HW2_S - 0306-250 Assembly Language Programming Fall 2009...

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Unformatted text preview: 0306-250 Assembly Language Programming Fall 2009 Homework Two Solution 1. Write an assembly language code fragment to implement the following conditional expression, where A and B refer to the accumulator registers A and B. if (A <= 0) A = 0 else A = A + B ; Compare A to zero cmpa #0,D0 ; same result as tsta ; If greater than zero do not clear it bgt Else ; Clear A to zero clra bra EndIf Else: ; Calculate sum aba EndIf: 2. Write an assembly language code fragment to implement the following loop expression using a conditional branch instruction, (i.e., Bcond). Use an index register to hold the address of the array element being added to the sum. A and B refer to the accumulator registers A and B, and Array is an array of byte values. A = 0 for (B = 0; B < 100; B++) A = A + Array[B] ; Initialize Sum clra ; Initialize pointer to array ldx #Array ; Initialize loop control variable clrb ForLoop: ; Compute Sum adda 1,x+ ; Increment loop control variable incb ; Terminal count reached? cmpb #100 blt ForLoop Page 1 of 2 0306-250 20091 Homework Two Solution Page 2 of 2 3. Write an assembly language code fragment which implements the following loop expression using a decrement and branch instruction, (i.e., DBcond). Use an index register to hold the address of the array element being added to the sum. A and B refer to the accumulator registers A and B, and Array is an array of byte values. A = 0 for (B = 0; B < 100; B++) A = A + Array[B] ; Initialize Sum clra ; Initialize pointer to array ldx #Array ; Initialize loop control variable ldab #100 ForLoop: ; Compute Sum adda 1,x+ ; Update loop control variable ; and check terminal count dbne b,ForLoop ...
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This note was uploaded on 05/06/2010 for the course EECC 0306-250 taught by Professor Roymelton during the Fall '10 term at RIT.

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