将地址存储在 MIPS 的寄存器中 [英] Storing addresses in a register for MIPS

问题描述

我已经分配了一定数量的内存，并希望将此内存的位置分配给我在程序的 .data 部分中声明的变量.我知道如何将内存位置分配给变量，但是一旦我这样做了，我如何使用该变量来访问分配的内存?

I have allocated a certain amount of memory and would like to assign the location of this memory to variable I have declared in the .data section of the program. I know how to assign the memory location to the variable, but once I do that how can I use that variable to access the allocated memory?

推荐答案

如果我正确理解你的问题，你会想要使用 la(加载地址)指令将地址放入寄存器.然后，您将使用 lw(加载字)和 sw(存储字)指令来操作数据.例如，考虑以下代码

If I understand your problem correctly, you will want to use the la (load address) instruction to get the address into a register. You will then use the lw (load word) and sw (store word) instructions to manipulate the data. For instance, consider the following piece of code

.data
tmpval: .word 5

__start:
  sub $sp, $sp, 12
  sw  $ra, 0($sp) # Return addy
  sw  $t0, 4($sp)
  sw  $t1, 8($sp)

  la  $t0, tmpval
  lw  $t1, 0($t0)  # $t1 == tmpval == 5
  li  $t1, $2      # $t1 == 2
  sw  $t1, 0($t0)  # tmpval == 2

  lw  $ra, 0($sp)
  lw  $t0, 4($sp)
  lw  $t1, 8($sp)
  add $sp, $sp, 12
  jr $ra

因此，在内部代码块中，您可以看到您将 $t0(或任何其他与此相关的寄存器)视为内存位置并对其进行适当处理.

So in the inner-block of code you can see that you treat $t0 (or any other register for that matter) as a memory location and work with it appropriately.

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