From 08fe16840fcc39e4cb7c1f55fa56762427734753 Mon Sep 17 00:00:00 2001
From: hathach <thach@tinyusb.org>
Date: Fri, 2 Apr 2021 14:26:55 +0700
Subject: [PATCH] refactor midi write into stream

---
 src/class/midi/midi_device.c | 77 +++++++++++++++++-------------------
 1 file changed, 37 insertions(+), 40 deletions(-)

diff --git a/src/class/midi/midi_device.c b/src/class/midi/midi_device.c
index 14748f18b..49bf2a27a 100644
--- a/src/class/midi/midi_device.c
+++ b/src/class/midi/midi_device.c
@@ -67,11 +67,7 @@ typedef struct
   // 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.
-  uint8_t write_buffer[4];
-  uint8_t write_buffer_length;
-  uint8_t write_target_length;
-
-//  midid_stream_t stream_write;
+  midid_stream_t stream_write;
 
   uint8_t read_buffer[4];
   uint8_t read_buffer_length;
@@ -229,7 +225,7 @@ uint32_t tud_midi_n_write(uint8_t itf, uint8_t cable_num, uint8_t const* buffer,
   midid_interface_t* midi = &_midid_itf[itf];
   TU_VERIFY(midi->itf_num, 0);
 
-//  midid_stream_t* stream = &midi->stream_write;
+  midid_stream_t* stream = &midi->stream_write;
 
   uint32_t written = 0;
   uint32_t i = 0;
@@ -237,93 +233,94 @@ uint32_t tud_midi_n_write(uint8_t itf, uint8_t cable_num, uint8_t const* buffer,
   {
     uint8_t const data = buffer[i];
 
-    if ( midi->write_buffer_length == 0 )
+    if ( stream->index == 0 )
     {
-      // new packet
+      // new event packet
 
       uint8_t const msg = data >> 4;
-      midi->write_buffer[1] = data;
-      midi->write_buffer_length = 2;
+
+      stream->index = 2;
+      stream->buffer[1] = data;
 
       // Check to see if we're still in a SysEx transmit.
-      if ( midi->write_buffer[0] == MIDI_CIN_SYSEX_START )
+      if ( stream->buffer[0] == MIDI_CIN_SYSEX_START )
       {
         if ( data == MIDI_STATUS_SYSEX_END )
         {
-          midi->write_buffer[0] = MIDI_CIN_SYSEX_END_1BYTE;
-          midi->write_target_length = 2;
+          stream->buffer[0] = MIDI_CIN_SYSEX_END_1BYTE;
+          stream->total = 2;
         }
         else
         {
-          midi->write_target_length = 4;
+          stream->total = 4;
         }
       }
       else if ( (msg >= 0x8 && msg <= 0xB) || msg == 0xE )
       {
         // Channel Voice Messages
-        midi->write_buffer[0] = (cable_num << 4) | msg;
-        midi->write_target_length = 4;
+        stream->buffer[0] = (cable_num << 4) | msg;
+        stream->total = 4;
       }
       else if ( msg == 0xf )
       {
         // System message
         if ( data == MIDI_STATUS_SYSEX_START )
         {
-          midi->write_buffer[0] = MIDI_CIN_SYSEX_START;
-          midi->write_target_length = 4;
+          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 )
         {
-          midi->write_buffer[0] = MIDI_CIN_SYSCOM_2BYTE;
-          midi->write_target_length = 3;
+          stream->buffer[0] = MIDI_CIN_SYSCOM_2BYTE;
+          stream->total = 3;
         }
         else if ( data == MIDI_STATUS_SYSCOM_SONG_POSITION_POINTER )
         {
-          midi->write_buffer[0] = MIDI_CIN_SYSCOM_3BYTE;
-          midi->write_target_length = 4;
+          stream->buffer[0] = MIDI_CIN_SYSCOM_3BYTE;
+          stream->total = 4;
         }
         else
         {
-          midi->write_buffer[0] = MIDI_CIN_SYSEX_END_1BYTE;
-          midi->write_target_length = 2;
+          stream->buffer[0] = MIDI_CIN_SYSEX_END_1BYTE;
+          stream->total = 2;
         }
       }
       else
       {
         // Pack individual bytes if we don't support packing them into words.
-        midi->write_buffer[0] = cable_num << 4 | 0xf;
-        midi->write_buffer[2] = 0;
-        midi->write_buffer[3] = 0;
-        midi->write_buffer_length = 2;
-        midi->write_target_length = 2;
+        stream->buffer[0] = cable_num << 4 | 0xf;
+        stream->buffer[2] = 0;
+        stream->buffer[3] = 0;
+        stream->index = 2;
+        stream->total = 2;
       }
     }
     else
     {
-      // On-going packet
+      // On-going (buffering) packet
 
-      TU_ASSERT(midi->write_buffer_length < 4, 0);
-      midi->write_buffer[midi->write_buffer_length] = data;
-      midi->write_buffer_length++;
+      TU_ASSERT(stream->index < 4, written);
+      stream->buffer[stream->index] = data;
+      stream->index++;
 
       // See if this byte ends a SysEx.
-      if ( midi->write_buffer[0] == MIDI_CIN_SYSEX_START && data == MIDI_STATUS_SYSEX_END )
+      if ( stream->buffer[0] == MIDI_CIN_SYSEX_START && data == MIDI_STATUS_SYSEX_END )
       {
-        midi->write_buffer[0] = MIDI_CIN_SYSEX_START + (midi->write_buffer_length - 1);
-        midi->write_target_length = midi->write_buffer_length;
+        stream->buffer[0] = MIDI_CIN_SYSEX_START + (stream->index - 1);
+        stream->total = stream->index;
       }
     }
 
     // Send out packet
-    if ( midi->write_buffer_length == midi->write_target_length )
+    if ( stream->index == stream->total )
     {
       // zeroes unused bytes
-      for(uint8_t idx = midi->write_target_length; idx < 4; idx++) midi->write_buffer[idx] = 0;
+      for(uint8_t idx = stream->total; idx < 4; idx++) stream->buffer[idx] = 0;
 
-      uint16_t const count = tu_fifo_write_n(&midi->tx_ff, midi->write_buffer, 4);
+      uint16_t const count = tu_fifo_write_n(&midi->tx_ff, stream->buffer, 4);
 
       // reset buffer
-      midi->write_buffer_length = midi->write_target_length = 0;
+      stream->index = stream->total = 0;
 
       // fifo overflow, here we assume FIFO is multiple of 4 and didn't check remaining before writing
       if ( count != 4 ) break;