lib/Simplifier/constantBitP/ConstantBitP_Utility.cpp

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 * BEGIN DATE: Jul 5, 2010
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#include "stp/Simplifier/constantBitP/ConstantBitP_Utility.h"
#include "extlib-constbv/constantbv.h"
#include "stp/Util/Attributes.h"

// Utility functions used by the transfer functions.

using std::vector;

namespace stp
{
typedef unsigned int* CBV;
DLL_PUBLIC ATTR_NORETURN void FatalError(const char* str);
}

namespace simplifier
{
namespace constantBitP
{

using stp::CBV;

// Find ALL the unfixed values in the column and fix it to the specified value.
void fixUnfixedTo(vector<FixedBits*>& operands, const unsigned position,
                  bool toFix)
{
  for (unsigned i = 0; i < operands.size(); i++)
  {
    if (!operands[i]->isFixed(position))
    {
      operands[i]->setFixed(position, true);
      operands[i]->setValue(position, toFix);
    }
  }
}

// counts of how many of each in the column.
stats getStats(const vector<FixedBits*>& operands, const unsigned position)
{
  stats result = {0, 0, 0};

  for (unsigned i = 0, size = operands.size(); i < size; i++)
  {
    if (operands[i]->isFixed(position))
    {
      if (operands[i]->getValue(position)) // fixed to one.
        result.fixedToOne++;
      else
        result.fixedToZero++; // fixed to zero.
    }
    else
      result.unfixed++;
  }

  assert(result.fixedToOne + result.fixedToZero + result.unfixed ==
         operands.size());
  return result;
}

Result makeEqual(FixedBits& a, FixedBits& b, unsigned from, unsigned to)
{
  assert(to >= from);
  assert(from <= a.getWidth());
  assert(from <= b.getWidth());

  Result result = NO_CHANGE;
  for (unsigned i = from; i < to; i++)
  {
    if (a.isFixed(i) && !b.isFixed(i))
    {
      b.setFixed(i, true);
      b.setValue(i, a.getValue(i));
      result = CHANGED;
    }
    else if (b.isFixed(i) && !a.isFixed(i))
    {
      a.setFixed(i, true);
      a.setValue(i, b.getValue(i));
      result = CHANGED;
    }
    else if (b.isFixed(i) && a.isFixed(i))
    {
      if (a.getValue(i) != b.getValue(i))
        return CONFLICT;
    }
  }
  return result;
}

void setSignedMinMax(FixedBits& v, CBV min, CBV max)
{
  const unsigned int msb = v.getWidth() - 1;

  for (unsigned i = 0; i < (unsigned)v.getWidth(); i++)
  {
    if (v.isFixed(i))
    {
      if (v.getValue(i)) // if it's on. It's on.

      {
        CONSTANTBV::BitVector_Bit_On(max, i);
        CONSTANTBV::BitVector_Bit_On(min, i);
      }
      else
      {
        CONSTANTBV::BitVector_Bit_Off(max, i);
        CONSTANTBV::BitVector_Bit_Off(min, i);
      }
    }
    else
    {
      if (i != msb)
      { // not fixed. Make the maximum Maximum.
        CONSTANTBV::BitVector_Bit_On(max, i);
        CONSTANTBV::BitVector_Bit_Off(min, i);
      }
      else
      { // except for the msb. Where we reduce the min.
        CONSTANTBV::BitVector_Bit_On(min, i);
        CONSTANTBV::BitVector_Bit_Off(max, i);
      }
    }
  }
  assert(CONSTANTBV::BitVector_Compare(min, max) <= 0);
}

void setUnsignedMinMax(const FixedBits& v, CBV min, CBV max)
{
  CONSTANTBV::BitVector_Fill(max);
  CONSTANTBV::BitVector_Empty(min);

  for (unsigned i = 0; i < v.getWidth(); i++)
  {
    if (v.isFixed(i))
    {
      if (v.getValue(i)) // if it's on. It's on.

      {
        // CONSTANTBV::BitVector_Bit_On(max, i);
        CONSTANTBV::BitVector_Bit_On(min, i);
      }
      else
      {
        CONSTANTBV::BitVector_Bit_Off(max, i);
        // CONSTANTBV::BitVector_Bit_Off(min, i);
      }
    }
    // else // not fixed. Just set the max.
    //{
    //	CONSTANTBV::BitVector_Bit_On(max, i);
    //	CONSTANTBV::BitVector_Bit_Off(min, i);
    //}
  }
  assert(CONSTANTBV::BitVector_Lexicompare(min, max) <= 0);
}

int unsignedCompare(const stp::CBV& lhs, const stp::CBV& rhs)
{
  /// NB: Uses the memory layout of the constant bit library to extract the
  /// bitwidth.
  // assert(*((unsigned *)&lhs-3) == *((unsigned *)&rhs-3));
  return CONSTANTBV::BitVector_Lexicompare(lhs, rhs);
}

int signedCompare(const stp::CBV& lhs, const stp::CBV& rhs)
{
  /// NB: Uses the memory layout of the constant bit library to extract the
  /// bitwidth.
  // assert(*((unsigned *)&lhs-3) == *((unsigned *)&rhs-3));
  return CONSTANTBV::BitVector_Compare(lhs, rhs);
}

Result merge(Result r1, Result r2)
{
  if (r1 == CONFLICT || r2 == CONFLICT)
    return CONFLICT;

  if (r1 == CHANGED || r2 == CHANGED)
    return CHANGED;

  if (r1 == NO_CHANGE && r2 == NO_CHANGE)
    return NO_CHANGE;

  return NOT_IMPLEMENTED;
}

int toInt(const stp::CBV value)
{
  return *((unsigned int*)value);
}
}
}