root
21 lines
730 B
ArmAsm
21 lines
730 B
ArmAsm
; ECHO -- copy each day's uplink into the downlink buffer.
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;
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.equ RX 0 ; uplink buffer
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.equ TX 1024 ; downlink buffer
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.equ P_UPNEW 0x70 ; uplink-arrived flag / acknowledge
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.equ P_UPLEN 0x71 ; uplink length in bytes
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wait: in r1, P_UPNEW
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ldi r2, 0
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beq r1, r2, sleep ; nothing new today
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in r4, P_UPLEN
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ldi r5, 0 ; r5 = byte index
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copy: bge r5, r4, done
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ldb r6, [r5+RX]
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stb r6, [r5+TX]
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addi r5, 1
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jmp copy
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done: out P_UPNEW, r1 ; acknowledge
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sleep: yield
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jmp wait
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