Add core files and use same toolchain as stmhal

1 files changed, 980 insertions, 0 deletions

diff --git a/teensy/core/usb_dev.c b/teensy/core/usb_dev.c
new file mode 100644
index 000000000..6cf85d3fd
--- /dev/null
+++ b/teensy/core/usb_dev.c
@@ -0,0 +1,980 @@
+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2013 PJRC.COM, LLC.
+ *
+ * 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:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * 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.
+ */
+
+#if F_CPU >= 20000000
+
+#include "mk20dx128.h"
+//#include "HardwareSerial.h"
+#include "usb_dev.h"
+#include "usb_mem.h"
+
+// buffer descriptor table
+
+typedef struct {
+	uint32_t desc;
+	void * addr;
+} bdt_t;
+
+__attribute__ ((section(".usbdescriptortable"), used))
+static bdt_t table[(NUM_ENDPOINTS+1)*4];
+
+static usb_packet_t *rx_first[NUM_ENDPOINTS];
+static usb_packet_t *rx_last[NUM_ENDPOINTS];
+static usb_packet_t *tx_first[NUM_ENDPOINTS];
+static usb_packet_t *tx_last[NUM_ENDPOINTS];
+uint16_t usb_rx_byte_count_data[NUM_ENDPOINTS];
+
+static uint8_t tx_state[NUM_ENDPOINTS];
+#define TX_STATE_BOTH_FREE_EVEN_FIRST	0
+#define TX_STATE_BOTH_FREE_ODD_FIRST	1
+#define TX_STATE_EVEN_FREE		2
+#define TX_STATE_ODD_FREE		3
+#define TX_STATE_NONE_FREE_EVEN_FIRST	4
+#define TX_STATE_NONE_FREE_ODD_FIRST	5
+
+#define BDT_OWN		0x80
+#define BDT_DATA1	0x40
+#define BDT_DATA0	0x00
+#define BDT_DTS		0x08
+#define BDT_STALL	0x04
+#define BDT_PID(n)	(((n) >> 2) & 15)
+
+#define BDT_DESC(count, data)	(BDT_OWN | BDT_DTS \
+				| ((data) ? BDT_DATA1 : BDT_DATA0) \
+				| ((count) << 16))
+
+#define TX   1
+#define RX   0
+#define ODD  1
+#define EVEN 0
+#define DATA0 0
+#define DATA1 1
+#define index(endpoint, tx, odd) (((endpoint) << 2) | ((tx) << 1) | (odd))
+#define stat2bufferdescriptor(stat) (table + ((stat) >> 2))
+
+
+static union {
+ struct {
+  union {
+   struct {
+	uint8_t bmRequestType;
+	uint8_t bRequest;
+   };
+	uint16_t wRequestAndType;
+  };
+	uint16_t wValue;
+	uint16_t wIndex;
+	uint16_t wLength;
+ };
+ struct {
+	uint32_t word1;
+	uint32_t word2;
+ };
+} setup;
+
+
+#define GET_STATUS		0
+#define CLEAR_FEATURE		1
+#define SET_FEATURE		3
+#define SET_ADDRESS		5
+#define GET_DESCRIPTOR		6
+#define SET_DESCRIPTOR		7
+#define GET_CONFIGURATION	8
+#define SET_CONFIGURATION	9
+#define GET_INTERFACE		10
+#define SET_INTERFACE		11
+#define SYNCH_FRAME		12
+
+// SETUP always uses a DATA0 PID for the data field of the SETUP transaction.
+// transactions in the data phase start with DATA1 and toggle (figure 8-12, USB1.1)
+// Status stage uses a DATA1 PID.
