start:

        push    31d
        push    0d
        push    3453445d
        call    get_bits
        add     esp,3*4         ; I entered 3 parameters
        cinvoke printf,mess,eax


        cinvoke  get_bits,0, 0,0
        cinvoke printf,mess,eax

        invoke  ExitProcess,0 ; exit and return zero


get_bits:
        ; take the value of the number given , from the a bit to the b bit.
        ; parameters:
        ; x - number  [ebp + 8]
        ; a - first bit [ebp + 12]
        ; b = last bit [ebp + 16]
        push    ebp
        mov     ebp,esp
        mov     esi,1b
        ror     esi,1           ; rotate the bit to be
                                ; the be an msb
        xor     eax,eax         ; init eax
        mov     ecx,[ebp + 12]  ; the first bit location
        shr     esi,cl          ; go the the first bit
.bitloop:
        or      eax,esi
        shr     esi,1h
        inc     ecx             ; add to the counter of bit locations
        cmp     ecx,[ebp + 16]
        jna     .bitloop
        
        ; now we have inside eax bits a to b marked as 1.
        ; The rest should be zeroes.
        mov     edx,[ebp + 8]   ; the number to be manipulated
        and     eax,edx         ; mask the number from a to b
        mov     ecx,[ebp + 12]  ; the first bit location
        shl     eax,cl
        ; result is in eax now

        pop     ebp             ; restore stack frame
        ; note that the caller should handle the stack frame
        ret                    
    

macro cinvoke proc,[arg]                ; indirectly call CDECL procedure
 { common
    size@ccall = 0
    if ~ arg eq
   reverse
    pushd arg
    size@ccall = size@ccall+4
   common
    end if
    call [proc]                   ; <------- this is line 45
    if size@ccall
    add esp,size@ccall
    end if }    
    

include 'win32axp.inc'

.code
start:
  cinvoke p_get_bits, 3453445d, 7, 20
  int3 ; Trap for debugging


p_get_bits dd get_bits ; Pointer to get_bits proc

get_bits:
; a <= b condition isn't checked so be careful 
  label .x at esp+4
  label .a at esp+8
  label .b at esp+12

; Calculate mask to start from a
  or      eax, -1
  mov     cl, byte [.a]
  shl     eax, cl

; Calculate mask to finish on b
  or      edx, -1
  mov     cl, 31
  sub     cl, byte [.b]
  shr     edx, cl

; Combine masks
  and     edx, eax

; Return bits
  mov     eax, [.x]
  and     eax, edx

  ret

.end start