751 lines
28 KiB
PHP
751 lines
28 KiB
PHP
/* Name: usbdrvasm128.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: 2008-10-11
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* Tabsize: 4
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* Copyright: (c) 2008 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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* This Revision: $Id$
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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 is the 12.8 MHz version of the USB driver. It is intended for use
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with the internal RC oscillator. Although 12.8 MHz is outside the guaranteed
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calibration range of the oscillator, almost all AVRs can reach this frequency.
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This version contains a phase locked loop in the receiver routine to cope with
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slight clock rate deviations of up to +/- 1%.
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See usbdrv.h for a description of the entire driver.
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LIMITATIONS
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===========
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Although it may seem very handy to save the crystal and use the internal
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RC oscillator of the CPU, this method (and this module) has some serious
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limitations:
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(1) The guaranteed calibration range of the oscillator is only 8.1 MHz.
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They typical range is 14.5 MHz and most AVRs can actually reach this rate.
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(2) Writing EEPROM and Flash may be unreliable (short data lifetime) since
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the write procedure is timed from the RC oscillator.
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(3) End Of Packet detection (SE0) should be in bit 1, bit it is only checked
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if bits 0 and 1 both read as 0 on D- and D+ read as 0 in the middle. This may
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cause problems with old hubs which delay SE0 by up to one cycle.
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(4) Code size is much larger than that of the other modules.
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Since almost all of this code is timing critical, don't change unless you
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really know what you are doing! Many parts require not only a maximum number
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of CPU cycles, but even an exact number of cycles!
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Implementation notes:
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======================
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min frequency: 67 cycles for 8 bit -> 12.5625 MHz
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max frequency: 69.286 cycles for 8 bit -> 12.99 MHz
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nominal frequency: 12.77 MHz ( = sqrt(min * max))
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sampling positions: (next even number in range [+/- 0.5])
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cycle index range: 0 ... 66
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bits:
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.5, 8.875, 17.25, 25.625, 34, 42.375, 50.75, 59.125
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[0/1], [9], [17], [25/+26], [34], [+42/43], [51], [59]
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bit number: 0 1 2 3 4 5 6 7
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spare cycles 1 2 1 2 1 1 1 0
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operations to perform: duration cycle
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----------------
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eor fix, shift 1 -> 00
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andi phase, USBMASK 1 -> 08
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breq se0 1 -> 16 (moved to 11)
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st y+, data 2 -> 24, 25
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mov data, fix 1 -> 33
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ser data 1 -> 41
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subi cnt, 1 1 -> 49
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brcs overflow 1 -> 50
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layout of samples and operations:
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[##] = sample bit
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<##> = sample phase
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*##* = operation
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0: *00* [01] 02 03 04 <05> 06 07
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1: *08* [09] 10 11 12 <13> 14 15 *16*
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2: [17] 18 19 20 <21> 22 23
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3: *24* *25* [26] 27 28 29 <30> 31 32
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4: *33* [34] 35 36 37 <38> 39 40
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5: *41* [42] 43 44 45 <46> 47 48
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6: *49* *50* [51] 52 53 54 <55> 56 57 58
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7: [59] 60 61 62 <63> 64 65 66
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*****************************************************************************/
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/* we prefer positive expressions (do if condition) instead of negative
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* (skip if condition), therefore use defines for skip instructions:
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*/
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#define ifioclr sbis
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#define ifioset sbic
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#define ifrclr sbrs
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#define ifrset sbrc
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/* The registers "fix" and "data" swap their meaning during the loop. Use
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* defines to keep their name constant.
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*/
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#define fix x2
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#define data x1
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#undef phase /* phase has a default definition to x4 */
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#define phase x3
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USB_INTR_VECTOR:
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;order of registers pushed: YL, SREG [sofError], YH, shift, x1, x2, x3, cnt, r0
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push YL ;2 push only what is necessary to sync with edge ASAP
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in YL, SREG ;1
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push YL ;2
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;----------------------------------------------------------------------------
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; Synchronize with sync pattern:
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;----------------------------------------------------------------------------
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;sync byte (D-) pattern LSb to MSb: 01010100 [1 = idle = J, 0 = K]
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;sync up with J to K edge during sync pattern -- use fastest possible loops
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;The first part waits at most 1 bit long since we must be in sync pattern.
