创建使用英特尔组件

Question

我试图创建的真值表为函数F =（A & B）XOR（C & d'）一个真值表。我正在使用英特尔汇编语言，整个代码必须相当短。

，我依然会碰到的主要问题是与回路操纵变量A，B，C和d创建真值表的所有可能的输入。通常这样做的方式就像变量都是4位二进制数的一位一样，并且从0到15计数，实现每个可能的输入。我只有4个寄存器堆栈和RAM存储器来完成这个任务，因此我将每个变量分配给一个寄存器，并且我使用RAM来存储计数器和表格的输出。我想不出用循环做这件事的好方法，但我必须使用一个，因为我使用的模拟器不会在代码生效的情况下用代码运行。 （这是256字节）

这里是代码，称为程序60的子程序是我想压缩的那一部分。我不必实际输出一个真值表，只是告诉它产生了多少“Minterm's”（输出为1）。

 ;MAIN 
    MOV AL,0 ;INITIALIZING VARIABLES 
    MOV BL,0 
    MOV CL,0 
    MOV DL,0 
    MOV [20],AL ;INITIALIZE CURRENT NUMBER OF MINTERMS WITH 0 
    MOV [21],AL ;INITIALIZE COUNTER WITH 0 
LOOP: CALL 30 
    CALL 60 
    MOV [21],CL 
    CMP CL,15 
    JS LOOP 
    CALL E0 
    MOV AL,[20] ;MOVE NUMBER OF MINTERMS TO AL 
    MOV [FF],AL ;OUPUT NUMBER OF MINTERMS TO VDU(LOCATIONS [C0] TO [FF]) 

     ;PROCEDURE 30, IMPLEMENTS THE GIVEN BOOLEAN FUNCTION 
    ORG 30 ;WRITE CODE BEGINNING AT [30] 
    PUSH DL ;CURRENT VALUE OF D 
    PUSH CL ;CURRENT VALUE OF C 
    PUSH AL ;CURRENT VALUE OF A, IMPLEMENTING FUNCTION WON'T CHANGE D 
    AND AL,BL ;PERFORMS (AL AND BL), STORES VALUE IN AL 
    NOT DL ;INVERSE OF DL STORED IN DL 
    AND CL,DL ;PERFORMS (CL AND DL), STORES VALUE IN CL 
    XOR AL,CL ;PERFORMS (AL XOR CL), STORES VALUE IN AL 
    MOV BL,[20] ;MOVES CURRENT NUMBER OF MINTERMS TO BL 
    ADD AL,BL ;ADD TO CURRENT NUMBER OF MINTERMS IF MINTERM RESULTED FROM FUNCTION 
    MOV [20],AL ;STORE NEW CURRENT NUMBER OF MINTERMS 
    MOV CL,[21] ;MOVE COUNTER TO CL 
    INC CL ;INCREMENT CL, INCREMENTING COUNTER 
    MOV [21],CL ;MOVE NEW VALUE OF COUNTER 
    POP AL ;RESTORE PREVIOUS VALUE OF D 
    POP CL ;RESTORE PREVIOUS VALUE OF C 
    POP DL ;RESTORE PREVIOUS VALUE OF A 
    RET 

     ;PROCEDURE 60, MANIPULATES VARIABLES TO IMPLEMENT FULL TRUTH TABLE 
    ORG 60 ;WRITE CODE BEGINNING AT [60] 
    MOV CL,[21] ;MOVE COUNTER VALUE TO CL REGISTER 
    CMP CL,1 ;NEED TO MAKE THIS INTO A LOOP 
    JZ FIRST 
    CMP CL,2 
    JZ SECOND 
    CMP CL,3 
    JZ FIRST 
    CMP CL,4 
    JZ FOURTH 
    CMP CL,5 
    JZ FIRST 
    CMP CL,6 
    JZ SECOND 
    CMP CL,7 
    JZ FIRST 
    CMP CL,8 
    JZ EIGHTH 
    CMP CL,9 
    JZ FIRST 
    CMP CL,10 
    JZ SECOND 
    CMP CL,11 
    JZ FIRST 
    CMP CL,12 
    JZ FOURTH 
    CMP CL,13 
    JZ FIRST 
    CMP CL,14 
    JZ SECOND 
    CMP CL,15 
    JZ FIRST 
    JMP LAST 
FIRST: 
    MOV AL,1 
    JMP LAST 
SECOND: 
    MOV AL,0 
    MOV BL,1 
    JMP LAST 
FOURTH: 
    MOV AL,0 
    MOV BL,0 
    MOV CL,1 
    JMP LAST 
EIGHTH: 
    MOV AL,0 
    MOV BL,0 
    MOV CL,0 
    MOV DL,1 
    JMP LAST 
LAST: 
    RET 

     FINISH: 
    ORG E0    ;WRITE CODE BEGINNING AT E0(OUTPUTS TO VDU) 
    DB "The number of Minterms in F is" ;OUTPUT STATEMENT 
    RET 

     END 

Answer 1

如何简单：

mov cl, 0 ; CL contains DCBA bits 
L: 
mov bl, cl ; BL contains DCBAb 
and bl, 101b ; BL contains 0C0Ab 
mov al, cl ; AL contains DCBAb 
shr al, 1 ; AL contains 0DCBb 
and al, 101b ; AL contains 0D0Bb 
and bl, al ; BL contains 0(C&D)0(A&B)b 
mov al, bl ; AL contains 0(C&D)0(A&B)b 
and bl, 1 ; BL contains 000(A&B)b 
shr al, 2 ; AL contains 000(C&D)b 
xor al, bl ; AL contains 000((C&D) XOR (A&B))b 
inc cl ; increment DCBA as a 4-bit number 
cmp cl, 16 ; all 16 combinations? 
jne L ; not yet, repeat 

Answer 2

xor cx,cx    ; init counter register 
repeatLoop: 
mov al,cx    ; bits a,b,c and d in lowest 4 nibbles 
call processtruthtable 
inc cx 
cmp cx,16    ; 4bits so 16 possibilities 
jl repeatLoop 
jmp exitProgram 
processtruthtable: 
.... 
.... 
.... 
.... 
ret 
exitProgram: 
// whatever OS you use, use the exit INT call 
for dos it's INT21/4C 
for linux it's INT80/01 
part after/is to be stored in AH 

纠正我，如果我错了