Add tud_midi_n_tx_avaiable interface created for easier flow control

[SukuWc]

Added publicly accessible Tx and Rx available functions to the MIDI class driver. this allow proper flow-control to prevent data loss when using non-peekable tx FIFOs in the application.

Files changed

• src/class/midi/midi_device.h
• src/class/midi/midi_device.c

New interfaces

uint32_t tud_midi_n_tx_available(uint8_t itf);
uint32_t tud_midi_n_rx_available(uint8_t itf);

New inline functions

TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_midi_tx_available(void) {
  return tud_midi_n_tx_available(0);
}

TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_midi_rx_available(void) {
  return tud_midi_n_rx_available(0);
}

[Copilot]

Pull request overview

This PR adds public “available” query APIs to the USB MIDI device class so applications can implement flow control (notably when using non-peekable FIFOs) by checking TX/RX capacity before writing/reading.

Changes:

• Add new multi-interface APIs tud_midi_n_tx_available() and tud_midi_n_rx_available().
• Add single-interface inline wrappers tud_midi_tx_available() / tud_midi_rx_available() for interface 0.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/class/midi/midi_device.h	Declares new public availability APIs and adds single-interface inline wrappers.
src/class/midi/midi_device.c	Implements new availability APIs using endpoint-stream availability helpers.

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