initial commit, 4.5 stable

thirdparty/libtheora/bitpack.c

@@ -0,0 +1,114 @@
+/********************************************************************
+ *                                                                  *
+ * 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                      *
+ * https://www.xiph.org/                                            *
+ *                                                                  *
+ ********************************************************************
+
+  function: packing variable sized words into an octet stream
+
+ ********************************************************************/
+#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);
+}