4.44 beta

CPP/7zip/Compress/RangeCoder/RangeCoderBit.cpp

@@ -0,0 +1,80 @@
+// Compress/RangeCoder/RangeCoderBit.cpp
+
+#include "StdAfx.h"
+
+#include "RangeCoderBit.h"
+
+namespace NCompress {
+namespace NRangeCoder {
+
+UInt32 CPriceTables::ProbPrices[kBitModelTotal >> kNumMoveReducingBits];
+static CPriceTables g_PriceTables;
+
+CPriceTables::CPriceTables() { Init(); }
+
+void CPriceTables::Init()
+{
+  const int kNumBits = (kNumBitModelTotalBits - kNumMoveReducingBits);
+  for(int i = kNumBits - 1; i >= 0; i--)
+  {
+    UInt32 start = 1 << (kNumBits - i - 1);
+    UInt32 end = 1 << (kNumBits - i);
+    for (UInt32 j = start; j < end; j++)
+      ProbPrices[j] = (i << kNumBitPriceShiftBits) + 
+          (((end - j) << kNumBitPriceShiftBits) >> (kNumBits - i - 1));
+  }
+
+  /*
+  // simplest: bad solution
+  for(UInt32 i = 1; i < (kBitModelTotal >> kNumMoveReducingBits) - 1; i++)
+    ProbPrices[i] = kBitPrice;
+  */
+  
+  /*
+  const double kDummyMultMid = (1.0 / kBitPrice) / 2;
+  const double kDummyMultMid = 0;
+  // float solution
+  double ln2 = log(double(2));
+  double lnAll = log(double(kBitModelTotal >> kNumMoveReducingBits));
+  for(UInt32 i = 1; i < (kBitModelTotal >> kNumMoveReducingBits) - 1; i++)
+    ProbPrices[i] = UInt32((fabs(lnAll - log(double(i))) / ln2 + kDummyMultMid) * kBitPrice);
+  */
+  
+  /*
+  // experimental, slow, solution:
+  for(UInt32 i = 1; i < (kBitModelTotal >> kNumMoveReducingBits) - 1; i++)
+  {
+    const int kCyclesBits = 5;
+    const UInt32 kCycles = (1 << kCyclesBits);
+
+    UInt32 range = UInt32(-1);
+    UInt32 bitCount = 0;
+    for (UInt32 j = 0; j < kCycles; j++)
+    {
+      range >>= (kNumBitModelTotalBits - kNumMoveReducingBits);
+      range *= i;
+      while(range < (1 << 31))
+      {
+        range <<= 1;
+        bitCount++;
+      }
+    }
+    bitCount <<= kNumBitPriceShiftBits;
+    range -= (1 << 31);
+    for (int k = kNumBitPriceShiftBits - 1; k >= 0; k--)
+    {
+      range <<= 1;
+      if (range > (1 << 31))
+      {
+        bitCount += (1 << k);
+        range -= (1 << 31);
+      }
+    }
+    ProbPrices[i] = (bitCount 
+      // + (1 << (kCyclesBits - 1))
+      ) >> kCyclesBits;
+  }
+  */
+}
+
+}}