+
+static uint8_t ep0_rx0_buf[EP0_SIZE] __attribute__ ((aligned (4)));
+static uint8_t ep0_rx1_buf[EP0_SIZE] __attribute__ ((aligned (4)));
+static const uint8_t *ep0_tx_ptr = NULL;
+static uint16_t ep0_tx_len;
+static uint8_t ep0_tx_bdt_bank = 0;
+static uint8_t ep0_tx_data_toggle = 0;
+uint8_t usb_rx_memory_needed = 0;
+
+volatile uint8_t usb_configuration = 0;
+volatile uint8_t usb_reboot_timer = 0;
+
+
+static void endpoint0_stall(void)
+{
+	USB0_ENDPT0 = USB_ENDPT_EPSTALL | USB_ENDPT_EPRXEN | USB_ENDPT_EPTXEN | USB_ENDPT_EPHSHK;
+}
+
+
+static void endpoint0_transmit(const void *data, uint32_t len)
+{
+#if 0
+	serial_print("tx0:");
+	serial_phex32((uint32_t)data);
+	serial_print(",");
+	serial_phex16(len);
+	serial_print(ep0_tx_bdt_bank ? ", odd" : ", even");
+	serial_print(ep0_tx_data_toggle ? ", d1\n" : ", d0\n");
+#endif
+	table[index(0, TX, ep0_tx_bdt_bank)].addr = (void *)data;
+	table[index(0, TX, ep0_tx_bdt_bank)].desc = BDT_DESC(len, ep0_tx_data_toggle);
+	ep0_tx_data_toggle ^= 1;
+	ep0_tx_bdt_bank ^= 1;
+}
+
+static uint8_t reply_buffer[8];
+
+static void usb_setup(void)
+{
+	const uint8_t *data = NULL;
+	uint32_t datalen = 0;
+	const usb_descriptor_list_t *list;
+	uint32_t size;
+	volatile uint8_t *reg;
+	uint8_t epconf;
+	const uint8_t *cfg;
+	int i;
+
+	switch (setup.wRequestAndType) {
+	  case 0x0500: // SET_ADDRESS
+		break;
+	  case 0x0900: // SET_CONFIGURATION
+		//serial_print("configure\n");
+		usb_configuration = setup.wValue;
+		reg = &USB0_ENDPT1;
+		cfg = usb_endpoint_config_table;
+		// clear all BDT entries, free any allocated memory...
+		for (i=4; i < (NUM_ENDPOINTS+1)*4; i++) {
+			if (table[i].desc & BDT_OWN) {
+				usb_free((usb_packet_t *)((uint8_t *)(table[i].addr) - 8));
+			}
+		}
+		// free all queued packets
+		for (i=0; i < NUM_ENDPOINTS; i++) {
+			usb_packet_t *p, *n;
+			p = rx_first[i];
+			while (p) {
+				n = p->next;
+				usb_free(p);
+				p = n;
+			}
+			rx_first[i] = NULL;
+			rx_last[i] = NULL;
+			p = tx_first[i];
+			while (p) {
+				n = p->next;
+				usb_free(p);
+				p = n;
+			}
+			tx_first[i] = NULL;
+			tx_last[i] = NULL;
+			usb_rx_byte_count_data[i] = 0;
+			switch (tx_state[i]) {
+			  case TX_STATE_EVEN_FREE:
+			  case TX_STATE_NONE_FREE_EVEN_FIRST:
+				tx_state[i] = TX_STATE_BOTH_FREE_EVEN_FIRST;
+				break;
+			  case TX_STATE_ODD_FREE:
+			  case TX_STATE_NONE_FREE_ODD_FIRST:
+				tx_state[i] = TX_STATE_BOTH_FREE_ODD_FIRST;
+				break;
+			  default:
+				break;
+			}
+		}
+		usb_rx_memory_needed = 0;
+		for (i=1; i <= NUM_ENDPOINTS; i++) {
+			epconf = *cfg++;
+			*reg = epconf;
+			reg += 4;
+			if (epconf & USB_ENDPT_EPRXEN) {
+				usb_packet_t *p;
+				p = usb_malloc();
+				if (p) {
+					table[index(i, RX, EVEN)].addr = p->buf;
+					table[index(i, RX, EVEN)].desc = BDT_DESC(64, 0);
+				} else {
+					table[index(i, RX, EVEN)].desc = 0;
+					usb_rx_memory_needed++;
+				}
+				p = usb_malloc();
+				if (p) {
+					table[index(i, RX, ODD)].addr = p->buf;
+					table[index(i, RX, ODD)].desc = BDT_DESC(64, 1);
+				} else {
+					table[index(i, RX, ODD)].desc = 0;
+					usb_rx_memory_needed++;
+				}
+			}
+			table[index(i, TX, EVEN)].desc = 0;
+			table[index(i, TX, ODD)].desc = 0;
+		}
+		break;
+	  case 0x0880: // GET_CONFIGURATION
+		reply_buffer[0] = usb_configuration;
+		datalen = 1;
+		data = reply_buffer;
+		break;
+	  case 0x0080: // GET_STATUS (device)
+		reply_buffer[0] = 0;
+		reply_buffer[1] = 0;
+		datalen = 2;
+		data = reply_buffer;
+		break;
+	  case 0x0082: // GET_STATUS (endpoint)
+		if (setup.wIndex > NUM_ENDPOINTS) {
+			// TODO: do we need to handle IN vs OUT here?
+			endpoint0_stall();
+			return;
+		}
+		reply_buffer[0] = 0;
+		reply_buffer[1] = 0;
+		if (*(uint8_t *)(&USB0_ENDPT0 + setup.wIndex * 4) & 0x02) reply_buffer[0] = 1;
+		data = reply_buffer;
+		datalen = 2;
+		break;
+	  case 0x0102: // CLEAR_FEATURE (endpoint)
+		i = setup.wIndex & 0x7F;
+		if (i > NUM_ENDPOINTS || setup.wValue != 0) {
+			// TODO: do we need to handle IN vs OUT here?
+			endpoint0_stall();
+			return;
+		}
+		(*(uint8_t *)(&USB0_ENDPT0 + setup.wIndex * 4)) &= ~0x02;
+		// TODO: do we need to clear the data toggle here?
+		break;
+	  case 0x0302: // SET_FEATURE (endpoint)
+		i = setup.wIndex & 0x7F;
+		if (i > NUM_ENDPOINTS || setup.wValue != 0) {
+			// TODO: do we need to handle IN vs OUT here?
+			endpoint0_stall();
+			return;
+		}
+		(*(uint8_t *)(&USB0_ENDPT0 + setup.wIndex * 4)) |= 0x02;
+		// TODO: do we need to clear the data toggle here?
+		break;
+	  case 0x0680: // GET_DESCRIPTOR
+	  case 0x0681:
+		//serial_print("desc:");
+		//serial_phex16(setup.wValue);
+		//serial_print("\n");
+		for (list = usb_descriptor_list; 1; list++) {
+			if (list->addr == NULL) break;
+			//if (setup.wValue == list->wValue &&
+			//(setup.wIndex == list->wIndex) || ((setup.wValue >> 8) == 3)) {
+			if (setup.wValue == list->wValue && setup.wIndex == list->wIndex) {
+				data = list->addr;
+				if ((setup.wValue >> 8) == 3) {
+					// for string descriptors, use the descriptor's
+					// length field, allowing runtime configured
+					// length.
+					datalen = *(list->addr);
+				} else {
+					datalen = list->length;
+				}
+#if 0
+				serial_print("Desc found, ");
+				serial_phex32((uint32_t)data);
+				serial_print(",");
+				serial_phex16(datalen);
+				serial_print(",");
+				serial_phex(data[0]);
+				serial_phex(data[1]);
+				serial_phex(data[2]);
+				serial_phex(data[3]);
+				serial_phex(data[4]);
+				serial_phex(data[5]);
+				serial_print("\n");
+#endif
+				goto send;
+			}
+		}
+		//serial_print("desc: not found\n");
+		endpoint0_stall();
+		return;
+#if defined(CDC_STATUS_INTERFACE)
+	  case 0x2221: // CDC_SET_CONTROL_LINE_STATE
+		usb_cdc_line_rtsdtr = setup.wValue;
+		//serial_print("set control line state\n");
+		break;
+	  case 0x2321: // CDC_SEND_BREAK
+		break;
+	  case 0x2021: // CDC_SET_LINE_CODING
+		//serial_print("set coding, waiting...\n");
+		return;
+#endif
+
+// TODO: this does not work... why?
+#if defined(SEREMU_INTERFACE) || defined(KEYBOARD_INTERFACE)
+	  case 0x0921: // HID SET_REPORT
+		//serial_print(":)\n");
+		return;
+	  case 0x0A21: // HID SET_IDLE
+		break;
+	  // case 0xC940:
+#endif
+	  default:
+		endpoint0_stall();
+		return;
+	}
+	send:
+	//serial_print("setup send ");
+	//serial_phex32(data);
+	//serial_print(",");
+	//serial_phex16(datalen);
+	//serial_print("\n");
+
+	if (datalen > setup.wLength) datalen = setup.wLength;
+	size = datalen;
+	if (size > EP0_SIZE) size = EP0_SIZE;
+	endpoint0_transmit(data, size);
+	data += size;
+	datalen -= size;
+	if (datalen == 0 && size < EP0_SIZE) return;
+
+	size = datalen;
+	if (size > EP0_SIZE) size = EP0_SIZE;
+	endpoint0_transmit(data, size);
+	data += size;
+	datalen -= size;
+	if (datalen == 0 && size < EP0_SIZE) return;
+
+	ep0_tx_ptr = data;
+	ep0_tx_len = datalen;
+}
+
+
+
+//A bulk endpoint's toggle sequence is initialized to DATA0 when the endpoint
+//experiences any configuration event (configuration events are explained in
+//Sections 9.1.1.5 and 9.4.5).
+
+//Configuring a device or changing an alternate setting causes all of the status
+//and configuration values associated with endpoints in the affected interfaces
+//to be set to their default values. This includes setting the data toggle of
+//any endpoint using data toggles to the value DATA0.
+
+//For endpoints using data toggle, regardless of whether an endpoint has the
+//Halt feature set, a ClearFeature(ENDPOINT_HALT) request always results in the
+//data toggle being reinitialized to DATA0.
+
+
+
+// #define stat2bufferdescriptor(stat) (table + ((stat) >> 2))
+
+static void usb_control(uint32_t stat)
+{
+	bdt_t *b;
+	uint32_t pid, size;
+	uint8_t *buf;
+	const uint8_t *data;
+
+	b = stat2bufferdescriptor(stat);
+	pid = BDT_PID(b->desc);
+	//count = b->desc >> 16;
+	buf = b->addr;
+	//serial_print("pid:");
+	//serial_phex(pid);
+	//serial_print(", count:");
+	//serial_phex(count);
+	//serial_print("\n");
+
+	switch (pid) {
+	case 0x0D: // Setup received from host
+		//serial_print("PID=Setup\n");
+		//if (count != 8) ; // panic?
+		// grab the 8 byte setup info
+		setup.word1 = *(uint32_t *)(buf);
+		setup.word2 = *(uint32_t *)(buf + 4);
+
+		// give the buffer back
+		b->desc = BDT_DESC(EP0_SIZE, DATA1);
+		//table[index(0, RX, EVEN)].desc = BDT_DESC(EP0_SIZE, 1);
+		//table[index(0, RX, ODD)].desc = BDT_DESC(EP0_SIZE, 1);
+
+		// clear any leftover pending IN transactions
+		ep0_tx_ptr = NULL;
+		if (ep0_tx_data_toggle) {
+		}
+		//if (table[index(0, TX, EVEN)].desc & 0x80) {
+			//serial_print("leftover tx even\n");
+		//}
+		//if (table[index(0, TX, ODD)].desc & 0x80) {
+			//serial_print("leftover tx odd\n");
+		//}
+		table[index(0, TX, EVEN)].desc = 0;
+		table[index(0, TX, ODD)].desc = 0;
+		// first IN after Setup is always DATA1
+		ep0_tx_data_toggle = 1;
+
+#if 0
+		serial_print("bmRequestType:");
+		serial_phex(setup.bmRequestType);
+		serial_print(", bRequest:");
+		serial_phex(setup.bRequest);
+		serial_print(", wValue:");
+		serial_phex16(setup.wValue);
+		serial_print(", wIndex:");
+		serial_phex16(setup.wIndex);
+		serial_print(", len:");
+		serial_phex16(setup.wLength);
+		serial_print("\n");
+#endif
+		// actually "do" the setup request
+		usb_setup();
+		// unfreeze the USB, now that we're ready
+		USB0_CTL = USB_CTL_USBENSOFEN; // clear TXSUSPENDTOKENBUSY bit
+		break;
+	case 0x01:  // OUT transaction received from host
+	case 0x02:
+		//serial_print("PID=OUT\n");
+#ifdef CDC_STATUS_INTERFACE
+		if (setup.wRequestAndType == 0x2021 /*CDC_SET_LINE_CODING*/) {
+			int i;
+			uint8_t *dst = (uint8_t *)usb_cdc_line_coding;
+			//serial_print("set line coding ");
+			for (i=0; i<7; i++) {
+				//serial_phex(*buf);
+				*dst++ = *buf++;
+			}
+			//serial_phex32(usb_cdc_line_coding[0]);
+			//serial_print("\n");
+			if (usb_cdc_line_coding[0] == 134) usb_reboot_timer = 15;
+			endpoint0_transmit(NULL, 0);
+		}
+#endif
+#ifdef KEYBOARD_INTERFACE
+		if (setup.word1 == 0x02000921 && setup.word2 == ((1<<16)|KEYBOARD_INTERFACE)) {
+			keyboard_leds = buf[0];
+			endpoint0_transmit(NULL, 0);
+		}
+#endif
+#ifdef SEREMU_INTERFACE
+		if (setup.word1 == 0x03000921 && setup.word2 == ((4<<16)|SEREMU_INTERFACE)
+		  && buf[0] == 0xA9 && buf[1] == 0x45 && buf[2] == 0xC2 && buf[3] == 0x6B) {
+			usb_reboot_timer = 5;
+			endpoint0_transmit(NULL, 0);
+		}
+#endif
+		// give the buffer back
+		b->desc = BDT_DESC(EP0_SIZE, DATA1);
+		break;
+
+	case 0x09: // IN transaction completed to host
+		//serial_print("PID=IN:");
+		//serial_phex(stat);
+		//serial_print("\n");
+
+		// send remaining data, if any...
