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int cvt_ftof void *x, int x_type, void *y, int y_type, options )
cvt_ftof() converts a floating-point value from one data type to another. x points to the input value to be converted, and y points to the converted result. The conversion is subject to the options specified in the options (bit field) argument.
x_type and y_type identify the data type of x and y as follows:
Values for x_type and y_type Floating-Point Data Type CVT_VAX_F VAX F Floating ( 4 bytes) CVT_VAX_D VAX D Floating ( 8 bytes) CVT_VAX_G VAX G Floating ( 8 bytes) CVT_VAX_H VAX H Floating (16 bytes) CVT_IEEE_S IEEE Little Endian S Floating ( 4 bytes) CVT_IEEE_T IEEE Little Endian T Floating ( 8 bytes) CVT_IEEE_X IEEE Little Endian X Floating (16 bytes) CVT_BIG_ENDIAN_IEEE_S IEEE Big Endian S Floating ( 4 bytes) CVT_BIG_ENDIAN_IEEE_T IEEE Big Endian T Floating ( 8 bytes) CVT_BIG_ENDIAN_IEEE_X IEEE Big Endian X Floating (16 bytes) CVT_IBM_SHORT IBM_Short_Floating ( 4 bytes) CVT_IBM_LONG IBM_Long_Floating ( 8 bytes) CVT_CRAY_SINGLE CRAY_Floating ( 8 bytes)
Provide a zero (0) value to the options argument to select default behavior or choose one or more options (status condition option, rounding options, "FORCE" options, CRAY and IBM options) from the tables below as the options argument. Specify only the options that apply to your conversion. A conflicting or incompatable options argument will be reported as an error (CVT_INVALID_OPTION).
Applicable Status Condition
Conversion Option Description
All CVT_REPORT_ALL Report all applicable
status conditions as the
default. The reporting
of recoverable status
conditions is disabled by
default when this option
is not used.
Applicable
Conversion Rounding Options Description
All CVT_ROUND_TO_NEAREST The default rounding
option for conversions
to IEEE data types. This
IEEE Std. 754 rounding
mode results in the
representable output
value nearest to the
infinitely precise
result. If the two
nearest representable
values are equally near,
the one with its least
significant bit zero is
the result.
All CVT_BIASED_ROUNDING The default rounding
option for conversions
to non-IEEE data types.
Performs "traditional"
style rounding. This
mode results in the
representable output
value nearest to the
infinitely precise
result. If the two
nearest representable
values are equally
near, the result is the
value with the largest
magnitude.
All CVT_ROUND_TO_ZERO Round the output value
toward zero (truncate).
All CVT_ROUND_TO_POS Round the output value
toward positive infinity.
All CVT_ROUND_TO_NEG Round the output value
toward negative infinity.
Applicable
Conversion "FORCE" Options Description
All CVT_FORCE_ALL_SPECIAL_VALUES Apply all applicable
"FORCE" options for the
current conversion.
IEEE CVT_FORCE_DENORM_TO_ZERO[1] Force a denormalized
IEEE output value to
zero.
IEEE CVT_FORCE_INF_TO_MAX_FLOAT[1] Force a positive IEEE
infinite output value to
+max_float and force a
negative IEEE infinite
output value to -max_
float.
IEEE or CVT_FORCE_INVALID_TO_ZERO[2] Force an invalid IEEE
VAX NaN (not a number)
output value or a VAX
ROP (reserved operand)
output value to zero.
[1]This option is valid only for conversions to IEEE output values.
[2]This option is valid only for conversions to IEEE or VAX output values.
Applicable
Conversion Options for CRAY Format Conversion Description
CRAY CVT_ALLOW_OVRFLW_RANGE_VALUES Allow an input
/output exponent
value > 60000 (8).
CRAY CVT_ALLOW_UDRFLW_RANGE_VALUES Allow an input
/output exponent
value < 20000 (8).
Applicable
Conversion Option for IBM Format Conversion Description
IBM CVT_ALLOW_UNNORMALIZED_VALUES Allow unnormalized
input arguments.
Allow an
unnormalized output
value for a small
value which would
normalize to zero.
Condition Name Condition (Always reported by default) CVT_INVALID_INPUT_TYPE Invalid input type code. CVT_INVALID_OUTPUT_TYPE Invalid output type code. CVT_INVALID_OPTION Invalid option argument.
Condition Name Condition (Only reported if
the CVT_REPORT_ALL option is
selected)
CVT_RESULT_INFINITE Conversion produced an infinite
result.[1]
CVT_RESULT_DENORMALIZED Conversion produced a denormalized
result.[1]
CVT_RESULT_OVERFLOW_RANGE Conversion yielded an exponent >
60000 (8).[2]
CVT_RESULT_UNDERFLOW_RANGE Conversion yielded an exponent <
20000 (8).[2]
CVT_RESULT_UNNORMALIZED Conversion produced an unnormalized
result.[3]
CVT_RESULT_INVALID Conversion result is either ROP
(reserved operand), NaN (not a
number), or closest equivalent. CRAY
and IBM data types return 0.[4]
CVT_RESULT_OVERFLOW Conversion resulted in overflow.[4]
CVT_RESULT_UNDERFLOW Conversion resulted in underflow.[4]
CVT_RESULT_INEXACT Conversion resulted in a loss of
precision.[4]
[1]For IEEE data type conversions.
[2]For CRAY data type conversions.
[3]For IBM data type conversions.
[4]For all data type conversions.
status = cvt_ftof( &big_x, CVT_BIG_ENDIAN_IEEE_T,
&little_x, CVT_IEEE_T, 0 );
This example converts the value pointed to by big_x which is of type
IEEE Big Endian T Floating, to the IEEE Little Endian T Floating
data type and stores the result in the location pointed to by
little_x. No conversion options are specified.
status = cvt_ftof(&x, CVT_VAX_D, &y, CVT_IEEE_T,
(CVT_FORCE_ALL_SPECIAL_VALUES | CVT_REPORT_ALL) );
This example converts the value pointed to by x which is of type
VAX D Floating, to the IEEE Little Endian T Floating data type and
stores the result in the location pointed to by y. Any special IEEE
values which would normally be generated will be removed. That is,
NaN and Denormalized results will be returned as zero and infinite
results will go to +- max_float. In addition, all recordable status
conditions will be reported.