If you are in a subroutine and have just created a stack frame with space for three words, how would you load that subroutine's first parameter into register $1?Question 8Select one:a.sw $1, 3($sp)b.pop $1c.lw $1, 3($sp)d.lw $1, 0($sp)
Question
If you are in a subroutine and have just created a stack frame with space for three words, how would you load that subroutine's first parameter into register 1, 3(1c.lw sp)d.lw sp)
Solution
The correct answer is d. lw sp)
Here's why:
In MIPS assembly language, the stack grows downwards, meaning that the most recently added element is at the lowest address. When a subroutine is called, the first parameter is pushed onto the stack last, so it will be at the top of the stack (the lowest address).
The lw instruction is used to load a word from memory into a register. The format of the lw instruction is lw register, offset(base register). In this case, the base register is sp.
So, lw sp) will load the first parameter of the subroutine (the word at the top of the stack) into register $1.
Similar Questions
ssume that a suitable stack frame has already been created, and you are preparing to call another subroutine. Which WRAMP assembly instruction would place the first parameter onto the stack?Question 4Select one:a.push $1b.sw $sp, 0($1)c.push $spd.sw $1, 0($sp)
If a WRAMP subroutine takes three parameters, what will the stack pointer be pointing at when that subroutine is first entered (i.e. before any instructions have been executed)?Question 11Select one:a.The first parameter.b.The last (third) parameter.c.The return address.d.The first instruction.
Could subroutines use a dedicated section of memory (allocated in .data or .bss) for backing up and restoring register values, instead of using the stack?Question 1Select one:a.Not possible.b.Yes, but it is impossible to use this method and also use the stack to pass parameters to any functions called.c.Yes, this would work fine but it requires more work.d.Yes, but this would only work for a small number of registers because .data and .bss are smaller than the stack segment.
What do WRAMP subroutines use the system stack for?Question 14Select one:a.Saving/restoring register values, passing parameters to other subroutines, and storing all local variables.b.Passing parameters to other subroutines, saving/restoring registers, and returning values to the caller.c.Saving/restoring register values, passing parameters to other subroutines, and storing any local variables that don't fit into registers.d.A general area of memory for storing data.
When a subroutine is called, the address of the instruction following the CALL instruction is stored in/on the a) stack pointerb) accumulatorc) program counterd) stack
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