Add MIDI host support to tinyusb

1 files changed, 944 insertions, 0 deletions

diff --git a/src/class/midi/midi_host.c b/src/class/midi/midi_host.c
new file mode 100644
index 000000000..e482f5265
--- /dev/null
+++ b/src/class/midi/midi_host.c
@@ -0,0 +1,944 @@
+/* 
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Ha Thach (tinyusb.org)
+ *
+ * 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.
+ *
+ * This file is part of the TinyUSB stack.
+ */
+
+#include "tusb_option.h"
+
+#if (TUSB_OPT_HOST_ENABLED && CFG_TUH_MIDI)
+
+#include "host/usbh.h"
+#include "host/usbh_classdriver.h"
+
+#include "midi_host.h"
+
+//--------------------------------------------------------------------+
+// MACRO CONSTANT TYPEDEF
+//--------------------------------------------------------------------+
+#ifndef CFG_TUH_MAX_CABLES
+  #define CFG_TUH_MAX_CABLES 16
+#endif
+#define CFG_TUH_MIDI_RX_BUFSIZE 64
+#define CFG_TUH_MIDI_TX_BUFSIZE 64
+#ifndef CFG_TUH_MIDI_EP_BUFSIZE
+  #define CFG_TUH_MIDI_EP_BUFSIZE 64
+#endif
+
+// TODO: refactor to share code with the MIDI Device driver
+typedef struct
+{
+  uint8_t buffer[4];
+  uint8_t index;
+  uint8_t total;
+}midi_stream_t;
+
+typedef struct
+{
+  uint8_t dev_addr;
+  uint8_t itf_num;
+
+  uint8_t ep_in;          // IN endpoint address
+  uint8_t ep_out;         // OUT endpoint address
+  uint16_t ep_in_max;     // min( CFG_TUH_MIDI_RX_BUFSIZE, wMaxPacketSize of the IN endpoint)
+  uint16_t ep_out_max;    //  min( CFG_TUH_MIDI_TX_BUFSIZE, wMaxPacketSize of the OUT endpoint)
+
+  uint8_t num_cables_rx;  // IN endpoint CS descriptor bNumEmbMIDIJack value
+  uint8_t num_cables_tx;  // OUT endpoint CS descriptor bNumEmbMIDIJack value
+
+  // For Stream read()/write() API
+  // Messages are always 4 bytes long, queue them for reading and writing so the
+  // callers can use the Stream interface with single-byte read/write calls.
+  midi_stream_t stream_write;
+  midi_stream_t stream_read;
+
+  /*------------- From this point, data is not cleared by bus reset -------------*/
+  // Endpoint FIFOs
+  tu_fifo_t rx_ff;
+  tu_fifo_t tx_ff;
+ 
+
+  uint8_t rx_ff_buf[CFG_TUH_MIDI_RX_BUFSIZE];
+  uint8_t tx_ff_buf[CFG_TUH_MIDI_TX_BUFSIZE];
+
+  #if CFG_FIFO_MUTEX
+  osal_mutex_def_t rx_ff_mutex;
+  osal_mutex_def_t tx_ff_mutex;
+  #endif
+
+  // Endpoint Transfer buffer
+  CFG_TUSB_MEM_ALIGN uint8_t epout_buf[CFG_TUH_MIDI_EP_BUFSIZE];
+  CFG_TUSB_MEM_ALIGN uint8_t epin_buf[CFG_TUH_MIDI_EP_BUFSIZE];
+
+  bool configured;
+
+#if CFG_MIDI_HOST_DEVSTRINGS
+#define MAX_STRING_INDICES 32
+  uint8_t all_string_indices[MAX_STRING_INDICES];
+  uint8_t num_string_indices;
+#define MAX_IN_JACKS 8
+#define MAX_OUT_JACKS 8
+  struct {
+    uint8_t jack_id;
+    int8_t jack_type;
+    uint8_t string_index;
+  } in_jack_info[MAX_IN_JACKS];
+  uint8_t next_in_jack;
+  struct {
+    uint8_t jack_id;
+    uint8_t jack_type;
+    uint8_t num_source_ids;
+    uint8_t source_ids[MAX_IN_JACKS/4];
+    uint8_t string_index;
+  } out_jack_info[MAX_OUT_JACKS];
+  uint8_t next_out_jack;
+  uint8_t ep_in_associated_jacks[MAX_OUT_JACKS/2];
+  uint8_t ep_out_associated_jacks[MAX_IN_JACKS/2];
+#endif
+}midih_interface_t;
+
+static midih_interface_t _midi_host[CFG_TUH_DEVICE_MAX];
+
+static midih_interface_t *get_midi_host(uint8_t dev_addr)
+{
+  TU_VERIFY(dev_addr >0 && dev_addr <= CFG_TUH_DEVICE_MAX);
+  return (_midi_host + dev_addr - 1);
+}
+
+//------------- Internal prototypes -------------//
+static uint32_t write_flush(uint8_t dev_addr, midih_interface_t* midi);
+
+//--------------------------------------------------------------------+
+// USBH API
+//--------------------------------------------------------------------+
+void midih_init(void)
+{
+  tu_memclr(&_midi_host, sizeof(_midi_host));
+  // config fifos
+  for (int inst = 0; inst < CFG_TUH_DEVICE_MAX; inst++)
+  {
+    midih_interface_t *p_midi_host = &_midi_host[inst];
+    tu_fifo_config(&p_midi_host->rx_ff, p_midi_host->rx_ff_buf, CFG_TUH_MIDI_RX_BUFSIZE, 1, false); // true, true
+    tu_fifo_config(&p_midi_host->tx_ff, p_midi_host->tx_ff_buf, CFG_TUH_MIDI_TX_BUFSIZE, 1, false); // OBVS.
