20. Which of the following gives the RTL description of the MIPS code, sw $8, 4(516) a. Mem[RI8R[16)+0 c. RI8] mem[R(16]+ 4] 21. Which of the following is the equivalent machine code for the MIPS ISA code, add $8, $9, $9 [hint: the fn-code of add is 32] a. b. c. d. 000000 01001 01001 01000 00000 100000 000000 10001 10001 10000 00000 10000 000000 10001 10001 10000 00000 10000 000000 10001 10001 10000 00000 10000 22. Which is the following is an equivalent MIPS ISA code for the following MIPS machine code given in hex digits, 012940207 a. addi $9, $9, 4 b. lw $9, 4($9) c. add $8, $9, $9 d. sub $8, $9, $9 //add's op-code is 34 //sw's op-code is 35 //add's fn-code is 32 //sub's fn-code is 36