target/sparc: Split out do_ms16b

The unit operation for fmul8x16 and friends is described in the
manual as "MS16b".  Split that out for clarity.  Improve rounding
with an unconditional addition of 0.5 as a fixed-point integer.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20240502165528.244004-8-richard.henderson@linaro.org>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
1 file changed