+
+  #if CFG_FIFO_MUTEX
+    tu_fifo_config_mutex(&p_midi_host->rx_ff, NULL, osal_mutex_create(&p_midi_host->rx_ff_mutex));
+    tu_fifo_config_mutex(&p_midi_host->tx_ff, osal_mutex_create(&p_midi_host->tx_ff_mutex), NULL);
+  #endif
+  }
+}
+
+bool midih_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes)
+{
+  (void)result;
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  if ( ep_addr == p_midi_host->ep_in)
+  {
+    if (0 == xferred_bytes)
+    {
+      return true; // No data to handle
+    }
+
+    // receive new data if available
+    uint32_t packets_queued = 0;
+    if (xferred_bytes)
+    {
+      // put in the RX FIFO only non-zero MIDI IN 4-byte packets
+      uint8_t* buf = p_midi_host->epin_buf;
+      uint32_t npackets = xferred_bytes / 4;
+      uint32_t packet_num;
+      for (packet_num = 0; packet_num < npackets; packet_num++)
+      {
+        // some devices send back all zero packets even if there is no data ready
+        uint32_t packet = (uint32_t)((*buf)<<24) | ((uint32_t)(*(buf+1))<<16) | ((uint32_t)(*(buf+2))<<8) | ((uint32_t)(*(buf+3)));
+        if (packet != 0)
+        {
+          tu_fifo_write_n(&p_midi_host->rx_ff, buf, 4);
+          ++packets_queued;
+          TU_LOG3("MIDI RX=%08x\r\n", packet);
+        }
+        buf += 4;
+      }
+    }
+    // invoke receive callback if available
+    if (tuh_midi_rx_cb)
+    {
+      tuh_midi_rx_cb(dev_addr, packets_queued);
+    }
+  }
+  else if ( ep_addr == p_midi_host->ep_out )
+  {
+    if (0 == write_flush(dev_addr, p_midi_host))
+    {
+      // If there is no data left, a ZLP should be sent if
+      // xferred_bytes is multiple of EP size and not zero
+      if ( !tu_fifo_count(&p_midi_host->tx_ff) && xferred_bytes && (0 == (xferred_bytes % p_midi_host->ep_out_max)) )
+      {
+        if ( usbh_edpt_claim(dev_addr, p_midi_host->ep_out) )
+        {
+          TU_ASSERT(usbh_edpt_xfer(dev_addr, p_midi_host->ep_out, XFER_RESULT_SUCCESS, 0));
+        }
+      }
+    }
+    if (tuh_midi_tx_cb)
+    {
+      tuh_midi_tx_cb(dev_addr);
+    }
+  }
+
+  return true;
+}
+
+void midih_close(uint8_t dev_addr)
+{
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  if (p_midi_host == NULL)
+    return;
+  if (tuh_midi_umount_cb)
+    tuh_midi_umount_cb(dev_addr, 0);
+  tu_fifo_clear(&p_midi_host->rx_ff);
+  tu_fifo_clear(&p_midi_host->tx_ff);
+  p_midi_host->ep_in = 0;
+  p_midi_host->ep_in_max = 0;
+  p_midi_host->ep_out = 0;
+  p_midi_host->ep_out_max = 0;
+  p_midi_host->itf_num = 0;
+  p_midi_host->num_cables_rx = 0;
+  p_midi_host->num_cables_tx = 0;
+  p_midi_host->dev_addr = 255; // invalid
+  p_midi_host->configured = false;
+  tu_memclr(&p_midi_host->stream_read, sizeof(p_midi_host->stream_read));
+  tu_memclr(&p_midi_host->stream_write, sizeof(p_midi_host->stream_write));
+}
+
+//--------------------------------------------------------------------+
+// Enumeration
+//--------------------------------------------------------------------+
+bool midih_open(uint8_t rhport, uint8_t dev_addr, tusb_desc_interface_t const *desc_itf, uint16_t max_len)
+{
+  (void) rhport;
+
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+
+  TU_VERIFY(p_midi_host != NULL);
+  p_midi_host->num_string_indices = 0;
+  TU_VERIFY(TUSB_CLASS_AUDIO == desc_itf->bInterfaceClass);
