我用汇编语言编写了一个程序，它执行以下操作：
-instructs user
-prompts the user to enter a character
-reads the user's input into a char variable
-the program terminates if the user enters 'q' (lower-case)
-if user enters a numeral, program echoes that numeral N+1 times
-any other character gets echoed just once
这是我的代码和示例输入/输出：
# Constants
.equ STDIN,0 #Input
.equ STDOUT,1 #Output
# Stack Frame
.equ count,-8
.equ response,-4
.equ localSize,-16
# Read only data
.section .rodata
instructions: # Displays instructions for user
.ascii "\nA single numeral, N, will be echoed N+1 times."
.asciz "\nOther characters are echoed once. 'q' ends the program.\n\n"
prompt:
.string "Enter a single character: "
msg:
.string "You entered: "
terminate:
.string "End of program.\n\n"
newline:
.byte '\n'
# Code
.text
.globl main
.type main, @function
main:
pushq %rbp # save caller's base pointer
movq %rsp, %rbp # establish our base pointer
addq $localSize, %rsp # local variables
movl $instructions, %esi # shows instructions for user
instructionLoop:
cmpb $0, (%esi) # check if end of string?
je runLoop # yes, run program
movl $1, %edx # no, one character
movl $STDOUT, %edi
call write
incl %esi # next character
jmp instructionLoop # check at top of loop
runLoop:
movl $prompt, %esi # prompt user
promptLoop:
cmpb $0, (%esi) # check if end of string?
je getChar # yes, get user input
movl $1, %edx # no, just one character
movl $STDOUT, %edi
call write
incl %esi # next character
jmp promptLoop # check at top of loop
getChar:
leaq response(%rbp), %rsi # place to store the user input
movl $2, %edx # include a newline
movl $STDIN, %edi
call read
movb response(%rbp), %al # get the input character
cmpb $'q', %al # if 'q'
je allDone # end program
# Otherwise, set up a count loop for N
movl $1, count(%rbp) # assume not numeral
cmpb $'0', %al # check for numeral
jb echoLoop
cmpb $'9', %al
ja echoLoop
andl $0xf, %eax # convert numeral to int
incl %eax # echo N+1 times
movl %eax, count(%rbp) # save counter
echoLoop:
movl $msg, %esi # pointer to the string
msgLoop:
cmpb $0, (%esi) # check if end of string?
je doChar # yes, show the character
movl $1, %edx # no, one character
movl $STDOUT, %edi
call write
incl %esi # next character
jmp msgLoop # check at top of loop
doChar:
movl $1, %edx # just one character
leaq response(%rbp), %rsi # store in this memory location
movl $STDOUT, %edi
call write
movl $1, %edx # and a newline
movl $newline, %esi
movl $STDOUT, %edi
call write
decl count(%rbp) # count--
jne echoLoop # continue if more to do
jmp runLoop # else get the next character
allDone:
movl $terminate, %esi # ending message
doneLoop:
cmpb $0, (%esi) # check if end of string?
je cleanUp # yes, get user input
movl $1, %edx # no, one character
movl $STDOUT, %edi
call write
incl %esi # next character
jmp doneLoop # check at top of loop
Enter a single character: a
You entered: a
Enter a single character: A
You entered: A
Enter a single character: Z
You entered: Z
Enter a single character: 0
You entered: 0
Enter a single character: 1
You entered: 1
You entered: 1
Enter a single character: 4
You entered: 4
You entered: 4
You entered: 4
You entered: 4
You entered: 4
Enter a single character:
You entered:
Enter a single character: *
You entered: *
Enter a single character: .
You entered: .
Enter a single character: 11
You entered: 1
You entered: 1
Enter a single character: You entered:
我的问题是： 如何计算输入字符串的长度，然后打印出该计数？
例如......
如果我要输入“11” 我希望我的程序确定输入的长度是2，然后打印出来： “您输入的长度为＆lt; 2＆gt;的字符串，因此只会显示第一个字符。”
然后我的输出的其余部分将保持不变