/* This is a simple delay based on a busy loop    */
/* with a 22.1184 MHz crystal, the delay lasts    */
/* for approximately 1 ms times the number passed */
/* Of course, it will take longer if there are    */
/* interrupts occuring...                         */

void delay_ms(unsigned char ms) { //real Milli Seconds
        ms;
        _asm
        mov     r0, dpl
00001$: mov     r1, #230
00002$: nop
        nop
        nop
        nop
        nop
        nop
        djnz    r1, 00002$
        djnz    r0, 00001$
        ret
        _endasm;
}

I found this some time ago. I don't remeber the orginal auther but, it has served me will. I used it with SDCC and With Dunfield C. As you can see it inline asm. The only real way to make sure it's accurate. Please note what it says about interrupts.

Hope this helps.