Question

我无法运行汇编代码。这是我记录的代码。我写了尽可能多的详细信息，所以希望你能告诉我我是如何误解的。我正在编写一个汇编程序，它将是C中的一个可调用函数。 C中的函数原型如下：

extern int count(char *string, char c)

汇编程序应该通过string并计算c的实例数。装配程序如下：

.text
.globl _count           # defining label _count with .globl for external reference

_count:
        pushl %ebp              # Create Stack frame
        movl %ebp, %esp

        xorl %eax, %eax         # Exclusive of eax register with itself to empty it
                                # Use of eax is proper as it is the accumulator for
                                # operands and results data

        movl 5(%ebp), %ecx      # Move parameters into temp register
        movl 6(%ebp), %edx

loop:
        compl $0, (%edx)        # Check if end of string char
        je end                  # Check for equality
        compl %ecx, (%edx)      # Check equality of character
        je Char                 # if equal to given char jump to char section
        addl $1, %edx           # Increment loop

Char:
        addl $1, $eax           # Add to the number of characters that are equal
        jmp loop                # Go back to loop

end:
        pop ebp                 # Reset the ebp register
        ret                     # Return value in eax
.end

我这样编译：

i386-as -o count.opc count.s

我收到以下错误：

count.s:19: Error: no such 386 instruction: `compl'
count.s:21: Error: no such 386 instruction: `compl'
count.s:26: Error: operands given don't match any known 386 instruction

所以它抱怨compl指令，我不知道为什么因为在另一个程序中似乎认出它，所以它必须是我的程序逻辑，至少我认为。虽然，如何在C内调用此函数，我是否需要同时编译这两个程序？感谢。

Answer 1

没有我能看到的compl，只有很多cmpl

http://www.fermimn.gov.it/linux/quarta/x86/cmp.htm

大会：没有这样的386指令

1 个答案: