encoder, dip update, adds bootloader
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								keyboards/planck/thk/bootloader/usbdrv/usbdrvasm20.inc
									
										
									
									
									
										Normal file
									
								
							
							
						
						
									
										359
									
								
								keyboards/planck/thk/bootloader/usbdrv/usbdrvasm20.inc
									
										
									
									
									
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/* Name: usbdrvasm20.inc
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 * Project: V-USB, virtual USB port for Atmel's(r) AVR(r) microcontrollers
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		||||
 * Author: Jeroen Benschop
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 * Based on usbdrvasm16.inc from Christian Starkjohann
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 * Creation Date: 2008-03-05
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 * Tabsize: 4
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 * Copyright: (c) 2008 by Jeroen Benschop and 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 is the 20 MHz version of the asssembler part of the USB driver. It
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requires a 20 MHz crystal (not a ceramic resonator and not a calibrated RC
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oscillator).
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See usbdrv.h for a description of the entire driver.
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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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*/
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#define leap2   x3
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#ifdef __IAR_SYSTEMS_ASM__
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#define nextInst    $+2
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#else
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#define nextInst    .+0
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#endif
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;max stack usage: [ret(2), YL, SREG, YH, bitcnt, shift, x1, x2, x3, x4, cnt] = 12 bytes
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;nominal frequency: 20 MHz -> 13.333333 cycles per bit, 106.666667 cycles per byte
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; Numbers in brackets are clocks counted from center of last sync bit
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; when instruction starts
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;register use in receive loop:
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; shift assembles the byte currently being received
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; x1 holds the D+ and D- line state
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; x2 holds the previous line state
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; x4 (leap)  is used to add a leap cycle once every three bytes received
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; X3 (leap2) is used to add a leap cycle once every three stuff bits received
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; bitcnt is used to determine when a stuff bit is due
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; cnt holds the number of bytes left in the receive buffer
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USB_INTR_VECTOR:
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;order of registers pushed: YL, SREG YH, [sofError], bitcnt, shift, x1, x2, x3, x4, cnt
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    push    YL                  ;[-28] push only what is necessary to sync with edge ASAP
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    in      YL, SREG            ;[-26]
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    push    YL                  ;[-25]
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    push    YH                  ;[-23]
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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     ;[-19]
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    rjmp    foundK              ;[-18]
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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
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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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#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:                         ;[-16]
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;{3, 5} after falling D- edge, average delay: 4 cycles
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;bit0 should be at 34 for center sampling. Currently at 4 so 30 cylces till bit 0 sample
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;use 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    bitcnt              ;[-16]
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;   [---]                       ;[-15]
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    lds     YL, usbInputBufOffset;[-14]
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;   [---]                       ;[-13]
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    clr     YH                  ;[-12]
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    subi    YL, lo8(-(usbRxBuf));[-11] [rx loop init]
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    sbci    YH, hi8(-(usbRxBuf));[-10] [rx loop init]
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    push    shift               ;[-9]
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;   [---]                       ;[-8]
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    ldi     shift,0x40          ;[-7] set msb to "1" so processing bit7 can be detected
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    nop2                        ;[-6]
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;   [---]                       ;[-5]
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    ldi     bitcnt, 5           ;[-4] [rx loop init]
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    sbis    USBIN, USBMINUS     ;[-3] we want two bits K (sample 3 cycles too early)
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    rjmp    haveTwoBitsK        ;[-2]
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    pop     shift               ;[-1] undo the push from before
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    pop     bitcnt              ;[1] 
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    rjmp    waitForK            ;[3] this was not the end of sync, retry
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; The entire loop from waitForK until rjmp waitForK above must not exceed two
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; bit times (= 27 cycles).
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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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haveTwoBitsK:
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    push    x1                  ;[0]
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    push    x2                  ;[2]
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    push    x3                  ;[4] (leap2)
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    ldi     leap2, 0x55         ;[6] add leap cycle on 2nd,5th,8th,... stuff bit
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    push    x4                  ;[7] == leap
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    ldi     leap, 0x55          ;[9] skip leap cycle on 2nd,5th,8th,... byte received
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    push    cnt                 ;[10]
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    ldi     cnt, USB_BUFSIZE    ;[12] [rx loop init]
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    ldi     x2, 1<<USBPLUS      ;[13] current line state is K state. D+=="1", D-=="0"
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bit0:       
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    in      x1, USBIN           ;[0] sample line state
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    andi    x1, USBMASK         ;[1] filter only D+ and D- bits
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    rjmp    handleBit           ;[2] make bit0 14 cycles long
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;----------------------------------------------------------------------------
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; Process bit7. However, bit 6 still may need unstuffing.
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;----------------------------------------------------------------------------
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b6checkUnstuff:
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    dec     bitcnt              ;[9]
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    breq    unstuff6            ;[10]
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bit7:
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    subi    cnt, 1              ;[11] cannot use dec becaus it does not affect the carry flag
