164 lines
5.0 KiB
NASM
164 lines
5.0 KiB
NASM
; ***************************************************************************
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; copyright : (C) 2023 by Martin Preuss
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; email : martin@libchipcard.de
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;
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; ***************************************************************************
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; * This file is part of the project "AqHome". *
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; * Please see toplevel file COPYING of that project for license details. *
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; ***************************************************************************
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; ---------------------------------------------------------------------------
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; receive packet into buffer pointed to by X.
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;
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; IN:
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; - R16: COM address to listen to
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; - R17: maximum value for accepted msg data (i.e. buffersize minus 3)
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; - X : buffer to receive to
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; OUT:
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; - CFLAG: set if okay (packet received), cleared on error
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; - R16: error code if CFLAG is cleared
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; REGS: r16, r17, r18, X (r19, r20, r21, r22)
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com2ReceivePacketRaw:
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mov r18, r17
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push r16
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; read destination address
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rcall com2ReceiveByte ; read byte (R16, R17, R20, R21, R22)
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pop r17 ; pop from R16 to R17
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brcc com2ReceivePacketRaw_ioError
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; compare destination address (accept "FF" and own address)
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cp r16, r17
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breq com2ReceivePacketRaw_acceptAddr
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cpi r16, 0xff
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breq com2ReceivePacketRaw_acceptAddr
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ldi r16, COM2_ERROR_NOTFORME
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rjmp com2ReceivePacketRaw_error ; clc/ret
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com2ReceivePacketRaw_acceptAddr:
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st X+, r16 ; store dest address, lock buffer
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; read msg length
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rcall com2ReceiveByte ; read packet length (R16, R17, R20, R21, R22)
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brcc com2ReceivePacketRaw_ioError
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st X+, r16
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cp r16, r18 ; (COM2_BUFFER_SIZE-3)
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brcc com2ReceivePacketRaw_contentError ; packet too long
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inc r16 ; account for checksum byte
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mov r17, r16
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com2ReceivePacketRaw_loop:
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push r17
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rcall com2ReceiveByte ; read byte (R16, R17, R20, R21, R22)
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pop r17
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brcc com2ReceivePacketRaw_ioError
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st X+, r16
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dec r17
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brne com2ReceivePacketRaw_loop
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rjmp com2PacketsSecRet
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com2ReceivePacketRaw_ioError:
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ldi r16, COM2_ERROR_IOERROR
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rjmp com2PacketsClcRet
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com2ReceivePacketRaw_contentError:
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ldi r16, COM2_ERROR_DATAERROR
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com2ReceivePacketRaw_error:
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rjmp com2PacketsClcRet
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; ---------------------------------------------------------------------------
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; send packet over wire, handle ATTN line.
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;
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; IN:
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; - x : ptr to buffer to send
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; OUT:
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; - CFLAGS: set if okay, cleared otherwise (errorcode in R16)
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; REGS: R16, R22 (R17, R21, X)
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COM2_SendPacketWithAttn:
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push r15
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in r15, SREG
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cli
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; rcall com2WaitForOneBitLength ; wait for one bit duration (R22)
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; check for ATTN line: busy?
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cbi COM_PORT_ATTN, COM_PINNUM_ATTN ; disable pullup on ATTN
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cbi COM_DDR_ATTN, COM_PINNUM_ATTN ; set ATTN as input
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nop ; needed to sample current input
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sbis COM_PIN_ATTN, COM_PINNUM_ATTN ; ATTN low?
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rjmp COM2_SendPacketWithAttn_lineBusyError ; jump if it is
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cbi COM_PORT_ATTN, COM_PINNUM_ATTN ; set ATTN low
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sbi COM_DDR_ATTN, COM_PINNUM_ATTN ; set ATTN as output
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rcall com2WaitForOneBitLength ; wait for one bit duration (R22)
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adiw xh:xl, COM2_MSG_OFFS_MSGLEN
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ld r16, X
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sbiw xh:xl, COM2_MSG_OFFS_MSGLEN
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inc r16 ; account for dest addr
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inc r16 ; account for msglen byte
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inc r16 ; account for crc byte
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rcall com2SendPacketRaw ; (r16, r17, r21, r22, X)
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cbi COM_DDR_ATTN, COM_PINNUM_ATTN ; release ATTN line (by setting direction to IN)
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brcc COM2_SendPacketWithAttn_ioError
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; packet successfully sent
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out SREG, r15
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pop r15
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rjmp com2PacketsSecRet
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COM2_SendPacketWithAttn_ioError:
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ldi r16,COM2_ERROR_COLLISION
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rjmp COM2_SendPacketWithAttn_retNc
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COM2_SendPacketWithAttn_lineBusyError:
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ldi r16,COM2_ERROR_BUSY
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COM2_SendPacketWithAttn_retNc:
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pop r15
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out SREG, r15
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rjmp com2PacketsClcRet
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; ---------------------------------------------------------------------------
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; wait for one bit length (minus cycles for call and ret).
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;
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; IN:
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; - nothing
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; OUT:
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; - nothing
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; REGS: r22
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com2WaitForOneBitLength:
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Utils_WaitNanoSecs COM_BIT_LENGTH, 7, r22 ; wait for one bit duration (minus RCALL/RET)
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ret
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; ---------------------------------------------------------------------------
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; send packet over wire, expects ATTN to be low.
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;
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; IN:
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; - r16: number of bytes to send
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; - x : ptr to buffer to send
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; OUT:
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; - nothing
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; REGS: r16, r17, x (r21, r22)
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com2SendPacketRaw:
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mov r17, r16
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com2SendPacket_loop:
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ld r16, X+
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rcall com2SendByte ; send byte (R16, R21, R22)
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brcc com2PacketsClcRet
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dec r17
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brne com2SendPacket_loop
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sec
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ret
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com2PacketsClcRet:
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clc
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ret
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com2PacketsSecRet:
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sec
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ret
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