REV8 - RISC-V instruction reference

rev8Reverse bytes 
Sets t1 to t2 with its bytes in reverse order, converting between little and big endian.
RISC-V manual: rev8 
Forms  rev8 ,   
Operands t1 Any integer register, x0 to x31, or its named alias, such as zero, t0 or t6. 
t2 An integer register. It may be the same register as t1. 
 .text
li t0, 13
# t0=13; rev8 writes 218103808 to t2.
rev8 t2, t0