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;YL is guarenteed to be < 0x80 because I flag is clear. When we jump to
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;waitForJ, ensure that this prerequisite is met.
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waitForJ:
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inc YL
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sbis USBIN, USBMINUS
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brne waitForJ ; just make sure we have ANY timeout
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waitForK:
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;The following code results in a sampling window of 1/4 bit which meets the spec.
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sbis USBIN, USBMINUS
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rjmp foundK
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sbis USBIN, USBMINUS
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rjmp foundK
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sbis USBIN, USBMINUS
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rjmp foundK
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sbis USBIN, USBMINUS
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rjmp foundK
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sbis USBIN, USBMINUS ;[0]
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rjmp foundK ;[1]
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#if USB_COUNT_SOF
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lds YL, usbSofCount
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inc YL
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sts usbSofCount, YL
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#endif /* USB_COUNT_SOF */
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#ifdef USB_SOF_HOOK
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USB_SOF_HOOK
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#endif
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rjmp sofError
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foundK:
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;{3, 5} after falling D- edge, average delay: 4 cycles [we want 4 for center sampling]
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;we have 1 bit time for setup purposes, then sample again. Numbers in brackets
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;are cycles from center of first sync (double K) bit after the instruction
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push YH ;[2]
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lds YL, usbInputBufOffset;[4]
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clr YH ;[6]
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subi YL, lo8(-(usbRxBuf));[7]
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sbci YH, hi8(-(usbRxBuf));[8]
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sbis USBIN, USBMINUS ;[9] we want two bits K [we want to sample at 8 + 4 - 1.5 = 10.5]
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rjmp haveTwoBitsK ;[10]
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pop YH ;[11] undo the push from before
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rjmp waitForK ;[13] this was not the end of sync, retry
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haveTwoBitsK:
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;----------------------------------------------------------------------------
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; push more registers and initialize values while we sample the first bits:
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;----------------------------------------------------------------------------
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#define fix x2
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#define data x1
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push shift ;[12]
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push x1 ;[14]
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push x2 ;[16]
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ldi shift, 0x80 ;[18] prevent bit-unstuffing but init low bits to 0
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ifioset USBIN, USBMINUS ;[19] [01] <--- bit 0 [10.5 + 8 = 18.5]
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ori shift, 1<<0 ;[02]
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push x3 ;[03]
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push cnt ;[05]
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push r0 ;[07]
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ifioset USBIN, USBMINUS ;[09] <--- bit 1
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ori shift, 1<<1 ;[10]
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ser fix ;[11]
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ldi cnt, USB_BUFSIZE ;[12]
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mov data, shift ;[13]
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lsl shift ;[14]
