text: /* Name: usbdrv.c
   * Project: V-USB, virtual USB port for Atmel's(r) AVR(r) microcontrollers
   * Author: Christian Starkjohann
   * Creation Date: 2004-12-29
   * Tabsize: 4
   * Copyright: (c) 2005 by OBJECTIVE DEVELOPMENT Software GmbH
   * License: GNU GPL v2 (see License.txt), GNU GPL v3 or proprietary (CommercialLicense.txt)
   * This Revision: $Id: usbdrv.c 763 2009-08-22 10:27:24Z cs $
   */
  
  #include "usbportability.h"
  #include "usbdrv.h"
  #include "oddebug.h"
  
  /*
  General Description:
  This module implements the C-part of the USB driver. See usbdrv.h for a
  documentation of the entire driver.
  */
  
  /* ------------------------------------------------------------------------- */
  
  /* raw USB registers / interface to assembler code: */
  uchar usbRxBuf[2*USB_BUFSIZE];  /* raw RX buffer: PID, 8 bytes data, 2 bytes CRC */
  uchar       usbInputBufOffset;  /* offset in usbRxBuf used for low level receiving */
  uchar       usbDeviceAddr;      /* assigned during enumeration, defaults to 0 */
  uchar       usbNewDeviceAddr;   /* device ID which should be set after status phase */
  uchar       usbConfiguration;   /* currently selected configuration. Administered by driver, but not used */
  volatile schar usbRxLen;        /* = 0; number of bytes in usbRxBuf; 0 means free, -1 for flow control */
  uchar       usbCurrentTok;      /* last token received or endpoint number for last OUT token if != 0 */
  uchar       usbRxToken;         /* token for data we received; or endpont number for last OUT */
  volatile uchar usbTxLen = USBPID_NAK;   /* number of bytes to transmit with next IN token or handshake token */
  uchar       usbTxBuf[USB_BUFSIZE];/* data to transmit with next IN, free if usbTxLen contains handshake token */
  #if USB_COUNT_SOF
  volatile uchar  usbSofCount;    /* incremented by assembler module every SOF */
  #endif
  #if USB_CFG_HAVE_INTRIN_ENDPOINT && !USB_CFG_SUPPRESS_INTR_CODE
  usbTxStatus_t  usbTxStatus1;
  #   if USB_CFG_HAVE_INTRIN_ENDPOINT3
  usbTxStatus_t  usbTxStatus3;
  #   endif
  #endif
  #if USB_CFG_CHECK_DATA_TOGGLING
  uchar       usbCurrentDataToken;/* when we check data toggling to ignore duplicate packets */
  #endif
  
  /* USB status registers / not shared with asm code */
  const uchar               *usbMsgPtr;     /* data to transmit next -- ROM or RAM address */
  static usbMsgLen_t  usbMsgLen = USB_NO_MSG; /* remaining number of bytes */
  static uchar        usbMsgFlags;    /* flag values see below */
  
  #define USB_FLG_MSGPTR_IS_ROM   (1<<6)
  #define USB_FLG_USE_USER_RW     (1<<7)
  
  /*
  optimizing hints:
  - do not post/pre inc/dec integer values in operations
  - assign value of USB_READ_FLASH() to register variables and don't use side effects in arg
  - use narrow scope for variables which should be in X/Y/Z register
  - assign char sized expressions to variables to force 8 bit arithmetics
  */
  
  /* -------------------------- String Descriptors --------------------------- */
  
  #if USB_CFG_DESCR_PROPS_STRINGS == 0
  
  #if USB_CFG_DESCR_PROPS_STRING_0 == 0
  #undef USB_CFG_DESCR_PROPS_STRING_0
  #define USB_CFG_DESCR_PROPS_STRING_0    sizeof(usbDescriptorString0)
  const PROGMEM char usbDescriptorString0[] = { /* language descriptor */
      4,          /* sizeof(usbDescriptorString0): length of descriptor in bytes */
      3,          /* descriptor type */
      0x09, 0x04, /* language index (0x0409 = US-English) */
  };
  #endif
  