+		data = ep0_tx_ptr;
+		if (data) {
+			size = ep0_tx_len;
+			if (size > EP0_SIZE) size = EP0_SIZE;
+			endpoint0_transmit(data, size);
+			data += size;
+			ep0_tx_len -= size;
+			ep0_tx_ptr = (ep0_tx_len > 0 || size == EP0_SIZE) ? data : NULL;
+		}
+
+		if (setup.bRequest == 5 && setup.bmRequestType == 0) {
+			setup.bRequest = 0;
+			//serial_print("set address: ");
+			//serial_phex16(setup.wValue);
+			//serial_print("\n");
+			USB0_ADDR = setup.wValue;
+		}
+
+		break;
+	//default:
+		//serial_print("PID=unknown:");
+		//serial_phex(pid);
+		//serial_print("\n");
+	}
+	USB0_CTL = USB_CTL_USBENSOFEN; // clear TXSUSPENDTOKENBUSY bit
+}
+
+
+
+
+
+
+usb_packet_t *usb_rx(uint32_t endpoint)
+{
+	usb_packet_t *ret;
+	endpoint--;
+	if (endpoint >= NUM_ENDPOINTS) return NULL;
+	__disable_irq();
+	ret = rx_first[endpoint];
+	if (ret) {
+		rx_first[endpoint] = ret->next;
+		usb_rx_byte_count_data[endpoint] -= ret->len;
+	}
+	__enable_irq();
+	//serial_print("rx, epidx=");
+	//serial_phex(endpoint);
+	//serial_print(", packet=");
+	//serial_phex32(ret);
+	//serial_print("\n");
+	return ret;
+}
+
+static uint32_t usb_queue_byte_count(const usb_packet_t *p)
+{
+	uint32_t count=0;
+
+	__disable_irq();
+	for ( ; p; p = p->next) {
+		count += p->len;
+	}
+	__enable_irq();
+	return count;
+}
+
+// TODO: make this an inline function...
+/*
+uint32_t usb_rx_byte_count(uint32_t endpoint)
+{
+	endpoint--;
+	if (endpoint >= NUM_ENDPOINTS) return 0;
+	return usb_rx_byte_count_data[endpoint];
+	//return usb_queue_byte_count(rx_first[endpoint]);
+}
+*/
+
+uint32_t usb_tx_byte_count(uint32_t endpoint)
+{
+	endpoint--;
+	if (endpoint >= NUM_ENDPOINTS) return 0;
+	return usb_queue_byte_count(tx_first[endpoint]);
+}
+
+uint32_t usb_tx_packet_count(uint32_t endpoint)
+{
+	const usb_packet_t *p;
+	uint32_t count=0;
+
+	endpoint--;
+	if (endpoint >= NUM_ENDPOINTS) return 0;
+	__disable_irq();
+	for (p = tx_first[endpoint]; p; p = p->next) count++;
+	__enable_irq();
+	return count;
+}
+
+
+// Called from usb_free, but only when usb_rx_memory_needed > 0, indicating
+// receive endpoints are starving for memory.  The intention is to give
+// endpoints needing receive memory priority over the user's code, which is
+// likely calling usb_malloc to obtain memory for transmitting.  When the
+// user is creating data very quickly, their consumption could starve reception
+// without this prioritization.  The packet buffer (input) is assigned to the
+// first endpoint needing memory.
+//
+void usb_rx_memory(usb_packet_t *packet)
+{
+	unsigned int i;
+	const uint8_t *cfg;
+
+	cfg = usb_endpoint_config_table;
+	//serial_print("rx_mem:");
+	__disable_irq();
+	for (i=1; i <= NUM_ENDPOINTS; i++) {
+		if (*cfg++ & USB_ENDPT_EPRXEN) {
+			if (table[index(i, RX, EVEN)].desc == 0) {
+				table[index(i, RX, EVEN)].addr = packet->buf;
+				table[index(i, RX, EVEN)].desc = BDT_DESC(64, 0);
+				usb_rx_memory_needed--;
+				__enable_irq();
+				//serial_phex(i);
+				//serial_print(",even\n");
+				return;
+			}
+			if (table[index(i, RX, ODD)].desc == 0) {
+				table[index(i, RX, ODD)].addr = packet->buf;
+				table[index(i, RX, ODD)].desc = BDT_DESC(64, 1);
+				usb_rx_memory_needed--;
+				__enable_irq();
+				//serial_phex(i);
+				//serial_print(",odd\n");
+				return;
+			}
+		}
+	}
+	__enable_irq();
+	// we should never reach this point.  If we get here, it means
+	// usb_rx_memory_needed was set greater than zero, but no memory
+	// was actually needed.
