Question

我有.s（x86汇编语言和语法）文件，.h（标题）文件，带有struct defenition和函数decleration，它们在汇编文件中实现，main.c文件带有函数调用（来自.s）文件）。

当尝试将它们全部编译在一起时，我收到以下错误：

main.o: In function `main':
/home/user/workspace/Assembly/main.c:7: undefined reference to `pstrlen'
collect2: error: ld returned 1 exit status
make: *** [a.out] Error 1

pstring.h：

typedef struct {
    char len;
    char str[255];
    } Pstring;


char pstrlen(Pstring* pstr);

main.c中：

#include <stdio.h>
#include "pstring.h"

int main() {
    Pstring a;
    a.len = 4;
    printf("Length: %d", pstrlen(&a));
    return 0;
}

pstring.s：

    .file   "pstring.s"
    .section    .rodata
invalid_input:  .string "invalid input!\n"


    .text
    .type   pstrlen,    @function
pstrlen:
    pushl   %ebp
    movl    %ebp, %esp

    movl    8(%ebp), %eax   # assign given pstring ptr address to eax
    movzbl  (%eax), %ecx    # set ecx with the value of the first byte (length) of the address at eax
    movl    %ecx, %eax      # set return value as the value at ecx

    ret

    .type   pstrcpy,    @function

生成文件：

a.out: main.o pstring.o
    gcc -m32 -g -o a.out main.o pstring.o

main.o: main.c pstring.h
    gcc -m32 -g -c -o main.o main.c

pstring.o: pstring.s
    gcc -m32 -g -c -o pstring.o pstring.s   

clean:
    rm -f *.o a.out

谢谢。

Answer 1

我通过将pstrlen声明为全局来解决问题，如下所示：

    .text
    .globl  pstrlen
    .type   pstrlen,    @function
pstrlen:
    pushl   %ebp
    movl    %ebp, %esp

    movl    8(%ebp), %eax   # assign given pstring ptr address to eax
    movzbl  (%eax), %ecx    # set ecx with the value of the first byte (length) of the     address at eax
    movl    %ecx, %eax      # set return value as the value at ecx

    ret

编译C文件和程序集文件时的链接错误

1 个答案: