添加汇编浮点/双号 [英] Adding floating point/double numbers in assembly

问题描述

我试图用内联汇编实验，和我试图内联汇编加入十进制数（不，不是整数）。问题是，当我打电话下面的函数：

I am trying to experiment with inline assembly, and I am trying to add decimal numbers (no, NOT integers) in inline assembly. Issue is, when I call the following function:

inline double ADD(double num1, double num2) {
  double res;
_asm{

    push eax; push the former state of eax onto stack
    mov eax, num1;
    add eax, num2;
    mov res, eax;
    pop eax; restore the former state of eax now that we are done   
     }  return res;}

编译器会抱怨的内联汇编不当操作数大小（不包括push和pop指令行大会的所有行）。所以，我必须改变为整数类型，如无符号长，然后它的作品，当然，只支持整数类型;小数结果四舍五入。

The compiler complains of improper operand size at the inline assembly (ALL lines of assembly excluding the push and pop instruction lines). So I have to change to an integer type, such as unsigned long, and then it works, but of course only supports integer types; decimal results are rounded.

有没有办法在程序集添加，允许像8.4小数的结果？

Is there any way to add in assembly that allows for decimal results like 8.4?

推荐答案

我没有做过的x87装配了十年，但它应该是这样的：

I haven't done x87 assembly in a decade, but it should be something like:

fld num1   ; load num1 and push it onto the fpu stack
fld num2   ; load num2 and push it onto the fpu stack
faddp      ; pop two numbers, add them, push sum on the stack
fstp res   ; pop sum from the stack and store it in res

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