intmath.h

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/*
 *    Copyright (C) 2016-2026 Grok Image Compression Inc.
 *
 *    This source code is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    This source code is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
 
#pragma once
 
#include <cassert>
#include <cstdint>
 
namespace grk
{
template<typename T>
uint32_t ceildiv(T a, T b)
{
  assert(b);
  return (uint32_t)((a + (uint64_t)b - 1) / b);
}
 
template<typename T>
T ceildivpow2(T a, uint8_t b)
{
  return (T)((a + ((uint64_t)1 << b) - 1) >> b);
}

static inline uint32_t floordivpow2(uint32_t a, uint8_t b)
{
  return a >> b;
}

static inline int32_t fix_mul(int32_t a, int32_t b)
{
  int64_t temp = (int64_t)a * (int64_t)b;
  temp += 4096; // round by adding "0.5" in 13-bit fixed point
  assert((temp >> 13) <= (int64_t)0x7FFFFFFF);
  assert((temp >> 13) >= (-(int64_t)0x7FFFFFFF - (int64_t)1));
 
  // return to N-bit precision
  return (int32_t)(temp >> 13);
}

static inline uint8_t floorlog2(uint32_t a)
{
  uint8_t l;
  for(l = 0; a > 1; l++)
  {
    a >>= 1;
  }
  return l;
}
 
} // namespace grk