Calculate total_cells() and frame capacity, and ...

... use it in fountain_chunk_size(). The existing calculation was built
around the 8x8 grid size (9300 bytes).

src/lib/cimb_translator/CimbReader.cpp

@@ -93,7 +93,7 @@ namespace {
 CimbReader::CimbReader(const cv::Mat& img, CimbDecoder& decoder, bool needs_sharpen, bool color_correction)
  : _image(img)
  , _cellSize(Config::cell_size() + 2)
- , _positions(Config::cell_spacing(), Config::num_cells(), Config::cell_offset(), Config::corner_padding())
+ , _positions(Config::cell_spacing(), Config::cells_per_col(), Config::cell_offset(), Config::corner_padding())
  , _decoder(decoder)
  , _good(_image.cols >= Config::image_size() and _image.rows >= Config::image_size())
 {

src/lib/cimb_translator/CimbWriter.cpp

@@ -36,7 +36,7 @@ namespace {
 }
 
 CimbWriter::CimbWriter(unsigned symbol_bits, unsigned color_bits, bool dark, int size)
- : _positions(Config::cell_spacing(), Config::num_cells(), Config::cell_offset(), Config::corner_padding(), Config::interleave_blocks(), Config::interleave_partitions())
+ : _positions(Config::cell_spacing(), Config::cells_per_col(), Config::cell_offset(), Config::corner_padding(), Config::interleave_blocks(), Config::interleave_partitions())
  , _encoder(symbol_bits, color_bits)
 {
  if (size > cimbar::Config::image_size())

src/lib/cimb_translator/Config.cpp

@@ -1,5 +1,6 @@
 /* This code is subject to the terms of the Mozilla Public License, v.2.0. http://mozilla.org/MPL/2.0/. */
 #include "Config.h"
+#include <cmath>
 
 namespace cimbar {
 
@@ -53,11 +54,23 @@ unsigned Config::cell_offset()
  return 9;
 }
 
-unsigned Config::num_cells()
+unsigned Config::cells_per_col()
 {
  return 168;
 }
 
+unsigned Config::total_cells()
+{
+ return std::pow(cells_per_col(), 2) - std::pow(corner_padding(), 2) * 4;
+}
+
+unsigned Config::capacity(unsigned bitspercell)
+{
+ if (!bitspercell)
+ bitspercell = bits_per_cell();
+ return total_cells() * bitspercell / 8;
+}
+
 unsigned Config::corner_padding()
 {
  return 54 / cell_spacing();
@@ -75,15 +88,11 @@ unsigned Config::interleave_partitions()
 
 unsigned Config::fountain_chunk_size(unsigned ecc, unsigned bitspercell)
 {
- // this calculation is based off the 112x112-6 grid.
- // in that grid, we have 155 * bits_per_cell * 10 total bytes of data.
- // so this neatly splits into 10 chunks per frame.
- // ex: 690=6900/10 for ecc=40.
- if (!bitspercell)
- bitspercell = bits_per_cell();
-
+ // TODO: sanity checks?
+ // this should neatly split into fountain_chunks_per_frame() [ex: 10] chunks per frame.
  // the other reasonable settings for fountain_chunks_per_frame are `2` and `5`
- return (155-ecc) * bitspercell * 10 / fountain_chunks_per_frame();
+ const unsigned eccBlockSize = 155;
+ return capacity(bitspercell) * (eccBlockSize-ecc) / eccBlockSize / fountain_chunks_per_frame();
 }
 
 unsigned Config::fountain_chunks_per_frame()

src/lib/cimb_translator/Config.h

@@ -19,7 +19,10 @@ namespace cimbar
  unsigned cell_size();
  unsigned cell_spacing();
  unsigned cell_offset();
- unsigned num_cells();
+ unsigned cells_per_col();
+ unsigned total_cells();
+ unsigned capacity(unsigned bitspercell=0);
+
  unsigned corner_padding();
  unsigned interleave_blocks();
  unsigned interleave_partitions();

src/lib/encoder/Decoder.h

@@ -62,9 +62,9 @@ inline Decoder::Decoder(int ecc_bytes, int color_bits, bool interleave)
 template <typename STREAM>
 inline unsigned Decoder::do_decode(CimbReader& reader, STREAM& ostream)
 {
- bitbuffer bb(13950); // TODO: should vary by _bitsPerOp
+ bitbuffer bb(cimbar::Config::capacity(_bitsPerOp));
  std::vector<unsigned> interleaveLookup = Interleave::interleave_reverse(reader.num_reads(), _interleaveBlocks, _interleavePartitions);
- std::array<PositionData, 27900> colorPositions; // 27900 = the number of cells == reader.num_reads(). Can we calculate this at compile time?
+ std::array<PositionData, 27900> colorPositions; // 27900 = the number of cells == reader.num_reads(). Can we calculate this from config at compile time?
 
  // read symbols first
  while (!reader.done())