How to call a linear assembly function?

  In one project, I wrote a file named as dotp.sa  with the above code, then I wrote a main.c file as follows:

short a[100] ={0};
short b[100] ={0};

void main()
{
   int sum = 0;  
 
   sum = _dotp(a,b);
}

But this can't be built with error:"undefined symbol _dotp".

Does it need any statement for _dotp in main.c, and how?  I run this project under 6678.

Looking forward to somebody can help me,

Best regards,

May