptr=_b->ptr;
+ window=_b->window;
+ available=_b->bits;
+ shift=OC_PB_WINDOW_SIZE-available;
+ while(7<shift&&ptr<stop){
+ shift-=8;
+ window|=(oc_pb_window)*ptr++<<shift;
+ }
+ _b->ptr=ptr;
+ available=OC_PB_WINDOW_SIZE-shift;
+ if(_bits>available){
+ if(ptr>=stop){
+ _b->eof=1;
+ available=OC_LOTS_OF_BITS;
+ }
+ else window|=*ptr>>(available&7);
+ }
+ _b->bits=available;
+ return window;
+}
+
+int oc_pack_look1(oc_pack_buf *_b){
+ oc_pb_window window;
+ int available;
+ window=_b->window;
+ available=_b->bits;
+ if(available<1)_b->window=window=oc_pack_refill(_b,1);
+ return window>>OC_PB_WINDOW_SIZE-1;
+}
+
+void oc_pack_adv1(oc_pack_buf *_b){
+ _b->window<<=1;
+ _b->bits--;
+}
+
+/*Here we assume that 0<=_bits&&_bits<=32.*/
+long oc_pack_read_c(oc_pack_buf *_b,int _bits){
+ oc_pb_window window;
+ int available;
+ long result;
+ window=_b->window;
+ available=_b->bits;
+ if(_bits==0)return 0;
+ if(available<_bits){
+ window=oc_pack_refill(_b,_bits);
+ available=_b->bits;
+ }
+ result=window>>OC_PB_WINDOW_SIZE-_bits;
+ available-=_bits;
+ window<<=1;
+ window<<=_bits-1;
+ _b->window=window;
+ _b->bits=available;
+ return result;
+}
+
+int oc_pack_read1_c(oc_pack_buf *_b){
+ oc_pb_window window;
+ int available;
+ int result;
+ window=_b->window;
+ available=_b->bits;
+ if(available<1){
+ window=oc_pack_refill(_b,1);
+ available=_b->bits;
+ }
+ result=window>>OC_PB_WINDOW_SIZE-1;
+ available--;
+ window<<=1;
+ _b->window=window;
+ _b->bits=available;
+ return result;
+}
+
+long oc_pack_bytes_left(oc_pack_buf *_b){
+ if(_b->eof)return -1;
+ return _b->stop-_b->ptr+(_b->bits>>3);
+}