Mips Technologies R4000 - Control;Status Register Rounding Mode Control Bits

MIPS R4000 Microprocessor User's Manual 163
Floating-Point Unit
Control/Status Register Rounding Mode Control Bits
Bits 1 and 0 in the Control/Status register constitute the Rounding Mode
(RM) field.
As shown in Table 6-4, these bits specify the rounding mode that the FPU
uses for all floating-point operations.
Table 6-4 Rounding Mode Bit Decoding
Rounding
Mode
RM(1:0)
Mnemonic Description
0RN
Round result to nearest representable
value; round to value with least-
significant bit 0 when the two nearest
representable values are equally near.
1RZ
Round toward 0: round to value closest to
and not greater in magnitude than the
infinitely precise result.
2RP
Round toward +∞: round to value closest
to and not less than the infinitely precise
result.
3RM
Round toward – ∞: round to value closest
to and not greater than the infinitely
precise result.