Implementation of recursive factorial algorithm code analysis in assembly language (8)

The code is from Chapter 8 of Intel assembly language programming (version 4), but I always feel that there are errors. The red code will never be executed logically. The following is the source code:

 

 

[Note: Because 32-bit registers are used, the maximum factorial that can be accommodated is 12! (479001600 )]

 

 

Title calculating a factorial (fact. ASM)

 

Include irvine32.inc

. Code

Main proc

Push 12; calc 12!

Call factorial; Calculate factorial (eax)

Returnmain:

Call writedec; display it

Call CRLF

Exit

Main endp

 

;------------------------------------------------------------------------

Factorial proc

; Calculates a factorial

; Es: [EBP + 8] = N, the number to calculate

; Returns: eax = the factorial of N

;------------------------------------------------------------------------

Push EBP

MoV EBP, ESP

MoV eax, [EBP + 8]; get n

CMP eax, 0; n> 0?

Ja L1; yes: continue

MoV eax, 1; NO: return 1

JMP L2

L1: Dec eax

Push eax; factorial (n-1)

Call factorial

 

; Instructions from this point on execute when each

; Recursive call returns.

 

Returnfact:

MoV EBX, [EBP + 8]; get n

Mul EBX; edX: eax = eax * EBX

 

L2: Pop EBP; return eax

RET 4; clean up stack

Factorial endp

End main

 

 

Why is there a problem? When will the red code be executed?