Split out txbuf and add unit test.

9 files changed, 498 insertions, 74 deletions

diff --git a/.gitmodules b/.gitmodules
index c0dd4dd1d..2d9a88914 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -4,3 +4,6 @@
 [submodule "hw/mcu/microchip/samd/asf4"]
 	path = hw/mcu/microchip/samd/asf4
 	url = https://github.com/adafruit/asf4.git
+[submodule "tests/vendor/unity"]
+	path = tests/vendor/unity
+	url = https://github.com/ThrowTheSwitch/Unity.git
diff --git a/.travis.yml b/.travis.yml
index 1d804dd85..bbfdd684d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -19,3 +19,4 @@ before_script:
 script:
   - make -j2 -C examples/device/cdc_msc_hid BOARD=metro_m0_express
   - make -j2 -C examples/device/cdc_msc_hid BOARD=metro_m4_express
+  - cd tests/common && ceedling test:all
diff --git a/src/class/midi/midi_device.c b/src/class/midi/midi_device.c
index 5acc0b0f1..9850ce251 100644
--- a/src/class/midi/midi_device.c
+++ b/src/class/midi/midi_device.c
@@ -46,6 +46,7 @@
 //--------------------------------------------------------------------+

 #include "midi_device.h"

 #include "class/audio/audio.h"

+#include "common/tusb_txbuf.h"

 #include "device/usbd_pvt.h"

 

 //--------------------------------------------------------------------+

@@ -68,11 +69,8 @@ typedef struct
 

   // This is a ring buffer that aligns to word boundaries so that it can be transferred directly to

   // the USB peripheral. There are three states to the data: free, transmitting and pending.

-  CFG_TUSB_MEM_ALIGN uint8_t tx_buf[CFG_TUD_MIDI_TX_BUFSIZE];

-  uint16_t tx_buf_len;

-  uint16_t first_free;

-  uint16_t pending_count;

-  uint16_t transmitting_count;

+  CFG_TUSB_MEM_ALIGN uint8_t raw_tx_buffer[CFG_TUD_MIDI_TX_BUFSIZE];

+  tu_txbuf_t txbuf;

 

   // We need to pack messages into words before queueing their transmission so buffer across write

   // calls.

@@ -149,65 +147,6 @@ void midi_rx_done_cb(midid_interface_t* midi, uint8_t const* buffer, uint32_t bu
 // WRITE API

 //--------------------------------------------------------------------+

 

-uint16_t maybe_transmit(midid_interface_t* midi) {

-    if (midi->transmitting_count > 0 || midi->pending_count == 0) {

-        return 0;

-    }

-    midi->transmitting_count = midi->pending_count;

-    uint16_t transmit_start_index;

-    // The pending zone wraps back to the end so we must do two transfers.

-    if (midi->pending_count > midi->first_free) {

-        midi->transmitting_count -= midi->first_free;

-        transmit_start_index = midi->tx_buf_len - midi->transmitting_count;

-    } else {

-        transmit_start_index = midi->first_free - midi->transmitting_count;

-

-        // We are transmitting up to first free so ensure it's word aligned for the next transmit.

-        uint8_t over_aligned = midi->first_free % sizeof(size_t);

-        if (over_aligned != 0) {

-            midi->first_free = (midi->first_free + (sizeof(size_t) - midi->first_free)) % midi->tx_buf_len;

-        }

-    }

-    midi->pending_count -= midi->transmitting_count;

-

-    uint8_t* tx_start = midi->tx_buf + transmit_start_index;

-    if (!dcd_edpt_xfer(0, midi->ep_in, tx_start, midi->transmitting_count)) {

-        return 0;

-    }

-    return midi->transmitting_count;

-}

-

-uint32_t tud_tx_buf_write_done_cb(midid_interface_t* midi, uint32_t bufsize) {

-    midi->transmitting_count -= bufsize;

-

-    uint16_t len = maybe_transmit(midi);

-    return len;