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    brcs    overflow            ;[12] Too many bytes received. Ignore packet
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    in      x1, USBIN           ;[0] sample line state
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    andi    x1, USBMASK         ;[1] filter only D+ and D- bits
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    cpse    x1, x2              ;[2] when previous line state equals current line state, handle "1"
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    rjmp    b7handle0           ;[3] when line state differs, handle "0"
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    sec                         ;[4]
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    ror     shift               ;[5] shift "1" into the data
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    st      y+, shift           ;[6] store the data into the buffer
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    ldi     shift, 0x40         ;[7] reset data for receiving the next byte
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    subi    leap, 0x55          ;[9] trick to introduce a leap cycle every 3 bytes
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    brcc    nextInst            ;[10 or 11] it will fail after 85 bytes. However low speed can only receive 11
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    dec     bitcnt              ;[11 or 12]
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    brne    bit0                ;[12 or 13]
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    ldi     x1, 1               ;[13 or 14] unstuffing bit 7
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    in      bitcnt, USBIN       ;[0] sample stuff bit
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    rjmp    unstuff             ;[1]
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b7handle0:
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    mov     x2,x1               ;[5] Set x2 to current line state
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    ldi     bitcnt, 6           ;[6]
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    lsr     shift               ;[7] shift "0" into the data
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    st      y+, shift           ;[8] store data into the buffer
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    ldi     shift, 0x40         ;[10] reset data for receiving the next byte
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    subi    leap, 0x55          ;[11] trick to introduce a leap cycle every 3 bytes
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    brcs    bit0                ;[12] it will fail after 85 bytes. However low speed can only receive 11
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    rjmp    bit0                ;[13]
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;----------------------------------------------------------------------------
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; Handle unstuff
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; x1==0xFF indicate unstuffing bit6
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;----------------------------------------------------------------------------
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unstuff6:
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    ldi     x1,0xFF             ;[12] indicate unstuffing bit 6
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    in      bitcnt, USBIN       ;[0]  sample stuff bit
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    nop                         ;[1]  fix timing
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unstuff:                        ;b0-5  b6   b7
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    mov     x2,bitcnt           ;[3]  [2]  [3]  Set x2 to match line state
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    subi    leap2, 0x55         ;[4]  [3]  [4]  delay loop
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    brcs    nextInst            ;[5]  [4]  [5]  add one cycle every three stuff bits
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    sbci    leap2,0             ;[6]  [5]  [6]
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    ldi     bitcnt,6            ;[7]  [6]  [7]  reset bit stuff counter
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    andi    x2, USBMASK         ;[8]  [7]  [8] only keep D+ and D-
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    cpi     x1,0                ;[9]  [8]  [9]
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    brmi    bit7                ;[10] [9]  [10] finished unstuffing bit6 When x1<0
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    breq    bitloop             ;[11] ---  [11] finished unstuffing bit0-5 when x1=0
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    nop                         ;---  ---  [12]
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    in      x1, USBIN           ;---  ---  [0] sample line state for bit0
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    andi    x1, USBMASK         ;---  ---  [1] filter only D+ and D- bits
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    rjmp    handleBit           ;---  ---  [2] make bit0 14 cycles long
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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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bitloop:
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    in      x1, USBIN           ;[0] sample line state
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    andi    x1, USBMASK         ;[1] filter only D+ and D- bits
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    breq    se0                 ;[2] both lines are low so handle se0
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handleBit:
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    cpse    x1, x2              ;[3] when previous line state equals current line state, handle "1"
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    rjmp    handle0             ;[4] when line state differs, handle "0"
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    sec                         ;[5]
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    ror     shift               ;[6] shift "1" into the data
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    brcs    b6checkUnstuff      ;[7] When after shift C is set, next bit is bit7
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    nop2                        ;[8]
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    dec     bitcnt              ;[10]
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    brne    bitloop             ;[11]
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    ldi     x1,0                ;[12] indicate unstuff for bit other than bit6 or bit7
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    in      bitcnt, USBIN       ;[0] sample stuff bit
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    rjmp    unstuff             ;[1]
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handle0:
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    mov     x2, x1              ;[6] Set x2 to current line state
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    ldi     bitcnt, 6           ;[7] reset unstuff counter. 
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    lsr     shift               ;[8] shift "0" into the data
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    brcs    bit7                ;[9] When after shift C is set, next bit is bit7
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    nop                         ;[10]
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    rjmp    bitloop             ;[11] 
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;----------------------------------------------------------------------------
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; End of receive loop. Now start handling EOP
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;----------------------------------------------------------------------------
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macro POP_STANDARD ; 14 cycles
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    pop     cnt
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    pop     x4
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    pop     x3
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    pop     x2
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    pop     x1
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    pop     shift
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    pop     bitcnt
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    endm
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macro POP_RETI     ; 7 cycles
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    pop     YH
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    pop     YL
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    out     SREG, YL
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    pop     YL
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    endm
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#include "asmcommon.inc"
 | 
			