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nop2 ;[15]
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ifioset USBIN, USBMINUS ;[17] <--- bit 2
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ori data, 3<<2 ;[18] store in bit 2 AND bit 3
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eor shift, data ;[19] do nrzi decoding
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andi data, 1<<3 ;[20]
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in phase, USBIN ;[21] <- phase
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brne jumpToEntryAfterSet ;[22] if USBMINS at bit 3 was 1
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nop ;[23]
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rjmp entryAfterClr ;[24]
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jumpToEntryAfterSet:
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rjmp entryAfterSet ;[24]
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;----------------------------------------------------------------------------
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; Receiver loop (numbers in brackets are cycles within byte after instr)
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;----------------------------------------------------------------------------
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#undef fix
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#define fix x1
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#undef data
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#define data x2
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bit7IsSet:
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ifrclr phase, USBMINUS ;[62] check phase only if D- changed
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lpm ;[63]
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in phase, USBIN ;[64] <- phase (one cycle too late)
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ori shift, 1 << 7 ;[65]
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nop ;[66]
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;;;;rjmp bit0AfterSet ; -> [00] == [67] moved block up to save jump
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bit0AfterSet:
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eor fix, shift ;[00]
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#undef fix
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#define fix x2
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#undef data
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#define data x1 /* we now have result in data, fix is reset to 0xff */
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ifioclr USBIN, USBMINUS ;[01] <--- sample 0
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rjmp bit0IsClr ;[02]
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andi shift, ~(7 << 0) ;[03]
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breq unstuff0s ;[04]
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in phase, USBIN ;[05] <- phase
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rjmp bit1AfterSet ;[06]
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unstuff0s:
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in phase, USBIN ;[06] <- phase (one cycle too late)
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andi fix, ~(1 << 0) ;[07]
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ifioclr USBIN, USBMINUS ;[00]
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ifioset USBIN, USBPLUS ;[01]
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rjmp bit0IsClr ;[02] executed if first expr false or second true
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se0AndStore: ; executed only if both bits 0
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st y+, x1 ;[15/17] cycles after start of byte
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rjmp se0 ;[17/19]
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bit0IsClr:
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ifrset phase, USBMINUS ;[04] check phase only if D- changed
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lpm ;[05]
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in phase, USBIN ;[06] <- phase (one cycle too late)
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ori shift, 1 << 0 ;[07]
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bit1AfterClr:
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andi phase, USBMASK ;[08]
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ifioset USBIN, USBMINUS ;[09] <--- sample 1
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rjmp bit1IsSet ;[10]
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breq se0AndStore ;[11] if D- was 0 in bits 0 AND 1 and D+ was 0 in between, we have SE0
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andi shift, ~(7 << 1) ;[12]
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in phase, USBIN ;[13] <- phase
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breq unstuff1c ;[14]
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rjmp bit2AfterClr ;[15]