  #if USB_CFG_DESCR_PROPS_STRING_VENDOR == 0 && USB_CFG_VENDOR_NAME_LEN
  #undef USB_CFG_DESCR_PROPS_STRING_VENDOR
  #define USB_CFG_DESCR_PROPS_STRING_VENDOR   sizeof(usbDescriptorStringVendor)
  const PROGMEM int  usbDescriptorStringVendor[] = {
      USB_STRING_DESCRIPTOR_HEADER(USB_CFG_VENDOR_NAME_LEN),
      USB_CFG_VENDOR_NAME
  };
  #endif
  
  #if USB_CFG_DESCR_PROPS_STRING_PRODUCT == 0 && USB_CFG_DEVICE_NAME_LEN
  #undef USB_CFG_DESCR_PROPS_STRING_PRODUCT
  #define USB_CFG_DESCR_PROPS_STRING_PRODUCT   sizeof(usbDescriptorStringDevice)
  const PROGMEM int  usbDescriptorStringDevice[] = {
      USB_STRING_DESCRIPTOR_HEADER(USB_CFG_DEVICE_NAME_LEN),
      USB_CFG_DEVICE_NAME
  };
  #endif
  
  #if USB_CFG_DESCR_PROPS_STRING_SERIAL_NUMBER == 0 && USB_CFG_SERIAL_NUMBER_LEN
  #undef USB_CFG_DESCR_PROPS_STRING_SERIAL_NUMBER
  #define USB_CFG_DESCR_PROPS_STRING_SERIAL_NUMBER    sizeof(usbDescriptorStringSerialNumber)
  const PROGMEM int usbDescriptorStringSerialNumber[] = {
      USB_STRING_DESCRIPTOR_HEADER(USB_CFG_SERIAL_NUMBER_LEN),
      USB_CFG_SERIAL_NUMBER
  };
  #endif
  
  #endif  /* USB_CFG_DESCR_PROPS_STRINGS == 0 */
  
  /* --------------------------- Device Descriptor --------------------------- */
  
  #if USB_CFG_DESCR_PROPS_DEVICE == 0
  #undef USB_CFG_DESCR_PROPS_DEVICE
  #define USB_CFG_DESCR_PROPS_DEVICE  sizeof(usbDescriptorDevice)
  const PROGMEM char usbDescriptorDevice[] = {    /* USB device descriptor */
      18,         /* sizeof(usbDescriptorDevice): length of descriptor in bytes */
      USBDESCR_DEVICE,        /* descriptor type */
      0x10, 0x01,             /* USB version supported */
      USB_CFG_DEVICE_CLASS,
      USB_CFG_DEVICE_SUBCLASS,
      0,                      /* protocol */
      8,                      /* max packet size */
      /* the following two casts affect the first byte of the constant only, but
       * that's sufficient to avoid a warning with the default values.
       */
      (char)USB_CFG_VENDOR_ID,/* 2 bytes */
      (char)USB_CFG_DEVICE_ID,/* 2 bytes */
      USB_CFG_DEVICE_VERSION, /* 2 bytes */
      USB_CFG_DESCR_PROPS_STRING_VENDOR != 0 ? 1 : 0,         /* manufacturer string index */
      USB_CFG_DESCR_PROPS_STRING_PRODUCT != 0 ? 2 : 0,        /* product string index */
      USB_CFG_DESCR_PROPS_STRING_SERIAL_NUMBER != 0 ? 3 : 0,  /* serial number string index */
      1,          /* number of configurations */
  };
  #endif
  
  /* ----------------------- Configuration Descriptor ------------------------ */
  
  #if USB_CFG_DESCR_PROPS_HID_REPORT != 0 && USB_CFG_DESCR_PROPS_HID == 0
  #undef USB_CFG_DESCR_PROPS_HID
  #define USB_CFG_DESCR_PROPS_HID     9   /* length of HID descriptor in config descriptor below */
  #endif
  
