I'm using Franklin C51 Release 8 to use multiply 2 integers together, as shown below:

int input1, input2;
result = input1 * input2;

The listing file I've got after compiling the program is as shown:

0110 AE00 R MOV R6,input2
0112 AF00 R MOV R7,input2+01H
0114 AC00 R MOV R4,input1
0116 AD00 R MOV R5,input1+01H
0118 120000 R LCALL ?C_IMUL
011B 8E00 R MOV result,R6
011D 8F00 R MOV result+01H,R7

What is the meaning of LCALL ?C_IMUL ? I can't find the label anywhere in the list file. Where can I find the source code for ?C_IMUL. Any help will be appreciated. Thanx!