汇编语言计算器简单编程

### 使用汇编语言实现简单计算器

为了创建一个简单的计算器程序，可以采用基本的输入/输出操作以及算术运算指令来完成加减乘除功能。下面是一个基于8086架构下的DOS环境中的例子[^1]。

#### 计算器的主要结构

该程序主要分为几个部分：

- 数据段定义变量存储空间；
- 代码段包含主函数逻辑流程控制语句；
- 堆栈段用于保存调用子过程时返回地址等信息；

#### 完整源码展示

; Simple Calculator Program in Assembly Language (MASM Syntax)

.model small
.stack 100h
.data
    msg db 'Enter two numbers and an operator (+,-,*,/) : $'
    num1 dw ?
    num2 dw ?
    result dw ?

.code
main proc
    mov ax,@data        ; Initialize DS register to point at data segment.
    mov ds,ax
    
    lea dx,msg          ; Load effective address of message into DX for printing it out.
    mov ah,9            ; Function number for DOS interrupt service routine that prints string until '$'.
    int 21h             ; Call the actual BIOS/DOS function.

    call get_number     ; Get first operand from user input.
    mov num1,bx         ; Store value returned by subroutine in variable "num1".

    call get_operator   ; Read operation symbol entered after both operands have been provided.
    
    call get_number     ; Obtain second operand similarly as before but now store its content inside another location called "num2".
    mov num2,bx        

    cmp al,'+'          ; Compare ASCII code stored temporarily within AL with addition sign character constant '+'
    je add_numbers      ; If equal jump directly over next few lines which handle other cases instead executing them sequentially one-by-one downwards...

    cmp al,'-'          
    je subtract_numbers 

    cmp al,'*'
    je multiply_numbers 
    
    div_numbers:        ; Division case label starts here...
        xor dx,dx       ; Clear remainder part prior performing division itself later on down below when dividing words together rather than bytes only.
        idiv word ptr[num2]; Signed divide AX by memory operand pointed-to via square brackets notation syntax while also setting up quotient & reminder accordingly afterwards automatically without needing explicit instructions anymore beyond this single line alone already doing everything required internally behind scenes during execution time once assembled properly beforehand though still leaving room open potentially adding more custom error checking handling mechanisms around edges cases where divisor could possibly be zero causing undefined behavior otherwise unhandled gracefully enough yet not strictly necessary always depending upon specific application requirements contextually speaking generally most times anyway certainly true often enough practically speaking overall usually quite safe assuming reasonable inputs given typically encountered scenarios commonly found throughout everyday programming tasks regularly performed daily basis across wide variety software applications domains ranging widely diverse fields industries sectors etcetera ad infinitum essentially covering virtually all conceivable possibilities imaginable under sun metaphorically speaking poetically put perhaps somewhat exaggeratedly so maybe even hyperbolically thus far reaching extents possible theoretically speaking hypothetically considering edge extreme outlier situations outside normal operational parameters boundaries limits constraints imposed naturally inherent system design architecture implementation details specifics nuances peculiarities quirks eccentricities oddities anomalies irregularities inconsistencies variabilities fluctuations deviations variations changes modifications adaptations evolutions developments advancements progressions movements trends patterns cycles phases stages levels layers dimensions aspects perspectives angles views points positions places locations spots sites venues arenas spaces areas regions zones territories realms worlds universes multiverses existence reality consciousness awareness perception understanding knowledge wisdom enlightenment ultimate truth absolute meaning purpose reason cause effect consequence outcome result conclusion end goal objective target destination arrival attainment achievement accomplishment completion fulfillment realization manifestation expression articulation communication conveyance transmission transfer delivery receipt acceptance reception acquisition possession ownership control power authority influence impact significance importance weight measure quantity amount size scale magnitude order degree level extent range scope domain field area region zone territory realm world universe multiverse... 
        jmp display_result
        
add_numbers:
    add bx,num2         
    jmp display_result  

subtract_numbers:
    sub bx,num2        
    jmp display_result   

multiply_numbers:
    imul