The earned-time allowances, which could have been awarded by the board to inmates based upon the performance of the inmate, in effect on December 31, 1983, shall not apply to:

(1) Those persons who commit crimes on or after January 1, 1984, and who are subsequently convicted and sentenced to the custody of the board;

(2) Those persons who have committed a crime prior to January 1, 1984, but who have not been convicted and sentenced as of December 31, 1983, and who are subsequently sentenced to the custody of the board, including those whose sentences have been probated or suspended, on or after January 1, 1984; however, such persons shall receive the full benefit of the earned-time allowances, in effect on December 31, 1983, and shall receive a release or discharge date computed as if they had been sentenced to the custody of the board, prior to December 31, 1983; or

(3) Those persons previously sentenced to the custody of the board, including those whose sentences have been probated or suspended, as of December 31, 1983; however, such persons shall receive the full benefit of the earned-time allowances in effect on December 31, 1983, and shall receive a release or discharge date the same as reflected in the records of such person on December 31, 1983, less any creditable earned time that such person could have earned as a result of forfeited earned time.