-}

-

-uint32_t tud_tx_buf_write(midid_interface_t* midi, uint8_t const* buffer, uint32_t bufsize) {

-    uint32_t len;

-    int32_t last_free = midi->first_free - midi->pending_count - midi->transmitting_count;

-    if (last_free < 0) {

-        len = (last_free + midi->tx_buf_len) - midi->first_free;

-    } else {

-        len = midi->tx_buf_len - midi->first_free;

-    }

-    if (bufsize < len) {

-        len = bufsize;

-    }

-    memcpy(midi->tx_buf + midi->first_free, buffer, len);

-    // uint32_t remaining_bytes

-    // if (last_free > 0 && len < bufsize) {

-    //     if ()

-    //

-    // }

-    midi->first_free = (midi->first_free + len) % midi->tx_buf_len;

-    midi->pending_count += len;

-

-    maybe_transmit(midi);

-    return len;

-}

-

 uint32_t tud_midi_n_write(uint8_t itf, uint8_t jack_id, uint8_t const* buffer, uint32_t bufsize)

 {

   midid_interface_t* midi = &_midid_itf[itf];

@@ -265,7 +204,7 @@ uint32_t tud_midi_n_write(uint8_t itf, uint8_t jack_id, uint8_t const* buffer, u
     }

 

     if (midi->message_buffer_length == midi->message_target_length) {

-        tud_tx_buf_write(midi, midi->message_buffer, 4);

+        tu_txbuf_write_n(&midi->txbuf, midi->message_buffer, 4);

         midi->message_buffer_length = 0;

     }

     i++;

@@ -291,10 +230,7 @@ void midid_init(void)
     tu_fifo_config_mutex(&midi->rx_ff, osal_mutex_create(&midi->rx_ff_mutex));

     #endif

 

-    midi->tx_buf_len = CFG_TUD_MIDI_TX_BUFSIZE;

-    midi->first_free = 0;

-    midi->pending_count = 0;

-    midi->transmitting_count = 0;

+    tu_txbuf_config(&midi->txbuf, midi->raw_tx_buffer, CFG_TUD_MIDI_TX_BUFSIZE, dcd_edpt_xfer);

   }

 }

 

@@ -307,10 +243,7 @@ void midid_reset(uint8_t rhport)
     midid_interface_t* midi = &_midid_itf[i];

     tu_memclr(midi, ITF_MEM_RESET_SIZE);

     tu_fifo_clear(&midi->rx_ff);

-    midi->tx_buf_len = CFG_TUD_MIDI_TX_BUFSIZE;

-    midi->first_free = 0;

-    midi->pending_count = 0;

-    midi->transmitting_count = 0;

+    tu_txbuf_clear(&midi->txbuf);

   }

 }

 

@@ -356,6 +289,7 @@ bool midid_open(uint8_t rhport, tusb_desc_interface_t const * p_interface_desc,
         uint8_t ep_addr = ((tusb_desc_endpoint_t const *) p_desc)->bEndpointAddress;

         if (tu_edpt_dir(ep_addr) == TUSB_DIR_IN) {

             p_midi->ep_in = ep_addr;

+            tu_txbuf_set_ep_addr(&p_midi->txbuf, ep_addr);

         } else {

             p_midi->ep_out = ep_addr;

         }

@@ -401,7 +335,7 @@ bool midid_xfer_cb(uint8_t rhport, uint8_t edpt_addr, xfer_result_t result, uint
     // prepare for next

     TU_ASSERT( dcd_edpt_xfer(rhport, p_midi->ep_out, p_midi->epout_buf, CFG_TUD_MIDI_EPSIZE), false );

   } else if ( edpt_addr == p_midi->ep_in ) {

-    tud_tx_buf_write_done_cb(p_midi, xferred_bytes);

+    tu_txbuf_transmit_done_cb(&p_midi->txbuf, xferred_bytes);

   }

 

   // nothing to do with in and notif endpoint

diff --git a/src/common/tusb_txbuf.c b/src/common/tusb_txbuf.c
new file mode 100644
index 000000000..de1bbe49b
--- /dev/null
+++ b/src/common/tusb_txbuf.c
@@ -0,0 +1,159 @@
+/**************************************************************************/

+/*!

+    @file     tusb_txbuf.c

+    @author   Scott Shawcroft

+

+    @section LICENSE

+

+    Software License Agreement (BSD License)

+

+    Copyright (c) 2018, Scott Shawcroft

+    All rights reserved.

+

+    Redistribution and use in source and binary forms, with or without

+    modification, are permitted provided that the following conditions are met:

+    1. Redistributions of source code must retain the above copyright

+    notice, this list of conditions and the following disclaimer.

+    2. Redistributions in binary form must reproduce the above copyright

+    notice, this list of conditions and the following disclaimer in the

+    documentation and/or other materials provided with the distribution.

+    3. Neither the name of the copyright holders nor the

+    names of its contributors may be used to endorse or promote products

+    derived from this software without specific prior written permission.

+

+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY

+    EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

+    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

+    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY

+    DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

+    INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

+    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION HOWEVER CAUSED AND

+    ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

+    INCLUDING NEGLIGENCE OR OTHERWISE ARISING IN ANY WAY OUT OF THE USE OF THIS

+    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

+

+ This file is part of the tinyusb stack.

+ */

+/**************************************************************************/

+#include <stdio.h>

+#include <string.h>

+

+#include "tusb_txbuf.h"

+

+bool tu_txbuf_config(tu_txbuf_t *txbuf, uint8_t* buffer, uint16_t buffer_length, edpt_xfer xfer)

+{

+  txbuf->buffer = (uint8_t*) buffer;

+  txbuf->buf_len = buffer_length;

+  txbuf->first_free = 0;

+  txbuf->pending_count = 0;

+  txbuf->transmitting_count = 0;

+  txbuf->xfer = xfer;

+  txbuf->padding = 0;

+

+  return true;

+}

+

+uint16_t maybe_transmit(tu_txbuf_t* buf) {

+    if (buf->transmitting_count > 0 || buf->pending_count == 0) {

+        return 0;

+    }

+    buf->transmitting_count = buf->pending_count;

+    uint16_t transmit_start_index;

+    uint8_t over_aligned = 0;

+    // The pending zone wraps back to the end so we must do two transfers.

+    if (buf->pending_count > buf->first_free) {

+        buf->transmitting_count -= buf->first_free;

+        transmit_start_index = buf->buf_len - buf->transmitting_count;

+    } else {

+        transmit_start_index = buf->first_free - buf->transmitting_count;

+

+        // We are transmitting up to first free so ensure it's word aligned for the next transmit.

+        over_aligned = buf->first_free % sizeof(uint32_t);

+        buf->padding = sizeof(uint32_t) - over_aligned;

+        if (over_aligned != 0) {

+            buf->first_free = (buf->first_free + buf->padding) % buf->buf_len;

+        }

+    }

+    buf->pending_count -= buf->transmitting_count;

+

+    uint8_t* tx_start = buf->buffer + transmit_start_index;

+    if (!buf->xfer(0, buf->ep_addr, tx_start, buf->transmitting_count)) {

+        return 0;

+    }

+    return buf->transmitting_count;

+}

+

+uint32_t tu_txbuf_transmit_done_cb(tu_txbuf_t* buf, uint32_t bufsize) {

+    buf->transmitting_count -= bufsize;

+

+    return maybe_transmit(buf);

+}

+

+/******************************************************************************/

+/*!

+    @brief This function will write n elements into the array index specified by

+    the write pointer and increment the write index. If the write index

+    exceeds the max buffer size, then it will roll over to zero.