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unstuff1c:
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andi fix, ~(1 << 1) ;[16]
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nop2 ;[08]
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nop2 ;[10]
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bit1IsSet:
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ifrclr phase, USBMINUS ;[12] check phase only if D- changed
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lpm ;[13]
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in phase, USBIN ;[14] <- phase (one cycle too late)
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ori shift, 1 << 1 ;[15]
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nop ;[16]
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bit2AfterSet:
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ifioclr USBIN, USBMINUS ;[17] <--- sample 2
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rjmp bit2IsClr ;[18]
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andi shift, ~(7 << 2) ;[19]
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breq unstuff2s ;[20]
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in phase, USBIN ;[21] <- phase
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rjmp bit3AfterSet ;[22]
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unstuff2s:
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in phase, USBIN ;[22] <- phase (one cycle too late)
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andi fix, ~(1 << 2) ;[23]
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nop2 ;[16]
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nop2 ;[18]
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bit2IsClr:
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ifrset phase, USBMINUS ;[20] check phase only if D- changed
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lpm ;[21]
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in phase, USBIN ;[22] <- phase (one cycle too late)
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ori shift, 1 << 2 ;[23]
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bit3AfterClr:
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st y+, data ;[24]
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entryAfterClr:
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ifioset USBIN, USBMINUS ;[26] <--- sample 3
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rjmp bit3IsSet ;[27]
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andi shift, ~(7 << 3) ;[28]
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breq unstuff3c ;[29]
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in phase, USBIN ;[30] <- phase
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rjmp bit4AfterClr ;[31]
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unstuff3c:
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in phase, USBIN ;[31] <- phase (one cycle too late)
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andi fix, ~(1 << 3) ;[32]
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nop2 ;[25]
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nop2 ;[27]
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bit3IsSet:
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ifrclr phase, USBMINUS ;[29] check phase only if D- changed
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lpm ;[30]
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in phase, USBIN ;[31] <- phase (one cycle too late)
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ori shift, 1 << 3 ;[32]
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bit4AfterSet:
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mov data, fix ;[33] undo this move by swapping defines
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#undef fix
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#define fix x1
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#undef data
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#define data x2
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ifioclr USBIN, USBMINUS ;[34] <--- sample 4
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rjmp bit4IsClr ;[35]
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andi shift, ~(7 << 4) ;[36]
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breq unstuff4s ;[37]
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in phase, USBIN ;[38] <- phase
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rjmp bit5AfterSet ;[39]
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unstuff4s:
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in phase, USBIN ;[39] <- phase (one cycle too late)
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andi fix, ~(1 << 4) ;[40]
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nop2 ;[33]
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nop2 ;[35]
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bit4IsClr:
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ifrset phase, USBMINUS ;[37] check phase only if D- changed
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lpm ;[38]