  #if USB_CFG_DESCR_PROPS_CONFIGURATION == 0
  #undef USB_CFG_DESCR_PROPS_CONFIGURATION
  #define USB_CFG_DESCR_PROPS_CONFIGURATION   sizeof(usbDescriptorConfiguration)
  const PROGMEM char usbDescriptorConfiguration[] = {    /* USB configuration descriptor */
      9,          /* sizeof(usbDescriptorConfiguration): length of descriptor in bytes */
      USBDESCR_CONFIG,    /* descriptor type */
      18 + 7 * USB_CFG_HAVE_INTRIN_ENDPOINT + 7 * USB_CFG_HAVE_INTRIN_ENDPOINT3 +
                  (USB_CFG_DESCR_PROPS_HID & 0xff), 0,
                  /* total length of data returned (including inlined descriptors) */
      1,          /* number of interfaces in this configuration */
      1,          /* index of this configuration */
      0,          /* configuration name string index */
  #if USB_CFG_IS_SELF_POWERED
      (1 << 7) | USBATTR_SELFPOWER,       /* attributes */
  #else
      (1 << 7),                           /* attributes */
  #endif
      USB_CFG_MAX_BUS_POWER/2,            /* max USB current in 2mA units */
  /* interface descriptor follows inline: */
      9,          /* sizeof(usbDescrInterface): length of descriptor in bytes */
      USBDESCR_INTERFACE, /* descriptor type */
      0,          /* index of this interface */
      0,          /* alternate setting for this interface */
      USB_CFG_HAVE_INTRIN_ENDPOINT + USB_CFG_HAVE_INTRIN_ENDPOINT3, /* endpoints excl 0: number of endpoint descriptors to follow */
      USB_CFG_INTERFACE_CLASS,
      USB_CFG_INTERFACE_SUBCLASS,
      USB_CFG_INTERFACE_PROTOCOL,
      0,          /* string index for interface */
  #if (USB_CFG_DESCR_PROPS_HID & 0xff)    /* HID descriptor */
      9,          /* sizeof(usbDescrHID): length of descriptor in bytes */
      USBDESCR_HID,   /* descriptor type: HID */
      0x01, 0x01, /* BCD representation of HID version */
      0x00,       /* target country code */
      0x01,       /* number of HID Report (or other HID class) Descriptor infos to follow */
      0x22,       /* descriptor type: report */
      USB_CFG_HID_REPORT_DESCRIPTOR_LENGTH, 0,  /* total length of report descriptor */
  #endif
  #if USB_CFG_HAVE_INTRIN_ENDPOINT    /* endpoint descriptor for endpoint 1 */
      7,          /* sizeof(usbDescrEndpoint) */
      USBDESCR_ENDPOINT,  /* descriptor type = endpoint */
      (char)0x81, /* IN endpoint number 1 */
      0x03,       /* attrib: Interrupt endpoint */
      8, 0,       /* maximum packet size */
      USB_CFG_INTR_POLL_INTERVAL, /* in ms */
  #endif
  #if USB_CFG_HAVE_INTRIN_ENDPOINT3   /* endpoint descriptor for endpoint 3 */
      7,          /* sizeof(usbDescrEndpoint) */
      USBDESCR_ENDPOINT,  /* descriptor type = endpoint */
      (char)0x83, /* IN endpoint number 1 */
      0x03,       /* attrib: Interrupt endpoint */
      8, 0,       /* maximum packet size */
      USB_CFG_INTR_POLL_INTERVAL, /* in ms */
  #endif
  };
  #endif
  
