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Answer:

The assembler in SPIM automatically assembles code starting at address 0x10000000.

  1. What address corresponds to the symbolic address x?           0x10000000
  2. What address corresponds to the symbolic address poly?     0x10000004

Here is what this part of the SPIM simulation looks like:

Data Section showing X

More Code

## poly.asm  
##
## evaluate  5x^2 -12x + 97 
##
## Register Use:
##
## $10 base register, address of x
## $11 x
## $12 value of the polynomial
## $13 temporary

        .text
        .globl  main

main: 
        lui   $10,       #  Init base register
        
        lw    $11,0($ )  #  Load x

        ori   $12,$0,    #  Initialize the accumulator
                              #  during the "load delay slot"

        . . .  many instructions

        sw    $12, ($ )  #  Store result in poly

        .data
                             # In SPIM, the data section
                             # starts at address 0x10000000
x:      .word   17           # The base register points here .
poly:   .word   0

## End of file

The program must load a register with data from memory, and, at the end, store a result back to memory. The above program fragment does this, when you complete it.

The register use table in the documentation summarizes how registers are used in this program. When you program, decide on the registers you need and what they are used for. Then write down your decisions! This is crucial for getting things correct.

A register where a value is built up after several calculations is called an accumulator. (Some old processors have a single, special register that is used for this purpose. But MIPS has many general purpose registers for this).

Remember that data loaded from memory is not available to the instruction following the load. The instruction after a lw, in the "load delay slot", should not try to use the loaded data.


QUESTION 15:

Fill in the blanks. Look at the previous answer to help with the lui instruction. Use it to load the upper half of the base register with the upper half of the first data address.


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