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in phase, USBIN ;[39] <- phase (one cycle too late)
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ori shift, 1 << 4 ;[40]
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bit5AfterClr:
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ser data ;[41]
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ifioset USBIN, USBMINUS ;[42] <--- sample 5
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rjmp bit5IsSet ;[43]
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andi shift, ~(7 << 5) ;[44]
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breq unstuff5c ;[45]
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in phase, USBIN ;[46] <- phase
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rjmp bit6AfterClr ;[47]
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unstuff5c:
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in phase, USBIN ;[47] <- phase (one cycle too late)
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andi fix, ~(1 << 5) ;[48]
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nop2 ;[41]
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nop2 ;[43]
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bit5IsSet:
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ifrclr phase, USBMINUS ;[45] check phase only if D- changed
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lpm ;[46]
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in phase, USBIN ;[47] <- phase (one cycle too late)
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ori shift, 1 << 5 ;[48]
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bit6AfterSet:
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subi cnt, 1 ;[49]
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brcs jumpToOverflow ;[50]
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ifioclr USBIN, USBMINUS ;[51] <--- sample 6
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rjmp bit6IsClr ;[52]
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andi shift, ~(3 << 6) ;[53]
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cpi shift, 2 ;[54]
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in phase, USBIN ;[55] <- phase
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brlt unstuff6s ;[56]
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rjmp bit7AfterSet ;[57]
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jumpToOverflow:
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rjmp overflow
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unstuff6s:
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andi fix, ~(1 << 6) ;[50]
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lpm ;[51]
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bit6IsClr:
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ifrset phase, USBMINUS ;[54] check phase only if D- changed
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lpm ;[55]
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in phase, USBIN ;[56] <- phase (one cycle too late)
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ori shift, 1 << 6 ;[57]
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nop ;[58]
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bit7AfterClr:
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ifioset USBIN, USBMINUS ;[59] <--- sample 7
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rjmp bit7IsSet ;[60]
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andi shift, ~(1 << 7) ;[61]
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cpi shift, 4 ;[62]
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in phase, USBIN ;[63] <- phase
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brlt unstuff7c ;[64]
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rjmp bit0AfterClr ;[65] -> [00] == [67]
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unstuff7c:
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andi fix, ~(1 << 7) ;[58]
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nop ;[59]
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rjmp bit7IsSet ;[60]
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bit7IsClr:
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ifrset phase, USBMINUS ;[62] check phase only if D- changed
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lpm ;[63]
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in phase, USBIN ;[64] <- phase (one cycle too late)
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ori shift, 1 << 7 ;[65]
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nop ;[66]
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;;;;rjmp bit0AfterClr ; -> [00] == [67] moved block up to save jump
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bit0AfterClr:
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eor fix, shift ;[00]
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#undef fix
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#define fix x2
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#undef data
