# A.3 Round to Float conversion

<!-- Power ISA Book I Version 3.0B Section A.3 page 782 -->

    def Round_Float( tgt_precision, sign, exp, frac, round_mode ):
       inc <- 0
       if tgt_precision = "single-precision" then
           lsb <- frac[23]
           gbit <- frac[24]
           rbit <- frac[25]
           xbit <- frac[26:63] > 0
        else # tgt_precision = "double-precision"
            lsb  <= frac[52]
            gbit <= frac[53]
            rbit <= frac[54]
            xbit <= frac[55:63] > 0

        if round_mode  = 0b00  then           # Round to Nearest
            if lsb = 1 and gbit = 1              then inc <- 1
            if lsb = 0 and gbit = 1 and rbit = 1 then inc <- 1
            if lsb = 0 and gbit = 1 and xbit = 1 then inc <- 1
        end
        if round_mode  = 0b10  then           # Round toward + Infinity
            if sign = 0 and gbit = 1 then inc <-1
            if sign = 0 and rbit = 1 then inc <-1
            if sign = 0 and xbit = 1 then inc <-1
        end
        if round_mode  = 0b11  then           # Round toward - Infinity
            if sign = 1 and gbit = 1 then inc <-1
            if sign = 1 and rbit = 1 then inc <-1
            if sign = 1 and xbit = 1 then inc <-1
        end
        if tgt_precision = "single-precision" then
            frac[0:23] <- frac[0:23] + inc
        else # tgt_precision = "double-precision"
            frac[0:52] <- frac[0:52] + inc
        if carry_out = 1 then exp <- exp + 1
        FPSCR[FR] <- inc
        FPSCR[FI] <- gbit | rbit | xbit
        FPSCR[XX] <- FPSCR[XX] | FPSCR[FI]