mirror of
https://github.com/raphnet/dreamcast_usb
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188 lines
7.8 KiB
PHP
188 lines
7.8 KiB
PHP
/* Name: asmcommon.inc
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* Project: V-USB, virtual USB port for Atmel's(r) AVR(r) microcontrollers
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* Author: Christian Starkjohann
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* Creation Date: 2007-11-05
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* Tabsize: 4
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* Copyright: (c) 2007 by OBJECTIVE DEVELOPMENT Software GmbH
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* License: GNU GPL v2 (see License.txt), GNU GPL v3 or proprietary (CommercialLicense.txt)
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*/
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/* Do not link this file! Link usbdrvasm.S instead, which includes the
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* appropriate implementation!
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*/
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/*
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General Description:
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This file contains assembler code which is shared among the USB driver
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implementations for different CPU cocks. Since the code must be inserted
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in the middle of the module, it's split out into this file and #included.
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Jump destinations called from outside:
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sofError: Called when no start sequence was found.
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se0: Called when a package has been successfully received.
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overflow: Called when receive buffer overflows.
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doReturn: Called after sending data.
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Outside jump destinations used by this module:
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waitForJ: Called to receive an already arriving packet.
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sendAckAndReti:
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sendNakAndReti:
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sendCntAndReti:
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usbSendAndReti:
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The following macros must be defined before this file is included:
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.macro POP_STANDARD
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.endm
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.macro POP_RETI
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.endm
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*/
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#define token x1
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overflow:
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ldi x2, 1<<USB_INTR_PENDING_BIT
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USB_STORE_PENDING(x2) ; clear any pending interrupts
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ignorePacket:
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clr token
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rjmp storeTokenAndReturn
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;----------------------------------------------------------------------------
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; Processing of received packet (numbers in brackets are cycles after center of SE0)
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;----------------------------------------------------------------------------
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;This is the only non-error exit point for the software receiver loop
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;we don't check any CRCs here because there is no time left.
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se0:
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subi cnt, USB_BUFSIZE ;[5]
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neg cnt ;[6]
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sub YL, cnt ;[7]
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sbci YH, 0 ;[8]
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ldi x2, 1<<USB_INTR_PENDING_BIT ;[9]
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USB_STORE_PENDING(x2) ;[10] clear pending intr and check flag later. SE0 should be over.
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ld token, y ;[11]
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cpi token, USBPID_DATA0 ;[13]
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breq handleData ;[14]
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cpi token, USBPID_DATA1 ;[15]
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breq handleData ;[16]
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lds shift, usbDeviceAddr;[17]
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ldd x2, y+1 ;[19] ADDR and 1 bit endpoint number
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lsl x2 ;[21] shift out 1 bit endpoint number
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cpse x2, shift ;[22]
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rjmp ignorePacket ;[23]
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/* only compute endpoint number in x3 if required later */
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#if USB_CFG_HAVE_INTRIN_ENDPOINT || USB_CFG_IMPLEMENT_FN_WRITEOUT
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ldd x3, y+2 ;[24] endpoint number + crc
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rol x3 ;[26] shift in LSB of endpoint
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#endif
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cpi token, USBPID_IN ;[27]
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breq handleIn ;[28]
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cpi token, USBPID_SETUP ;[29]
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breq handleSetupOrOut ;[30]
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cpi token, USBPID_OUT ;[31]
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brne ignorePacket ;[32] must be ack, nak or whatever
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; rjmp handleSetupOrOut ; fallthrough
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;Setup and Out are followed by a data packet two bit times (16 cycles) after
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;the end of SE0. The sync code allows up to 40 cycles delay from the start of
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;the sync pattern until the first bit is sampled. That's a total of 56 cycles.
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handleSetupOrOut: ;[32]
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#if USB_CFG_IMPLEMENT_FN_WRITEOUT /* if we have data for endpoint != 0, set usbCurrentTok to address */
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andi x3, 0xf ;[32]
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breq storeTokenAndReturn ;[33]
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mov token, x3 ;[34] indicate that this is endpoint x OUT
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#endif
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storeTokenAndReturn:
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sts usbCurrentTok, token;[35]
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doReturn:
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POP_STANDARD ;[37] 12...16 cycles
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USB_LOAD_PENDING(YL) ;[49]
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sbrc YL, USB_INTR_PENDING_BIT;[50] check whether data is already arriving
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rjmp waitForJ ;[51] save the pops and pushes -- a new interrupt is already pending
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sofError:
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POP_RETI ;macro call
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reti
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handleData:
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#if USB_CFG_CHECK_CRC
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CRC_CLEANUP_AND_CHECK ; jumps to ignorePacket if CRC error
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#endif
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lds shift, usbCurrentTok;[18]
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tst shift ;[20]
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breq doReturn ;[21]
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lds x2, usbRxLen ;[22]
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tst x2 ;[24]
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brne sendNakAndReti ;[25]
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; 2006-03-11: The following two lines fix a problem where the device was not
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; recognized if usbPoll() was called less frequently than once every 4 ms.