  /* ------------------------------------------------------------------------- */
  
  static inline void  usbResetDataToggling(void)
  {
  #if USB_CFG_HAVE_INTRIN_ENDPOINT && !USB_CFG_SUPPRESS_INTR_CODE
      USB_SET_DATATOKEN1(USB_INITIAL_DATATOKEN);  /* reset data toggling for interrupt endpoint */
  #   if USB_CFG_HAVE_INTRIN_ENDPOINT3
      USB_SET_DATATOKEN3(USB_INITIAL_DATATOKEN);  /* reset data toggling for interrupt endpoint */
  #   endif
  #endif
  }
  
  static inline void  usbResetStall(void)
  {
  #if USB_CFG_IMPLEMENT_HALT && USB_CFG_HAVE_INTRIN_ENDPOINT
          usbTxLen1 = USBPID_NAK;
  #if USB_CFG_HAVE_INTRIN_ENDPOINT3
          usbTxLen3 = USBPID_NAK;
  #endif
  #endif
  }
  
  /* ------------------------------------------------------------------------- */
  
  #if !USB_CFG_SUPPRESS_INTR_CODE
  #if USB_CFG_HAVE_INTRIN_ENDPOINT
  static void usbGenericSetInterrupt(uchar *data, uchar len, usbTxStatus_t *txStatus)
  {
  uchar   *p;
  char    i;
  
  #if USB_CFG_IMPLEMENT_HALT
      if(usbTxLen1 == USBPID_STALL)
          return;
  #endif
      if(txStatus->len & 0x10){   /* packet buffer was empty */
          txStatus->buffer[0] ^= USBPID_DATA0 ^ USBPID_DATA1; /* toggle token */
      }else{
          txStatus->len = USBPID_NAK; /* avoid sending outdated (overwritten) interrupt data */
      }
      p = txStatus->buffer + 1;
      i = len;
      do{                         /* if len == 0, we still copy 1 byte, but that's no problem */
          *p++ = *data++;
      }while(--i > 0);            /* loop control at the end is 2 bytes shorter than at beginning */
      usbCrc16Append(&txStatus->buffer[1], len);
      txStatus->len = len + 4;    /* len must be given including sync byte */
      DBG2(0x21 + (((int)txStatus >> 3) & 3), txStatus->buffer, len + 3);
  }
  
  USB_PUBLIC void usbSetInterrupt(uchar *data, uchar len)
  {
      usbGenericSetInterrupt(data, len, &usbTxStatus1);
  }
  #endif
  
  #if USB_CFG_HAVE_INTRIN_ENDPOINT3
  USB_PUBLIC void usbSetInterrupt3(uchar *data, uchar len)
  {
      usbGenericSetInterrupt(data, len, &usbTxStatus3);
  }
  #endif
  #endif /* USB_CFG_SUPPRESS_INTR_CODE */
  
  /* ------------------ utilities for code following below ------------------- */
  
  /* Use defines for the switch statement so that we can choose between an
   * if()else if() and a switch/case based implementation. switch() is more
   * efficient for a LARGE set of sequential choices, if() is better in all other
   * cases.
   */
  #if USB_CFG_USE_SWITCH_STATEMENT
  #   define SWITCH_START(cmd)       switch(cmd){{
  #   define SWITCH_CASE(value)      }break; case (value):{
  #   define SWITCH_CASE2(v1,v2)     }break; case (v1): case(v2):{
  #   define SWITCH_CASE3(v1,v2,v3)  }break; case (v1): case(v2): case(v3):{
  #   define SWITCH_DEFAULT          }break; default:{
  #   define SWITCH_END              }}
  #else
  #   define SWITCH_START(cmd)       {uchar _cmd = cmd; if(0){
  #   define SWITCH_CASE(value)      }else if(_cmd == (value)){
  #   define SWITCH_CASE2(v1,v2)     }else if(_cmd == (v1) || _cmd == (v2)){
  #   define SWITCH_CASE3(v1,v2,v3)  }else if(_cmd == (v1) || _cmd == (v2) || (_cmd == v3)){
  #   define SWITCH_DEFAULT          }else{
  #   define SWITCH_END              }}
  #endif
  
  #ifndef USB_RX_USER_HOOK
  #define USB_RX_USER_HOOK(data, len)
  #endif
  #ifndef USB_SET_ADDRESS_HOOK
  #define USB_SET_ADDRESS_HOOK()
  #endif
  
