Microchip Technology SW006023-3N 数据表

Implementation-Defined Behavior

 2012 Microchip Technology Inc.

DS51686E-page 195

ISO Standard:

“The direction of rounding when an integer is converted to a float-
ing-point number that cannot exactly represent the original value (C90
6.2.1.3, C99 6.3.1.4).”

Implementation:

C99 Annex F is followed.

ISO Standard:

“The direction of rounding when a floating-point number is converted to
a narrower floating-point number (C90 6.2.1.4, 6.3.1.5).”

Implementation:

C99 Annex F is followed.

ISO Standard:

“How the nearest representable value or the larger or smaller repre-
sentable value immediately adjacent to the nearest representable value
is chosen for certain floating constants (C90 6.1.3.1, C99 6.4.4.2).”

Implementation:

C99 Annex F is followed.

ISO Standard:

“Whether and how floating expressions are contracted when not disal-
lowed by the FP_CONTRACT pragma (C99 6.5).”

Implementation:

The pragma is not implemented.

ISO Standard:

“The default state for the FENV_ACCESS pragma (C99 7.6.1).”

Implementation:

This pragma is not implemented.

ISO Standard:

“Additional floating-point exceptions, rounding modes, environments,
and classifications, and their macro names (C99 7.6, 7.12).”

Implementation:

None supported.

ISO Standard:

“The default state for the FP_CONTRACT pragma (C99 7.12.2).”

Implementation:

This pragma is not implemented.

ISO Standard:

“Whether the “inexact” floating-point exception can be raised when the
rounded result actually does equal the mathematical result in an IEC
60559 conformant implementation (C99 F.9).”

Implementation:

Unknown.

ISO Standard:

“Whether the “underflow” (and “inexact”) floating-point exception can
be raised when a result is tiny but not inexact in an IEC 60559 confor-
mant implementation (C99 F.9).”

Implementation:

Unknown.