Datasheet

Floating-point Support
ARM DUI 0067D Copyright © 1999-2001 ARM Limited. All rights reserved. 5-19
The flags contained in edata are:
•
edata & FE_EX_RDIR is nonzero if the intermediate result in Underflow was
rounded down, and 0 if it was rounded up or not rounded. (The difference between
the last two is given in the Inexact Result bit.) This bit is meaningless for any other
type of exception.
•
edata & FE_EX_exception is nonzero if the given exception ( INVALID , DIVBYZERO ,
OVERFLOW , UNDERFLOW or INEXACT ) occurred. This enables you to:
— use the same handler function for more than one exception type (the
function can test these bits to tell what exception it is supposed to handle)
— determine whether Overflow and Underflow intermediate results have been
rounded or are exact.
Because the
FE_EX_INEXACT bit can be set in combination with either
FE_EX_OVERFLOW or FE_EX_UNDERFLOW , you must determine the type of exception that
actually occurred by testing Overflow and Underflow before testing Inexact.
•
edata & FE_EX_FLUSHZERO is nonzero if the FZ bit was set when the operation was
performed (see The __ieee_status function on page 5-8).
•
edata & FE_EX_ROUND_MASK gives the rounding mode that applies to the operation.
This is normally the same as the current rounding mode, unless the operation that
caused the exception was a routine such as
_ffix , that always rounds toward zero.
The available rounding mode values are
FE_EX_ROUND_NEAREST ,
FE_EX_ROUND_PLUSINF , FE_EX_ROUND_MINUSINF and FE_EX_ROUND_ZERO .
•
edata & FE_EX_INTYPE_MASK gives the type of the operands to the function, as one
of the type values shown in Table 5-8.
Table 5-8 FE_EX_INTYPE_MASK operand type flags
Flag Operand type
FE_EX_INTYPE_FLOAT float
FE_EX_INTYPE_DOUBLE double
FE_EX_INTYPE_INT int
FE_EX_INTYPE_UINT unsigned int
FE_EX_INTYPE_LONGLONG long long
FE_EX_INTYPE_ULONGLONG unsigned long long