+  // There can be just a MIDI interface or an audio and a MIDI interface. Only open the MIDI interface
+  uint8_t const *p_desc = (uint8_t const *) desc_itf;
+  uint16_t len_parsed = 0;
+  if (AUDIO_SUBCLASS_CONTROL == desc_itf->bInterfaceSubClass)
+  {
+    // Keep track of any string descriptor that might be here
+    if (desc_itf->iInterface != 0)
+        p_midi_host->all_string_indices[p_midi_host->num_string_indices++] = desc_itf->iInterface;
+    // This driver does not support audio streaming. However, if this is the audio control interface
+    // there might be a MIDI interface following it. Search through every descriptor until a MIDI
+    // interface is found or the end of the descriptor is found
+    while (len_parsed < max_len && (desc_itf->bInterfaceClass != TUSB_CLASS_AUDIO || desc_itf->bInterfaceSubClass != AUDIO_SUBCLASS_MIDI_STREAMING))
+    {
+      len_parsed += desc_itf->bLength;
+      p_desc = tu_desc_next(p_desc);
+      desc_itf = (tusb_desc_interface_t const *)p_desc;
+    }
+
+    TU_VERIFY(TUSB_CLASS_AUDIO == desc_itf->bInterfaceClass);
+  }
+  TU_VERIFY(AUDIO_SUBCLASS_MIDI_STREAMING == desc_itf->bInterfaceSubClass);
+  len_parsed += desc_itf->bLength;
+
+  // Keep track of any string descriptor that might be here
+  if (desc_itf->iInterface != 0)
+      p_midi_host->all_string_indices[p_midi_host->num_string_indices++] = desc_itf->iInterface;
+
+  p_desc = tu_desc_next(p_desc);
+  TU_LOG1("MIDI opening Interface %u (addr = %u)\r\n", desc_itf->bInterfaceNumber, dev_addr);
+  // Find out if getting the MIDI class specific interface header or an endpoint descriptor
+  // or a class-specific endpoint descriptor
+  // Jack descriptors or element descriptors must follow the cs interface header,
+  // but this driver does not support devices that contain element descriptors
+
+  // assume it is an interface header
+  midi_desc_header_t const *p_mdh = (midi_desc_header_t const *)p_desc;
+  TU_VERIFY((p_mdh->bDescriptorType == TUSB_DESC_CS_INTERFACE && p_mdh->bDescriptorSubType == MIDI_CS_INTERFACE_HEADER) || 
+    (p_mdh->bDescriptorType == TUSB_DESC_CS_ENDPOINT && p_mdh->bDescriptorSubType == MIDI_CS_ENDPOINT_GENERAL) ||
+    p_mdh->bDescriptorType == TUSB_DESC_ENDPOINT);
+
+  uint8_t prev_ep_addr = 0; // the CS endpoint descriptor is associated with the previous endpoint descrptor
+  p_midi_host->itf_num = desc_itf->bInterfaceNumber;
+  tusb_desc_endpoint_t const* in_desc = NULL;
+  tusb_desc_endpoint_t const* out_desc = NULL;
+  while (len_parsed < max_len)
+  {
+    TU_VERIFY((p_mdh->bDescriptorType == TUSB_DESC_CS_INTERFACE) || 
+      (p_mdh->bDescriptorType == TUSB_DESC_CS_ENDPOINT && p_mdh->bDescriptorSubType == MIDI_CS_ENDPOINT_GENERAL) ||
+      p_mdh->bDescriptorType == TUSB_DESC_ENDPOINT);
+
+    if (p_mdh->bDescriptorType == TUSB_DESC_CS_INTERFACE) {
+      // The USB host doesn't really need this information unless it uses
+      // the string descriptor for a jack or Element
+
+      // assume it is an input jack
+      midi_desc_in_jack_t const *p_mdij = (midi_desc_in_jack_t const *)p_desc;
+      if (p_mdij->bDescriptorSubType == MIDI_CS_INTERFACE_HEADER)
+      {
+        TU_LOG2("Found MIDI Interface Header\r\b");
+      }
+      else if (p_mdij->bDescriptorSubType == MIDI_CS_INTERFACE_IN_JACK)
+      {
+        // Then it is an in jack. 
