16. Extend Sign Byte X-form (extsb/EXTSB)

The meaning of this PPC hardware instruction is obvious: copy the byte from source register to destination register and extend the signed bit of the byte to the remaining 56 bits ( bit0-bit55).

extsb RA,RS (Rc=0)
extsb. RA,RS (Rc=1)
s <- (RS)56
RA56:63 <- (RS)56:63
RA0:55 <- 56s

(RS)56:63 are placed into RA56:63.
RA0:55 are filled with
a copy of (RS)56.

Special Registers Altered:
CR0 (if Rc=1)