X-Git-Url: http://cvs.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/8b9de94afe7436eb14bf6e6c801bd4054842abe2..555fa197730c061bbf0ab01334e99bc47fb3dc06:/common/usb_cdc.c?ds=inline

diff --git a/common/usb_cdc.c b/common/usb_cdc.c
index 3553d850..acd16b4e 100644
--- a/common/usb_cdc.c
+++ b/common/usb_cdc.c
@@ -33,10 +33,15 @@
  */
 
 #include "usb_cdc.h"
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "common.h"
 #include "at91sam7s512.h"
 #include "config_gpio.h"
 
-
 #define AT91C_EP_CONTROL     0
 #define AT91C_EP_OUT         1
 #define AT91C_EP_IN          2
@@ -49,6 +54,7 @@
 #define STR_MANUFACTURER   0x01
 #define STR_PRODUCT        0x02
 
+
 static const char devDescriptor[] = {
 	/* Device descriptor */
 	0x12,      // bLength
@@ -67,6 +73,7 @@ static const char devDescriptor[] = {
 	0x01       // bNumConfigs
 };
 
+
 static const char cfgDescriptor[] = {
 	/* ============== CONFIGURATION 1 =========== */
 	/* Configuration 1 descriptor */
@@ -157,41 +164,50 @@ static const char cfgDescriptor[] = {
 	0x00    // bInterval
 };
 
+
 static const char StrDescLanguageCodes[] = {
-  4,			// Length
-  0x03,			// Type is string
-  0x09, 0x04	// supported language Code 0 = 0x0409 (English)
+	4,          // Length
+	0x03,       // Type is string
+	0x09, 0x04  // supported language Code 0 = 0x0409 (English)
 };
 
+
 // Note: ModemManager (Linux) ignores Proxmark3 devices by matching the
 // manufacturer string "proxmark.org". Don't change this.
 static const char StrDescManufacturer[] = {
-  26,			// Length
-  0x03,			// Type is string
-  'p', 0x00,
-  'r', 0x00,
-  'o', 0x00,
-  'x', 0x00,
-  'm', 0x00,
-  'a', 0x00,
-  'r', 0x00,
-  'k', 0x00,
-  '.', 0x00,
-  'o', 0x00,
-  'r', 0x00,
-  'g', 0x00
+	26,         // Length
+	0x03,       // Type is string
+	'p', 0x00,
+	'r', 0x00,
+	'o', 0x00,
+	'x', 0x00,
+	'm', 0x00,
+	'a', 0x00,
+	'r', 0x00,
+	'k', 0x00,
+	'.', 0x00,
+	'o', 0x00,
+	'r', 0x00,
+	'g', 0x00
 };
 
+
 static const char StrDescProduct[] = {
-  8,			// Length
-  0x03,			// Type is string
-  'P', 0x00,
-  'M', 0x00,
-  '3', 0x00
+	20,         // Length
+	0x03,       // Type is string
+	'p', 0x00,
+	'r', 0x00,
+	'o', 0x00,
+	'x', 0x00,
+	'm', 0x00,
+	'a', 0x00,
+	'r', 0x00,
+	'k', 0x00,
+	'3', 0x00
 };
 
-const char* getStringDescriptor(uint8_t idx)
-{
+
+static const char* getStringDescriptor(uint8_t idx) {
 	switch (idx) {
 		case STR_LANGUAGE_CODES:
 			return StrDescLanguageCodes;
@@ -204,29 +220,31 @@ const char* getStringDescriptor(uint8_t idx)
 	}
 }
 
+
 // Bitmap for all status bits in CSR which must be written as 1 to cause no effect
-#define REG_NO_EFFECT_1_ALL      AT91C_UDP_RX_DATA_BK0 | AT91C_UDP_RX_DATA_BK1 \
-                                |AT91C_UDP_STALLSENT   | AT91C_UDP_RXSETUP \
-                                |AT91C_UDP_TXCOMP
+#define REG_NO_EFFECT_1_ALL     (AT91C_UDP_RX_DATA_BK0 | AT91C_UDP_RX_DATA_BK1 | AT91C_UDP_STALLSENT | AT91C_UDP_RXSETUP | AT91C_UDP_TXCOMP)
+
 
 // Clear flags in the UDP_CSR register
 #define UDP_CLEAR_EP_FLAGS(endpoint, flags) { \
 	volatile unsigned int reg; \
-	reg = pUdp->UDP_CSR[(endpoint)]; \
+	reg = AT91C_BASE_UDP->UDP_CSR[(endpoint)]; \
 	reg |= REG_NO_EFFECT_1_ALL; \
 	reg &= ~(flags); \
-	pUdp->UDP_CSR[(endpoint)] = reg; \
-} 
+	AT91C_BASE_UDP->UDP_CSR[(endpoint)] = reg; \
+}
+
 
