text: // Copyright 2012 Emilie Gillet.
  //
  // Author: Emilie Gillet (emilie.o.gillet@gmail.com)
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  // 
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  // 
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  // THE SOFTWARE.
  // 
  // See http://creativecommons.org/licenses/MIT/ for more information.
  //
  // -----------------------------------------------------------------------------
  //
  // A set of basic operands, especially useful for fixed-point arithmetic, with
  // fast ASM implementations.
  
  #ifndef STMLIB_UTILS_DSP_H_
  #define STMLIB_UTILS_DSP_H_
  
  #include "stmlib/stmlib.h"
  
  namespace stmlib {
  
  inline int16_t Interpolate824(const int16_t* table, uint32_t phase)
    __attribute__((always_inline));
  
  inline uint16_t Interpolate824(const uint16_t* table, uint32_t phase)
    __attribute__((always_inline));
  
  inline int16_t Interpolate824(const uint8_t* table, uint32_t phase)
    __attribute__((always_inline));
  
  inline uint16_t Interpolate88(const uint16_t* table, uint16_t index)
    __attribute__((always_inline));
  
  inline int16_t Interpolate88(const int16_t* table, uint16_t index)
    __attribute__((always_inline));
  
  inline int16_t Interpolate1022(const int16_t* table, uint32_t phase)
    __attribute__((always_inline));
  
  inline int16_t Interpolate115(const int16_t* table, uint32_t phase)
    __attribute__((always_inline));
  
  inline int16_t Crossfade(
      const int16_t* table_a,
      const int16_t* table_b,
      uint32_t phase,
      uint16_t balance)
    __attribute__((always_inline));
  
  inline int16_t Crossfade(
      const uint8_t* table_a,
      const uint8_t* table_b,
      uint32_t phase,
      uint16_t balance)
    __attribute__((always_inline));
  
  inline int16_t Crossfade1022(
      const uint8_t* table_a,
      const uint8_t* table_b,
      uint32_t phase,
      uint16_t balance)
    __attribute__((always_inline));
  
  inline int16_t Crossfade115(
      const uint8_t* table_a,
      const uint8_t* table_b,
      uint16_t phase,
      uint16_t balance)
    __attribute__((always_inline));
  
  inline int16_t Mix(int16_t a, int16_t b, uint16_t balance) {
    return (a * (65535 - balance) + b * balance) >> 16;
  }
  
  inline uint16_t Mix(uint16_t a, uint16_t b, uint16_t balance) {
    return (a * (65535 - balance) + b * balance) >> 16;
  }
  
  inline int16_t Interpolate824(const int16_t* table, uint32_t phase) {
    int32_t a = table[phase >> 24];
    int32_t b = table[(phase >> 24) + 1];
    return a + ((b - a) * static_cast<int32_t>((phase >> 8) & 0xffff) >> 16);
  }
  
  inline uint16_t Interpolate824(const uint16_t* table, uint32_t phase) {
    uint32_t a = table[phase >> 24];
    uint32_t b = table[(phase >> 24) + 1];
    return a + ((b - a) * static_cast<uint32_t>((phase >> 8) & 0xffff) >> 16);
  }
  
  inline int16_t Interpolate824(const uint8_t* table, uint32_t phase) {
    int32_t a = table[phase >> 24];
    int32_t b = table[(phase >> 24) + 1];
    return (a << 8) + \
        ((b - a) * static_cast<int32_t>(phase & 0xffffff) >> 16) - 32768;
  }
  
  inline uint16_t Interpolate88(const uint16_t* table, uint16_t index) {
    int32_t a = table[index >> 8];
    int32_t b = table[(index >> 8) + 1];
    return a + ((b - a) * static_cast<int32_t>(index & 0xff) >> 8);
  }
  
  inline int16_t Interpolate88(const int16_t* table, uint16_t index) {
    int32_t a = table[index >> 8];
    int32_t b = table[(index >> 8) + 1];
    return a + ((b - a) * static_cast<int32_t>(index & 0xff) >> 8);
  }
  
  inline int16_t Interpolate1022(const int16_t* table, uint32_t phase) {
    int32_t a = table[phase >> 22];
    int32_t b = table[(phase >> 22) + 1];
    return a + ((b - a) * static_cast<int32_t>((phase >> 6) & 0xffff) >> 16);
  }
  
  inline int16_t Interpolate115(const int16_t* table, uint16_t phase) {
    int32_t a = table[phase >> 5];
    int32_t b = table[(phase >> 5) + 1];
    return a + ((b - a) * static_cast<int32_t>(phase & 0x1f) >> 5);
  }
  
  inline int16_t Crossfade(
      const int16_t* table_a,
      const int16_t* table_b,
      uint32_t phase,
      uint16_t balance) {
    int32_t a = Interpolate824(table_a, phase);
    int32_t b = Interpolate824(table_b, phase);
    return a + ((b - a) * static_cast<int32_t>(balance) >> 16);
  }
  
  inline int16_t Crossfade(
      const uint8_t* table_a,
      const uint8_t* table_b,
      uint32_t phase,
      uint16_t balance) {
    int32_t a = Interpolate824(table_a, phase);
    int32_t b = Interpolate824(table_b, phase);
    return a + ((b - a) * static_cast<int32_t>(balance) >> 16);
  }
  
  inline int16_t Crossfade1022(
      const int16_t* table_a,
      const int16_t* table_b,
      uint32_t phase,
      uint16_t balance) {
    int32_t a = Interpolate1022(table_a, phase);
    int32_t b = Interpolate1022(table_b, phase);
    return a + ((b - a) * static_cast<int32_t>(balance) >> 16);
  }
  
  inline int16_t Crossfade115(
      const int16_t* table_a,
      const int16_t* table_b,
      uint16_t phase,
      uint16_t balance) {
    int32_t a = Interpolate115(table_a, phase);
    int32_t b = Interpolate115(table_b, phase);
    return a + ((b - a) * static_cast<int32_t>(balance) >> 16);
  }
  
  }  // namespace stmlib
  
  #endif  // STMLIB_UTILS_DSP_H_