+	usb_rx_memory_needed = 0;
+	usb_free(packet);
+	return;
+}
+
+//#define index(endpoint, tx, odd) (((endpoint) << 2) | ((tx) << 1) | (odd))
+//#define stat2bufferdescriptor(stat) (table + ((stat) >> 2))
+
+void usb_tx(uint32_t endpoint, usb_packet_t *packet)
+{
+	bdt_t *b = &table[index(endpoint, TX, EVEN)];
+	uint8_t next;
+
+	endpoint--;
+	if (endpoint >= NUM_ENDPOINTS) return;
+	__disable_irq();
+	//serial_print("txstate=");
+	//serial_phex(tx_state[endpoint]);
+	//serial_print("\n");
+	switch (tx_state[endpoint]) {
+	  case TX_STATE_BOTH_FREE_EVEN_FIRST:
+		next = TX_STATE_ODD_FREE;
+		break;
+	  case TX_STATE_BOTH_FREE_ODD_FIRST:
+		b++;
+		next = TX_STATE_EVEN_FREE;
+		break;
+	  case TX_STATE_EVEN_FREE:
+		next = TX_STATE_NONE_FREE_ODD_FIRST;
+		break;
+	  case TX_STATE_ODD_FREE:
+		b++;
+		next = TX_STATE_NONE_FREE_EVEN_FIRST;
+		break;
+	  default:
+		if (tx_first[endpoint] == NULL) {
+			tx_first[endpoint] = packet;
+		} else {
+			tx_last[endpoint]->next = packet;
+		}
+		tx_last[endpoint] = packet;
+		__enable_irq();
+		return;
+	}
+	tx_state[endpoint] = next;
+	b->addr = packet->buf;
+	b->desc = BDT_DESC(packet->len, ((uint32_t)b & 8) ? DATA1 : DATA0);
+	__enable_irq();
+}
+
+
+
+
+
+
+void _reboot_Teensyduino_(void)
+{
+	// TODO: initialize R0 with a code....
+	__asm__ volatile("bkpt");
+}
+
+
+
+void usb_isr(void)
+{
+	uint8_t status, stat, t;
+
+	//serial_print("isr");
+	//status = USB0_ISTAT;
+	//serial_phex(status);
+	//serial_print("\n");
+	restart:
+	status = USB0_ISTAT;
+
+	if ((status & USB_INTEN_SOFTOKEN /* 04 */ )) {
+		if (usb_configuration) {
+			t = usb_reboot_timer;
+			if (t) {
+				usb_reboot_timer = --t;
+				if (!t) _reboot_Teensyduino_();
+			}
+#ifdef CDC_DATA_INTERFACE
+			t = usb_cdc_transmit_flush_timer;
+			if (t) {
+				usb_cdc_transmit_flush_timer = --t;
+				if (t == 0) usb_serial_flush_callback();
+			}
+#endif
+#ifdef SEREMU_INTERFACE
+			t = usb_seremu_transmit_flush_timer;
+			if (t) {
+				usb_seremu_transmit_flush_timer = --t;
+				if (t == 0) usb_seremu_flush_callback();
+			}
+#endif
+#ifdef MIDI_INTERFACE
+                        usb_midi_flush_output();
+#endif
+#ifdef FLIGHTSIM_INTERFACE
+			usb_flightsim_flush_callback();
+#endif
+		}
+		USB0_ISTAT = USB_INTEN_SOFTOKEN;
+	}
+
+	if ((status & USB_ISTAT_TOKDNE /* 08 */ )) {
+		uint8_t endpoint;
+		stat = USB0_STAT;
+		//serial_print("token: ep=");
+		//serial_phex(stat >> 4);
+		//serial_print(stat & 0x08 ? ",tx" : ",rx");
+		//serial_print(stat & 0x04 ? ",odd\n" : ",even\n");
+		endpoint = stat >> 4;
+		if (endpoint == 0) {
+			usb_control(stat);
+		} else {
+			bdt_t *b = stat2bufferdescriptor(stat);
+			usb_packet_t *packet = (usb_packet_t *)((uint8_t *)(b->addr) - 8);
+#if 0
+			serial_print("ep:");
+			serial_phex(endpoint);
+			serial_print(", pid:");
+			serial_phex(BDT_PID(b->desc));
+			serial_print(((uint32_t)b & 8) ? ", odd" : ", even");