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#define data x1 /* we now have result in data, fix is reset to 0xff */
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ifioset USBIN, USBMINUS ;[01] <--- sample 0
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rjmp bit0IsSet ;[02]
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andi shift, ~(7 << 0) ;[03]
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breq unstuff0c ;[04]
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in phase, USBIN ;[05] <- phase
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rjmp bit1AfterClr ;[06]
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unstuff0c:
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in phase, USBIN ;[06] <- phase (one cycle too late)
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andi fix, ~(1 << 0) ;[07]
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ifioclr USBIN, USBMINUS ;[00]
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ifioset USBIN, USBPLUS ;[01]
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rjmp bit0IsSet ;[02] executed if first expr false or second true
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rjmp se0AndStore ;[03] executed only if both bits 0
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bit0IsSet:
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ifrclr phase, USBMINUS ;[04] check phase only if D- changed
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lpm ;[05]
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in phase, USBIN ;[06] <- phase (one cycle too late)
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ori shift, 1 << 0 ;[07]
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bit1AfterSet:
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andi shift, ~(7 << 1) ;[08] compensated by "ori shift, 1<<1" if bit1IsClr
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ifioclr USBIN, USBMINUS ;[09] <--- sample 1
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rjmp bit1IsClr ;[10]
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breq unstuff1s ;[11]
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nop2 ;[12] do not check for SE0 if bit 0 was 1
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in phase, USBIN ;[14] <- phase (one cycle too late)
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rjmp bit2AfterSet ;[15]
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unstuff1s:
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in phase, USBIN ;[13] <- phase
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andi fix, ~(1 << 1) ;[14]
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lpm ;[07]
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nop2 ;[10]
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bit1IsClr:
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ifrset phase, USBMINUS ;[12] check phase only if D- changed
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lpm ;[13]
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in phase, USBIN ;[14] <- phase (one cycle too late)
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ori shift, 1 << 1 ;[15]
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nop ;[16]
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bit2AfterClr:
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ifioset USBIN, USBMINUS ;[17] <--- sample 2
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rjmp bit2IsSet ;[18]
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andi shift, ~(7 << 2) ;[19]
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breq unstuff2c ;[20]
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in phase, USBIN ;[21] <- phase
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rjmp bit3AfterClr ;[22]
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unstuff2c:
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in phase, USBIN ;[22] <- phase (one cycle too late)
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andi fix, ~(1 << 2) ;[23]
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nop2 ;[16]
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nop2 ;[18]
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bit2IsSet:
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ifrclr phase, USBMINUS ;[20] check phase only if D- changed
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lpm ;[21]
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in phase, USBIN ;[22] <- phase (one cycle too late)
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ori shift, 1 << 2 ;[23]
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bit3AfterSet:
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st y+, data ;[24]
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entryAfterSet:
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ifioclr USBIN, USBMINUS ;[26] <--- sample 3
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rjmp bit3IsClr ;[27]
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andi shift, ~(7 << 3) ;[28]
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breq unstuff3s ;[29]