 // Set flags in the UDP_CSR register
 #define UDP_SET_EP_FLAGS(endpoint, flags) { \
 	volatile unsigned int reg; \
-	reg = pUdp->UDP_CSR[(endpoint)]; \
+	reg = AT91C_BASE_UDP->UDP_CSR[(endpoint)]; \
 	reg |= REG_NO_EFFECT_1_ALL; \
 	reg |= (flags); \
-	pUdp->UDP_CSR[(endpoint)] = reg; \
+	AT91C_BASE_UDP->UDP_CSR[(endpoint)] = reg; \
 }
 
+
 /* USB standard request codes */
 #define STD_GET_STATUS_ZERO           0x0080
 #define STD_GET_STATUS_INTERFACE      0x0081
@@ -254,6 +272,7 @@ const char* getStringDescriptor(uint8_t idx)
 #define SET_LINE_CODING               0x2021
 #define SET_CONTROL_LINE_STATE        0x2221
 
+
 typedef struct {
 	unsigned int dwDTERRate;
 	char bCharFormat;
@@ -261,19 +280,17 @@ typedef struct {
 	char bDataBits;
 } AT91S_CDC_LINE_CODING, *AT91PS_CDC_LINE_CODING;
 
-AT91S_CDC_LINE_CODING line = {
+
+static AT91S_CDC_LINE_CODING line = {
 	115200, // baudrate
 	0,      // 1 Stop Bit
 	0,      // None Parity
 	8};     // 8 Data bits
 
 
-void AT91F_CDC_Enumerate();
-
-AT91PS_UDP pUdp = AT91C_BASE_UDP;
-byte_t btConfiguration = 0;
-byte_t btConnection    = 0;
-byte_t btReceiveBank   = AT91C_UDP_RX_DATA_BK0;
+static uint8_t btConfiguration = 0;
+static uint8_t btConnection    = 0;
+static uint8_t btReceiveBank   = AT91C_UDP_RX_DATA_BK0;
 
 
 //*----------------------------------------------------------------------------
@@ -285,8 +302,8 @@ void usb_disable() {
 	AT91C_BASE_PIOA->PIO_ODR = GPIO_USB_PU;
 
 	// Clear all lingering interrupts
-	if(pUdp->UDP_ISR & AT91C_UDP_ENDBUSRES) {
-		pUdp->UDP_ICR = AT91C_UDP_ENDBUSRES;
+	if (AT91C_BASE_UDP->UDP_ISR & AT91C_UDP_ENDBUSRES) {
+		AT91C_BASE_UDP->UDP_ICR = AT91C_UDP_ENDBUSRES;
 	}
 }
 
@@ -316,7 +333,7 @@ void usb_enable() {
 	usb_disable();
 
 	// Wait for a short while
-	for (volatile size_t i=0; i<0x100000; i++);
+	for (volatile size_t i = 0; i < 0x100000; i++);
 
 	// Reconnect USB reconnect
 	AT91C_BASE_PIOA->PIO_SODR = GPIO_USB_PU;
@@ -325,127 +342,16 @@ void usb_enable() {
 
