我正在逐步阅读 jeff 令人惊叹的书籍汇编，我在第 8 章中，他展示了一个汇编程序示例，该程序以这种方式从用户那里获取文件：
SECTION .bss ; Section containing uninitialized data
BUFFLEN equ 1024 ; Length of buffer
Buff: resb BUFFLEN ; Text buffer itself
它将文件文本读入Buff，并将所有大写的文本版本输出到不同的文件。
我想在调试模式下运行这个程序来逐步分析所有寄存器的情况。
我正在使用 INSIGHT 在 ubuntu 上运行它。
我是一个完整的初学者。我知道如何使用 Insight 单步执行，但用户需要运行此程序的方式是：
myProgram > outputfile.txt < inputfile.txt
我如何在调试器中模仿这个？
这是完整的来源：
; Executable name : uppercaser2
; Version : 1.0
; Created date : 3/25/2009
; Last update : 3/25/2009
; Author : Jeff Duntemann
; Description : A simple program in assembly for Linux, using NASM 2.05,
; demonstrating simple text file I/O (through redirection) for reading an
; input file to a buffer in blocks, forcing lowercase characters to
; uppercase, and writing the modified buffer to an output file.
;
; Run it this way:
; uppercaser2 > (output file) < (input file)
;
; Build using these commands:
; nasm -f elf -g -F stabs uppercaser2.asm
; ld -o uppercaser2 uppercaser2.o
;
SECTION .bss ; Section containing uninitialized data
BUFFLEN equ 1024 ; Length of buffer
Buff: resb BUFFLEN ; Text buffer itself
SECTION .data ; Section containing initialised data
SECTION .text ; Section containing code
global _start ; Linker needs this to find the entry point!
_start:
nop ; This no-op keeps gdb happy...
; Read a buffer full of text from stdin:
read:
mov eax,3 ; Specify sys_read call
mov ebx,0 ; Specify File Descriptor 0: Standard Input
mov ecx,Buff ; Pass offset of the buffer to read to
mov edx,BUFFLEN ; Pass number of bytes to read at one pass
int 80h ; Call sys_read to fill the buffer
mov esi,eax ; Copy sys_read return value for safekeeping
cmp eax,0 ; If eax=0, sys_read reached EOF on stdin
je Done ; Jump If Equal (to 0, from compare)
; Set up the registers for the process buffer step:
mov ecx,esi ; Place the number of bytes read into ecx
mov ebp,Buff ; Place address of buffer into ebp
dec ebp ; Adjust count to offset
; Go through the buffer and convert lowercase to uppercase characters:
Scan:
cmp byte [ebp+ecx],61h ; Test input char against lowercase 'a'
jb Next ; If below 'a' in ASCII, not lowercase
cmp byte [ebp+ecx],7Ah ; Test input char against lowercase 'z'
ja Next ; If above 'z' in ASCII, not lowercase
; At this point, we have a lowercase char
sub byte [ebp+ecx],20h ; Subtract 20h to give uppercase...
Next: dec ecx ; Decrement counter
jnz Scan ; If characters remain, loop back
; Write the buffer full of processed text to stdout:
Write:
mov eax,4 ; Specify sys_write call
mov ebx,1 ; Specify File Descriptor 1: Standard output
mov ecx,Buff ; Pass offset of the buffer
mov edx,esi ; Pass the # of bytes of data in the buffer
int 80h ; Make kernel call
jmp read ; Loop back and load another buffer full
; All done! Let's end this party:
Done:
mov eax,1 ; Code for Exit Syscall
mov ebx,0 ; Return a code of zero
int 80H ; Make kernel call