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; USB spec says:
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; idle = J
 | 
			
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; J = (D+ = 0), (D- = 1)
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; K = (D+ = 1), (D- = 0)
 | 
			
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; Spec allows 7.5 bit times from EOP to SOP for replies
 | 
			
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; 7.5 bit times is 100 cycles. This implementation arrives a bit later at se0
 | 
			
		||||
; then specified in the include file but there is plenty of time
 | 
			
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bitstuffN:
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    eor     x1, x4          ;[8]
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    ldi     x2, 0           ;[9]
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    nop2                    ;[10]
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    out     USBOUT, x1      ;[12] <-- out
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    rjmp    didStuffN       ;[0]
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		||||
bitstuff7:
 | 
			
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    eor     x1, x4          ;[6]
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    ldi     x2, 0           ;[7] Carry is zero due to brcc
 | 
			
		||||
    rol     shift           ;[8] compensate for ror shift at branch destination
 | 
			
		||||
    nop2                    ;[9]
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		||||
    rjmp    didStuff7       ;[11]
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		||||
sendNakAndReti:
 | 
			
		||||
    ldi     x3, USBPID_NAK  ;[-18]
 | 
			
		||||
    rjmp    sendX3AndReti   ;[-17]
 | 
			
		||||
sendAckAndReti:
 | 
			
		||||
    ldi     cnt, USBPID_ACK ;[-17]
 | 
			
		||||
sendCntAndReti:
 | 
			
		||||
    mov     x3, cnt         ;[-16]
 | 
			
		||||
sendX3AndReti:
 | 
			
		||||
    ldi     YL, 20          ;[-15] x3==r20 address is 20
 | 
			
		||||
    ldi     YH, 0           ;[-14]
 | 
			
		||||
    ldi     cnt, 2          ;[-13]
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		||||
;   rjmp    usbSendAndReti      fallthrough
 | 
			
		||||
 | 
			
		||||
;usbSend:
 | 
			
		||||
;pointer to data in 'Y'
 | 
			
		||||
;number of bytes in 'cnt' -- including sync byte [range 2 ... 12]
 | 
			
		||||
;uses: x1...x4, btcnt, shift, cnt, Y
 | 
			
		||||
;Numbers in brackets are time since first bit of sync pattern is sent
 | 
			
		||||
;We don't match the transfer rate exactly (don't insert leap cycles every third
 | 
			
		||||
;byte) because the spec demands only 1.5% precision anyway.
 | 
			
		||||
usbSendAndReti:             ; 12 cycles until SOP
 | 
			
		||||
    in      x2, USBDDR      ;[-12]
 | 
			
		||||
    ori     x2, USBMASK     ;[-11]
 | 
			
		||||
    sbi     USBOUT, USBMINUS;[-10] prepare idle state; D+ and D- must have been 0 (no pullups)
 | 
			
