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[/] [diogenes/] [tags/] [initial/] [diogenes/] [old/] [video.asm] - Rev 236
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@ l0 : temp
@ l1 : constant 1
@ l2 : current address for memwrites
@ l3 : temp, holds the value received from uart
@ h1 : toggle bit = 0 zero, when a full 16 Bit word was received
@ h2 : holds the bitmask of the invalid instruction 0xffff = special with
@ l4 : temp, used for branch condition
80:
ldi l2, 0x80
lsi l2, 0x40 @ start of user program
ldi h2, 0xff
lsi h2, 0xff @ h2 = 0xffff
ldi l1, 1 @ constant 1
ldi h1, 0 @ toggle bit (hi low)
stio h2, [h1] @ leds echo
1: @ wait for byte
ldi l0, 0x80 @ uart status address
ldio l3, [l0]
ldi h0, 2 @ uart data ready bit
and l4, l3, h0
brz l4, :1
ldi h0, 0x81 @ uart data address
ldio l3, [h0] @ uart rcv
xor h1, h1, l1 @ toggle state (16 bit Ready)
stio l3, [h0] @ uart echo (uart should be ready at this point)
ldi h0, 0x00 @ leds address
stio l3, [h0] @ leds echo
brz h1, :2
@ olny first half (LSB) of instruction was received
brnz h1, :1
mov h3, l3 @ h3: holds 16-bit instr (here LSB are set)
2: @ full 16-Bit instruction is ready
shi l3, 8 @ move received 8 bits
or h3, h3, l3 @ merge the two instructionbytes
stio h3, [l2] @ write instruction to programm-mem
xor l4, h3, h2 @ check if the instruction writen to pmem is 0xffff
brnz l4, :1
adi l2, 1 @ increase program-write address
@@ programm loaded
@ jump to begin of loaded program
ldi l0, 0x40
jump <l0>
nop