+        TU_LOG2("Found in jack\r\n");
+#if CFG_MIDI_HOST_DEVSTRINGS
+        if (p_midi_host->next_in_jack < MAX_IN_JACKS)
+        {
+          p_midi_host->in_jack_info[p_midi_host->next_in_jack].jack_id = p_mdij->bJackID;
+          p_midi_host->in_jack_info[p_midi_host->next_in_jack].jack_type = p_mdij->bJackType;
+          p_midi_host->in_jack_info[p_midi_host->next_in_jack].string_index = p_mdij->iJack;
+          ++p_midi_host->next_in_jack;
+          // Keep track of any string descriptor that might be here
+          if (p_mdij->iJack != 0)
+            p_midi_host->all_string_indices[p_midi_host->num_string_indices++] = p_mdij->iJack;
+
+        }
+#endif
+      }
+      else if (p_mdij->bDescriptorSubType == MIDI_CS_INTERFACE_OUT_JACK)
+      {
+        // then it is an out jack
+        TU_LOG2("Found out jack\r\n");
+#if CFG_MIDI_HOST_DEVSTRINGS
+        if (p_midi_host->next_out_jack < MAX_OUT_JACKS)
+        {
+          midi_desc_out_jack_t const *p_mdoj = (midi_desc_out_jack_t const *)p_desc;
+          p_midi_host->out_jack_info[p_midi_host->next_out_jack].jack_id = p_mdoj->bJackID;
+          p_midi_host->out_jack_info[p_midi_host->next_out_jack].jack_type = p_mdoj->bJackType;
+          p_midi_host->out_jack_info[p_midi_host->next_out_jack].num_source_ids = p_mdoj->bNrInputPins;
+          struct associated_jack_s {
+              uint8_t id;
+              uint8_t pin;
+          } *associated_jack = (struct associated_jack_s *)(p_desc+6);
+          int jack;
+          for (jack = 0; jack < p_mdoj->bNrInputPins; jack++)
+          {
+            p_midi_host->out_jack_info[p_midi_host->next_out_jack].source_ids[jack] = associated_jack->id;
+          }
+          p_midi_host->out_jack_info[p_midi_host->next_out_jack].string_index = *(p_desc+6+p_mdoj->bNrInputPins*2);
+          ++p_midi_host->next_out_jack;
+          if (p_mdoj->iJack != 0)
+            p_midi_host->all_string_indices[p_midi_host->num_string_indices++] = p_mdoj->iJack;
+        }
+#endif
+      }
+      else if (p_mdij->bDescriptorSubType == MIDI_CS_INTERFACE_ELEMENT)
+      {
+        // the it is an element;
+    #if CFG_MIDI_HOST_DEVSTRINGS
+        TU_LOG1("Found element; strings not supported\r\n");
+    #else
+        TU_LOG2("Found element\r\n");
+    #endif
+      }
+      else
+      {
+        TU_LOG2("Unknown CS Interface sub-type %u\r\n", p_mdij->bDescriptorSubType);
+        TU_VERIFY(false); // unknown CS Interface sub-type
+      }
+      len_parsed += p_mdij->bLength;
+    }
+    else if (p_mdh->bDescriptorType == TUSB_DESC_CS_ENDPOINT)
+    {
+      TU_LOG2("found CS_ENDPOINT Descriptor for %u\r\n", prev_ep_addr);
+      TU_VERIFY(prev_ep_addr != 0);
+      // parse out the mapping between the device's embedded jacks and the endpoints
+      // Each embedded IN jack is assocated with an OUT endpoint
+      midi_cs_desc_endpoint_t const* p_csep = (midi_cs_desc_endpoint_t const*)p_mdh;
+      if (tu_edpt_dir(prev_ep_addr) == TUSB_DIR_OUT)
+      {
+        TU_VERIFY(p_midi_host->ep_out == prev_ep_addr);
+        TU_VERIFY(p_midi_host->num_cables_tx == 0);
+        p_midi_host->num_cables_tx = p_csep->bNumEmbMIDIJack;
+#if CFG_MIDI_HOST_DEVSTRINGS
+        uint8_t jack;
+        uint8_t max_jack = p_midi_host->num_cables_tx;
+        if (max_jack > sizeof(p_midi_host->ep_out_associated_jacks))
+        {
+            max_jack = sizeof(p_midi_host->ep_out_associated_jacks);
+        }
+        for (jack = 0; jack < max_jack; jack++)
+        {
+          p_midi_host->ep_out_associated_jacks[jack] = p_csep->baAssocJackID[jack];
+        }
+#endif
+      }
+      else
+      {
+        TU_VERIFY(p_midi_host->ep_in == prev_ep_addr);
+        TU_VERIFY(p_midi_host->num_cables_rx == 0);
+        p_midi_host->num_cables_rx = p_csep->bNumEmbMIDIJack;
+#if CFG_MIDI_HOST_DEVSTRINGS
+        uint8_t jack;
+        uint8_t max_jack = p_midi_host->num_cables_rx;
+        if (max_jack > sizeof(p_midi_host->ep_in_associated_jacks))
+        {
+            max_jack = sizeof(p_midi_host->ep_in_associated_jacks);
+        }
+        for (jack = 0; jack < max_jack; jack++)
+        {
+          p_midi_host->ep_in_associated_jacks[jack] = p_csep->baAssocJackID[jack];
+        }
+#endif
+      }
+      len_parsed += p_csep->bLength;
+      prev_ep_addr = 0;
+    }
+    else if (p_mdh->bDescriptorType == TUSB_DESC_ENDPOINT) {
+      // parse out the bulk endpoint info
+      tusb_desc_endpoint_t const *p_ep = (tusb_desc_endpoint_t const *)p_mdh;
