ADD - RISC-V instruction reference

addAddition 
Adds t2 and t3 and stores the sum in t1.
RISC-V manual: add 
Used in The RISC-V instruction setRISC-V assembly
Loads, stores and immediatesRISC-V assembly
Going 64-bitRISC-V assembly
if, else and jump tablesRISC-V assembly
LoopsRISC-V assembly
Arithmetic, logic and bitsRISC-V assembly
Arrays and stringsRISC-V assembly
The stack and spRISC-V assembly
jal, ret and the calling conventionRISC-V assembly
ecallRISC-V assembly
 
Forms  add , ,   
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. 
t3 An integer register. It may be the same register as t1. 
 .text
li t0, 13
li t1, 5
# t0=13, t1=5; add writes 18 to t2.
add t2, t0, t1