 
 //*----------------------------------------------------------------------------
-//* \fn    usb_check
-//* \brief Test if the device is configured and handle enumeration
-//*----------------------------------------------------------------------------
-bool usb_check() {
-	AT91_REG isr = pUdp->UDP_ISR;
-
-	if (isr & AT91C_UDP_ENDBUSRES) {
-		pUdp->UDP_ICR = AT91C_UDP_ENDBUSRES;
-		// reset all endpoints
-		pUdp->UDP_RSTEP  = (unsigned int)-1;
-		pUdp->UDP_RSTEP  = 0;
-		// Enable the function
-		pUdp->UDP_FADDR = AT91C_UDP_FEN;
-		// Configure endpoint 0
-		pUdp->UDP_CSR[AT91C_EP_CONTROL] = (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_CTRL);
-	} else if (isr & AT91C_UDP_EPINT0) {
-		pUdp->UDP_ICR = AT91C_UDP_EPINT0;
-		AT91F_CDC_Enumerate();
-	}
-	return (btConfiguration) ? true : false;
-}
-
-
-bool usb_poll()
-{
-	if (!usb_check()) return false;
-	return (pUdp->UDP_CSR[AT91C_EP_OUT] & btReceiveBank);
-}
-
-
-/**
-	In github PR #129, some users appears to get a false positive from
-	usb_poll, which returns true, but the usb_read operation
-	still returns 0.
-	This check is basically the same as above, but also checks
-	that the length available to read is non-zero, thus hopefully fixes the
-	bug.
-**/
-bool usb_poll_validate_length()
-{
-	if (!usb_check()) return false;
-	if (!(pUdp->UDP_CSR[AT91C_EP_OUT] & btReceiveBank)) return false;
-	return (pUdp->UDP_CSR[AT91C_EP_OUT] >> 16) >  0;
-}
-
-//*----------------------------------------------------------------------------
-//* \fn    usb_read
-//* \brief Read available data from Endpoint OUT
-//*----------------------------------------------------------------------------
-uint32_t usb_read(byte_t* data, size_t len) {
-	byte_t bank = btReceiveBank;
-	uint32_t packetSize, nbBytesRcv = 0;
-	uint32_t time_out = 0;
-  
-	while (len)  {
-		if (!usb_check()) break;
-
-		if ( pUdp->UDP_CSR[AT91C_EP_OUT] & bank ) {
-			packetSize = MIN(pUdp->UDP_CSR[AT91C_EP_OUT] >> 16, len);
-			len -= packetSize;
-			while(packetSize--)
-				data[nbBytesRcv++] = pUdp->UDP_FDR[AT91C_EP_OUT];
-			UDP_CLEAR_EP_FLAGS(AT91C_EP_OUT, bank);
-			if (bank == AT91C_UDP_RX_DATA_BK0) {
-				bank = AT91C_UDP_RX_DATA_BK1;
-			} else {
-				bank = AT91C_UDP_RX_DATA_BK0;
-			}
-		}
-		if (time_out++ == 0x1fff) break;
-	}
-
-	btReceiveBank = bank;
-	return nbBytesRcv;
-}
-
-
-//*----------------------------------------------------------------------------
-//* \fn    usb_write
-//* \brief Send through endpoint 2
+//* \fn    AT91F_USB_SendZlp
+//* \brief Send zero length packet through an endpoint
 //*----------------------------------------------------------------------------
-uint32_t usb_write(const byte_t* data, const size_t len) {
-	size_t length = len;
-	uint32_t cpt = 0;
-
-	if (!length) return 0;
-	if (!usb_check()) return 0;
-
-	// Send the first packet
-	cpt = MIN(length, AT91C_EP_IN_SIZE);
-	length -= cpt;
-	while (cpt--) {
-		pUdp->UDP_FDR[AT91C_EP_IN] = *data++;
-	}
-	UDP_SET_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXPKTRDY);
-
-	while (length) {
-		// Fill the next bank
-		cpt = MIN(length, AT91C_EP_IN_SIZE);
-		length -= cpt;
-		while (cpt--) {
-			pUdp->UDP_FDR[AT91C_EP_IN] = *data++;
-		}
-		// Wait for the previous bank to be sent
-		while (!(pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP)) {
-			if (!usb_check()) return length;
-		}
-		UDP_CLEAR_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXCOMP);
-		while (pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP);
-		UDP_SET_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXPKTRDY);
-	}
-
-	// Wait for the end of transfer
-	while (!(pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP)) {
-		if (!usb_check()) return length;
-	}
-
-	UDP_CLEAR_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXCOMP);
-	while (pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP);
-
-	return length;
+static void AT91F_USB_SendZlp(uint8_t endpoint) {
+	UDP_SET_EP_FLAGS(endpoint, AT91C_UDP_TXPKTRDY);
+	while (!(AT91C_BASE_UDP->UDP_CSR[endpoint] & AT91C_UDP_TXCOMP))
+		/* wait */;
+	UDP_CLEAR_EP_FLAGS(endpoint, AT91C_UDP_TXCOMP);
+	while (AT91C_BASE_UDP->UDP_CSR[endpoint] & AT91C_UDP_TXCOMP)
+		/* wait */;
 }
 
 
@@ -453,10 +359,7 @@ uint32_t usb_write(const byte_t* data, const size_t len) {
 //* \fn    AT91F_USB_SendData
 //* \brief Send Data through the control endpoint
 //*----------------------------------------------------------------------------
-unsigned int csrTab[100] = {0x00};
-unsigned char csrIdx = 0;
-
-static void AT91F_USB_SendData(AT91PS_UDP pUdp, const char *pData, uint32_t length) {
+static void AT91F_USB_SendData(const char *pData, uint32_t length) {
 	uint32_t cpt = 0;
 	AT91_REG csr;
 
@@ -465,54 +368,46 @@ static void AT91F_USB_SendData(AT91PS_UDP pUdp, const char *pData, uint32_t leng
 		length -= cpt;
 
 		while (cpt--)
-			pUdp->UDP_FDR[0] = *pData++;
+			AT91C_BASE_UDP->UDP_FDR[0] = *pData++;
 
-		if (pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP) {
+		if (AT91C_BASE_UDP->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP) {
 			UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_TXCOMP);
-			while (pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP);
+			while (AT91C_BASE_UDP->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP)
+				/* wait */;
 		}
 