+      TU_LOG2("found ENDPOINT Descriptor for %u\r\n", p_ep->bEndpointAddress);
+      if (tu_edpt_dir(p_ep->bEndpointAddress) == TUSB_DIR_OUT)
+      {
+        TU_VERIFY(p_midi_host->ep_out == 0);
+        TU_VERIFY(p_midi_host->num_cables_tx == 0);
+        p_midi_host->ep_out = p_ep->bEndpointAddress;
+        p_midi_host->ep_out_max = p_ep->wMaxPacketSize;
+        if (p_midi_host->ep_out_max > CFG_TUH_MIDI_TX_BUFSIZE)
+          p_midi_host->ep_out_max = CFG_TUH_MIDI_TX_BUFSIZE;
+        prev_ep_addr = p_midi_host->ep_out;
+        out_desc = p_ep;
+      }
+      else
+      {
+        TU_VERIFY(p_midi_host->ep_in == 0);
+        TU_VERIFY(p_midi_host->num_cables_rx == 0);
+        p_midi_host->ep_in = p_ep->bEndpointAddress;
+        p_midi_host->ep_in_max = p_ep->wMaxPacketSize;
+        if (p_midi_host->ep_in_max > CFG_TUH_MIDI_RX_BUFSIZE)
+          p_midi_host->ep_in_max = CFG_TUH_MIDI_RX_BUFSIZE;
+        prev_ep_addr = p_midi_host->ep_in;
+        in_desc = p_ep;
+      }
+      len_parsed += p_mdh->bLength;
+    }
+    p_desc = tu_desc_next(p_desc);
+    p_mdh = (midi_desc_header_t const *)p_desc;
+  }
+  TU_VERIFY((p_midi_host->ep_out != 0 && p_midi_host->num_cables_tx != 0) ||
+            (p_midi_host->ep_in != 0 && p_midi_host->num_cables_rx != 0));
+  TU_LOG1("MIDI descriptor parsed successfully\r\n");
+  // remove duplicate string indices
+  for (int idx=0; idx < p_midi_host->num_string_indices; idx++) {
+      for (int jdx = idx+1; jdx < p_midi_host->num_string_indices; jdx++) {
+          while (jdx < p_midi_host->num_string_indices &&  p_midi_host->all_string_indices[idx] == p_midi_host->all_string_indices[jdx]) {
+              // delete the duplicate by overwriting it with the last entry and reducing the number of entries by 1
+              p_midi_host->all_string_indices[jdx] = p_midi_host->all_string_indices[p_midi_host->num_string_indices-1];
+              --p_midi_host->num_string_indices;
+          }
+      }
+  }
+  if (in_desc)
+  {
+    TU_ASSERT(tuh_edpt_open(dev_addr, in_desc));
+    // Some devices always return exactly the request length so transfers won't complete
+    // unless you assume every transfer is the last one.
+    // TODO usbh_edpt_force_last_buffer(dev_addr, p_midi_host->ep_in, true);
+  }
+  if (out_desc)
+  {
+    TU_ASSERT(tuh_edpt_open(dev_addr, out_desc));
+  }
+  p_midi_host->dev_addr = dev_addr;
+
+  if (tuh_midi_mount_cb)
+  {
+    tuh_midi_mount_cb(dev_addr, p_midi_host->ep_in, p_midi_host->ep_out, p_midi_host->num_cables_rx, p_midi_host->num_cables_tx);
+  }
+  return true;
+}
+
+bool tuh_midi_configured(uint8_t dev_addr)
+{
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  return p_midi_host->configured;
+}
+
+bool midih_set_config(uint8_t dev_addr, uint8_t itf_num)
+{
+  (void) itf_num;
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  p_midi_host->configured = true;
+
+  // TODO I don't think there are any special config things to do for MIDI
+
+  return true;
+}
+
+//--------------------------------------------------------------------+
+// Stream API
+//--------------------------------------------------------------------+
+static uint32_t write_flush(uint8_t dev_addr, midih_interface_t* midi)
+{
+  // No data to send
+  if ( !tu_fifo_count(&midi->tx_ff) ) return 0;
+
+  // skip if previous transfer not complete
+  TU_VERIFY( usbh_edpt_claim(dev_addr, midi->ep_out) );
+
+  uint16_t count = tu_fifo_read_n(&midi->tx_ff, midi->epout_buf, midi->ep_out_max);
+
+  if (count)
+  {
+    TU_ASSERT( usbh_edpt_xfer(dev_addr, midi->ep_out, midi->epout_buf, count), 0 );
+    return count;
+  }else
+  {
+    // Release endpoint since we don't make any transfer
+    usbh_edpt_release(dev_addr, midi->ep_out);
+    return 0;
+  }
+}
+
+bool tuh_midi_read_poll( uint8_t dev_addr )
+{
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  bool result = false;
+
+  bool in_edpt_not_busy = !usbh_edpt_busy(dev_addr, p_midi_host->ep_in);
+  if (in_edpt_not_busy)
+  {
+    TU_LOG2("Requesting poll IN endpoint %d\r\n", p_midi_host->ep_in);
+    TU_ASSERT(usbh_edpt_xfer(p_midi_host->dev_addr, p_midi_host->ep_in, _midi_host->epin_buf, _midi_host->ep_in_max), 0);
+    result = true;
+  }
+  else
+  {
+    // Maybe the IN endpoint is only busy because the RP2040 host hardware
+    // is retrying a NAK'd IN transfer forever. Try aborting the NAK'd
+    // transfer to allow other transfers to happen on the one shared
+    // epx endpoint.