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in phase, USBIN ;[30] <- phase
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rjmp bit4AfterSet ;[31]
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unstuff3s:
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in phase, USBIN ;[31] <- phase (one cycle too late)
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andi fix, ~(1 << 3) ;[32]
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nop2 ;[25]
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nop2 ;[27]
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bit3IsClr:
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ifrset phase, USBMINUS ;[29] check phase only if D- changed
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lpm ;[30]
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in phase, USBIN ;[31] <- phase (one cycle too late)
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ori shift, 1 << 3 ;[32]
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bit4AfterClr:
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mov data, fix ;[33] undo this move by swapping defines
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#undef fix
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#define fix x1
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|
#undef data
|
|
#define data x2
|
|
ifioset USBIN, USBMINUS ;[34] <--- sample 4
|
|
rjmp bit4IsSet ;[35]
|
|
andi shift, ~(7 << 4) ;[36]
|
|
breq unstuff4c ;[37]
|
|
in phase, USBIN ;[38] <- phase
|
|
rjmp bit5AfterClr ;[39]
|
|
unstuff4c:
|
|
in phase, USBIN ;[39] <- phase (one cycle too late)
|
|
andi fix, ~(1 << 4) ;[40]
|
|
nop2 ;[33]
|
|
nop2 ;[35]
|
|
bit4IsSet:
|
|
ifrclr phase, USBMINUS ;[37] check phase only if D- changed
|
|
lpm ;[38]
|
|
in phase, USBIN ;[39] <- phase (one cycle too late)
|
|
ori shift, 1 << 4 ;[40]
|
|
bit5AfterSet:
|
|
ser data ;[41]
|
|
ifioclr USBIN, USBMINUS ;[42] <--- sample 5
|
|
rjmp bit5IsClr ;[43]
|
|
andi shift, ~(7 << 5) ;[44]
|
|
breq unstuff5s ;[45]
|
|
in phase, USBIN ;[46] <- phase
|
|
rjmp bit6AfterSet ;[47]
|
|
unstuff5s:
|
|
in phase, USBIN ;[47] <- phase (one cycle too late)
|
|
andi fix, ~(1 << 5) ;[48]
|
|
nop2 ;[41]
|
|
nop2 ;[43]
|
|
bit5IsClr:
|
|
ifrset phase, USBMINUS ;[45] check phase only if D- changed
|
|
lpm ;[46]
|
|
in phase, USBIN ;[47] <- phase (one cycle too late)
|
|
ori shift, 1 << 5 ;[48]
|
|
bit6AfterClr:
|
|
subi cnt, 1 ;[49]
|
|
brcs overflow ;[50]
|
|
ifioset USBIN, USBMINUS ;[51] <--- sample 6
|
|
rjmp bit6IsSet ;[52]
|
|
andi shift, ~(3 << 6) ;[53]
|
|
cpi shift, 2 ;[54]
|
|
in phase, USBIN ;[55] <- phase
|
|
brlt unstuff6c ;[56]
|
|
rjmp bit7AfterClr ;[57]
|
|
unstuff6c:
|
|
andi fix, ~(1 << 6) ;[50]
|
|
lpm ;[51]
|
|
bit6IsSet:
|
|
ifrclr phase, USBMINUS ;[54] check phase only if D- changed
|
|
lpm ;[55]
|
|
in phase, USBIN ;[56] <- phase (one cycle too late)
|
|
ori shift, 1 << 6 ;[57]
|
|
bit7AfterSet:
|
|
ifioclr USBIN, USBMINUS ;[59] <--- sample 7
|
|
rjmp bit7IsClr ;[60]
|
|
andi shift, ~(1 << 7) ;[61]
|
|
cpi shift, 4 ;[62]
|
|
in phase, USBIN ;[63] <- phase
|
|
brlt unstuff7s ;[64]
|
|
rjmp bit0AfterSet ;[65] -> [00] == [67]
|
|
unstuff7s:
|
|
andi fix, ~(1 << 7) ;[58]
|
|
nop ;[59]
|
|
rjmp bit7IsClr ;[60]
|
|
|
|
macro POP_STANDARD ; 14 cycles
|
|
pop r0
|
|
pop cnt
|
|
pop x3
|
|
pop x2
|
|
pop x1
|
|
pop shift
|
|
pop YH
|
|
endm
|
|
macro POP_RETI ; 5 cycles
|
|
pop YL
|
|
out SREG, YL
|
|
pop YL
|
|
endm
|
|
|
|
#include "asmcommon.inc"
|
|
|
|
;----------------------------------------------------------------------------
|
|
; Transmitting data
|
|
;----------------------------------------------------------------------------
|
|
|
|
txByteLoop:
|
|
txBitloop:
|
|
stuffN1Delay: ; [03]
|
|
ror shift ;[-5] [11] [63]
|
|
brcc doExorN1 ;[-4] [64]
|
|
subi x3, 1 ;[-3]
|
|
brne commonN1 ;[-2]
|
|
lsl shift ;[-1] compensate ror after rjmp stuffDelay
|
|
nop ;[00] stuffing consists of just waiting 8 cycles
|
|
rjmp stuffN1Delay ;[01] after ror, C bit is reliably clear
|
|
|
|
sendNakAndReti:
|
|
ldi cnt, USBPID_NAK ;[-19]
|
|
rjmp sendCntAndReti ;[-18]
|
|
sendAckAndReti:
|
|
ldi cnt, USBPID_ACK ;[-17]
|
|
sendCntAndReti:
|
|
mov r0, cnt ;[-16]
|
|
ldi YL, 0 ;[-15] R0 address is 0
|
|
ldi YH, 0 ;[-14]
|
|
ldi cnt, 2 ;[-13]
|
|
; rjmp usbSendAndReti fallthrough
|
|
|
|
; USB spec says:
|
|
; idle = J
|
|
; J = (D+ = 0), (D- = 1) or USBOUT = 0x01
|
|
; K = (D+ = 1), (D- = 0) or USBOUT = 0x02
|
|
; Spec allows 7.5 bit times from EOP to SOP for replies (= 60 cycles)
|
|
|
|
;usbSend:
|
|
;pointer to data in 'Y'
|
|
;number of bytes in 'cnt' -- including sync byte
|
|
;uses: x1...x3, shift, cnt, Y [x1 = mirror USBOUT, x2 = USBMASK, x3 = bitstuff cnt]
|
|
;Numbers in brackets are time since first bit of sync pattern is sent (start of instruction)
|
|
usbSendAndReti:
|
|
in x2, USBDDR ;[-10] 10 cycles until SOP
|
|
ori x2, USBMASK ;[-9]
|
|
sbi USBOUT, USBMINUS ;[-8] prepare idle state; D+ and D- must have been 0 (no pullups)
|
|
out USBDDR, x2 ;[-6] <--- acquire bus
|
|
in x1, USBOUT ;[-5] port mirror for tx loop
|
|
ldi shift, 0x40 ;[-4] sync byte is first byte sent (we enter loop after ror)
