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TRAX User Manual Page 37

7.2 Parameter Formats

7.2.1 Endianness

TRAX can treat 32-bit and 16-bit parameters as having big or little Endian formatting.

For 32-bit parameters, the big Endian byte order is ABCD EFGH, while the little Endian

byte order is DCBA HGFE. For 16-bit parameters the big Endian byte order is ABCD,

while the little Endian byte order is DCBA. The Endianness is selectable by the user per

Section 7.4.2. The default is big Endian, and this is generally assumed in the manual.

7.2.2 Floating Point

Floating-point parameters conform to ANSI/IEEE Std 754-1985. A hex-to-floating-point

converter can be found at http://babbage.cs.qc.cuny.edu/IEEE-754.old/32bit.html. Note

that for this converter, little Endian values must be manually converted to big Endian.

Please refer to the Standard for more information. PNI also recommends referencing the

user’s compiler instructions to understand how the compiler implements floating-point.

64-Bit Floating Point (Float64)

Below is the 64-bit float format in big Endian. In little Endian the bytes are in reverse

order in 4-byte groups (e.g. DCBA HGFE).

ExponentS Mantissa

63 62 5251 0

The value (v) is determined as:

v = (-1)S * 2(Exponent-1023) * 1.Mantissa, if and only if 0 < Exponent < 2047

32-Bit Floating Point (Float32)

Shown below is the 32-bit float format in big Endian. In little Endian, the 4 bytes are

in reverse order (e.g. DCBA).

ExponentS Mantissa

3130 2322 0

The value (v) is determined as:

v = (-1)S * 2(Exponent-127) * 1.Mantissa, if and only if 0 < Exponent < 255

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