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简单的上级循环无限循环简单的上级循环无限
我的代码有什么问题?
有什么建议吗?
我的编程环境是Linux,emacs的,装配,在&吨语法
.section .data
.section .bss
.lcomm buffer,1
.section .text
.global _start
_start:
movl %esp,%ebp
subl $8,%esp
#8(%ebp) is 2nd arg == input
#12(%ebp) is 3rd arg == output
#open,read,open,write,close
movl $5,%eax
movl 8(%ebp),%ebx
movl $0,%ecx
movl $0666,%edx
int $0x80
#%eax contains input's fd
#movl to first local var
movl %eax,-4(%ebp)
movl $5,%eax
movl 12(%ebp),%ebx
movl $03101,%ecx
movl $0666,%edx
int $0x80
#eax contains output's fd
#movl to second local var
movl %eax,-8(%ebp)
loop:
#read 1 byte from file 1st byte of data
movl $3,%eax
movl -4(%ebp),%ebx
movl $buffer,%ecx
movl $1,%edx
int $0x80
#buffer contains 1 byte of file
cmpb $0,buffer
je program_exit
pushl buffer
call convert #will return converted to %al
addl $4,%esp
movb %al,buffer
#write 1 byte from buffer to file
movl $1,%edx
movl $buffer,%ecx
movl -8(%ebp),%ebx
movl $4,%eax
int $0x80
jmp loop
program_exit:
movl buffer,%ebx
movl $1,%eax
int $0x80
.type convert,@function
convert:
pushl %ebp
movl %esp,%ebp
movb 8(%ebp),%al #1 byte data in the buffer
cmpb $'a',%al
jl convert_end
cmpb $'z',%al
jg convert_end
addb $32,%al #convert to upper
convert_end:
movl %ebp,%esp
popl %ebp
ret
是否因为在文件末尾没有空字符?用鼠标滑块输入文件并键入abcdefghij。如果我将退出条件0更改为'j',它不会无限循环,出什么问题了? – 2011-03-28 00:50:05