+    // TODO for RP2040 USB shared endpoint: usbh_edpt_clear_in_on_nak(p_midi_host->dev_addr, p_midi_host->ep_in);
+  }
+  return result;
+}
+
+uint32_t tuh_midi_stream_write (uint8_t dev_addr, uint8_t cable_num, uint8_t const* buffer, uint32_t bufsize)
+{
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  TU_VERIFY(cable_num < p_midi_host->num_cables_tx);
+  midi_stream_t *stream = &p_midi_host->stream_write;
+
+  uint32_t i = 0;
+  while ( (i < bufsize) && (tu_fifo_remaining(&p_midi_host->tx_ff) >= 4) )
+  {
+    uint8_t const data = buffer[i];
+    i++;
+    if (data >= MIDI_STATUS_SYSREAL_TIMING_CLOCK)
+    {
+      // real-time messages need to be sent right away
+      midi_stream_t streamrt;
+      streamrt.buffer[0] = MIDI_CIN_SYSEX_END_1BYTE;
+      streamrt.buffer[1] = data;
+      streamrt.index = 2;
+      streamrt.total = 2;
+      uint16_t const count = tu_fifo_write_n(&p_midi_host->tx_ff, streamrt.buffer, 4);
+      // FIFO overflown, since we already check fifo remaining. It is probably race condition
+      TU_ASSERT(count == 4, i);
+    }
+    else if ( stream->index == 0 )
+    {
+      //------------- New event packet -------------//
+
+      uint8_t const msg = data >> 4;
+
+      stream->index = 2;
+      stream->buffer[1] = data;
+
+      // Check to see if we're still in a SysEx transmit.
+      if ( stream->buffer[0] == MIDI_CIN_SYSEX_START )
+      {
+        if ( data == MIDI_STATUS_SYSEX_END )
+        {
+          stream->buffer[0] = MIDI_CIN_SYSEX_END_1BYTE;
+          stream->total = 2;
+        }
+        else
+        {
+          stream->total = 4;
+        }
+      }
+      else if ( (msg >= 0x8 && msg <= 0xB) || msg == 0xE )
+      {
+        // Channel Voice Messages
+        stream->buffer[0] = (cable_num << 4) | msg;
+        stream->total = 4;
+      }
+      else if ( msg == 0xC || msg == 0xD)
+      {
+        // Channel Voice Messages, two-byte variants (Program Change and Channel Pressure)
+        stream->buffer[0] = (cable_num << 4) | msg;
+        stream->total = 3;
+      }
+      else if ( msg == 0xf )
+      {
+        // System message
+        if ( data == MIDI_STATUS_SYSEX_START )
+        {
+          stream->buffer[0] = MIDI_CIN_SYSEX_START;
+          stream->total = 4;
+        }
+        else if ( data == MIDI_STATUS_SYSCOM_TIME_CODE_QUARTER_FRAME || data == MIDI_STATUS_SYSCOM_SONG_SELECT )
+        {
+          stream->buffer[0] = MIDI_CIN_SYSCOM_2BYTE;
+          stream->total = 3;
+        }
+        else if ( data == MIDI_STATUS_SYSCOM_SONG_POSITION_POINTER )
+        {
+          stream->buffer[0] = MIDI_CIN_SYSCOM_3BYTE;
+          stream->total = 4;
+        }
+        else
+        {
+          stream->buffer[0] = MIDI_CIN_SYSEX_END_1BYTE;
+          stream->total = 2;
+        }
+      }
+      else
+      {
+        // Pack individual bytes if we don't support packing them into words.
+        stream->buffer[0] = cable_num << 4 | 0xf;
+        stream->buffer[2] = 0;
+        stream->buffer[3] = 0;
+        stream->index = 2;
+        stream->total = 2;
+      }
+    }
+    else
+    {
+      //------------- On-going (buffering) packet -------------//
+
+      TU_ASSERT(stream->index < 4, i);
+      stream->buffer[stream->index] = data;
+      stream->index++;
+      // See if this byte ends a SysEx.
