FSFLAGS - RISC-V instruction reference

fsflagsSwap FP exception flags Pseudo-instruction
Swaps t2 into the FP exception flags, storing the old flags in t1, or only writes t1 when given one register.
RISC-V manual: csrrw 
Used in Floating point and the F and D extensionsRISC-V assembly
 
Forms  fsflags ,   
 fsflags   
Write FP exception flags
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. 
 # Initialize fflags, then use fsflags to read its old value or update it.
.text
li t3, 0
csrw t3, fflags
li t0, 1
fsflags t1, t0
# t1=0 is the old value; fflags becomes 1.