Delphi "Invalid floating point operation." Wrong workaround (Use the SET8087CW function provided by the system unit to disable floating-point exceptions)

These two days write things with Webbrower, sometimes open SSL encryption site will appear "Invalid floating point operation." Error, the Internet search, the solution is affixed.

导致原因


在Delphi2011中需要通过浮点单位控制指令设置浮点运算单位。浮点单位控制指令控制着浮点运算的精度、四舍五入的方式以及特定的浮点运算是否触发异常。可以参阅Intel处理器的详细文档。


在Delphi2011中有函数可以直接访问处理器的控制指令。比如，可以使用Set8087CW函数改变8087CW控制指令的值，从而改变程序浮点计算的行为。编程人员需要自己负责在程序结束时重置这个指令。

solution, is to disable floating-point exceptions directly, by doing the following:
In Delphi2011, when using OpenGL for 3D rendering, it is recommended to use the SET8087CW function to disable floating-point exceptions. Can be written before the OpenGL function is called, such as in the MainForm OnCreate: SET8087CW (0x133f)
Instance code:
1. Declare global variables to save the original 8087CW settings
Var
Saved8087cw:word;
2. Change the value of 8087CW in the oncreate process of MainForm, save the default value before changing
SAVED8087CW: = DEFAULT8087CW;
SET8087CW ($133f); {Disable all FPU exceptions}
3. Reset the 8087CW instruction value using the default value before the program ends. In the onclose process of mainform
SET8087CW (SAVED8087CW);
4. It is also important to note that If you use Scenecontrol.loadsxfile to load a 3D document in your program, you must call Iscene's Clearlayers method to clear the layer before SET8087CW exits, or the program exits with an exception.
The reference code is:
SceneControl1.Scene.ClearLayers;
SET8087CW (SAVED8087CW);
5. There is also a need to call the following statement before the program exits
(Coaoinitialize.create as Iaoinitialize). Shutdown

http://blog.csdn.net/shuaihj/article/details/6406781

Delphi "Invalid floating point operation." Wrong workaround (Use the SET8087CW function provided by the system unit to disable floating-point exceptions)