Offenders who work at the penitentiary or in its prison industries shall receive compensation in an amount to be determined by the warden and approved by the director of the department of corrections and rehabilitation within the limits of legislative appropriations for that purpose. The warden shall assign work to each offender and shall pay the offender based on the amount of work the offender performs, up to the maximum compensation determined by the warden. If an offender has worked in excess of ten hours per day, the offender shall receive such additional compensation as the warden may allow. All offenders working in prison industries may receive pay based upon actual production of salable items as determined by the warden, to be paid out of funds the legislative assembly appropriates.