  /* ------------------------------------------------------------------------- */
  
  /* We use if() instead of #if in the macro below because #if can't be used
   * in macros and the compiler optimizes constant conditions anyway.
   * This may cause problems with undefined symbols if compiled without
   * optimizing!
   */
  #define GET_DESCRIPTOR(cfgProp, staticName)         \
      if(cfgProp){                                    \
          if((cfgProp) & USB_PROP_IS_RAM)             \
              flags = 0;                              \
          if((cfgProp) & USB_PROP_IS_DYNAMIC){        \
              len = usbFunctionDescriptor(rq);        \
          }else{                                      \
              len = USB_PROP_LENGTH(cfgProp);         \
              usbMsgPtr = (uchar *)(staticName);      \
          }                                           \
      }
  
  /* usbDriverDescriptor() is similar to usbFunctionDescriptor(), but used
   * internally for all types of descriptors.
   */
  static inline usbMsgLen_t usbDriverDescriptor(usbRequest_t *rq)
  {
  usbMsgLen_t len = 0;
  uchar       flags = USB_FLG_MSGPTR_IS_ROM;
  
      SWITCH_START(rq->wValue.bytes[1])
      SWITCH_CASE(USBDESCR_DEVICE)    /* 1 */
          GET_DESCRIPTOR(USB_CFG_DESCR_PROPS_DEVICE, usbDescriptorDevice)
      SWITCH_CASE(USBDESCR_CONFIG)    /* 2 */
          GET_DESCRIPTOR(USB_CFG_DESCR_PROPS_CONFIGURATION, usbDescriptorConfiguration)
      SWITCH_CASE(USBDESCR_STRING)    /* 3 */
  #if USB_CFG_DESCR_PROPS_STRINGS & USB_PROP_IS_DYNAMIC
          if(USB_CFG_DESCR_PROPS_STRINGS & USB_PROP_IS_RAM)
              flags = 0;
          len = usbFunctionDescriptor(rq);
  #else   /* USB_CFG_DESCR_PROPS_STRINGS & USB_PROP_IS_DYNAMIC */
          SWITCH_START(rq->wValue.bytes[0])
          SWITCH_CASE(0)
              GET_DESCRIPTOR(USB_CFG_DESCR_PROPS_STRING_0, usbDescriptorString0)
          SWITCH_CASE(1)
              GET_DESCRIPTOR(USB_CFG_DESCR_PROPS_STRING_VENDOR, usbDescriptorStringVendor)
          SWITCH_CASE(2)
              GET_DESCRIPTOR(USB_CFG_DESCR_PROPS_STRING_PRODUCT, usbDescriptorStringDevice)
          SWITCH_CASE(3)
              GET_DESCRIPTOR(USB_CFG_DESCR_PROPS_STRING_SERIAL_NUMBER, usbDescriptorStringSerialNumber)
          SWITCH_DEFAULT
              if(USB_CFG_DESCR_PROPS_UNKNOWN & USB_PROP_IS_DYNAMIC){
                  len = usbFunctionDescriptor(rq);
              }
          SWITCH_END
  #endif  /* USB_CFG_DESCR_PROPS_STRINGS & USB_PROP_IS_DYNAMIC */
  #if USB_CFG_DESCR_PROPS_HID_REPORT  /* only support HID descriptors if enabled */
      SWITCH_CASE(USBDESCR_HID)       /* 0x21 */
          GET_DESCRIPTOR(USB_CFG_DESCR_PROPS_HID, usbDescriptorConfiguration + 18)
      SWITCH_CASE(USBDESCR_HID_REPORT)/* 0x22 */
          GET_DESCRIPTOR(USB_CFG_DESCR_PROPS_HID_REPORT, usbDescriptorHidReport)
  #endif
      SWITCH_DEFAULT
          if(USB_CFG_DESCR_PROPS_UNKNOWN & USB_PROP_IS_DYNAMIC){
              len = usbFunctionDescriptor(rq);
          }
      SWITCH_END
      usbMsgFlags = flags;
      return len;
  }
  