 		UDP_SET_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_TXPKTRDY);
 		do {
-			csr = pUdp->UDP_CSR[AT91C_EP_CONTROL];
+			csr = AT91C_BASE_UDP->UDP_CSR[AT91C_EP_CONTROL];
 
 			// Data IN stage has been stopped by a status OUT
 			if (csr & AT91C_UDP_RX_DATA_BK0) {
 				UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_RX_DATA_BK0);
 				return;
 			}
-		} while ( !(csr & AT91C_UDP_TXCOMP) );
+		} while (!(csr & AT91C_UDP_TXCOMP));
 
 	} while (length);
 
-	if (pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP) {
+	if (AT91C_BASE_UDP->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP) {
 		UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_TXCOMP);
-		while (pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP);
+		while (AT91C_BASE_UDP->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP)
+			/* wait */;
 	}
 }
 
 
-//*----------------------------------------------------------------------------
-//* \fn    AT91F_USB_SendZlp
-//* \brief Send zero length packet through the control endpoint
-//*----------------------------------------------------------------------------
-void AT91F_USB_SendZlp(AT91PS_UDP pUdp) {
-	UDP_SET_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_TXPKTRDY);
-	while ( !(pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP) );
-	UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_TXCOMP);
-	while (pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP);
-}
-
-
 //*----------------------------------------------------------------------------
 //* \fn    AT91F_USB_SendStall
 //* \brief Stall the control endpoint
 //*----------------------------------------------------------------------------
-void AT91F_USB_SendStall(AT91PS_UDP pUdp) {
+static void AT91F_USB_SendStall(void) {
 	UDP_SET_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_FORCESTALL);
-	while ( !(pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_ISOERROR) );
+	while (!(AT91C_BASE_UDP->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_ISOERROR))
+		/* wait */;
 	UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_FORCESTALL | AT91C_UDP_ISOERROR);
-	while (pUdp->UDP_CSR[AT91C_EP_CONTROL] & (AT91C_UDP_FORCESTALL | AT91C_UDP_ISOERROR));
+	while (AT91C_BASE_UDP->UDP_CSR[AT91C_EP_CONTROL] & (AT91C_UDP_FORCESTALL | AT91C_UDP_ISOERROR))
+		/* wait */;
 }
 
 
@@ -520,138 +415,349 @@ void AT91F_USB_SendStall(AT91PS_UDP pUdp) {
 //* \fn    AT91F_CDC_Enumerate
 //* \brief This function is a callback invoked when a SETUP packet is received
 //*----------------------------------------------------------------------------
-void AT91F_CDC_Enumerate() {
-	byte_t bmRequestType, bRequest;
+static void AT91F_CDC_Enumerate() {
+	uint8_t bmRequestType, bRequest;
 	uint16_t wValue, wIndex, wLength, wStatus;
 
-	if ( !(pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_RXSETUP) )
+	if (!(AT91C_BASE_UDP->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_RXSETUP))
 		return;
 
-	bmRequestType = pUdp->UDP_FDR[AT91C_EP_CONTROL];
-	bRequest      = pUdp->UDP_FDR[AT91C_EP_CONTROL];
-	wValue        = (pUdp->UDP_FDR[AT91C_EP_CONTROL] & 0xFF);
-	wValue       |= (pUdp->UDP_FDR[AT91C_EP_CONTROL] << 8);
-	wIndex        = (pUdp->UDP_FDR[AT91C_EP_CONTROL] & 0xFF);
-	wIndex       |= (pUdp->UDP_FDR[AT91C_EP_CONTROL] << 8);
-	wLength       = (pUdp->UDP_FDR[AT91C_EP_CONTROL] & 0xFF);
-	wLength      |= (pUdp->UDP_FDR[AT91C_EP_CONTROL] << 8);
+	bmRequestType = AT91C_BASE_UDP->UDP_FDR[AT91C_EP_CONTROL];
+	bRequest      = AT91C_BASE_UDP->UDP_FDR[AT91C_EP_CONTROL];
+	wValue        = (AT91C_BASE_UDP->UDP_FDR[AT91C_EP_CONTROL] & 0xFF);
+	wValue       |= (AT91C_BASE_UDP->UDP_FDR[AT91C_EP_CONTROL] << 8);
+	wIndex        = (AT91C_BASE_UDP->UDP_FDR[AT91C_EP_CONTROL] & 0xFF);
+	wIndex       |= (AT91C_BASE_UDP->UDP_FDR[AT91C_EP_CONTROL] << 8);
+	wLength       = (AT91C_BASE_UDP->UDP_FDR[AT91C_EP_CONTROL] & 0xFF);
+	wLength      |= (AT91C_BASE_UDP->UDP_FDR[AT91C_EP_CONTROL] << 8);
 
