C语言 MIPS（或 SPIM）：加载浮点数
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MIPS (or SPIM): Loading floating point numbers
提问by James
I am working on a little mini compiler while trying to learn some MIPS here. Here's my issue:
我正在开发一个小型编译器，同时尝试在这里学习一些 MIPS。这是我的问题：
MIPS has an instruction li (load immediate) which would work like this
MIPS 有一个指令 li（立即加载），它会像这样工作
li ,100
which would load 100 into register 5.
这会将 100 加载到寄存器 5 中。
However, I need to load floats into registers right now and am struggling with figuring out a way to do it...since li $5,2.5 does not work.
但是，我现在需要将浮点数加载到寄存器中，并且正在努力寻找一种方法来做到这一点......因为 li $5,2.5 不起作用。
Anyone have any advice?
有人有什么建议吗？
I am working in C, I was thinking I could somehow get the integer representation of the float I am working with (i.e. so the floats binary representation == the ints binary representation) then load the "integer" into the register and treat it like a float from then on.
我在 C 中工作，我想我可以以某种方式获得我正在使用的浮点数的整数表示（即浮点数二进制表示 == 整数二进制表示）然后将“整数”加载到寄存器中并像对待它一样从此浮动。
Maybe its too late but Im stuck right now.
也许为时已晚，但我现在卡住了。
回答by Zack
MARS does notappear to have any instructions/pseudo instructions that load floating point immediate values into floating registers. Instead, you need to put the floating point value in memory and load the register from memory:
MARS似乎没有任何将浮点立即数加载到浮点寄存器的指令/伪指令。相反，您需要将浮点值放入内存并从内存中加载寄存器：
.data
fp1: .double 2.5
fp2: .double -0.75
.text
l.d $f0, fp1
l.d $f2, fp2
回答by WhirlWind
You will need to use the floating point registers to load your floats.
您将需要使用浮点寄存器来加载您的浮点数。
Instead of:
代替：
li ,2.5
Try:
尝试：
li.s $f5,2.5
Take a look at mfc1 and mtc1 instructions to move between integer and floating point registers.
查看 mfc1 和 mtc1 指令以在整数和浮点寄存器之间移动。
