atmel stepper programming for AT90S2313

I need a simple program to run in a stk500, must run OK in avrstudio simulator, for basic stepper control routine, must be clearly commented and this will lead to more coding with slighter increase in payment if complexity increases. four outputs are to be used for the stepper, a dip switch as input (four lines) is used to control the stepping sequence and two normal off key push button for increase and decrease of the speed the at which the sequence is running. this is just for the software, no hardware design is necessary, just coding whether in C for microcontrollers (avrlibc) or preferably in assembler for atmel. Thank you. please feel free to send any questions through the freelancer platform.