-	if (bmRequestType & 0x80) {	// Data Phase Transfer Direction Device to Host
+	if (bmRequestType & 0x80) { // Data Phase Transfer Direction Device to Host
 		UDP_SET_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_DIR);
-		while ( !(pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_DIR) );
+		while (!(AT91C_BASE_UDP->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_DIR))
+			/* wait */;
 	}
 	UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_RXSETUP);
-	while ( (pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_RXSETUP)  );
+	while (AT91C_BASE_UDP->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_RXSETUP)
+		/* wait */;
 
 	// Handle supported standard device request Cf Table 9-3 in USB specification Rev 1.1
 	switch ((bRequest << 8) | bmRequestType) {
 	case STD_GET_DESCRIPTOR:
 		if (wValue == 0x100)       // Return Device Descriptor
-			AT91F_USB_SendData(pUdp, devDescriptor, MIN(sizeof(devDescriptor), wLength));
+			AT91F_USB_SendData(devDescriptor, MIN(sizeof(devDescriptor), wLength));
 		else if (wValue == 0x200)  // Return Configuration Descriptor
-			AT91F_USB_SendData(pUdp, cfgDescriptor, MIN(sizeof(cfgDescriptor), wLength));
-		else if ((wValue & 0x300) == 0x300)  // Return Manufacturer Descriptor - this is needed by Android
-			AT91F_USB_SendData(pUdp, StrDescManufacturer, MIN(sizeof(StrDescManufacturer), wLength));
+			AT91F_USB_SendData(cfgDescriptor, MIN(sizeof(cfgDescriptor), wLength));
 		else if ((wValue & 0xF00) == 0x300) { // Return String Descriptor
 			const char *strDescriptor = getStringDescriptor(wValue & 0xff);
 			if (strDescriptor != NULL) {
-				AT91F_USB_SendData(pUdp, strDescriptor, MIN(strDescriptor[0], wLength));
+				AT91F_USB_SendData(strDescriptor, MIN(strDescriptor[0], wLength));
 			} else {
-				AT91F_USB_SendStall(pUdp);
+				AT91F_USB_SendStall();
 			}
 		}
 		else
-			AT91F_USB_SendStall(pUdp);
+			AT91F_USB_SendStall();
 		break;
 	case STD_SET_ADDRESS:
-		AT91F_USB_SendZlp(pUdp);
-		pUdp->UDP_FADDR = (AT91C_UDP_FEN | wValue);
-		pUdp->UDP_GLBSTATE  = (wValue) ? AT91C_UDP_FADDEN : 0;
+		AT91F_USB_SendZlp(AT91C_EP_CONTROL);
+		AT91C_BASE_UDP->UDP_FADDR = (AT91C_UDP_FEN | wValue);
+		AT91C_BASE_UDP->UDP_GLBSTATE  = (wValue) ? AT91C_UDP_FADDEN : 0;
 		break;
 	case STD_SET_CONFIGURATION:
 		btConfiguration = wValue;
-		AT91F_USB_SendZlp(pUdp);
-		pUdp->UDP_GLBSTATE  = (wValue) ? AT91C_UDP_CONFG : AT91C_UDP_FADDEN;
-		pUdp->UDP_CSR[AT91C_EP_OUT]    = (wValue) ? (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_BULK_OUT) : 0;
-		pUdp->UDP_CSR[AT91C_EP_IN]     = (wValue) ? (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_BULK_IN)  : 0;
-		pUdp->UDP_CSR[AT91C_EP_NOTIFY] = (wValue) ? (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_INT_IN)   : 0;
+		AT91F_USB_SendZlp(AT91C_EP_CONTROL);
+		AT91C_BASE_UDP->UDP_GLBSTATE  = (wValue) ? AT91C_UDP_CONFG : AT91C_UDP_FADDEN;
+		AT91C_BASE_UDP->UDP_CSR[AT91C_EP_OUT]    = (wValue) ? (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_BULK_OUT) : 0;
+		AT91C_BASE_UDP->UDP_CSR[AT91C_EP_IN]     = (wValue) ? (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_BULK_IN)  : 0;
+		AT91C_BASE_UDP->UDP_CSR[AT91C_EP_NOTIFY] = (wValue) ? (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_INT_IN)   : 0;
 		break;
 	case STD_GET_CONFIGURATION:
-		AT91F_USB_SendData(pUdp, (char *) &(btConfiguration), sizeof(btConfiguration));
+		AT91F_USB_SendData((char *) &(btConfiguration), sizeof(btConfiguration));