|
|
ldi x2, USBMASK ;[-3]
|
|
doExorN1:
|
|
eor x1, x2 ;[-2] [06] [62]
|
|
ldi x3, 6 ;[-1] [07] [63]
|
|
commonN1:
|
|
stuffN2Delay:
|
|
out USBOUT, x1 ;[00] [08] [64] <--- set bit
|
|
ror shift ;[01]
|
|
brcc doExorN2 ;[02]
|
|
subi x3, 1 ;[03]
|
|
brne commonN2 ;[04]
|
|
lsl shift ;[05] compensate ror after rjmp stuffDelay
|
|
rjmp stuffN2Delay ;[06] after ror, C bit is reliably clear
|
|
doExorN2:
|
|
eor x1, x2 ;[04] [12]
|
|
ldi x3, 6 ;[05] [13]
|
|
commonN2:
|
|
nop2 ;[06] [14]
|
|
subi cnt, 171 ;[08] [16] trick: (3 * 171) & 0xff = 1
|
|
out USBOUT, x1 ;[09] [17] <--- set bit
|
|
brcs txBitloop ;[10] [27] [44]
|
|
|
|
stuff6Delay:
|
|
ror shift ;[45] [53]
|
|
brcc doExor6 ;[46]
|
|
subi x3, 1 ;[47]
|
|
brne common6 ;[48]
|
|
lsl shift ;[49] compensate ror after rjmp stuffDelay
|
|
nop ;[50] stuffing consists of just waiting 8 cycles
|
|
rjmp stuff6Delay ;[51] after ror, C bit is reliably clear
|
|
doExor6:
|
|
eor x1, x2 ;[48] [56]
|
|
ldi x3, 6 ;[49]
|
|
common6:
|
|
stuff7Delay:
|
|
ror shift ;[50] [58]
|
|
out USBOUT, x1 ;[51] <--- set bit
|
|
brcc doExor7 ;[52]
|
|
subi x3, 1 ;[53]
|
|
brne common7 ;[54]
|
|
lsl shift ;[55] compensate ror after rjmp stuffDelay
|
|
rjmp stuff7Delay ;[56] after ror, C bit is reliably clear
|
|
doExor7:
|
|
eor x1, x2 ;[54] [62]
|
|
ldi x3, 6 ;[55]
|
|
common7:
|
|
ld shift, y+ ;[56]
|
|
nop ;[58]
|
|
tst cnt ;[59]
|
|
out USBOUT, x1 ;[60] [00]<--- set bit
|
|
brne txByteLoop ;[61] [01]
|
|
;make SE0:
|
|
cbr x1, USBMASK ;[02] prepare SE0 [spec says EOP may be 15 to 18 cycles]
|
|
lds x2, usbNewDeviceAddr;[03]
|
|
lsl x2 ;[05] we compare with left shifted address
|
|
subi YL, 2 + 0 ;[06] Only assign address on data packets, not ACK/NAK in r0
|
|
sbci YH, 0 ;[07]
|
|
out USBOUT, x1 ;[00] <-- out SE0 -- from now 2 bits = 16 cycles until bus idle
|
|
;2006-03-06: moved transfer of new address to usbDeviceAddr from C-Code to asm:
|
|
;set address only after data packet was sent, not after handshake
|
|
breq skipAddrAssign ;[01]
|
|
sts usbDeviceAddr, x2 ; if not skipped: SE0 is one cycle longer
|
|
skipAddrAssign:
|
|
;end of usbDeviceAddress transfer
|
|
ldi x2, 1<<USB_INTR_PENDING_BIT;[03] int0 occurred during TX -- clear pending flag
|
|
USB_STORE_PENDING(x2) ;[04]
|
|
ori x1, USBIDLE ;[05]
|
|
in x2, USBDDR ;[06]
|
|
cbr x2, USBMASK ;[07] set both pins to input
|
|
mov x3, x1 ;[08]
|
|
cbr x3, USBMASK ;[09] configure no pullup on both pins
|
|
lpm ;[10]
|
|
lpm ;[13]
|
|
out USBOUT, x1 ;[16] <-- out J (idle) -- end of SE0 (EOP signal)
|
|
out USBDDR, x2 ;[17] <-- release bus now
|
|
out USBOUT, x3 ;[18] <-- ensure no pull-up resistors are active
|
|
rjmp doReturn
|
|
|
|
|
|
|
|
/*****************************************************************************
|
|
The following PHP script generates a code skeleton for the receiver routine:
|
|
|
|
<?php
|
|
|
|
function printCmdBuffer($thisBit)
|
|
{
|
|
global $cycle;
|
|
|
|
$nextBit = ($thisBit + 1) % 8;
|
|
$s = ob_get_contents();
|
|
ob_end_clean();
|
|
$s = str_replace("#", $thisBit, $s);
|
|
$s = str_replace("@", $nextBit, $s);
|
|
$lines = explode("\n", $s);
|
|
for($i = 0; $i < count($lines); $i++){
|
|
$s = $lines[$i];
|
|
if(ereg("\\[([0-9-][0-9])\\]", $s, $regs)){
|
|
$c = $cycle + (int)$regs[1];
|
|
$s = ereg_replace("\\[[0-9-][0-9]\\]", sprintf("[%02d]", $c), $s);
|
|
}
|
|
if(strlen($s) > 0)
|
|
echo "$s\n";
|
|
}
|
|
}
|
|
|
|
function printBit($isAfterSet, $bitNum)
|
|
{
|
|
ob_start();
|
|
if($isAfterSet){
|
|
?>
|
|
ifioclr USBIN, USBMINUS ;[00] <--- sample
|
|
rjmp bit#IsClr ;[01]
|
|
andi shift, ~(7 << #) ;[02]
|
|
breq unstuff#s ;[03]
|
|
in phase, USBIN ;[04] <- phase
|
|
rjmp bit@AfterSet ;[05]
|
|
unstuff#s:
|
|
in phase, USBIN ;[05] <- phase (one cycle too late)
|
|
andi fix, ~(1 << #) ;[06]
|
|
nop2 ;[-1]
|
|
nop2 ;[01]
|
|
bit#IsClr:
|
|
ifrset phase, USBMINUS ;[03] check phase only if D- changed
|
|
lpm ;[04]
|
|
in phase, USBIN ;[05] <- phase (one cycle too late)
|
|
ori shift, 1 << # ;[06]
|
|
<?php
|
|
}else{
|
|
?>
|
|
ifioset USBIN, USBMINUS ;[00] <--- sample
|
|
rjmp bit#IsSet ;[01]
|
|
andi shift, ~(7 << #) ;[02]
|
|
breq unstuff#c ;[03]
|
|
in phase, USBIN ;[04] <- phase
|
|
rjmp bit@AfterClr ;[05]
|
|
unstuff#c:
|
|
in phase, USBIN ;[05] <- phase (one cycle too late)
|
|
andi fix, ~(1 << #) ;[06]
|
|
nop2 ;[-1]
|
|
nop2 ;[01]
|
|
bit#IsSet:
|
|
ifrclr phase, USBMINUS ;[03] check phase only if D- changed
|
|
lpm ;[04]
|
|
in phase, USBIN ;[05] <- phase (one cycle too late)
|
|
ori shift, 1 << # ;[06]
|
|
<?php
|
|
}
|
|
printCmdBuffer($bitNum);
|
|
}
|
|
|
|
$bitStartCycles = array(1, 9, 17, 26, 34, 42, 51, 59);
|
|
for($i = 0; $i < 16; $i++){
|
|
$bit = $i % 8;
|
|
$emitClrCode = ($i + (int)($i / 8)) % 2;
|
|
$cycle = $bitStartCycles[$bit];
|
|
if($emitClrCode){
|
|
printf("bit%dAfterClr:\n", $bit);
|
|
}else{
|
|
printf("bit%dAfterSet:\n", $bit);
|
|
}
|
|
ob_start();
|
|
echo " ***** ;[-1]\n";
|
|
printCmdBuffer($bit);
|
|
printBit(!$emitClrCode, $bit);
|
|
if($i == 7)
|
|
echo "\n";
|
|
}
|
|
|
|
?>
|
|
*****************************************************************************/
|