FIX: CV 4.0 Port Input Command Does Not Display Value

ID: Q87550

The information in this article applies to:

Microsoft CodeView for MS-DOS, versions 4.0, 4.01, 4.05

SYMPTOMS

The Port Input (I) command should display the byte from the specified hardware port. This feature does not work correctly in Microsoft CodeView versions 4.0, 4.01, and 4.05.

(Note: This command is only valid under MS-DOS. Under Windows, it should be ignored, and as a result does not display a value.)

RESOLUTION

You can write a function that will achieve the same result. The following is an example. To use it to check port 2f0h, type ?in(0x2f0) at the CodeView command prompt.


  #pragma check_stack(off)
   unsigned in( unsigned x ) {
      _asm {
         push dx             // save register
         mov  dx, x
         in   ax, dx
         pop  dx             // restore register
         }
   }                         // 
   #pragma check_stack()

To use this function, it must be compiled and linked with CodeView symbolic information. It is not necessary to call this function in the program to use it when debugging, but you must step into the program before evaluating this function.

STATUS

Microsoft has confirmed this to be a problem in CodeView versions 4.0, 4.01, and 4.05. This problem was corrected in CodeView version 4.1.

Additional query words: 4.00 inp

Keywords : kb16bitonly
Version : :4.0,4.01,4.05
Platform :
Issue type :