School Commit Init

2024-08-31 12:07:21 +03:00
commit 0b130ee18c
2801 changed files with 4720552 additions and 0 deletions
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+bits 32 ; assembling for the 32 bits architecture
+
+; declare the EntryPoint (a label defining the very first instruction of the program)
+global start        
+
+; declare external functions needed by our program
+extern exit               ; tell nasm that exit exists even if we won't be defining it
+import exit msvcrt.dll    ; exit is a function that ends the calling process. It is defined in msvcrt.dll
+                          ; msvcrt.dll contains exit, printf and all the other important C-runtime specific functions
+
+; our data is declared here (the variables needed by our program)
+segment data use32 class=data
+    a db 4Fh
+    b dw 8241h
+    c resd 1
+
+; our code starts here
+segment code use32 class=code
+    start:
+        mov ECX,0
+        mov CL,1111_1111b
+        mov EAX,0
+        mov AL,[a]
+        and AL,1111_0000b
+        shl EAX,4
+        or ECX,EAX
+        
+        mov EBX,0
+        mov BX,[b]
+        and EBX, 0000_0011_1111_1100b
+        shl EBX,10
+        or ECX,EBX
+        mov EAX,0
+        mov AL,[a]
+        and AL,0000_1111b
+        shl EAX,20
+        or ECX,EAX
+        mov EAX,0
+        mov AL,[b+1]
+        ror EAX,8
+        or ECX,EAX
+        mov [c],ECX
+    
+        ; exit(0)
+        push    dword 0      ; push the parameter for exit onto the stack
+        call    [exit]       ; call exit to terminate the program