汇编语言-求分段函数值

 1 ; Example assembly language program -- 
 2 ; Author:  karllen
 3 ; Date:    revised 5/2014
 4 
 5 .386
 6 .MODEL FLAT
 7 
 8 ExitProcess PROTO NEAR32 stdcall, dwExitCode:DWORD
 9 
10 INCLUDE io.h            ; header file for input/output
11 
12 cr      EQU     0dh     ; carriage return character
13 Lf      EQU     0ah     ; line feed
14 
15 .STACK  4096            ; reserve 4096-byte stack
16 
17 .DATA
18       promotX  BYTE "Please enter a number as X ",0
19       promotY  BYTE "Please enter a number as Y ",0
20       value    BYTE 11 DUP(?)
21       answer   BYTE "The a is"
22         rsa    BYTE 11 DUP(?)
23                BYTE cr,Lf,0
24 .CODE
25 _start:
26       output   promotX       ;ebx = x
27       input    value,11
28       atod     value
29       mov      ebx,eax
30       
31       output   promotY       ;eax = y
32       input    value,11
33       atod     value
34       
35       cmp      ebx,0
36       jl       lzero         ;ebx < 0
37       
38       cmp      ebx,0
39       jg       oo            ;x>0
40       oo: 
41            cmp eax,0 
42            jl  oneg          ;y<0
43       cmp      eax,0         ;ebx>=0
44       jge      ltwozero      ;eax>=0
45      lzero:
46            cmp    eax,0
47            jl     ltwzero      ;eax < 0    
48      oneg:
49            mov     eax,0
50            dtoa   rsa,eax
51            output answer
52            jmp    endCMP      
53      ltwzero:
54            mov    eax,1
55            neg    eax
56            dtoa   rsa,eax
57            output answer
58            jmp    endCMP
59      ltwozero:
60            mov    eax,1
61            dtoa   rsa,eax
62            output answer
63      endCMP:
64       
65               INVOKE  ExitProcess, 0  ; exit with return code 0
66 
67 PUBLIC _start                   ; make entry point public
68 
69 END                             ; end of source code