 		break;
 	case STD_GET_STATUS_ZERO:
-		wStatus = 0;	// Device is Bus powered, remote wakeup disabled
-		AT91F_USB_SendData(pUdp, (char *) &wStatus, sizeof(wStatus));
+		wStatus = 0;    // Device is Bus powered, remote wakeup disabled
+		AT91F_USB_SendData((char *) &wStatus, sizeof(wStatus));
 		break;
 	case STD_GET_STATUS_INTERFACE:
-		wStatus = 0; 	// reserved for future use
-		AT91F_USB_SendData(pUdp, (char *) &wStatus, sizeof(wStatus));
+		wStatus = 0;    // reserved for future use
+		AT91F_USB_SendData((char *) &wStatus, sizeof(wStatus));
 		break;
 	case STD_GET_STATUS_ENDPOINT:
 		wStatus = 0;
 		wIndex &= 0x0F;
-		if ((pUdp->UDP_GLBSTATE & AT91C_UDP_CONFG) && (wIndex <= AT91C_EP_NOTIFY)) {
-			wStatus = (pUdp->UDP_CSR[wIndex] & AT91C_UDP_EPEDS) ? 0 : 1;
-			AT91F_USB_SendData(pUdp, (char *) &wStatus, sizeof(wStatus));
-		}
-		else if ((pUdp->UDP_GLBSTATE & AT91C_UDP_FADDEN) && (wIndex == AT91C_EP_CONTROL)) {
-			wStatus = (pUdp->UDP_CSR[wIndex] & AT91C_UDP_EPEDS) ? 0 : 1;
-			AT91F_USB_SendData(pUdp, (char *) &wStatus, sizeof(wStatus));
-		}
-		else
-			AT91F_USB_SendStall(pUdp);
+		if ((AT91C_BASE_UDP->UDP_GLBSTATE & AT91C_UDP_CONFG) && (wIndex <= AT91C_EP_NOTIFY)) {
+			wStatus = (AT91C_BASE_UDP->UDP_CSR[wIndex] & AT91C_UDP_EPEDS) ? 0 : 1;
+			AT91F_USB_SendData((char *) &wStatus, sizeof(wStatus));
+		} else if ((AT91C_BASE_UDP->UDP_GLBSTATE & AT91C_UDP_FADDEN) && (wIndex == AT91C_EP_CONTROL)) {
+			wStatus = (AT91C_BASE_UDP->UDP_CSR[wIndex] & AT91C_UDP_EPEDS) ? 0 : 1;
+			AT91F_USB_SendData((char *) &wStatus, sizeof(wStatus));
+		} else
+			AT91F_USB_SendStall();
 		break;
 	case STD_SET_FEATURE_ZERO:
-		AT91F_USB_SendStall(pUdp);
-	    break;
+		AT91F_USB_SendStall();
+		break;
 	case STD_SET_FEATURE_INTERFACE:
-		AT91F_USB_SendZlp(pUdp);
+		AT91F_USB_SendZlp(AT91C_EP_CONTROL);
 		break;
 	case STD_SET_FEATURE_ENDPOINT:
 		wIndex &= 0x0F;
 		if ((wValue == 0) && (wIndex >= AT91C_EP_OUT) && (wIndex <= AT91C_EP_NOTIFY)) {
-			pUdp->UDP_CSR[wIndex] = 0;
-			AT91F_USB_SendZlp(pUdp);
-		}
-		else
-			AT91F_USB_SendStall(pUdp);
+			AT91C_BASE_UDP->UDP_CSR[wIndex] = 0;
+			AT91F_USB_SendZlp(AT91C_EP_CONTROL);
+		} else
+			AT91F_USB_SendStall();
 		break;
 	case STD_CLEAR_FEATURE_ZERO:
-		AT91F_USB_SendStall(pUdp);
-	    break;
+		AT91F_USB_SendStall();
+		break;
 	case STD_CLEAR_FEATURE_INTERFACE:
-		AT91F_USB_SendZlp(pUdp);
+		AT91F_USB_SendZlp(AT91C_EP_CONTROL);
 		break;
 	case STD_CLEAR_FEATURE_ENDPOINT:
 		wIndex &= 0x0F;
 		if ((wValue == 0) && (wIndex >= AT91C_EP_OUT) && (wIndex <= AT91C_EP_NOTIFY)) {
 			if (wIndex == AT91C_EP_OUT)
-				pUdp->UDP_CSR[AT91C_EP_OUT] = (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_BULK_OUT);
+				AT91C_BASE_UDP->UDP_CSR[AT91C_EP_OUT] = (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_BULK_OUT);
 			else if (wIndex == AT91C_EP_IN)
-				pUdp->UDP_CSR[AT91C_EP_IN] = (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_BULK_IN);
+				AT91C_BASE_UDP->UDP_CSR[AT91C_EP_IN] = (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_BULK_IN);
 			else if (wIndex == AT91C_EP_NOTIFY)
-				pUdp->UDP_CSR[AT91C_EP_NOTIFY] = (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_INT_IN);
-			AT91F_USB_SendZlp(pUdp);
+				AT91C_BASE_UDP->UDP_CSR[AT91C_EP_NOTIFY] = (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_INT_IN);
+			AT91F_USB_SendZlp(AT91C_EP_CONTROL);
 		}
 		else
-			AT91F_USB_SendStall(pUdp);
+			AT91F_USB_SendStall();
 		break;
 