		||||
    in      x1, USBOUT      ;[-8] port mirror for tx loop
 | 
			
		||||
    out     USBDDR, x2      ;[-7] <- acquire bus
 | 
			
		||||
; need not init x2 (bitstuff history) because sync starts with 0
 | 
			
		||||
    ldi     x4, USBMASK     ;[-6] exor mask
 | 
			
		||||
    ldi     shift, 0x80     ;[-5] sync byte is first byte sent
 | 
			
		||||
txByteLoop:
 | 
			
		||||
    ldi     bitcnt, 0x49    ;[-4]        [10] binary 01001001
 | 
			
		||||
txBitLoop:
 | 
			
		||||
    sbrs    shift, 0        ;[-3] [10]   [11]
 | 
			
		||||
    eor     x1, x4          ;[-2] [11]   [12]
 | 
			
		||||
    out     USBOUT, x1      ;[-1] [12]   [13]   <-- out N
 | 
			
		||||
    ror     shift           ;[0]  [13]   [14]
 | 
			
		||||
    ror     x2              ;[1]
 | 
			
		||||
didStuffN:
 | 
			
		||||
    nop2                    ;[2]
 | 
			
		||||
    nop                     ;[4]
 | 
			
		||||
    cpi     x2, 0xfc        ;[5]
 | 
			
		||||
    brcc    bitstuffN       ;[6]
 | 
			
		||||
    lsr     bitcnt          ;[7]
 | 
			
		||||
    brcc    txBitLoop       ;[8]
 | 
			
		||||
    brne    txBitLoop       ;[9]
 | 
			
		||||
 | 
			
		||||
    sbrs    shift, 0        ;[10]
 | 
			
		||||
    eor     x1, x4          ;[11]
 | 
			
		||||
didStuff7:
 | 
			
		||||
    out     USBOUT, x1      ;[-1] [13] <-- out 7
 | 
			
		||||
    ror     shift           ;[0] [14]
 | 
			
		||||
    ror     x2              ;[1]
 | 
			
		||||
    nop                     ;[2]
 | 
			
		||||
    cpi     x2, 0xfc        ;[3]
 | 
			
		||||
    brcc    bitstuff7       ;[4]
 | 
			
		||||
    ld      shift, y+       ;[5]
 | 
			
		||||
    dec     cnt             ;[7]
 | 
			
		||||
    brne    txByteLoop      ;[8]
 | 
			
		||||
;make SE0:
 | 
			
		||||
    cbr     x1, USBMASK     ;[9] prepare SE0 [spec says EOP may be 25 to 30 cycles]
 | 
			
		||||
    lds     x2, usbNewDeviceAddr;[10]
 | 
			
		||||
    lsl     x2              ;[12] we compare with left shifted address
 | 
			
		||||
    out     USBOUT, x1      ;[13] <-- out SE0 -- from now 2 bits = 22 cycles until bus idle
 | 
			
		||||
    subi    YL, 20 + 2      ;[0] Only assign address on data packets, not ACK/NAK in x3
 | 
			
		||||
    sbci    YH, 0           ;[1]
 | 
			
		||||
;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  ;[2]
 | 
			
		||||
    sts     usbDeviceAddr, x2; if not skipped: SE0 is one cycle longer
 | 
			
		||||
skipAddrAssign:
 | 
			
		||||
;end of usbDeviceAddress transfer
 | 
			
		||||
    ldi     x2, 1<<USB_INTR_PENDING_BIT;[4] int0 occurred during TX -- clear pending flag
 | 
			
		||||
    USB_STORE_PENDING(x2)   ;[5]
 | 
			
		||||
    ori     x1, USBIDLE     ;[6]
 | 
			
		||||
    in      x2, USBDDR      ;[7]
 | 
			
		||||
    cbr     x2, USBMASK     ;[8] set both pins to input
 | 
			
		||||
    mov     x3, x1          ;[9]
 | 
			
		||||
    cbr     x3, USBMASK     ;[10] configure no pullup on both pins
 | 
			
		||||
    ldi     x4, 5           ;[11]
 | 
			
		||||
se0Delay:
 | 
			
		||||
    dec     x4              ;[12] [15] [18] [21] [24]
 | 
			
		||||
    brne    se0Delay        ;[13] [16] [19] [22] [25]
 | 
			
		||||
    out     USBOUT, x1      ;[26] <-- out J (idle) -- end of SE0 (EOP signal)
 | 
			
		||||
    out     USBDDR, x2      ;[27] <-- release bus now
 | 
			
		||||
    out     USBOUT, x3      ;[28] <-- ensure no pull-up resistors are active
 | 
			
		||||
    rjmp    doReturn
 | 
			
		||||
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