masm for windows 显示系统日期源程序

MASM (Microsoft Assembler) 是微软的汇编语言，用于编写Windows平台下的低级程序。如果你想在MASM中显示当前系统的日期，你可以使用INT 21H中断服务函数(IFS)来调用实模式下的时间戳功能。下面是一个简单的示例：

; Windows MASM32 示例
.model small
.stack 100h

.data
msg db 'Current Date: $'
fmt db '%d/%m/%y', 0Ah, '$'

.code
main proc
    ; 调用 DOS日期/时间函数
    mov ah, 2Ch          ; Function to get system date and time
    int 21h             ; Call DOS interrupt
    
    ; 将得到的年月日转换成字符串并输出
    mov dx, offset msg   ; Point to message string
    call DispDate       ; Display the date using our custom function

    exit
main endp

DispDate proc near
    push bx              ; Save registers
    lea si, [dateStr]   ; Load address of formatted date into SI
    mov al, cl           ; AL holds the day value
    add al, 48           ; Convert from ASCII 0-9 to ASCII 48-57
    stosb               ; Store in buffer
    
    mov al, ch           ; Hour in AL
    add al, 48
    stosb               ; Store in buffer
    
    mov al, dl           ; Minute in AL
    add al, 48
    stosb               ; Store in buffer
    
    mov al, dh           ; Second in AL
    add al, 48
    stosb               ; Store in buffer
    
    ; Add separator
    mov byte ptr [si], '/'; Separator between day and month
    inc si               ; Move to next position
    
    mov al, bl           ; Month in AL
    add al, 48
    stosb               ; Store in buffer
    
    mov al, bh           ; Month number as character (0-based)
    add al, 48
    stosb               ; Store in buffer
    
    ; Add year separator and year
    mov byte ptr [si], '-'; Separator between month and year
    inc si               ; Move to next position
    
    mov ax, [dx+4]       ; Year is at offset +4 from INT 21H return value
    add ax, 1900         ; Shift to four-digit format
    mov bx, 100          ; Multiply by 100 for two-digit representation
    mul bx
    mov cx, ax           ; High part of result
    shr cx, 4            ; Divide by 100 (remainder discarded)
    add al, cl           ; Add high digit to low digit
    stosb               ; Store in buffer
    
    mov byte ptr [si], '$'; End of line
    pop bx               ; Restore registers
    ret
DispDate endp

dateStr db 13 dup ('$')   ; Buffer to store formatted date

times 510 - $$) db 0     ; Fill rest with zeros to make a valid DOS executable
end main

在这个示例中，`main` 函数首先通过 `int 21h` 调用 DOS的`2Ch`中断获取系统日期和时间，然后将结果传递给自定义的 `DispDate` 函数，该函数格式化这些值并打印到屏幕上。