执行从x86汇编程序编译的程序时出现分段错误? [英] Segmentation fault when executing program compiled from x86 assembly?
问题描述
我是汇编语言的新手，我必须实现一个函数(在我的情况下为sin(x))，可以从C源文件中调用该函数. 我必须制作2个单独的文件:* .c和* .s 在ubuntu上通过gcc编译时，一切都很好，但是当程序执行时，出现错误分段错误" ...
I'm new to assembly language and I have to implement a function, in my case sin(x), that could be called from a C source file. I have to make 2 separate files: *.c and *.s When compiling through gcc on ubuntu all good, but when the program executes it gives me the error "Segmentation fault"...
要进行编译，请输入:
gcc -c -o sinc.o sinx.c -g3
gcc -c -o sins.o sinx.s -g3
gcc -o sinx sinc.o sins.o -g3
当我启动程序时:
./sinx
它打印:
.......insert x:
我把x放进去，然后:
segmentation fault
，然后停止. 这是两个文件:
and it stops. Here are the two files:
/*-----------------------------------Sin[x]----------------------------------------*/
extern float Sin(float x); //extern assembly function
#include <stdio.h> //necessary libraries
int main() // main function
{
float x; //allocate variable 'x' as a float
float sine; //allocate variable 'sine' as a float
printf("Calculate Sin[x], with 'x' in radians\n"); //purpose of the program
printf("Insert 'x': "); //user prompt
scanf("%f",&x); //get input value
sine=Sin(x); //calculate sin(x)
printf("Sin[%f]=%f\n",x,sine); //print sin(x)
return 0; //successful exit
}
/*----------------------------------------------------------------------------------*/
和
#---------------------------Sin[x]-----------------------------#
.data
.text
.globl Sin #global function visible by main function
#function sumplus
sumplus:
pushl %ebp
movl %esp,%ebp
fld1 #load 1 in ST(0)
movl 12(%ebp),%ecx #ecx=i
power:
fmul %st(0),%st(1) #ST(0)=ST(0)*ST(1),ST(1)=x
loop power #at the end ST(0)=x^i
movl 12(%ebp),%ecx #ecx=i
xorl %edx,%edx #reset edx used in mul
movl $1,%eax #set accumulator
factorial:
mul %ecx #eax=eax*ecx
loop factorial #at the end eax=i!
pushl %eax
fild -4(%ebp) #ST(0)=i!,ST(1)=x^i,ST(2)=x
popl %eax
fdiv %st(1),%st(0) #ST(1)=ST(1)/ST(0)=(x^i)/i!
fld 8(%ebp) #load partial result in ST(0)
fadd %st(0),%st(2) #ST(0)=updated partial result
fstp 8(%ebp) #store partial result into the stack
fcomip %st(0),%st(0) #pop i!
fcomip %st(0),%st(0) #pop x^i/i!,ST(0)=x
leave
ret
#function summinus
summinus:
pushl %ebp
movl %esp,%ebp
fld1 #load 1 in ST(0)
movl 12(%ebp),%ecx #ecx=i
power2:
fmul %st(0),%st(1) #ST(0)=ST(0)*ST(1),ST(1)=x
loop power2 #at the end ST(0)=x^i
movl 12(%ebp),%ecx #ecx=i
xorl %edx,%edx #reset edx used in mul
movl $1,%eax #set accumulator
factorial2:
mul %ecx #eax=eax*ecx
loop factorial2 #at the end eax=i!
pushl %eax
fild -4(%ebp) #ST(0)=i!,ST(1)=x^i,ST(2)=x
popl %eax
fdiv %st(1),%st(0) #ST(1)=ST(1)/ST(0)=(x^i)/i!
fld 8(%ebp) #load partial result in ST(0)
fsub %st(0),%st(2) #ST(0)=updated partial result
fstp 8(%ebp) #store partial result into the stack
fcomip %st(0),%st(0) #pop i!
fcomip %st(0),%st(0) #pop x^i/i!,ST(0)=x
leave
ret
#function develop
develop:
pushl %ebp
movl %esp,%ebp
sub $8,%esp #allocate room for local variables
movl $9,-4(%ebp) #store development-order,only odd values
fldz #load 0.0 in ST(0)
fstp -8(%ebp) #store ST(0) and pop to collect results
Cycle:
movl -4(%ebp),%eax #eax=i,development-order
xorl %edx,%edx #reset edx because of div
sub $1,%eax #i-1
movl $2,%ecx #divisor
div %ecx #eax=(i-1)/2,edx=0
div %ecx #eax=((i-1)/2)/2,remainder edx=0 or edx!=0
movl %edx,%ecx #ecx=remainder
jecxz Sumplus #n even,(-1)^n=+1
Summinus:
call summinus #n odd,(-1)^n=-1
jmp Restore #if sum- occured skip sum+
Sumplus:
call sumplus
Restore:
movl -4(%ebp),%ecx #restore counter
sub $2,-4(%ebp) #update order
loop Cycle #decrement ecx
fcomip %st(0),%st(0) #pop x
fld -8(%ebp) #load final result in ST(0)
leave
ret
#function sin
Sin:
pushl %ebp
movl %esp,%ebp
fld 8(%ebp) #push onto the stack 'x' value
fldpi #load pi into ST(0),x in ST(1)
ControlPi:
fcomi %st(1) #compare pi and x
jae LoadNPi #stop ControlPi, x is less than pi
fsub %st(1),%st(0) #store (x-pi) in ST(1)
jmp ControlPi #return to control
LoadNPi:
fimul -1 #(-pi) in ST(0),x in ST(1)
ControlPi2:
fcomi %st(1) #compare -pi and x
jbe PopStack #stop ControlPi2, x is greater than -pi
fadd %st(1),%st(0) #store (x+pi) in ST(1)
jmp ControlPi2 #return to control
PopStack:
fcomip %st,%st(0) #compare -pi to -pi then pop register stack
call develop #call develop function
leave #restore ebp
ret #return
那么，错误在哪里?我怎么解决这个问题? 谢谢.
So,where are the errors? How can I solve this problem? Thank you.
推荐答案
我建议创建一个非常简单的汇编语言函数，该函数除了返回所传递的参数外，什么也不做.这将等效于C函数:
I would suggest creating a very simple assembly language function that does nothing but return the same argument it's passed. This would be equivalent to the C function:
float identity(float x) {
return x;
}
完成此工作将确保您在开始实际编写代码之前正确设置了所有编译，组装，链接，调用约定等.一旦可行，编写一个将参数加1并返回的函数.然后，在进行一些练习之后，开始实现您的Sin()函数.到目前为止，对于刚接触汇编语言的人来说，这里有很多代码.
Making this work will ensure that you have all the compiling, assembling, linking, calling conventions, etc all set up properly before you start actually writing code. Once that works, write a function to add 1 to the argument and return that. Then, start implementing your Sin() function after you've got some practice. What you've got so far is a heck of a lot of code for somebody new to assembly language.
这篇关于执行从x86汇编程序编译的程序时出现分段错误?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