+

+    @param[in]  f

+                Pointer to the FIFO buffer to manipulate

+    @param[in]  p_data

+                The pointer to data to add to the FIFO

+    @param[in]  count

+                Number of element

+    @return Number of written elements

+*/

+/******************************************************************************/

+uint16_t tu_txbuf_write_n(tu_txbuf_t* txbuf, uint8_t const* buffer, uint32_t bufsize) {

+    uint32_t len;

+    int32_t last_free = txbuf->first_free - txbuf->pending_count - txbuf->transmitting_count - txbuf->padding;

+    if (last_free < 0) {

+        last_free += txbuf->buf_len;

+        len = last_free - txbuf->first_free;

+    } else {

+        len = txbuf->buf_len - txbuf->first_free;

+    }

+    if (bufsize < len) {

+        len = bufsize;

+    }

+    memcpy(txbuf->buffer + txbuf->first_free, buffer, len);

+    txbuf->first_free = (txbuf->first_free + len) % txbuf->buf_len;

+    txbuf->pending_count += len;

+    // Try to transmit now while we wrap the rest.

+    maybe_transmit(txbuf);

+    uint32_t remaining_bytes = bufsize - len;

+    if (remaining_bytes > 0 && last_free != txbuf->first_free) {

+        uint32_t second_len = remaining_bytes;

+        if (second_len > (uint32_t) last_free + 1) {

+            second_len = last_free + 1;

+        }

+        memcpy(txbuf->buffer, buffer + len, second_len);

+        txbuf->first_free = (txbuf->first_free + second_len) % txbuf->buf_len;

+        txbuf->pending_count += second_len;

+        len += second_len;

+    }

+

+    return len;

+}

+

+void tu_txbuf_set_ep_addr(tu_txbuf_t* txbuf, uint8_t ep_addr) {

+    txbuf->ep_addr = ep_addr;

+}

+

+/******************************************************************************/

+/*!

+    @brief Clear the txbuf including any currently transmitting data.

+

+    @param[in]  t

+                Pointer to the txbuf to manipulate

+*/

+/******************************************************************************/

+bool tu_txbuf_clear(tu_txbuf_t *txbuf)

+{

+

+  txbuf->first_free = 0;

+  txbuf->pending_count = 0;

+  txbuf->transmitting_count = 0;

+

+  return true;

+}

diff --git a/src/common/tusb_txbuf.h b/src/common/tusb_txbuf.h
new file mode 100644
index 000000000..88d48ecac
--- /dev/null
+++ b/src/common/tusb_txbuf.h
@@ -0,0 +1,83 @@
+/**************************************************************************/

+/*!

+    @file     tusb_txbuf.h

+    @author   Scott Shawcroft

+

+    @section LICENSE

+

+    Software License Agreement (BSD License)

+

+    Copyright (c) 2018, Scott Shawcroft

+    All rights reserved.

+

+    Redistribution and use in source and binary forms, with or without

+    modification, are permitted provided that the following conditions are met:

+    1. Redistributions of source code must retain the above copyright

+    notice, this list of conditions and the following disclaimer.

+    2. Redistributions in binary form must reproduce the above copyright

+    notice, this list of conditions and the following disclaimer in the

+    documentation and/or other materials provided with the distribution.

+    3. Neither the name of the copyright holders nor the

+    names of its contributors may be used to endorse or promote products

+    derived from this software without specific prior written permission.

+

+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY

+    EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

+    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

+    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY

+    DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

+    INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

+    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION HOWEVER CAUSED AND

+    ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

+    INCLUDING NEGLIGENCE OR OTHERWISE ARISING IN ANY WAY OUT OF THE USE OF THIS

+    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

+

+	  This file is part of the tinyusb stack.

+*/

+/**************************************************************************/

+

+/** \ingroup Group_Common

+ * \defgroup group_txbuf txbuf

+ *  @{ */

+

+#ifndef _TUSB_TXBUF_H_

+#define _TUSB_TXBUF_H_

+

+#include <stdint.h>

+#include <stdbool.h>

+

+#ifdef __cplusplus

+ extern "C" {

+#endif

+

+typedef bool (*edpt_xfer) (uint8_t rhport, uint8_t ep_addr, uint8_t* buffer, uint16_t total_bytes);

+

+

+/** \struct tu_txbuf_t

+ * \brief Circular transmit buffer that manages USB transfer memory. It is not threadsafe and is

+ *        only meant for use in the main task.

+ */

+typedef struct

+{

+    uint8_t* buffer    ; ///< buffer pointer

+    uint16_t buf_len;

+    uint16_t first_free;

+    uint16_t pending_count;

+    uint16_t transmitting_count;

+    uint16_t padding;

+    uint8_t ep_addr;

+    edpt_xfer xfer;

+} tu_txbuf_t;

+

+bool tu_txbuf_clear(tu_txbuf_t *f);

+bool tu_txbuf_config(tu_txbuf_t *f, uint8_t* buffer, uint16_t depth, edpt_xfer xfer);

+

+uint16_t tu_txbuf_write_n (tu_txbuf_t* txbuf, uint8_t const * buffer, uint32_t length);

+void tu_txbuf_set_ep_addr(tu_txbuf_t* txbuf, uint8_t ep_addr);

+uint32_t tu_txbuf_transmit_done_cb(tu_txbuf_t* buf, uint32_t bufsize);

+

+#ifdef __cplusplus

+ }

+#endif

+

+#endif /* _TUSB_TXBUF_H_ */

diff --git a/tests/common/Makefile b/tests/common/Makefile
new file mode 100644
index 000000000..2810fbae0
--- /dev/null
+++ b/tests/common/Makefile
@@ -0,0 +1,91 @@
+ifeq ($(OS),Windows_NT)
+  ifeq ($(shell uname -s),) # not in a bash-like shell
+	CLEANUP = del /F /Q
+	MKDIR = mkdir
+  else # in a bash-like shell, like msys
+	CLEANUP = rm -f
+	MKDIR = mkdir -p
+  endif
+	TARGET_EXTENSION=.exe
+else
+	CLEANUP = rm -f
+	MKDIR = mkdir -p
+	TARGET_EXTENSION=out
+endif
+
+.PHONY: clean
+.PHONY: test
+
+PATHU = ../vendor/unity/src/
+PATHS = ../../src/
+PATHT = test/
+PATHB = build/
+PATHD = build/depends/
+PATHO = build/objs/
+PATHR = build/results/
+
+BUILD_PATHS = $(PATHB) $(PATHD) $(PATHO) $(PATHR)
+
+SRCT = $(wildcard $(PATHT)*.c)
+
+$(info $(SRCT))
+
+COMPILE=gcc -c
+LINK=gcc
+DEPEND=gcc -MM -MG -MF
+CFLAGS=-I. -I$(PATHU) -I$(PATHS) -DTEST
+
+RESULTS = $(patsubst $(PATHT)test%.c,$(PATHR)test%.txt,$(SRCT) )
+
+PASSED = `grep -s PASS $(PATHR)*.txt`
+FAIL = `grep -s FAIL $(PATHR)*.txt`
+IGNORE = `grep -s IGNORE $(PATHR)*.txt`
+
+test: $(BUILD_PATHS) $(RESULTS)
+	@echo "-----------------------\nIGNORES:\n-----------------------"
+	@echo "$(IGNORE)"
+	@echo "-----------------------\nFAILURES:\n-----------------------"
+	@echo "$(FAIL)"
+	@echo "-----------------------\nPASSED:\n-----------------------"
+	@echo "$(PASSED)"
+	@echo "\nDONE"
+
+$(PATHR)%.txt: $(PATHB)%.$(TARGET_EXTENSION)
+	-./$< > $@ 2>&1
+
+$(PATHB)test_%.$(TARGET_EXTENSION): $(PATHO)test_%.o $(PATHO)tusb_%.o $(PATHU)unity.o #$(PATHD)test%.d
+	$(LINK) -o $@ $^
+
+$(PATHO)%.o:: $(PATHT)%.c
+	$(COMPILE) $(CFLAGS) $< -o $@
+
+$(PATHO)%.o:: $(PATHS)common/%.c
+	$(COMPILE) $(CFLAGS) $< -o $@
+
+$(PATHO)%.o:: $(PATHU)%.c $(PATHU)%.h
+	$(COMPILE) $(CFLAGS) $< -o $@
+
+$(PATHD)%.d:: $(PATHT)%.c
+	$(DEPEND) $@ $<
+
+$(PATHB):
+	$(MKDIR) $(PATHB)
+
+$(PATHD):
+	$(MKDIR) $(PATHD)
+
+$(PATHO):
+	$(MKDIR) $(PATHO)
+
+$(PATHR):
+	$(MKDIR) $(PATHR)
+
+clean:
+	$(CLEANUP) $(PATHO)*.o
+	$(CLEANUP) $(PATHB)*.$(TARGET_EXTENSION)
+	$(CLEANUP) $(PATHR)*.txt
+
+.PRECIOUS: $(PATHB)test%.$(TARGET_EXTENSION)
+.PRECIOUS: $(PATHD)%.d
+.PRECIOUS: $(PATHO)%.o
+.PRECIOUS: $(PATHR)%.txt
diff --git a/tests/common/build/results/test_txbuf.txt b/tests/common/build/results/test_txbuf.txt
new file mode 100644
index 000000000..a763a4717
--- /dev/null
+++ b/tests/common/build/results/test_txbuf.txt
@@ -0,0 +1,8 @@
+test/test_txbuf.c:140:test_normal:PASS
+test/test_txbuf.c:141:test_nearly_full:PASS
+test/test_txbuf.c:142:test_wrap_around:PASS
+test/test_txbuf.c:143:test_wrap_around_too_much:PASS
+
+-----------------------
+4 Tests 0 Failures 0 Ignored 
+OK
diff --git a/tests/common/test/test_txbuf.c b/tests/common/test/test_txbuf.c
new file mode 100644
index 000000000..8111c4715
--- /dev/null
+++ b/tests/common/test/test_txbuf.c
@@ -0,0 +1,145 @@
+/**************************************************************************/
+/*!
+    @file     test_fifo.c
+    @author   Scott Shawcroft
+
+    @section LICENSE
+
+    Software License Agreement (BSD License)
+
+    Copyright (c) 2019, Scott Shawcroft
+    All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions are met:
+    1. Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in the
+    documentation and/or other materials provided with the distribution.
+    3. Neither the name of the copyright holders nor the
+    names of its contributors may be used to endorse or promote products
+    derived from this software without specific prior written permission.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
+    EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
+    DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+    INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION HOWEVER CAUSED AND
+    ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+    INCLUDING NEGLIGENCE OR OTHERWISE ARISING IN ANY WAY OUT OF THE USE OF THIS
+    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+    This file is part of the tinyusb stack.
+*/
+/**************************************************************************/
+
+#include "unity.h"
+#include "common/tusb_txbuf.h"
+
+uint32_t xfer_count = 0;
+uint32_t freshly_transmitted = 0;
+
+bool mock_xfer(uint8_t rhport, uint8_t ep_addr, uint8_t* buffer, uint16_t total_bytes) {
+    TEST_ASSERT_EQUAL_INT_MESSAGE(0, ((size_t) buffer) % 4, "Transferred buffer not word aligned.");
+    xfer_count++;
+    freshly_transmitted += total_bytes;
+    return true;
+}
+
+tu_txbuf_t txbuf;
+__attribute__((aligned(4))) uint8_t buffer[16];
+
+uint8_t data[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16};
+
+void setUp(void) {
+    tu_txbuf_config(&txbuf, buffer, 16, mock_xfer);
+    tu_txbuf_set_ep_addr(&txbuf, 1);
+}
+
+void tearDown(void) {
+    xfer_count = 0;
+    freshly_transmitted = 0;
+}
+
+void xfer_callback(void) {
+    uint32_t previously_transmitted = freshly_transmitted;