+      if ( stream->buffer[0] == MIDI_CIN_SYSEX_START && data == MIDI_STATUS_SYSEX_END )
+      {
+        stream->buffer[0] = MIDI_CIN_SYSEX_START + (stream->index - 1);
+        stream->total = stream->index;
+      }
+    }
+
+    // Send out packet
+    if ( stream->index >= 2 && stream->index == stream->total )
+    {
+      // zeroes unused bytes
+      for(uint8_t idx = stream->total; idx < 4; idx++) stream->buffer[idx] = 0;
+      TU_LOG3_MEM(stream->buffer, 4, 2);
+
+      uint16_t const count = tu_fifo_write_n(&p_midi_host->tx_ff, stream->buffer, 4);
+
+      // complete current event packet, reset stream
+      stream->index = 0;
+      stream->total = 0;
+
+      // FIFO overflown, since we already check fifo remaining. It is probably race condition
+      TU_ASSERT(count == 4, i);
+    }
+  }
+  return i;
+}
+
+bool tuh_midi_packet_write (uint8_t dev_addr, uint8_t const packet[4])
+{
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+
+  if (tu_fifo_remaining(&p_midi_host->tx_ff) < 4)
+  {
+    return false;
+  }
+
+  tu_fifo_write_n(&p_midi_host->tx_ff, packet, 4);
+
+  return true;
+}
+
+uint32_t tuh_midi_stream_flush( uint8_t dev_addr )
+{
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+
+  uint32_t bytes_flushed = 0;
+  if (!usbh_edpt_busy(p_midi_host->dev_addr, p_midi_host->ep_out))
+  {
+    bytes_flushed = write_flush(dev_addr, p_midi_host);
+  }
+  return bytes_flushed;
+}
+//--------------------------------------------------------------------+
+// Helper
+//--------------------------------------------------------------------+
+uint8_t tuh_midih_get_num_tx_cables (uint8_t dev_addr)
+{
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  TU_VERIFY(p_midi_host->ep_out != 0); // returns 0 if fails
+  return p_midi_host->num_cables_tx;
+}
+
+uint8_t tuh_midih_get_num_rx_cables (uint8_t dev_addr)
+{
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  TU_VERIFY(p_midi_host->ep_in != 0); // returns 0 if fails
+  return p_midi_host->num_cables_rx;
+}
+
+bool tuh_midi_packet_read (uint8_t dev_addr, uint8_t packet[4])
+{
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  TU_VERIFY(tu_fifo_count(&p_midi_host->rx_ff) >= 4);
+  return tu_fifo_read_n(&p_midi_host->rx_ff, packet, 4) == 4;
+}
+
+uint32_t tuh_midi_stream_read (uint8_t dev_addr, uint8_t *p_cable_num, uint8_t *p_buffer, uint16_t bufsize)
+{
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  uint32_t bytes_buffered = 0;
+  TU_ASSERT(p_cable_num);
+  TU_ASSERT(p_buffer);
+  TU_ASSERT(bufsize);
+  uint8_t one_byte;
+  if (!tu_fifo_peek(&p_midi_host->rx_ff, &one_byte))
+  {
+    return 0;
+  }
+  *p_cable_num = (one_byte >> 4) & 0xf;
+  uint32_t nread = tu_fifo_read_n(&p_midi_host->rx_ff, p_midi_host->stream_read.buffer, 4);
+  static uint16_t cable_sysex_in_progress; // bit i is set if received MIDI_STATUS_SYSEX_START but not MIDI_STATUS_SYSEX_END
+  while (nread == 4 && bytes_buffered < bufsize)
+  {
+    *p_cable_num=(p_midi_host->stream_read.buffer[0] >> 4) & 0x0f;
+    uint8_t bytes_to_add_to_stream = 0;
+    if (*p_cable_num < p_midi_host->num_cables_rx)
+    {
+      // ignore the CIN field; too many devices out there encode this wrong
+      uint8_t status = p_midi_host->stream_read.buffer[1];
+      uint16_t cable_mask = 1 << *p_cable_num;
+      if (status <= MIDI_MAX_DATA_VAL || status == MIDI_STATUS_SYSEX_START)
+      {
+        if (status == MIDI_STATUS_SYSEX_START)
+        {
+          cable_sysex_in_progress |= cable_mask;
+        }
+        // only add the packet if a sysex message is in progress
+        if (cable_sysex_in_progress & cable_mask)
+        {
+          ++bytes_to_add_to_stream;
+          uint8_t idx;
+          for (idx = 2; idx < 4; idx++)
+          {
+            if (p_midi_host->stream_read.buffer[idx] <= MIDI_MAX_DATA_VAL)
+            {
+              ++bytes_to_add_to_stream;
+            }
+            else if (p_midi_host->stream_read.buffer[idx] == MIDI_STATUS_SYSEX_END)
+            {
+              ++bytes_to_add_to_stream;
+              cable_sysex_in_progress &= ~cable_mask;
+              idx = 4; // force the loop to exit; I hate break statements in loops
+            }
+          }
+        }
+      }
+      else if (status < MIDI_STATUS_SYSEX_START)
+      {
+        // then it is a channel message either three bytes or two
+        uint8_t fake_cin = (status & 0xf0) >> 4;
+        switch (fake_cin)
+        {
