Introduction to Machine And Assembly Language

1
Introduction to Machine And Assembly Language

• 32-Bit Windows Programming GUI
• Dr. Richard Ford

2
Okay

• So, we can call random Win32 functions from
  assembly language
• Thats nice
• But lets do some graphical output

3
Displaying a Window

• There are two ways we can do this look at the
  functions and then look at the program
• Or look at the program and then look at the
  functions
• Well take option B.

4
WinMain

• All Windows applications startup with a
  procedure, usually called WinMain
• Get a handle to the current program
• Load the programs icon
• Register the main window class and set up an
  event handler
• Create a window
• Show and update this window
• Begin a loop to handle messages

5
GetModuleHandle

• Look at http//msdn.microsoft.com/library/default
  .asp?url/library/en-us/dllproc/base/getmodulehand
  le.asp
• So, what does it do in this context?

6
MainWin.hInstance

• WNDCLASS http//msdn.microsoft.com/library/defaul
  t.asp?url/library/en-us/winui/winui/windowsuserin
  terface/windowing/windowclasses/windowclassreferen
  ce/windowclassstructures/wndclass.asp
• So, how can we use it? What is the PROTO?

7
More

• Look up these in context
• LoadIcon
• LoadCursor
• RegisterClass
• CreateWindowEx
• Basically, lets look up each call one after
  another
• Now trace through it in NTSD

8
IA-32 Memory Management

• Understanding how
• Translating logical addresses into linear
  addresses
• Translating linear addresses into physical
  addresses (paging)

9
Two new terms

• Segment Selector a 16-bit value stored in a
  segment register
• CS, DS, ES, FS, GS (ooh, new registers!)
• Logical Address combination of a segment
  selector and a 32-bit offset

10
How can two programs both access

• Imagine we run the same program in two different
  windows
• They both store something at 404000h. How?
• Answer this address is mapped to a linear address

11
Linear Address

• Combines selector and offset to compute a linear
  address
• 32-bit Integer
• Converted to a physical address by the OS
• May need to be loaded from a page file this is
  a page fault
• Look in task manager!
• Important to understand when you really do
  low-level stuff (wait and see ?)