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2534
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1 *******************************************************
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2 *
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3 * DWRdMess
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4 * Receive a response from the DriveWire server via MESS FIFO
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5 * 4/27/10 AAW - Based on John Linville's example driver
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6 *
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7 * Entry:
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8 * X = starting address where data is to be stored
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9 * Y = number of bytes expected
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10 *
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11 * Exit:
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12 * CC = carry set on framing error, Z set if all bytes received
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13 * X = starting address of data received
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14 * Y = checksum
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15 * U is preserved. All accumulators are clobbered
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16 *
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17
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18 DWRead clra ; clear Carry (no framing error)
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19 pshs u,x,cc ; preserve registers, push timeout msb
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20 orcc #$50 ; mask interrupts
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21
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22 leau ,x ; U = storage ptr
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23 ldx #0 ; initialize checksum
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24
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25 * Read a byte
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26 rxByte ldb $ffe1 ; check for data in FIFO
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27 beq rxByte ; loop while empty
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28 ldb $ffe0 ; read data value
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29
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30 stb ,u+ ; store received byte to memory
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31 abx ; update checksum
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32 leay ,-y ; decrement request count
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33 bne rxByte ; loop if another byte wanted
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34
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35
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36 * Clean up, set status and return
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37 rxExit leay ,x ; return checksum in Y
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38 puls cc,x,u,pc ; restore registers and return
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39 setdp $00
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40
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41
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