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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 * 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 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 * 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 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, is serialized into big-endian order (most significant byte first) by default,
using the number of bytes implied by the bit width. using the number of bytes implied by the bit width.
For example, the `U16` value 10 (decimal) is serialized as the For example, the `U16` value 10 (decimal) is serialized as the
two bytes `00` `0A` (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).
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).
.. A value of signed integer type (`I8`, `I16`, `I32`, or `I64`) .. 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 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. Otherwise the unsigned value is the two's complement of the signed value.
For example: For example:
... The `I16` value 10 (decimal) is serialized as two bytes ... 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.
in big-endian order, yielding the bytes `00` `0A` (hex).
... The `I16` value -10 (decimal) is serialized by ... The `I16` value -10 (decimal) is serialized by
(1) computing the `U16` value 2^16^ - 10 = 65526 (1) computing the `U16` value 2^16^ - 10 = 65526
and (2) serializing that value as two bytes in big-endian order, and (2) serializing that value as two bytes in the selected byte order,
yielding the bytes `FF` `F6` (hex). yielding the bytes `FF` `F6` (hex) big-endian and `F6` `FF` (hex) little-endian.
. A value of floating-point type (`F32` or `F64`) . 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. standard for representing these values.
. A value of Boolean type is serialized as a single byte. . A value of Boolean type is serialized as a single byte.