MIDI.cpp

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#include "MIDI.h"
 
// -----------------------------------------------------------------------------
 
BEGIN_MIDI_NAMESPACE
 
unsigned encodeSysEx(const byte* inData,
                     byte* outSysEx,
                     unsigned inLength,
                     bool inFlipHeaderBits)
{
    unsigned outLength  = 0;     // Num bytes in output array.
    byte count          = 0;     // Num 7bytes in a block.
    outSysEx[0]         = 0;
 
    for (unsigned i = 0; i < inLength; ++i)
    {
        const byte data = inData[i];
        const byte msb  = data >> 7;
        const byte body = data & 0x7f;
 
        outSysEx[0] |= (msb << (inFlipHeaderBits ? count : (6 - count)));
        outSysEx[1 + count] = body;
 
        if (count++ == 6)
        {
            outSysEx   += 8;
            outLength  += 8;
            outSysEx[0] = 0;
            count       = 0;
        }
    }
    return outLength + count + (count != 0 ? 1 : 0);
}
 
unsigned decodeSysEx(const byte* inSysEx,
                     byte* outData,
                     unsigned inLength,
                     bool inFlipHeaderBits)
{
    unsigned count  = 0;
    byte msbStorage = 0;
    byte byteIndex  = 0;
 
    for (unsigned i = 0; i < inLength; ++i)
    {
        if ((i % 8) == 0)
        {
            msbStorage = inSysEx[i];
            byteIndex  = 6;
        }
        else
        {
            const byte body     = inSysEx[i];
            const byte shift    = inFlipHeaderBits ? 6 - byteIndex : byteIndex;
            const byte msb      = byte(((msbStorage >> shift) & 1) << 7);
            byteIndex--;
            outData[count++] = msb | body;
        }
    }
    return count;
}
 
END_MIDI_NAMESPACE