  /* ------------------------------------------------------------------------- */
  
  /* usbDriverSetup() is similar to usbFunctionSetup(), but it's used for
   * standard requests instead of class and custom requests.
   */
  static inline usbMsgLen_t usbDriverSetup(usbRequest_t *rq)
  {
  uchar   len  = 0, *dataPtr = usbTxBuf + 9;  /* there are 2 bytes free space at the end of the buffer */
  uchar   value = rq->wValue.bytes[0];
  #if USB_CFG_IMPLEMENT_HALT
  uchar   index = rq->wIndex.bytes[0];
  #endif
  
      dataPtr[0] = 0; /* default reply common to USBRQ_GET_STATUS and USBRQ_GET_INTERFACE */
      SWITCH_START(rq->bRequest)
      SWITCH_CASE(USBRQ_GET_STATUS)           /* 0 */
          uchar recipient = rq->bmRequestType & USBRQ_RCPT_MASK;  /* assign arith ops to variables to enforce byte size */
          if(USB_CFG_IS_SELF_POWERED && recipient == USBRQ_RCPT_DEVICE)
              dataPtr[0] =  USB_CFG_IS_SELF_POWERED;
  #if USB_CFG_IMPLEMENT_HALT
          if(recipient == USBRQ_RCPT_ENDPOINT && index == 0x81)   /* request status for endpoint 1 */
              dataPtr[0] = usbTxLen1 == USBPID_STALL;
  #endif
          dataPtr[1] = 0;
          len = 2;
  #if USB_CFG_IMPLEMENT_HALT
      SWITCH_CASE2(USBRQ_CLEAR_FEATURE, USBRQ_SET_FEATURE)    /* 1, 3 */
          if(value == 0 && index == 0x81){    /* feature 0 == HALT for endpoint == 1 */
              usbTxLen1 = rq->bRequest == USBRQ_CLEAR_FEATURE ? USBPID_NAK : USBPID_STALL;
              usbResetDataToggling();
          }
  #endif
      SWITCH_CASE(USBRQ_SET_ADDRESS)          /* 5 */
          usbNewDeviceAddr = value;
          USB_SET_ADDRESS_HOOK();
      SWITCH_CASE(USBRQ_GET_DESCRIPTOR)       /* 6 */
          len = usbDriverDescriptor(rq);
          goto skipMsgPtrAssignment;
      SWITCH_CASE(USBRQ_GET_CONFIGURATION)    /* 8 */
          dataPtr = &usbConfiguration;  /* send current configuration value */
          len = 1;
      SWITCH_CASE(USBRQ_SET_CONFIGURATION)    /* 9 */
          usbConfiguration = value;
          usbResetStall();
      SWITCH_CASE(USBRQ_GET_INTERFACE)        /* 10 */
          len = 1;
  #if USB_CFG_HAVE_INTRIN_ENDPOINT && !USB_CFG_SUPPRESS_INTR_CODE
      SWITCH_CASE(USBRQ_SET_INTERFACE)        /* 11 */
          usbResetDataToggling();
          usbResetStall();
  #endif
      SWITCH_DEFAULT                          /* 7=SET_DESCRIPTOR, 12=SYNC_FRAME */
          /* Should we add an optional hook here? */
      SWITCH_END
      usbMsgPtr = dataPtr;
  skipMsgPtrAssignment:
      return len;
  }
  
  /* ------------------------------------------------------------------------- */
  
  /* usbProcessRx() is called for every message received by the interrupt
   * routine. It distinguishes between SETUP and DATA packets and processes
   * them accordingly.
   */
  static inline void usbProcessRx(uchar *data, uchar len)
  {
    usbRequest_t    *rq = (usbRequest_t *)((void *)data);
  
