Function:

FSCALE multiplies the value in ST by a power of two, given in ST(1).
Pre-387s assume the value in ST(1) to be an integer in the range
-215 <= , < +215. 387+ do not assume anything about the value.
The value in ST(1) is always chopped to the nearest integer closest
to zero.

There is a bug in some 486s which allows denormal or pseudo-denormals to
be returned as a result, apparently without issuing an Invalid Operation
exception. For this to happen, ST(1) must be within the range
-1 < ST(1) < 1 and ST must be a pseudo-denormal or denormal while
underflow exceptions must not be masked. When it occurs, the value from
ST is returned as the result.

There is no workaround other than to avoid the situation. Leaving
underflow exceptions masked may prevent this bug from showing up.




FSINCOS  Calculate both Sine and Cosine of ST
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