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Little Endian Serialization Tweaks to User Guide

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Will MacCormack 2025-10-10 10:27:42 -05:00
parent b5e4c7b23f
commit 59a7f6d9e1
1 changed files with 7 additions and 10 deletions
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17
docs/users-guide/Writing-C-Plus-Plus-Implementations.adoc
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@ -79,7 +79,7 @@ Your class definition should include the following:
* An implementation of the virtual function
+
----
Fw::SerializeStatus T::serializeTo(Fw::SerializeBufferBase&, Fw::Serialization::Endianness) const
Fw::SerializeStatus T::serializeTo(Fw::SerializeBufferBase&, Fw::Serialization::Endianness = Fw::Serialization::BIG) const
----
+
that specifies how to *serialize* a class instance to a buffer
@ -88,7 +88,7 @@ that specifies how to *serialize* a class instance to a buffer
* An implementation of the function
+
----
Fw::SerializeStatus T::deserializeFrom(Fw::SerializeBufferBase&, Fw::Serialization::Endianness)
Fw::SerializeStatus T::deserializeFrom(Fw::SerializeBufferBase&, Fw::Serialization::Endianness = Fw::Serialization::BIG)
----
+
that specifies how to *deserialize* a class instance from a
@ -497,9 +497,7 @@ F Prime uses the following rules for serializing data:
is serialized into big-endian order (most significant byte first) by default,
using the number of bytes implied by the bit width.
For example, the `U16` value 10 (decimal) is serialized as the
two bytes `00` `0A` (hex).
If little-endian order is desired, the optional mode parameter can be specified as `Fw::Serialization::LITTLE`. This stores the data least significant byte order in the number of bytes implied by the bit width. The `U16` value 10 (decimal) is serialized in little-endian as the two bytes `0A` `00` (hex).
two bytes `00` `0A` (hex). If little-endian order is desired, the optional mode parameter can be specified as `Fw::Serialization::LITTLE`. This stores the data least significant byte order. The `U16` value 10 (decimal) is serialized in little-endian as the two bytes `0A` `00` (hex).
.. A value of signed integer type (`I8`, `I16`, `I32`, or `I64`)
is serialized by first converting the value to an unsigned value of the same bit
@ -509,16 +507,15 @@ the same as the signed value.
Otherwise the unsigned value is the two's complement of the signed value.
For example:
... The `I16` value 10 (decimal) is serialized as two bytes
in big-endian order, yielding the bytes `00` `0A` (hex).
... The `I16` value 10 (decimal) is serialized as two bytes, yielding the bytes `00` `0A` (hex) in big-endian and `0A` `00` (hex) in little-endian.
... The `I16` value -10 (decimal) is serialized by
(1) computing the `U16` value 2^16^ - 10 = 65526
and (2) serializing that value as two bytes in big-endian order,
yielding the bytes `FF` `F6` (hex).
and (2) serializing that value as two bytes in the selected byte order,
yielding the bytes `FF` `F6` (hex) big-endian and `F6` `FF` (hex) little-endian.
. A value of floating-point type (`F32` or `F64`)
is serialized in big-endian order according to the IEEE
is serialized in the selected byte order according to the IEEE
standard for representing these values.
. A value of Boolean type is serialized as a single byte.