Line data    Source code

       1             : #pragma once
       2             : 
       3             : #include <Control_Surface/Control_Surface_Class.hpp>
       4             : 
       5             : #include <Arduino.h> // for constrain
       6             : 
       7             : BEGIN_CS_NAMESPACE
       8             : 
       9             : /// The encoding to use for relative control change value.
      10             : enum relativeCCmode {
      11             :     /**
      12             :      * @brief    Encode negative MIDI CC values as 7-bit two's complement.
      13             :      *
      14             :      * | Encoded  | Value | 
      15             :      * |---------:|------:|
      16             :      * | 000'0000 | 0     |
      17             :      * | 000'0001 | +1    |
      18             :      * | 011'1111 | +63   |
      19             :      * | 100'0000 | -64   |
      20             :      * | 100'0001 | -63   |
      21             :      * | 111'1111 | -1    |
      22             :      */
      23             :     TWOS_COMPLEMENT,
      24             :     /** 
      25             :      * @brief   Encode negative MIDI CC values by adding a fixed offset of 
      26             :      *          @f$ 2^6 = 64 @f$.
      27             :      *
      28             :      * | Encoded  | Value | 
      29             :      * |---------:|------:|
      30             :      * | 000'0000 | -64   |
      31             :      * | 000'0001 | -63   |
      32             :      * | 011'1111 | -1    |
      33             :      * | 100'0000 | 0     |
      34             :      * | 100'0001 | +1    |
      35             :      * | 111'1111 | +63   |
      36             :      */
      37             :     BINARY_OFFSET,
      38             :     /**
      39             :      * @brief   Encode negative MIDI CC values by using the most significant bit
      40             :      *          as a sign bit, and the six least significant bits as the 
      41             :      *          absolute value.
      42             :      *
      43             :      * | Encoded  | Value | 
      44             :      * |---------:|------:|
      45             :      * | 000'0000 | +0    |
      46             :      * | 000'0001 | 1     |
      47             :      * | 011'1111 | 63    |
      48             :      * | 100'0000 | -0    |
      49             :      * | 100'0001 | -1    |
      50             :      * | 111'1111 | -63   |
      51             :      */
      52             :     SIGN_MAGNITUDE,
      53             :     /// First relative mode in Reaper.
      54             :     REAPER_RELATIVE_1 = TWOS_COMPLEMENT,
      55             :     /// Second relative mode in Reaper.
      56             :     REAPER_RELATIVE_2 = BINARY_OFFSET,
      57             :     /// Third relative mode in Reaper.
      58             :     REAPER_RELATIVE_3 = SIGN_MAGNITUDE,
      59             :     /// Relative mode in Tracktion.
      60             :     TRACKTION_RELATIVE = TWOS_COMPLEMENT,
      61             :     /// Relative mode used by the Mackie Control Universal protocol.
      62             :     MACKIE_CONTROL_RELATIVE = SIGN_MAGNITUDE,
      63             : };
      64             : 
      65             : class RelativeCCSender {
      66             :   public:
      67             :     /** Convert an 8-bit two's complement integer to a 7-bit two's complement
      68             :      *  integer. */
      69          18 :     static uint8_t toTwosComplement7bit(int8_t value) { return value & 0x7F; }
      70             :     /** Convert an 8-bit two's complement integer to a 7-bit integer with a
      71             :      *  binary offset of 64. In other words, a value of 0 corresponds to -64,
      72             :      *  a value of 64 corresponds to 0, and a value of 127 corresponds to 63. */
      73           9 :     static uint8_t toBinaryOffset7bit(int8_t value) { return value + 64; }
      74             :     /** Convert an 8-bit two's complement integer to 7-bit sign-magnitude
      75             :      *  format. */
      76           8 :     static uint8_t toSignedMagnitude7bit(int8_t value) {
      77           8 :         uint8_t mask = value >> 7;
      78           8 :         uint8_t abs = (value + mask) ^ mask;
      79           8 :         uint8_t sign = mask & 0b01000000;
      80           8 :         return (abs & 0b00111111) | sign;
      81             :     }
      82             :     /** Convert an 8-bit two's complement integer to a 7-bit value to send over
      83             :      *  MIDI. */
      84          35 :     static uint8_t mapRelativeCC(int8_t value) {
      85          35 :         switch (mode) {
      86          18 :             case TWOS_COMPLEMENT: return toTwosComplement7bit(value);
      87           9 :             case BINARY_OFFSET: return toBinaryOffset7bit(value);
      88           8 :             case SIGN_MAGNITUDE: return toSignedMagnitude7bit(value);
      89           0 :             default: return 0; // Keeps the compiler happy
      90             :         }
      91          35 :     }
      92             : 
      93          10 :     static void send(long delta, MIDICNChannelAddress address) {
      94          28 :         while (delta != 0) {
      95             :             // Constrain relative movement to +/-15 for
      96             :             // Mackie Control Universal compatibility
      97          18 :             long thisDelta = constrain(delta, -15, 15);
      98          18 :             uint8_t msgVal = mapRelativeCC(thisDelta);
      99             :             // send a Control Change MIDI event
     100          18 :             Control_Surface.MIDI().sendCC(address, msgVal);
     101          18 :             delta -= thisDelta;
     102             :         }
     103          10 :     }
     104             : 
     105          13 :     static void setMode(relativeCCmode mode) { RelativeCCSender::mode = mode; }
     106             : 
     107             :   private:
     108             :     static relativeCCmode mode;
     109             : };
     110             : 
     111             : END_CS_NAMESPACE