+          case MIDI_CIN_NOTE_OFF:
+          case MIDI_CIN_NOTE_ON:
+          case MIDI_CIN_POLY_KEYPRESS:
+          case MIDI_CIN_CONTROL_CHANGE:
+          case MIDI_CIN_PITCH_BEND_CHANGE:
+            bytes_to_add_to_stream = 3;
+            break;
+          case MIDI_CIN_PROGRAM_CHANGE:
+          case MIDI_CIN_CHANNEL_PRESSURE:
+            bytes_to_add_to_stream = 2;
+            break;
+          default:
+            break; // Should not get this
+        }
+        cable_sysex_in_progress &= ~cable_mask;
+      }
+      else if (status < MIDI_STATUS_SYSREAL_TIMING_CLOCK)
+      {
+        switch (status)
+        {
+          case MIDI_STATUS_SYSCOM_TIME_CODE_QUARTER_FRAME:
+          case MIDI_STATUS_SYSCOM_SONG_SELECT:
+            bytes_to_add_to_stream = 2;
+            break;
+          case MIDI_STATUS_SYSCOM_SONG_POSITION_POINTER:
+            bytes_to_add_to_stream = 3;
+            break;
+          case MIDI_STATUS_SYSCOM_TUNE_REQUEST:
+          case MIDI_STATUS_SYSEX_END:
+            bytes_to_add_to_stream = 1;
+            break;
+          default:
+            break;
+          cable_sysex_in_progress &= ~cable_mask;
+        }
+      }
+      else
+      {
+        // Real-time message: can be inserted into a sysex message,
+        // so do don't clear cable_sysex_in_progress bit
+        bytes_to_add_to_stream = 1;
+      }
+    }
+    uint8_t idx;
+    for (idx = 1; idx <= bytes_to_add_to_stream; idx++)
+    {
+      *p_buffer++ = p_midi_host->stream_read.buffer[idx];
+    }
+    bytes_buffered += bytes_to_add_to_stream;
+    nread = 0;
+    if (tu_fifo_peek(&p_midi_host->rx_ff, &one_byte))
+    {
+      uint8_t new_cable = (one_byte >> 4) & 0xf;
+      if (new_cable == *p_cable_num)
+      {
+        // still on the same cable. Continue reading the stream
+        nread = tu_fifo_read_n(&p_midi_host->rx_ff, p_midi_host->stream_read.buffer, 4);
+      }
+    }
+  }
+
+  return bytes_buffered;
+}
+
+uint8_t tuh_midi_get_num_rx_cables(uint8_t dev_addr)
+{
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  uint8_t num_cables = 0;
+  if (p_midi_host)
+  {
+    num_cables = p_midi_host->num_cables_rx;
+  }
+  return num_cables;
+}
+
+uint8_t tuh_midi_get_num_tx_cables(uint8_t dev_addr)
+{
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  uint8_t num_cables = 0;
+  if (p_midi_host)
+  {
+    num_cables = p_midi_host->num_cables_tx;
+  }
+  return num_cables;
+}
+
+#if CFG_MIDI_HOST_DEVSTRINGS
+static uint8_t find_string_index(midih_interface_t *ptr, uint8_t jack_id)
+{
+  uint8_t index = 0;
+  uint8_t assoc;
+  for (assoc = 0; index == 0 && assoc < ptr->next_in_jack; assoc++)
+  {
+    if (jack_id == ptr->in_jack_info[assoc].jack_id)
+    {
+      index = ptr->in_jack_info[assoc].string_index;
+    }
+  }
+  for (assoc = 0; index == 0 && assoc < ptr->next_out_jack; assoc++)
+  {
+    if (jack_id == ptr->out_jack_info[assoc].jack_id)
+    {
+      index = ptr->out_jack_info[assoc].string_index;
+    }
+  }
+  return index;
+}
+#endif
+
+#if CFG_MIDI_HOST_DEVSTRINGS
+uint8_t tuh_midi_get_rx_cable_istrings(uint8_t dev_addr, uint8_t* istrings, uint8_t max_istrings)
+{
+  uint8_t nstrings = 0;
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  nstrings = p_midi_host->num_cables_rx;
+  if (nstrings > max_istrings)
+  {
+      nstrings = max_istrings;
+  }
+  uint8_t jack;
+  for (jack=0; jack<nstrings; jack++)
+  {
+    uint8_t jack_id = p_midi_host->ep_in_associated_jacks[jack];
+    istrings[jack] = find_string_index(p_midi_host, jack_id);
+  }
+  return nstrings;
+}
+
+uint8_t tuh_midi_get_tx_cable_istrings(uint8_t dev_addr, uint8_t* istrings, uint8_t max_istrings)
+{
+  uint8_t nstrings = 0;
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  nstrings = p_midi_host->num_cables_tx;
+  if (nstrings > max_istrings)
+  {
+      nstrings = max_istrings;
+  }
+  uint8_t jack;
+  for (jack=0; jack<nstrings; jack++)
+  {
+    uint8_t jack_id = p_midi_host->ep_out_associated_jacks[jack];
+    istrings[jack] = find_string_index(p_midi_host, jack_id);
+  }
+  return nstrings;
+}
+#endif
+
+uint8_t tuh_midi_get_all_istrings(uint8_t dev_addr, const uint8_t** istrings)
+{
+  midih_interface_t *p_midi_host = get_midi_host(dev_addr);
+  TU_VERIFY(p_midi_host != NULL);
+  uint8_t nstrings = p_midi_host->num_string_indices;
+  if (nstrings)
+    *istrings = p_midi_host->all_string_indices;
+  return nstrings;
+}
+#endif