How can I accessing a variable in Assembler Code ?

I use #pragma asm/#pragma endasm to embed Assembler Code in C Function.

My question is:

How can I accessing a variable in Assembler Code,which define by C code.

Just like this:

I need height speed to accessing XDATA from Addr 0x0000.

void Func()
{

unsigned char Var_C,i=0;

#pragma asm

mov DPTR,#0x0000

#pragma endasm

while(i++ < 0x10)

{

Var_C = ReadOneByte();

if(Var_C == 0xff)

{

Var_C = 0;

}

#pragma asm

MOV A,Var_C /* This line is not work */

MOVX @DPTR,A

INC DPTR

#pragma endasm

}

}

Build target 'Target 1'

compiling main.c...

main.src(181): error A45: UNDEFINED SYMBOL (PASS-2)

Thanks!!!