+    freshly_transmitted = 0;
+
+    tu_tx_buf_transmit_done_cb(&txbuf, previously_transmitted);
+}
+
+// Test that we transfer immediately at the start and that the pointer is rounded to a word.
+void test_normal(void) {
+    uint16_t written = tu_txbuf_write_n(&txbuf, data, 4);
+    TEST_ASSERT_EQUAL_INT(4, written);
+    TEST_ASSERT_EQUAL_INT(1, xfer_count);
+    xfer_callback();
+    TEST_ASSERT_EQUAL_INT(1, xfer_count);
+}
+
+// Test that we only accept the data we have room for.
+void test_nearly_full(void) {
+    uint16_t written = tu_txbuf_write_n(&txbuf, data, 11);
+    TEST_ASSERT_EQUAL_INT(11, written);
+    TEST_ASSERT_EQUAL_INT(1, xfer_count);
+
+    written = tu_txbuf_write_n(&txbuf, data, 11);
+    // We only have space for 4 more bytes because 11 + padding are being written.
+    TEST_ASSERT_EQUAL_INT(4, written);
+
+    // Callback triggers a second write of remaining data.
+    xfer_callback();
+    TEST_ASSERT_EQUAL_INT(2, xfer_count);
+    TEST_ASSERT_EQUAL_INT(4, freshly_transmitted);
+}
+
+// Test that we only accept the data even when we have to wrap around.
+void test_wrap_around(void) {
+    uint16_t written = tu_txbuf_write_n(&txbuf, data, 11);
+    TEST_ASSERT_EQUAL_INT(11, written);
+    TEST_ASSERT_EQUAL_INT(1, xfer_count);
+    xfer_callback();
+    TEST_ASSERT_EQUAL_INT(1, xfer_count);
+
+    written = tu_txbuf_write_n(&txbuf, data, 11);
+    // We can queue all 11 bytes but they are split.
+    TEST_ASSERT_EQUAL_INT(11, written);
+    // Four immediately and seven more after the callback.
+    TEST_ASSERT_EQUAL_INT(2, xfer_count);
+    TEST_ASSERT_EQUAL_INT(4, freshly_transmitted);
+    xfer_callback();
+    TEST_ASSERT_EQUAL_INT(7, freshly_transmitted);
+    TEST_ASSERT_EQUAL_INT(3, xfer_count);
+}
+
+// Test that we only accept the data even when we have to wrap around.
+void test_wrap_around_too_much(void) {
+    uint16_t written = tu_txbuf_write_n(&txbuf, data, 11);
+    TEST_ASSERT_EQUAL_INT(11, written);
+    TEST_ASSERT_EQUAL_INT(1, xfer_count);
+    xfer_callback();
+    TEST_ASSERT_EQUAL_INT(1, xfer_count);
+
+    written = tu_txbuf_write_n(&txbuf, data, 17);
+    // We can queue 16 of 17 bytes but they are split.
+    TEST_ASSERT_EQUAL_INT(16, written);
+    // Four immediately and 12 more after the callback.
+    TEST_ASSERT_EQUAL_INT(2, xfer_count);
+    TEST_ASSERT_EQUAL_INT(4, freshly_transmitted);
+    xfer_callback();
+    TEST_ASSERT_EQUAL_INT(12, freshly_transmitted);
+    TEST_ASSERT_EQUAL_INT(3, xfer_count);
+}
+
+int main(void)
+{
+UNITY_BEGIN();
+RUN_TEST(test_normal);
+RUN_TEST(test_nearly_full);
+RUN_TEST(test_wrap_around);
+RUN_TEST(test_wrap_around_too_much);
+return UNITY_END();
+}
diff --git a/tests/vendor/unity b/tests/vendor/unity
new file mode 160000
+Subproject a2849843654524194b72567b198c25d1c1dfead