<!-- Instructions here described in PowerISA Version 3.0 B Book 1 -->

<!-- Section 3.3.15 Binary Coded Decimal (BCD) Assist Instructions. Page 111 -->

<!-- The Binary Coded Decimal Assist instructions operate on Binary Coded Decimal -->
<!-- operands (cbcdtd and addg6s) and Decimal Floating-Point operands (cdtbcd) -->
<!-- See Chapter 5. for additional information. -->


# Convert Declets To Binary Coded Decimal

X-Form

* cdtbcd RA, RS

Pseudo-code:

    do i = 0 to 1
      n <- i * 32
      RA[n+0:n+7] <- 0
      RA[n+8:n+19 ] <- DPD_TO_BCD ( (RS)[n+12:n+21] )
      RA[n+20:n+31] <- DPD_TO_BCD ( (RS)[n+22:n+31] )

Special Registers Altered:

    None

# Add and Generate Sixes

XO-Form

* addg6s RT,RA,RB

Pseudo-code:

    dc <- [0]*16
    do i = 0 to 15
        temp <- (0b0 || RA[4*i:63]) + (0b0 || RB[4*i:63])
        dc[i] <- temp[0]
    c <- ([dc[0]]*4 || [dc[1]]*4 || [dc[2]]*4 || [dc[3]]*4 ||
            [dc[4]]*4 || [dc[5]]*4 || [dc[6]]*4 || [dc[7]]*4 ||
            [dc[8]]*4 || [dc[9]]*4 || [dc[10]]*4 || [dc[11]]*4 ||
            [dc[12]]*4 || [dc[13]]*4 || [dc[14]]*4 || [dc[15]]*4)
    RT <- (¬c) & 0x6666_6666_6666_6666

Special Registers Altered:

    None

# Convert Binary Coded Decimal To Declets

X-Form

* cbcdtd RA, RS

Pseudo-code:

    do i = 0 to 1
      n <- i * 32
      RA[n+0:n+11] <- 0
      RA[n+12:n+21] <- BCD_TO_DPD ( (RS)[n+8:n+19] )
      RA[n+22:n+31] <- BCD_TO_DPD ( (RS)[n+20:n+31] )

Special Registers Altered:

    None

<!-- Checked March 2021 -->