  /* usbRxToken can be:
   * 0x2d 00101101 (USBPID_SETUP for setup data)
   * 0xe1 11100001 (USBPID_OUT: data phase of setup transfer)
   * 0...0x0f for OUT on endpoint X
   */
      DBG2(0x10 + (usbRxToken & 0xf), data, len + 2); /* SETUP=1d, SETUP-DATA=11, OUTx=1x */
      USB_RX_USER_HOOK(data, len)
  #if USB_CFG_IMPLEMENT_FN_WRITEOUT
      if(usbRxToken < 0x10){  /* OUT to endpoint != 0: endpoint number in usbRxToken */
          usbFunctionWriteOut(data, len);
          return;
      }
  #endif
      if(usbRxToken == (uchar)USBPID_SETUP){
          if(len != 8)    /* Setup size must be always 8 bytes. Ignore otherwise. */
              return;
          usbMsgLen_t replyLen;
          usbTxBuf[0] = USBPID_DATA0;         /* initialize data toggling */
          usbTxLen = USBPID_NAK;              /* abort pending transmit */
          usbMsgFlags = 0;
          uchar type = rq->bmRequestType & USBRQ_TYPE_MASK;
          if(type != USBRQ_TYPE_STANDARD){    /* standard requests are handled by driver */
              replyLen = usbFunctionSetup(data);
          }else{
              replyLen = usbDriverSetup(rq);
          }
  #if USB_CFG_IMPLEMENT_FN_READ || USB_CFG_IMPLEMENT_FN_WRITE
          if(replyLen == USB_NO_MSG){         /* use user-supplied read/write function */
              /* do some conditioning on replyLen, but on IN transfers only */
              if((rq->bmRequestType & USBRQ_DIR_MASK) != USBRQ_DIR_HOST_TO_DEVICE){
                  if(sizeof(replyLen) < sizeof(rq->wLength.word)){ /* help compiler with optimizing */
                      replyLen = rq->wLength.bytes[0];
                  }else{
                      replyLen = rq->wLength.word;
                  }
              }
              usbMsgFlags = USB_FLG_USE_USER_RW;
          }else   /* The 'else' prevents that we limit a replyLen of USB_NO_MSG to the maximum transfer len. */
  #endif
          if(sizeof(replyLen) < sizeof(rq->wLength.word)){ /* help compiler with optimizing */
              if(!rq->wLength.bytes[1] && replyLen > rq->wLength.bytes[0])    /* limit length to max */
                  replyLen = rq->wLength.bytes[0];
          }else{
              if(replyLen > rq->wLength.word)     /* limit length to max */
                  replyLen = rq->wLength.word;
          }
          usbMsgLen = replyLen;
      }else{  /* usbRxToken must be USBPID_OUT, which means data phase of setup (control-out) */
  #if USB_CFG_IMPLEMENT_FN_WRITE
          if(usbMsgFlags & USB_FLG_USE_USER_RW){
              uchar rval = usbFunctionWrite(data, len);
              if(rval == 0xff){   /* an error occurred */
                  usbTxLen = USBPID_STALL;
              }else if(rval != 0){    /* This was the final package */
                  usbMsgLen = 0;  /* answer with a zero-sized data packet */
              }
          }
  #endif
      }
  }
  
  /* ------------------------------------------------------------------------- */
  
  /* This function is similar to usbFunctionRead(), but it's also called for
   * data handled automatically by the driver (e.g. descriptor reads).
   */
  static uchar usbDeviceRead(uchar *data, uchar len)
  {
      if(len > 0){    /* don't bother app with 0 sized reads */
  #if USB_CFG_IMPLEMENT_FN_READ
          if(usbMsgFlags & USB_FLG_USE_USER_RW){
              len = usbFunctionRead(data, len);
          }else
  #endif
          {
              uchar i = len, *r = usbMsgPtr;
              if(usbMsgFlags & USB_FLG_MSGPTR_IS_ROM){    /* ROM data */
                  do{
                      uchar c = USB_READ_FLASH(r);    /* assign to char size variable to enforce byte ops */
                      *data++ = c;
                      r++;
                  }while(--i);
              }else{  /* RAM data */
                  do{
                      *data++ = *r++;
                  }while(--i);
              }
              usbMsgPtr = r;
          }
      }
      return len;
  }
  
