CTC1 - MIPS instruction reference

ctc1Move control word to FPU 
Copies integer register $t1 into an FPU control register.
Forms  ctc1 ,   
Operands $t1 Any general-purpose register, $0 to $31, using its numeric or named spelling, such as $8 or $t0 ($zero is $0; $ra is $31). 
$f31 $f31 here names the floating-point control and status register (FCSR), containing the rounding mode and exception flags. 
Register 31 is FCSR and register 25 is FCCR. Only the condition code bits take effect; the rounding mode and exception fields are ignored because this simulator always rounds to nearest and does not track FP exceptions.
 # Set FPU control/status to zero and read it back. Inspect $t1: 0.
li $t0, 0
ctc1 $t0, $f31
cfc1 $t1, $f31