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/* 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)

 */

#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 */

usbMsgPtr_t         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)

PROGMEM const 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)

PROGMEM const 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)

PROGMEM const 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)

PROGMEM const 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)

PROGMEM const 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)

PROGMEM const 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)(0x80 | USB_CFG_EP3_NUMBER), /* IN endpoint number 3 */

    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 = (usbMsgPtr_t)(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)

{

usbMsgLen_t len = 0;

uchar   *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 = (usbMsgPtr_t)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 = (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;

            usbMsgPtr_t 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++ = *((uchar *)r);

                    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;

    }

#else

    notResetState = notResetState;  // avoid compiler warning

#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

}

/* ------------------------------------------------------------------------- */