 	// handle CDC class requests
 	case SET_LINE_CODING:
-		while ( !(pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_RX_DATA_BK0) );
+		while (!(AT91C_BASE_UDP->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_RX_DATA_BK0))
+			/* wait */;
 		UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_RX_DATA_BK0);
-		AT91F_USB_SendZlp(pUdp);
+		AT91F_USB_SendZlp(AT91C_EP_CONTROL);
 		break;
 	case GET_LINE_CODING:
-		AT91F_USB_SendData(pUdp, (char *) &line, MIN(sizeof(line), wLength));
+		AT91F_USB_SendData((char *) &line, MIN(sizeof(line), wLength));
 		break;
 	case SET_CONTROL_LINE_STATE:
 		btConnection = wValue;
-		AT91F_USB_SendZlp(pUdp);
+		AT91F_USB_SendZlp(AT91C_EP_CONTROL);
 		break;
 	default:
-		AT91F_USB_SendStall(pUdp);
-	    break;
+		AT91F_USB_SendStall();
+		break;
+	}
+}
+
+
+//*----------------------------------------------------------------------------
+//* \fn    usb_check
+//* \brief Test if the device is configured and handle enumeration
+//*----------------------------------------------------------------------------
+static bool usb_check() {
+	AT91_REG isr = AT91C_BASE_UDP->UDP_ISR;
+
+	if (isr & AT91C_UDP_ENDBUSRES) {
+		AT91C_BASE_UDP->UDP_ICR = AT91C_UDP_ENDBUSRES;
+		// reset all endpoints
+		AT91C_BASE_UDP->UDP_RSTEP  = (unsigned int)-1;
+		AT91C_BASE_UDP->UDP_RSTEP  = 0;
+		// Enable the function
+		AT91C_BASE_UDP->UDP_FADDR = AT91C_UDP_FEN;
+		// Configure endpoint 0
+		AT91C_BASE_UDP->UDP_CSR[AT91C_EP_CONTROL] = (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_CTRL);
+	} else if (isr & AT91C_UDP_EPINT0) {
+		AT91C_BASE_UDP->UDP_ICR = AT91C_UDP_EPINT0;
+		AT91F_CDC_Enumerate();
+	}
+	return (btConfiguration) ? true : false;
+}
+
+
+bool usb_poll() {
+	if (!usb_check()) return false;
+	return (AT91C_BASE_UDP->UDP_CSR[AT91C_EP_OUT] & btReceiveBank);
+}
+
+
+/**
+	In github PR #129, some users appears to get a false positive from
+	usb_poll, which returns true, but the usb_read operation
+	still returns 0.
+	This check is basically the same as above, but also checks
+	that the length available to read is non-zero, thus hopefully fixes the
+	bug.
+**/
+bool usb_poll_validate_length() {
+	if (!usb_check()) return false;
+	if (!(AT91C_BASE_UDP->UDP_CSR[AT91C_EP_OUT] & btReceiveBank)) return false;
+	return (AT91C_BASE_UDP->UDP_CSR[AT91C_EP_OUT] >> 16) >  0;
+}
+
+
+//*----------------------------------------------------------------------------
+//* \fn    usb_read
+//* \brief Read available data from Endpoint OUT
+//*----------------------------------------------------------------------------
+static uint32_t usb_read(uint8_t* data, size_t len) {
+	uint8_t bank = btReceiveBank;
+	uint32_t packetSize, nbBytesRcv = 0;
+	uint32_t time_out = 0;
+
+	while (len)  {
+		if (!usb_check()) break;
+
+		if ( AT91C_BASE_UDP->UDP_CSR[AT91C_EP_OUT] & bank ) {
+			packetSize = MIN(AT91C_BASE_UDP->UDP_CSR[AT91C_EP_OUT] >> 16, len);
+			len -= packetSize;
+			while (packetSize--)
+				data[nbBytesRcv++] = AT91C_BASE_UDP->UDP_FDR[AT91C_EP_OUT];
+			UDP_CLEAR_EP_FLAGS(AT91C_EP_OUT, bank);
+			if (bank == AT91C_UDP_RX_DATA_BK0) {
+				bank = AT91C_UDP_RX_DATA_BK1;
+			} else {
+				bank = AT91C_UDP_RX_DATA_BK0;
+			}
+		}
+		if (time_out++ == 0x1fff) break;
+	}
+
+	btReceiveBank = bank;
+	return nbBytesRcv;
+}
+
+
+//*----------------------------------------------------------------------------
+//* \fn    usb_write
+//* \brief Send through endpoint 2
+//*----------------------------------------------------------------------------
+static uint32_t usb_write(const uint8_t* data, const size_t len) {
+	size_t length = len;
+	uint32_t cpt = 0;
+
+	if (!length) return 0;
+	if (!usb_check()) return 0;
+
+	// Send the first packet
+	cpt = MIN(length, AT91C_EP_IN_SIZE);
