3.8 Quadrupleprecision Floatingpoint
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3.8 Quadrupleprecision Floatingpoint
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3.8 Quadrupleprecision Floatingpoint
3.8 Quadrupleprecision Floatingpoint
The standard defines the encoding for the quadrupleprecision
floatingpoint data type "quadruple" (128 bits or 16 bytes). The
encoding used is designed to be a simple analog of of the encoding
used for single and doubleprecision floatingpoint numbers using one
form of IEEE double extended precision. The standard encodes the
following three fields, which describe the quadrupleprecision
floatingpoint number:
S: The sign of the number. Values 0 and 1 represent positive and
negative, respectively. One bit.
E: The exponent of the number, base 2. 15 bits are devoted to
this field. The exponent is biased by 16383.
F: The fractional part of the number's mantissa, base 2. 112 bits
are devoted to this field.
Therefore, the floatingpoint number is described by:
(1)**S * 2**(EBias) * 1.F
It is declared as follows:
quadruple identifier;
+++++++...++
byte 0byte 1byte 2byte 3byte 4byte 5 ... byte15
S E  F 
+++++++...++
1<15><112 bits>
<128 bits>
QUADRUPLEPRECISION FLOATINGPOINT
Just as the most and least significant bytes of a number are 0 and 3,
the most and least significant bits of a quadrupleprecision
floatingpoint number are 0 and 127. The beginning bit (and most
significant bit) offsets of S, E , and F are 0, 1, and 16,
respectively. Note that these numbers refer to the mathematical
positions of the bits, and NOT to their actual physical locations
(which vary from medium to medium).
The encoding for signed zero, signed infinity (overflow), and
denormalized numbers are analogs of the corresponding encodings for
single and doubleprecision floatingpoint numbers [5], [6]. The
"NaN" encoding as it applies to quadrupleprecision floatingpoint
numbers is system dependent and should not be interpreted within XDR
as anything other than "NaN".
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3.8 Quadrupleprecision Floatingpoint
