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Engineering, 30.11.2021 21:40 itsyagirlgona21

Case 1) CPU-initiated data transfer: X EQU … ; a decimal number where X is #iterations.
; Set the source and the destination in A0 and A1 respectively.
LEA $A000, A0 ; 20 CPU cycles
LEA $B000, A1 ; 20 CPU cycles
; Set the transfer repetition to transfer in D7.
MOVE. W #X, D7 ; 12 CPU cycles
; Move long-word data X times. (X * 4 bytes transfer)
LOOP:
MOVE. L (A0)+, (A1)+ ; 28 CPU cycles
SUBI. W #1, D7 ; 8 CPU cycles
BNE. W LOOP ; 10 CPU cycles

Case 2) DMA-initiated data transfer:
Y EQU ... ; a decimal number where Y = X * 4 (in bytes)
; Set the source/destination and the transfer repetition into DMAC. Finally start DMAC.
MOVE. L #$A000, $8000 ; set the source address into DMAC (28 cycles)
MOVE. L #$B000, $8004 ; set the destination address into DMAC (28 cycles)
MOVE. L #Y, $8008 ; set the transfer length (in bytes) into DMAC (28 cycles)
MOVE. L #1, $800C ; start DMAC (28 cycles)

DMAC needs 10 cycles to read long data (4 bytes) from one memory address and to write them to another address. Therefore, DMAC will complete all data transfer in X times.
Finally, DMAC assets an IRQ, which takes 100 CPU cycles until CPU starts handling the interrupt.

Given the above two scenarios, calculate the minimum X iteration and Y = X * 4 bytes if CPU takes advantage of DMAC, (i. e., for cast 2 to run faster)?

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; Se...
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