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CMPE12c Homework #4 Spring 2003 Use the MAL/TAL sheets passed out during the exam

CMPE12c Homework #4 Spring 2003 Use the MAL/TAL sheets passed out during the exam.

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CMPE12c Homework #4 Spring 2003 Use the MAL/TAL sheets passed out during the exam

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  1. CMPE12c Homework #4 Spring 2003Use the MAL/TAL sheets passed out during the exam 1) (15 pts) Write a MAL code procedure that calculates the factorial of the number passed in $a0. The return value should be in $v0. Use recursion and use the system stack to store the return address. For example, if 5 is in $a0 then return 5x4x3x2x1= 120 in $v0. # assumes that a value >= 1 is passed in $a0factorial: bne $a0, 1, continue li $v0, 1 jr $racontinue: sub $sp, $sp, 8 # make room on stack sw $ra, 4($sp) # store return address sw $a0, 8($sp) # store value sub $a0, $a0, 1 jal factorial lw $t0, 8($sp) # get number off stack mul $v0, $t0, $v0 lw $ra, 4($sp) # get return address jr $ra 2) (10 pts) Hand assemble the following MAL code. Start instructions at address 0x0004 4800. and $4, $5, $8 beq $4, $0, bob lui $20, 0x66aabob: lb $9, -8($20)0000 0000 1010 1000 0010 0000 0010 0100 (and)0001 0000 1000 0000 0000 0000 0000 0001 (beq)0011 1100 0001 0100 0110 0110 1010 1010 (lui)1000 0010 1000 1001 1111 1111 1111 1000 (lb) Or in Hex0x00A8 2024 (and)0x1080 0004 (beq)0x3C14 66AA (lui)0x8289 FFF8 (lb)

  2. 3) (15 pts) Hand assemble the following MAL .text section. Start instructions at address 0x0008 8800 and data starts at 0x0004 4400. Show what the .data section would also look like. .datavalue: .word 12 .textloop: getc $8 # convert to TAL syscall la $9, value bltz $9, $0, loop done # convert to TAL syscall 0010 0000 0000 0010 0000 0000 0000 1100 (addi $2, $0, 12)0000 0000 0000 0000 0000 0000 0000 1100 (syscall)0000 0000 0000 0010 0100 0000 0010 0000 (add $8, $0, $2)0011 1100 0000 1001 0000 0000 0000 0100 (lui $9, 0x0004)0011 0101 0010 1001 0100 0100 0000 0000 (ori $9, $9, 0x4400)0000 0101 0010 0000 1111 1111 1111 1010 (bltz $9, -6)0010 0000 0000 0010 0000 0000 0000 1010 (addi $2, $0, 10)0000 0000 0000 0000 0000 0000 0000 1100 (syscall) 4) (5 pts) Disassemble the following MIPS RISC code. Make up label names when needed. The code starts at address 0x0040 0000. 5) (5 pts) Give a correct TAL translation of the virtual instruction la $15, variable if “variable” has been assigned the address 0x0024 6088 lui $15, 0x0024ori $15, 0x6088

  3. 6) (5 pts) How can the MAL “move” instruction be implemented in TAL? “add”, “or”, “and”, “sub”, etc instructions with $0 register 7) (5 pts) Give two ways that the MAL instruction blt $3, $18, branchcan be translated into TAL instructions. sub $7, $3, $18bltz $7, branch OR sub $7, $18, $3bgez $7, branch 8) (5pts) What can an assembler do if a calculated branch offset is too large to fit into the offset field of an instruction? The assembly could use a “j” instruction which would give it a longer jump range (226 words displacement verses 216 words displacement). If that is not enough then the assembler could be tricky and load a 32bit address into a register and do a “jr” to that register, giving it the ability to go to any address.

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