汇编代码不起作用；需要帮助查找问题

Question

我正在为我的大学课程编写汇编代码，但它根本不起作用。我以前从未写过这样的代码，我不确定我做错了什么。该代码链接到一些用于不同事物的其他代码。这是代码：

%include "asm_io.inc"

section .data
    name_prompt db "Enter your name: ", 0
    count_prompt db "Enter the number of repetitions (50-100): ", 0
    error_msg db "Error: Number must be between 50 and 100.", 10, 0
    welcome_msg db "Welcome, ", 0
    newline db 10, 0

section .bss
    name resb 128   ; Allocate 128 bytes for the name
    num_reps resd 1

section .text
    global asm_main      ; Declare the function to be used by the C code
    extern print_string  ; External declarations from asm_io.inc
    extern read_char
    extern read_int
    extern print_nl

asm_main:                ; Entry point for the C code
    push ebp             ; Save the base pointer (set up stack frame)
    mov ebp, esp         ; Move stack pointer into base pointer

    ; Prompt for name
    push name_prompt
    call print_string
    add esp, 4            ; Properly clean up the stack after calling print_string

    ; Read the name character-by-character
    lea eax, [name]
    call read_char_loop
    call print_nl

validate_reps:
    ; Prompt for number of repetitions
    push count_prompt
    call print_string
    add esp, 4

    ; Read number of repetitions
    call read_int
    mov [num_reps], eax

    ; Validate repetitions (must be between 50 and 100)
    cmp eax, 50
    jl invalid_reps
    cmp eax, 100
    jg invalid_reps

    ; Print welcome message the number of times specified
    mov ecx, [num_reps]
print_loop:
    cmp ecx, 0
    jle end_loop

    push welcome_msg
    call print_string
    add esp, 4

    lea eax, [name]
    push eax
    call print_string
    add esp, 4

    call print_nl
    dec ecx
    jmp print_loop

invalid_reps:
    push error_msg
    call print_string
    add esp, 4
    call print_nl
    jmp validate_reps

end_loop:
    ; Exit program cleanly using the exit system call
    mov eax, 1           ; SYS_exit
    xor ebx, ebx         ; Status code 0
    int 0x80

read_char_loop:
    lea edi, [name]
    mov ecx, 128

read_next_char:
    call read_char
    cmp al, 10
    je end_read_char
    mov [edi], al
    inc edi
    loop read_next_char

end_read_char:
    mov byte [edi], 0
    ret

运行调试器后，我相信分段错误发生在print_string函数内，这与堆栈和内存访问的操作有关。

“asm_io.inc”也是下面的代码：

    extern  read_int, print_int, print_string
    extern  read_char, print_char, print_nl
    extern  sub_dump_regs, sub_dump_mem, sub_dump_math, sub_dump_stack

%macro  dump_regs 1
    push      dword %1
    call      sub_dump_regs
%endmacro


;
; usage: dump_mem label, start-address, # paragraphs
%macro  dump_mem 3
    push     dword %1
    push     dword %2
    push     dword %3
    call     sub_dump_mem
%endmacro

%macro  dump_math 1
    push     dword %1
    call     sub_dump_math
%endmacro

%macro  dump_stack 3
    push     dword %3
        push     dword %2
    push     dword %1
        call     sub_dump_stack
%endmacro

我得到了该代码以及名为 asm_io.asm 的代码，其中包含函数的所有定义以及如下所示的 C 代码文件：

int __attribute__((cdecl)) asm_main( void );
int main() {
int ret_status;
ret_status = asm_main();
return ret_status;
}

print_string:
    enter   0,0
    pusha
    pushf

    push    eax
    push    dword string_format
    call    _printf
    pop ecx
    pop ecx

    popf
    popa
    leave
    ret

Answer 1

您将参数压入堆栈

push name_prompt
call print_string

而

print_string

正在里面寻找它

eax

push    eax
push    dword string_format ; assuming a "%s" constant for printf
call    _printf

建议修复：在 eax 中传递字符串的地址。

而且在我看来，该函数会在其自身之后恢复堆栈，因此您应该仔细检查是否确实需要

add esp, 4

。

如果有说明您正在使用的 IO 库如何期望其参数被传递，您应该再看一遍。