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187 lines
7.8 KiB
187 lines
7.8 KiB
/* 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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