If r0 initially contains 1 what will it contain after the th

If r0 initially contains 1, what will it contain after the third instruction in the sequence below? add r0, r0, #l mov r1, r0 add r0, r1.r0 1s1 #1 What will r0 and r1 contain after each of the following instructions? Give your answers in base 10. mov r01, #1 mov r1, #0 times 20 orr r1, r1.r0 1s1 r1, //0 times 2 orr r1.r1.r0 eor r0.r0.r1 lsr r11, r0, #3

Solution

//In the following all the contents of registers are specified in there decimal equivalent means base 10.

4.1) answer :

Initially r0=1

1. add r0,r0,#1       -> After this instruction r0=2

2. mov r1,r0            -> After this instruction r1=r0

3. add r0,r1,r0 lsl #1   ->This instruction first logically shift the content of r0 to left and add this value with content of r1 and store result to r0

Finally r0=6 and r1=2

4.2) answer :

1. mov r0,#1 -> After this instruction r0=1

2. mov r1,#0x20 ->After this instruction r1=32

3. orr r1,r1,r0     -> This instruction performs logical or .After this instruction r1=33

4. lsl r1,#0x2       -> This instruction logically shift the content of r1 by 2 ,r1=132

5. orr r1,r1,r0      -> After this r1=133

6. eor r0,r0,r1      ->This instruction is logical exclusive or.After this r0=132

7. lsr r1,r0,#3      ->This instruction perform logical right shift on content of r0 by 3 and store result in r1. After this r1=16

Finally the content of r0=132 and r1=16.