+	length -= cpt;
+	while (cpt--) {
+		AT91C_BASE_UDP->UDP_FDR[AT91C_EP_IN] = *data++;
+	}
+	UDP_SET_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXPKTRDY);
+	while (!(AT91C_BASE_UDP->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXPKTRDY))
+		/* wait */;
+
+	while (length) {
+		// Fill the next bank
+		cpt = MIN(length, AT91C_EP_IN_SIZE);
+		length -= cpt;
+		while (cpt--) {
+			AT91C_BASE_UDP->UDP_FDR[AT91C_EP_IN] = *data++;
+		}
+		// Wait for the previous bank to be sent
+		while (!(AT91C_BASE_UDP->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP)) {
+			if (!usb_check()) return length;
+		}
+		UDP_SET_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXPKTRDY);
+		while (!(AT91C_BASE_UDP->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXPKTRDY))
+			/* wait */;
+		UDP_CLEAR_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXCOMP);
+		while (AT91C_BASE_UDP->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP)
+			/* wait */;
+	}
+
+	// Wait for the end of transfer
+	while (!(AT91C_BASE_UDP->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP)) {
+		if (!usb_check()) return length;
+	}
+	UDP_CLEAR_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXCOMP);
+	while (AT91C_BASE_UDP->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP)
+		/* wait */;
+
+	if (len % AT91C_EP_IN_SIZE == 0) { // need to send a zero length packet to complete the transfer
+		AT91F_USB_SendZlp(AT91C_EP_IN);
 	}
+
+	return length;
+}
+
+
+//***************************************************************************
+// Interface to the main program
+//***************************************************************************
+
+// The function to receive a command from the client via USB
+bool cmd_receive(UsbCommand* cmd) {
+
+	// Check if there is a usb packet available
+	if (!usb_poll())
+		return false;
+
+	// Try to retrieve the available command frame
+	size_t rxlen = usb_read((uint8_t*)cmd, sizeof(UsbCommand));
+
+	// Check if the transfer was complete
+	if (rxlen != sizeof(UsbCommand))
+		return false;
+
+	// Received command successfully
+	return true;
 }
+
+
+// The function to send a response to the client via USB
+bool cmd_send(uint16_t cmd, uint32_t arg0, uint32_t arg1, uint32_t arg2, void* data, uint16_t datalen) {
+
+	UsbResponse txcmd;
+
+	// Compose the outgoing response frame
+	txcmd.cmd = cmd | CMD_VARIABLE_SIZE_FLAG;
+	txcmd.arg[0] = arg0;
+	txcmd.arg[1] = arg1;
+	txcmd.arg[2] = arg2;
+
+	// Add the (optional) content to the frame, with a maximum size of USB_CMD_DATA_SIZE
+	if (data) {
+		datalen = MIN(datalen, USB_CMD_DATA_SIZE);
+		for (uint16_t i = 0; i < datalen; i++) {
+			txcmd.d.asBytes[i] = ((uint8_t*)data)[i];
+		}
+		txcmd.datalen = datalen;
+	} else {
+		txcmd.datalen = 0;
+	}
+
+	// Send frame and make sure all bytes are transmitted
+	size_t tx_size = offsetof(UsbResponse, d) + datalen;
+	if (usb_write((uint8_t*)&txcmd, tx_size) != 0) return false;
+
+	return true;
+}
+
+
+// For compatibility only: legacy function to send a response with fixed size to the client via USB
+bool cmd_send_old(uint16_t cmd, uint32_t arg0, uint32_t arg1, uint32_t arg2, void* data, uint16_t datalen) {
+
+	UsbCommand txcmd;
+
+	// Compose the outgoing response frame
+	txcmd.cmd = cmd;
+	txcmd.arg[0] = arg0;
+	txcmd.arg[1] = arg1;
+	txcmd.arg[2] = arg2;
+
+	// Add the (optional) content to the frame, with a maximum size of USB_CMD_DATA_SIZE
+	if (data) {
+		datalen = MIN(datalen, USB_CMD_DATA_SIZE);
+		for (uint16_t i = 0; i < datalen; i++) {
+			txcmd.d.asBytes[i] = ((uint8_t*)data)[i];
+		}
+	}
+
+	// Send frame and make sure all bytes are transmitted
+	if (usb_write((uint8_t*)&txcmd, sizeof(UsbCommand)) != 0) return false;
+
+	return true;
+}
+