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27 Floating-point rounding modes

For floating-point instructions with a rounding mode field, the rounding mode can be specified by adding an additional operand. e.g. fcvt.w.s with round-to-zero can be written as fcvt.w.s a0, fa0, rtz. If unspecified, the default dyn rounding mode will be used.

Supported rounding modes are as follows (must be specified in lowercase):

  • rne: round to nearest, ties to even
  • rtz: round towards zero
  • rdn: round down
  • rup: round up
  • rmm: round to nearest, ties to max magnitude
  • dyn: dynamic rounding mode (the rounding mode specified in the frm field of the fcsr register is used)