Question 261 The following problems deal with translating fr

Question #2.6.1

The following problems deal with translating from C to ARM. Assume that the variables f, g, h, i, and j are assigned to registers r0 r1, r2, r3, and r4, respectively. Assume that the base address of the arrays A and Beta are in registers r6 and r7, respectively. [10] For the C statements above, what is the corresponding ARM assembly code? [5] For the C statements above, how many ARM assembly instructions are needed to perform the C statement?

Solution

Answer to Question #2.6.1

For C code -a

MOV R5,#1              ; Move Constrant 1 into R5

MOV R8,[R7,R5]               ; Move to R8 , the content of R7[R5] I,e B[1]

ADD R5,R2,R8                    ;R5=R2+R8   I,e h+B[1]

SUB R0,R5,R1              ; R0=R5-R1 , I,e f=h+B[1]-g

For C code –b

MOV R5,#1                         ; Move Constrant 1 into R5

MOV R9,[R7,R1]               ; Move TO R9 ,THE Valueof B[g]

ADD R9,R9,R5                    ; R9=R9+R5    ,I,e R9= B[g]+1

MOV R0,[R6,R9]               ;R0=R6[R9]    ,I,e R0=A[B[g]+1]