  /* ------------------------------------------------------------------------- */
  
  /* usbBuildTxBlock() is called when we have data to transmit and the
   * interrupt routine's transmit buffer is empty.
   */
  static inline void usbBuildTxBlock(void)
  {
  usbMsgLen_t wantLen;
  uchar       len;
  
      wantLen = usbMsgLen;
      if(wantLen > 8)
          wantLen = 8;
      usbMsgLen -= wantLen;
      usbTxBuf[0] ^= USBPID_DATA0 ^ USBPID_DATA1; /* DATA toggling */
      len = usbDeviceRead(usbTxBuf + 1, wantLen);
      if(len <= 8){           /* valid data packet */
          usbCrc16Append(&usbTxBuf[1], len);
          len += 4;           /* length including sync byte */
          if(len < 12)        /* a partial package identifies end of message */
              usbMsgLen = USB_NO_MSG;
      }else{
          len = USBPID_STALL;   /* stall the endpoint */
          usbMsgLen = USB_NO_MSG;
      }
      usbTxLen = len;
      DBG2(0x20, usbTxBuf, len-1);
  }
  
  /* ------------------------------------------------------------------------- */
  
  static inline void usbHandleResetHook(uchar notResetState)
  {
  #ifdef USB_RESET_HOOK
  static uchar    wasReset;
  uchar           isReset = !notResetState;
  
      if(wasReset != isReset){
          USB_RESET_HOOK(isReset);
          wasReset = isReset;
      }
  #endif
  }
  
  /* ------------------------------------------------------------------------- */
  
  USB_PUBLIC void usbPoll(void)
  {
  schar   len;
  uchar   i;
  
      len = usbRxLen - 3;
      if(len >= 0){
  /* We could check CRC16 here -- but ACK has already been sent anyway. If you
   * need data integrity checks with this driver, check the CRC in your app
   * code and report errors back to the host. Since the ACK was already sent,
   * retries must be handled on application level.
   * unsigned crc = usbCrc16(buffer + 1, usbRxLen - 3);
   */
          usbProcessRx(usbRxBuf + USB_BUFSIZE + 1 - usbInputBufOffset, len);
  #if USB_CFG_HAVE_FLOWCONTROL
          if(usbRxLen > 0)    /* only mark as available if not inactivated */
              usbRxLen = 0;
  #else
          usbRxLen = 0;       /* mark rx buffer as available */
  #endif
      }
      if(usbTxLen & 0x10){    /* transmit system idle */
          if(usbMsgLen != USB_NO_MSG){    /* transmit data pending? */
              usbBuildTxBlock();
          }
      }
      for(i = 20; i > 0; i--){
          uchar usbLineStatus = USBIN & USBMASK;
          if(usbLineStatus != 0)  /* SE0 has ended */
              goto isNotReset;
      }
      /* RESET condition, called multiple times during reset */
      usbNewDeviceAddr = 0;
      usbDeviceAddr = 0;
      usbResetStall();
      DBG1(0xff, 0, 0);
  isNotReset:
      usbHandleResetHook(i);
  }
  
  /* ------------------------------------------------------------------------- */
  
  USB_PUBLIC void usbInit(void)
  {
  #if USB_INTR_CFG_SET != 0
      USB_INTR_CFG |= USB_INTR_CFG_SET;
  #endif
  #if USB_INTR_CFG_CLR != 0
      USB_INTR_CFG &= ~(USB_INTR_CFG_CLR);
  #endif
      USB_INTR_ENABLE |= (1 << USB_INTR_ENABLE_BIT);
      usbResetDataToggling();
  #if USB_CFG_HAVE_INTRIN_ENDPOINT && !USB_CFG_SUPPRESS_INTR_CODE
      usbTxLen1 = USBPID_NAK;
  #if USB_CFG_HAVE_INTRIN_ENDPOINT3
      usbTxLen3 = USBPID_NAK;
  #endif
  #endif
  }
  
  /* ------------------------------------------------------------------------- */
  