我发现了一个名为：ProgrammingGroundUp-1-0-booksize.pdf的pdf文件,其中一个项目是制作一个汇编程序,它接收文件并将它们转换为大写,

.section .data

#######CONSTANTS########

#system call numbers

.equ SYS_OPEN, 5

.equ SYS_WRITE, 4

.equ SYS_READ, 3

.equ SYS_CLOSE, 6

.equ SYS_EXIT, 1

#options for open (look at

#/usr/include/asm/fcntl.h for

#various values. You can combine them

#by adding them or ORing them)

#This is discussed at greater length

#in "Counting Like a Computer"

.equ O_RDONLY, 0

.equ O_CREAT_WRONLY_TRUNC, 03101

#standard file descriptors

.equ STDIN, 0

.equ STDOUT, 1

.equ STDERR, 2

#system call interrupt

.equ LINUX_SYSCALL, 0x80

.equ END_OF_FILE, 0

#This is the return value

#of read which means we’ve

#hit the end of the file

.equ NUMBER_ARGUMENTS, 2

.section .bss

.equ BUFFER_SIZE, 500

.lcomm BUFFER_DATA, BUFFER_SIZE

.section .text

#STACK POSITIONS

.equ ST_SIZE_RESERVE, 8

.equ ST_FD_IN, -4

.equ ST_FD_OUT, -8

.equ ST_ARGC, 0

#Number of arguments

.equ ST_ARGV_0, 4

#Name of program

.equ ST_ARGV_1, 8

#Input file name

.equ ST_ARGV_2, 12

#Output file name

.globl _start

_start:

###INITIALIZE PROGRAM###

#save the stack pointer

movl %esp, %ebp

#Allocate space for our file descriptors

#on the stack

subl $ST_SIZE_RESERVE, %esp

open_files:

open_fd_in:

###OPEN INPUT FILE###

#open syscall

movl $SYS_OPEN, %eax

#input filename into %ebx

movl ST_ARGV_1(%ebp), %ebx

#read-only flag

movl $O_RDONLY, %ecx

#this doesn’t really matter for reading

movl $0666, %edx

#call Linux

int $LINUX_SYSCALL

store_fd_in:

#save the given file descriptor

movl %eax, ST_FD_IN(%ebp)

open_fd_out:

###OPEN OUTPUT FILE###

#open the file

movl $SYS_OPEN, %eax

#output filename into %ebx

movl ST_ARGV_2(%ebp), %ebx

#flags for writing to the file

movl $O_CREAT_WRONLY_TRUNC, %ecx

#mode for new file (if it’s created)

movl $0666, %edx

#call Linux

int

$LINUX_SYSCALL

store_fd_out:

#store the file descriptor here

movl %eax, ST_FD_OUT(%ebp)

###BEGIN MAIN LOOP###

read_loop_begin:

###READ IN A BLOCK FROM THE INPUT FILE###

movl $SYS_READ, %eax

#get the input file descriptor

movl ST_FD_IN(%ebp), %ebx

#the location to read into

movl $BUFFER_DATA, %ecx

#the size of the buffer

movl $BUFFER_SIZE, %edx

#Size of buffer read is returned in %eax

int

$LINUX_SYSCALL

###EXIT IF WE’VE REACHED THE END###

#check for end of file marker

cmpl $END_OF_FILE, %eax

#if found or on error, go to the end

jle end_loop

continue_read_loop:

###CONVERT THE BLOCK TO UPPER CASE###

pushl $BUFFER_DATA

#location of buffer

pushl %eax

#size of the buffer

call convert_to_upper

popl %eax

#get the size back

addl $4, %esp

#restore %esp

###WRITE THE BLOCK OUT TO THE OUTPUT FILE###

#size of the buffer

movl %eax, %edx

movl $SYS_WRITE, %eax

#file to use

movl ST_FD_OUT(%ebp), %ebx

#location of the buffer

movl $BUFFER_DATA, %ecx

int $LINUX_SYSCALL

###CONTINUE THE LOOP###

jmp read_loop_begin

end_loop:

###CLOSE THE FILES###

#NOTE - we don’t need to do error checking

movl $SYS_CLOSE, %eax

movl ST_FD_OUT(%ebp), %ebx

int $LINUX_SYSCALL

movl ST_FD_IN(%ebp), %ebx

movl $SYS_CLOSE, %eax

int $LINUX_SYSCALL

###EXIT###

movl $SYS_EXIT, %eax

movl $0, %ebx

int $LINUX_SYSCALL

###CONSTANTS##

#The lower boundary of our search

.equ LOWERCASE_A, ’a’

#The upper boundary of our search

.equ LOWERCASE_Z, ’z’

#Conversion between upper and lower case

.equ UPPER_CONVERSION, ’A’ - ’a’

###STACK STUFF###

.equ ST_BUFFER_LEN, 8 #Length of buffer

.equ ST_BUFFER, 12

#actual buffer

convert_to_upper:

pushl %ebp

movl %esp, %ebp

###SET UP VARIABLES###

movl ST_BUFFER(%ebp), %eax

movl ST_BUFFER_LEN(%ebp), %ebx

movl $0, %edi

#if a buffer with zero length was given

#to us, just leave

cmpl $0, %ebx

je end_convert_loop

convert_loop:

#get the current byte

movb (%eax,%edi,1), %cl

#go to the next byte unless it is between

#’a’ and ’z’

cmpb $LOWERCASE_A, %cl

jl next_byte

cmpb $LOWERCASE_Z, %cl

jg next_byte

#otherwise convert the byte to uppercase

addb $UPPER_CONVERSION, %cl

#and store it back

movb %cl, (%eax,%edi,1)

next_byte:

incl %edi

#next byte

cmpl %edi, %ebx

#continue unless

#we’ve reached the

#end

jne convert_loop

end_convert_loop:

#no return value, just leave

movl %ebp, %esp

popl %ebp

ret

`

汇编程序被称为“as”,代码在文件的第87页,如果你在谷歌上查找它你很容易得到,也因为某些原因代码没有正确复制和粘贴,所以你有时可能会看到像：

JMP

to_another_point

我试图摆脱尽可能多的那些,但仍然可能有一些,并且一些评论可能在此过程中丢失,所以我建议打开原始的pdf文件.

我正在运行Ubuntu linux版本10.04.1,我使用的是版本2.20.1,问题是它创建了文件,但文件始终为空.