+			serial_print(", count:");
+			serial_phex(b->desc >> 16);
+			serial_print("\n");
+#endif
+			endpoint--;	// endpoint is index to zero-based arrays
+
+			if (stat & 0x08) { // transmit
+				usb_free(packet);
+				packet = tx_first[endpoint];
+				if (packet) {
+					//serial_print("tx packet\n");
+					tx_first[endpoint] = packet->next;
+					b->addr = packet->buf;
+					switch (tx_state[endpoint]) {
+					  case TX_STATE_BOTH_FREE_EVEN_FIRST:
+						tx_state[endpoint] = TX_STATE_ODD_FREE;
+						break;
+					  case TX_STATE_BOTH_FREE_ODD_FIRST:
+						tx_state[endpoint] = TX_STATE_EVEN_FREE;
+						break;
+					  case TX_STATE_EVEN_FREE:
+						tx_state[endpoint] = TX_STATE_NONE_FREE_ODD_FIRST;
+						break;
+					  case TX_STATE_ODD_FREE:
+						tx_state[endpoint] = TX_STATE_NONE_FREE_EVEN_FIRST;
+						break;
+					  default:
+						break;
+					}
+					b->desc = BDT_DESC(packet->len, ((uint32_t)b & 8) ? DATA1 : DATA0);
+				} else {
+					//serial_print("tx no packet\n");
+					switch (tx_state[endpoint]) {
+					  case TX_STATE_BOTH_FREE_EVEN_FIRST:
+					  case TX_STATE_BOTH_FREE_ODD_FIRST:
+						break;
+					  case TX_STATE_EVEN_FREE:
+						tx_state[endpoint] = TX_STATE_BOTH_FREE_EVEN_FIRST;
+						break;
+					  case TX_STATE_ODD_FREE:
+						tx_state[endpoint] = TX_STATE_BOTH_FREE_ODD_FIRST;
+						break;
+					  default:
+						tx_state[endpoint] = ((uint32_t)b & 8) ?
+						  TX_STATE_ODD_FREE : TX_STATE_EVEN_FREE;
+						break;
+					}
+				}
+			} else { // receive
+				packet->len = b->desc >> 16;
+				if (packet->len > 0) {
+					packet->index = 0;
+					packet->next = NULL;
+					if (rx_first[endpoint] == NULL) {
+						//serial_print("rx 1st, epidx=");
+						//serial_phex(endpoint);
+						//serial_print(", packet=");
+						//serial_phex32((uint32_t)packet);
+						//serial_print("\n");
+						rx_first[endpoint] = packet;
+					} else {
+						//serial_print("rx Nth, epidx=");
+						//serial_phex(endpoint);
+						//serial_print(", packet=");
+						//serial_phex32((uint32_t)packet);
+						//serial_print("\n");
+						rx_last[endpoint]->next = packet;
+					}
+					rx_last[endpoint] = packet;
+					usb_rx_byte_count_data[endpoint] += packet->len;
+					// TODO: implement a per-endpoint maximum # of allocated packets
+					// so a flood of incoming data on 1 endpoint doesn't starve
+					// the others if the user isn't reading it regularly
+					packet = usb_malloc();
+					if (packet) {
+						b->addr = packet->buf;
+						b->desc = BDT_DESC(64, ((uint32_t)b & 8) ? DATA1 : DATA0);
+					} else {
+						//serial_print("starving ");
+						//serial_phex(endpoint + 1);
+						//serial_print(((uint32_t)b & 8) ? ",odd\n" : ",even\n");
+						b->desc = 0;
+						usb_rx_memory_needed++;
+					}
+				} else {
+					b->desc = BDT_DESC(64, ((uint32_t)b & 8) ? DATA1 : DATA0);
+				}
+			}
+
+
+
+
+		}
+		USB0_ISTAT = USB_ISTAT_TOKDNE;
