Refactor the entropy coder.

This unifies the byte buffer, encoder, and decoder into a single
 struct.
The common encoder and decoder functions (such as ec_tell()) can
 operate on either one, simplifying code which uses both.
The precision argument to ec_tell() has been removed.
It now comes in two precisions:
  ec_tell() gives 1 bit precision in two operations, and
  ec_tell_frac() gives 1/8th bit precision in... somewhat more.
ec_{enc|dec}_bit_prob() were removed (they are no longer needed).
Some of the byte buffer access functions were made static and
 removed from the cross-module API.
All of the code in rangeenc.c and rangedec.c was merged into
 entenc.c and entdec.c, respectively, as we are no longer
 considering alternative backends.
rangeenc.c and rangede.c have been removed entirely.

This passes make check, after disabling the modes that we removed
 support for in cf5d3a8c.

1 files changed, 27 insertions, 57 deletions

diff --git a/libcelt/entenc.h b/libcelt/entenc.h
index 4840440..49917b5 100644
--- a/libcelt/entenc.h
+++ b/libcelt/entenc.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2001-2008 Timothy B. Terriberry
+/* Copyright (c) 2001-2011 Timothy B. Terriberry
    Copyright (c) 2008-2009 Xiph.Org Foundation */
 /*
    Redistribution and use in source and binary forms, with or without
@@ -36,37 +36,10 @@
 
 
 
-typedef struct ec_enc ec_enc;
-
-
-
-/*The entropy encoder.*/
-struct ec_enc{
-   /*Buffered output.*/
-   ec_byte_buffer *buf;
-   /*A buffered output symbol, awaiting carry propagation.*/
-   int             rem;
-   /*Number of extra carry propagating symbols.*/
-   size_t          ext;
-   /*The number of values in the current range.*/
-   ec_uint32       rng;
-   /*The low end of the current range (inclusive).*/
-   ec_uint32       low;
-   /*Bits that will be written at the end.*/
-   ec_window       end_window;
-   /*Number of valid bits in end_window.*/
-   int             nend_bits;
-   /*The total number of whole bits written.*/
-   int             nbits_total;
-   /*Nonzero if an error occurred.*/
-   int             error;
-};
-
-
 /*Initializes the encoder.
-  _buf: The buffer to store output bytes in.
-        This must have already been initialized for writing and reset.*/
-void ec_enc_init(ec_enc *_this,ec_byte_buffer *_buf);
+  _buf:  The buffer to store output bytes in.
+  _size: The size of the buffer, in chars.*/
+void ec_enc_init(ec_enc *_this,unsigned char *_buf,ec_uint32 _size);
 /*Encodes a symbol given its frequency information.
   The frequency information must be discernable by the decoder, assuming it
    has read only the previous symbols from the stream.
@@ -81,21 +54,9 @@ void ec_enc_init(ec_enc *_this,ec_byte_buffer *_buf);
         decoded value will fall.
   _ft: The sum of the frequencies of all the symbols*/
 void ec_encode(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned _ft);
-void ec_encode_bin(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned _bits);
-/*Encodes a sequence of raw bits in the stream.
-  _fl:  The bits to encode.
-  _ftb: The number of bits to encode.
-        This must be between 0 and 25, inclusive.*/
-void ec_enc_bits(ec_enc *_this,ec_uint32 _fl,unsigned _ftb);
 
-/*Encodes a raw unsigned integer in the stream.
-  _fl: The integer to encode.
-  _ft: The number of integers that can be encoded (one more than the max).
-       This must be at least one, and no more than 2**32-1.*/
-void ec_enc_uint(ec_enc *_this,ec_uint32 _fl,ec_uint32 _ft);
-
-/* Encode a bit that has a _prob/65536 probability of being a one */
-void ec_enc_bit_prob(ec_enc *_this,int val,unsigned _prob);
+/*Equivalent to ec_encode() with _ft==1<<_bits.*/
+void ec_encode_bin(ec_enc *_this,unsigned _fl,unsigned _fh,unsigned _bits);
 
 /* Encode a bit that has a 1/(1<<_logp) probability of being a one */
 void ec_enc_bit_logp(ec_enc *_this,int _val,unsigned _logp);
@@ -109,22 +70,31 @@ void ec_enc_bit_logp(ec_enc *_this,int _val,unsigned _logp);
   _ftb: The number of bits of precision in the cumulative distribution.*/
 void ec_enc_icdf(ec_enc *_this,int _s,const unsigned char *_icdf,unsigned _ftb);
 
-/*Returns the number of bits "used" by the encoded symbols so far.
-  This same number can be computed by the decoder, and is suitable for making
-   coding decisions.
-  _b: The number of extra bits of precision to include.
-      At most 16 will be accurate.
-  Return: The number of bits scaled by 2**_b.
-          This will always be slightly larger than the exact value (e.g., all
-           rounding error is in the positive direction).*/
-ec_uint32 ec_enc_tell(ec_enc *_this,int _b);
+/*Encodes a raw unsigned integer in the stream.
+  _fl: The integer to encode.
+  _ft: The number of integers that can be encoded (one more than the max).
+       This must be at least one, and no more than 2**32-1.*/
+void ec_enc_uint(ec_enc *_this,ec_uint32 _fl,ec_uint32 _ft);
+
+/*Encodes a sequence of raw bits in the stream.
+  _fl:  The bits to encode.
+  _ftb: The number of bits to encode.
+        This must be between 0 and 25, inclusive.*/
+void ec_enc_bits(ec_enc *_this,ec_uint32 _fl,unsigned _ftb);
+
+/*Compacts the data to fit in the target size.
+  This moves up the raw bits at the end of the current buffer so they are at
+   the end of the new buffer size.
+  The caller must ensure that the amount of data that's already been written
+   will fit in the new size.
+  _size: The number of bytes in the new buffer.
+         This must be large enough to contain the bits already written, and
+          must be no larger than the existing size.*/
+void ec_enc_shrink(ec_enc *_this,ec_uint32 _size);
 
 /*Indicates that there are no more symbols to encode.
   All reamining output bytes are flushed to the output buffer.
   ec_enc_init() must be called before the encoder can be used again.*/
 void ec_enc_done(ec_enc *_this);
 
-/*Returns a nonzero value if any error has been detected during encoding*/
-int ec_enc_get_error(ec_enc *_this);
-
 #endif