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cpi cnt, 4 ;[26] zero sized data packets are status phase only -- ignore and ack
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brmi sendAckAndReti ;[27] keep rx buffer clean -- we must not NAK next SETUP
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#if USB_CFG_CHECK_DATA_TOGGLING
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sts usbCurrentDataToken, token ; store for checking by C code
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#endif
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sts usbRxLen, cnt ;[28] store received data, swap buffers
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sts usbRxToken, shift ;[30]
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lds x2, usbInputBufOffset;[32] swap buffers
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ldi cnt, USB_BUFSIZE ;[34]
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sub cnt, x2 ;[35]
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sts usbInputBufOffset, cnt;[36] buffers now swapped
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rjmp sendAckAndReti ;[38] 40 + 17 = 57 until SOP
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handleIn:
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;We don't send any data as long as the C code has not processed the current
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;input data and potentially updated the output data. That's more efficient
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;in terms of code size than clearing the tx buffers when a packet is received.
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lds x1, usbRxLen ;[30]
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cpi x1, 1 ;[32] negative values are flow control, 0 means "buffer free"
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brge sendNakAndReti ;[33] unprocessed input packet?
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ldi x1, USBPID_NAK ;[34] prepare value for usbTxLen
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#if USB_CFG_HAVE_INTRIN_ENDPOINT
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andi x3, 0xf ;[35] x3 contains endpoint
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#if USB_CFG_SUPPRESS_INTR_CODE
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brne sendNakAndReti ;[36]
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#else
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brne handleIn1 ;[36]
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#endif
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#endif
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lds cnt, usbTxLen ;[37]
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sbrc cnt, 4 ;[39] all handshake tokens have bit 4 set
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rjmp sendCntAndReti ;[40] 42 + 16 = 58 until SOP
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sts usbTxLen, x1 ;[41] x1 == USBPID_NAK from above
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ldi YL, lo8(usbTxBuf) ;[43]
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ldi YH, hi8(usbTxBuf) ;[44]
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rjmp usbSendAndReti ;[45] 57 + 12 = 59 until SOP
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; Comment about when to set usbTxLen to USBPID_NAK:
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; We should set it back when we receive the ACK from the host. This would
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; be simple to implement: One static variable which stores whether the last
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; tx was for endpoint 0 or 1 and a compare in the receiver to distinguish the
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; ACK. However, we set it back immediately when we send the package,
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; assuming that no error occurs and the host sends an ACK. We save one byte
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; RAM this way and avoid potential problems with endless retries. The rest of
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; the driver assumes error-free transfers anyway.
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#if !USB_CFG_SUPPRESS_INTR_CODE && USB_CFG_HAVE_INTRIN_ENDPOINT /* placed here due to relative jump range */
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handleIn1: ;[38]
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#if USB_CFG_HAVE_INTRIN_ENDPOINT3
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; 2006-06-10 as suggested by O.Tamura: support second INTR IN / BULK IN endpoint
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cpi x3, USB_CFG_EP3_NUMBER;[38]
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breq handleIn3 ;[39]
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#endif
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lds cnt, usbTxLen1 ;[40]
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sbrc cnt, 4 ;[42] all handshake tokens have bit 4 set
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rjmp sendCntAndReti ;[43] 47 + 16 = 63 until SOP
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sts usbTxLen1, x1 ;[44] x1 == USBPID_NAK from above
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ldi YL, lo8(usbTxBuf1) ;[46]
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ldi YH, hi8(usbTxBuf1) ;[47]
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rjmp usbSendAndReti ;[48] 50 + 12 = 62 until SOP
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#if USB_CFG_HAVE_INTRIN_ENDPOINT3
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handleIn3:
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lds cnt, usbTxLen3 ;[41]
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sbrc cnt, 4 ;[43]
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rjmp sendCntAndReti ;[44] 49 + 16 = 65 until SOP
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sts usbTxLen3, x1 ;[45] x1 == USBPID_NAK from above
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ldi YL, lo8(usbTxBuf3) ;[47]
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ldi YH, hi8(usbTxBuf3) ;[48]
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rjmp usbSendAndReti ;[49] 51 + 12 = 63 until SOP
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#endif
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#endif
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