USBMIDI_Teensy2.hpp

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#include <AH/Teensy/TeensyUSBTypes.hpp>
 
#include <AH/Containers/Array.hpp>
#include <Settings/NamespaceSettings.hpp>
 
BEGIN_CS_NAMESPACE
 
struct USBDeviceMIDIBackend {
    using MIDIUSBPacket_t = AH::Array<uint8_t, 4>;
    MIDIUSBPacket_t read();
    void write(MIDIUSBPacket_t data);
    void sendNow();
    bool preferImmediateSend();
};
 
END_CS_NAMESPACE
 
#ifdef TEENSY_MIDIUSB_ENABLED
 
#include <usb_private.h>
 
BEGIN_CS_NAMESPACE
 
inline USBDeviceMIDIBackend::MIDIUSBPacket_t USBDeviceMIDIBackend::read() {
    // https://github.com/PaulStoffregen/cores/blob/73ea157600a7082686d9cc48786a73caa7567da9/usb_midi/usb_api.cpp#L195
    uint8_t c, intr_state;
 
    intr_state = SREG;
    cli();
    if (!usb_configuration) {
        SREG = intr_state;
        return MIDIUSBPacket_t{0};
    }
    UENUM = MIDI_RX_ENDPOINT;
retry:
    c = UEINTX;
    if (!(c & (1 << RWAL))) {
        if (c & (1 << RXOUTI)) {
            UEINTX = 0x6B;
            goto retry;
        }
        SREG = intr_state;
        return MIDIUSBPacket_t{0};
    }
    MIDIUSBPacket_t packet;
    packet.data[0] = UEDATX;
    packet.data[1] = UEDATX;
    packet.data[2] = UEDATX;
    packet.data[3] = UEDATX;
    if (!(UEINTX & (1 << RWAL)))
        UEINTX = 0x6B;
    SREG = intr_state;
 
    return packet;
}
 
inline void USBDeviceMIDIBackend::write(MIDIUSBPacket_t data) {
    uint8_t intr_state, timeout;
 
    if (!usb_configuration)
        return;
    intr_state = SREG;
    cli();
    UENUM = MIDI_TX_ENDPOINT;
    timeout = UDFNUML + 2;
    while (1) {
        // are we ready to transmit?
        if (UEINTX & (1 << RWAL))
            break;
        SREG = intr_state;
        if (UDFNUML == timeout)
            return;
        if (!usb_configuration)
            return;
        intr_state = SREG;
        cli();
        UENUM = MIDI_TX_ENDPOINT;
    }
    UEDATX = data.data[0];
    UEDATX = data.data[1];
    UEDATX = data.data[2];
    UEDATX = data.data[3];
    if (!(UEINTX & (1 << RWAL)))
        UEINTX = 0x3A;
    SREG = intr_state;
}
 
inline void USBDeviceMIDIBackend::sendNow() {
    // TODO: I think the UEINTX = 0x3A actually sends/flushes the data, but I'm
    //       not sure, and I don't have the right hardware to test it.
}
 
inline bool USBDeviceMIDIBackend::preferImmediateSend() { return false; }
 
END_CS_NAMESPACE
 
#endif