在x86程序集中打印A到Z和Z到A的程序

Question

我正在编写一个程序，在程序集中使用循环打印A到Z和Z到A，但是每次输出'A‘之后，它都会崩溃。

 TITLE A to Z
 ;loop that prints from a to z & z to a

INCLUDE Irvine32.inc
.code
letter BYTE 65, 0
space BYTE ' ', 0

main PROC

MOV ECX, 26
myloop:
    MOV EDX, offset letter
    CALL writechar
    INC letter
    MOV EDX, offset space
    CALL writechar
LOOP myloop

CALL crlf

MOV ECX, 26

myloop2:
    MOV EDX, offset letter
    CALL writechar
    DEC letter
    MOV EDX, offset space
    CALL writechar
LOOP myloop2

exit    

main ENDP
END main

这个程序使用Irvine32.inc库中的一些函数，但我确信这与问题无关，所以我现在忽略它。。。如果有要求，我会提供更多的细节。

非常感谢!

JLL

下面是Irvine32.inc文件：

; Include file for Irvine32.lib             (Irvine32.inc)

INCLUDE SmallWin.inc        ; MS-Windows prototypes, structures, and constants
.NOLIST

; Last update: 1/27/02

;----------------------------------------
; Procedure Prototypes
;----------------------------------------
ClrScr PROTO        ; clear the screen
Crlf PROTO      ; output carriage-return / linefeed
Delay PROTO     ; delay for n milliseconds
DumpMem PROTO       ; display memory dump
DumpRegs PROTO      ; display register dump
GetCommandTail PROTO        ; get command-line string
GetDateTime PROTO,      ; get system date and time
startTime:PTR QWORD
GetMseconds PROTO       ; get milliseconds past midnight
Gotoxy PROTO
IsDigit PROTO       ; return ZF=1 if AL is a decimal digit
Randomize PROTO     ; reseed random number generator
RandomRange PROTO       ; generate random integer in specified range
Random32 PROTO      ; generate 32-bit random integer
ReadInt PROTO       ; read signed integer from console
ReadChar PROTO      ; reach single character from console
ReadHex PROTO       ; read hexadecimal integer from console
ReadString PROTO        ; read string from console
SetTextColor PROTO      ; set console text color
WaitMsg PROTO       ; display wait message, wait for Enter key
WriteBin PROTO      ; write integer to output in binary format
WriteChar PROTO     ; write single character to output
WriteDec PROTO      ; write unsigned decimal integer to output
WriteHex PROTO      ; write hexadecimal integer to output
WriteInt PROTO      ; write signed integer to output
WriteString PROTO       ; write null-terminated string to output

; Copy a source string to a target string.
Str_copy PROTO,
source:PTR BYTE,
target:PTR BYTE

; Return the length of a null-terminated string..
Str_length PROTO,
pString:PTR BYTE

; Compare string1 to string2. Set the Zero and
; Carry flags in the same way as the CMP instruction.
Str_compare PROTO,
string1:PTR BYTE,
string2:PTR BYTE

; Trim a given trailing character from a string.
; The second argument is the character to trim.
Str_trim PROTO,
pString:PTR BYTE,
char:BYTE

; Convert a null-terminated string to upper case.
Str_ucase PROTO,
pString:PTR BYTE

;-----------------------------------
; Standard 4-bit color definitions
;----------------------------------- 
black        = 0000b
blue         = 0001b
green        = 0010b
cyan         = 0011b
red          = 0100b
magenta      = 0101b
brown        = 0110b
lightGray    = 0111b
gray         = 1000b
lightBlue    = 1001b
lightGreen   = 1010b
lightCyan    = 1011b
lightRed     = 1100b
lightMagenta = 1101b
yellow       = 1110b
white        = 1111b
.LIST

Answer 1

我有点恼火--你把函数称为writechar和crlf，然而，Kip创建了这些函数，并将它们称为WriteChar和Crlf。

您所需要做的就是打开Irvine32.幕，查看WriteChar的源代码，在这个过程开始时，Irvine先生将这个留给所有人看：

WriteChar PROC
;
; Write a character to the console window
; Recevies: AL = character
; Last update: 10/30/02
; Note: WriteConole will not work unless direction flag is clear.
;------------------------------------------------------

因此，在调用WriteChar之前，要将字符的ASCII值打印到AL中，而不是地址！

MOV     al, letter
CALL    WriteChar
INC     letter

此外，正如弗兰克提到的，变量应该位于.data或.data?部分，而不是.code部分。