+		goto restart;
+	}
+
+
+
+	if (status & USB_ISTAT_USBRST /* 01 */ ) {
+		//serial_print("reset\n");
+
+		// initialize BDT toggle bits
+		USB0_CTL = USB_CTL_ODDRST;
+		ep0_tx_bdt_bank = 0;
+
+		// set up buffers to receive Setup and OUT packets
+		table[index(0, RX, EVEN)].desc = BDT_DESC(EP0_SIZE, 0);
+		table[index(0, RX, EVEN)].addr = ep0_rx0_buf;
+		table[index(0, RX, ODD)].desc = BDT_DESC(EP0_SIZE, 0);
+		table[index(0, RX, ODD)].addr = ep0_rx1_buf;
+		table[index(0, TX, EVEN)].desc = 0;
+		table[index(0, TX, ODD)].desc = 0;
+
+		// activate endpoint 0
+		USB0_ENDPT0 = USB_ENDPT_EPRXEN | USB_ENDPT_EPTXEN | USB_ENDPT_EPHSHK;
+
+		// clear all ending interrupts
+		USB0_ERRSTAT = 0xFF;
+		USB0_ISTAT = 0xFF;
+
+		// set the address to zero during enumeration
+		USB0_ADDR = 0;
+
+		// enable other interrupts
+		USB0_ERREN = 0xFF;
+		USB0_INTEN = USB_INTEN_TOKDNEEN |
+			USB_INTEN_SOFTOKEN |
+			USB_INTEN_STALLEN |
+			USB_INTEN_ERROREN |
+			USB_INTEN_USBRSTEN |
+			USB_INTEN_SLEEPEN;
+
+		// is this necessary?
+		USB0_CTL = USB_CTL_USBENSOFEN;
+		return;
+	}
+
+
+	if ((status & USB_ISTAT_STALL /* 80 */ )) {
+		//serial_print("stall:\n");
+		USB0_ENDPT0 = USB_ENDPT_EPRXEN | USB_ENDPT_EPTXEN | USB_ENDPT_EPHSHK;
+		USB0_ISTAT = USB_ISTAT_STALL;
+	}
+	if ((status & USB_ISTAT_ERROR /* 02 */ )) {
+		uint8_t err = USB0_ERRSTAT;
+		USB0_ERRSTAT = err;
+		//serial_print("err:");
+		//serial_phex(err);
+		//serial_print("\n");
+		USB0_ISTAT = USB_ISTAT_ERROR;
+	}
+
+	if ((status & USB_ISTAT_SLEEP /* 10 */ )) {
+		//serial_print("sleep\n");
+		USB0_ISTAT = USB_ISTAT_SLEEP;
+	}
+
+}
+
+
+
+void usb_init(void)
+{
+	int i;
+
+	//serial_begin(BAUD2DIV(115200));
+	//serial_print("usb_init\n");
+
+	usb_init_serialnumber();
+
+	for (i=0; i <= NUM_ENDPOINTS*4; i++) {
+		table[i].desc = 0;
+		table[i].addr = 0;
+	}
+
+	// this basically follows the flowchart in the Kinetis
+	// Quick Reference User Guide, Rev. 1, 03/2012, page 141
+
+	// assume 48 MHz clock already running
+	// SIM - enable clock
+	SIM_SCGC4 |= SIM_SCGC4_USBOTG;
+
+	// reset USB module
+	USB0_USBTRC0 = USB_USBTRC_USBRESET;
+	while ((USB0_USBTRC0 & USB_USBTRC_USBRESET) != 0) ; // wait for reset to end
+
+	// set desc table base addr
+	USB0_BDTPAGE1 = ((uint32_t)table) >> 8;
+	USB0_BDTPAGE2 = ((uint32_t)table) >> 16;
+	USB0_BDTPAGE3 = ((uint32_t)table) >> 24;
+
+	// clear all ISR flags
+	USB0_ISTAT = 0xFF;
+	USB0_ERRSTAT = 0xFF;
+	USB0_OTGISTAT = 0xFF;
+
+	USB0_USBTRC0 |= 0x40; // undocumented bit
+
+	// enable USB
+	USB0_CTL = USB_CTL_USBENSOFEN;
+	USB0_USBCTRL = 0;
+
+	// enable reset interrupt
+	USB0_INTEN = USB_INTEN_USBRSTEN;
+
+	// enable interrupt in NVIC...
+	NVIC_SET_PRIORITY(IRQ_USBOTG, 112);
+	NVIC_ENABLE_IRQ(IRQ_USBOTG);
+
+	// enable d+ pullup
+	USB0_CONTROL = USB_CONTROL_DPPULLUPNONOTG;
+}
+
+
+#else // F_CPU < 20 MHz
+
+void usb_init(void)
+{
+}
+
+#endif // F_CPU >= 20 MHz