Module params 

Mechanisms for selecting parameters.

Traits and structures in this module are not normally needed by the typical user. Their purpose is to provide a systematic way, and in particular a default way, to select parameters for parameterized traits such as GammaReadParam and GammaWriteParam.

The traits and structure in this module work closely with the bitstream readers and writers in impls, which have an additional type parameter RP/WP that must implement marker traits ReadParams or WriteParams, respectively. The type is then used as a selector type to provide blanket implementations of parameterless traits in codes such as GammaRead, GammaWrite, DeltaRead, DeltaWrite, and so on.

This module provides default selector types DefaultReadParams and DefaultWriteParams which are also the default value for the parameter RP/WP in the bitstream readers and writers in crate::impls. Type-selected blanket implementations of all parameterless traits in crate::codes are provided for the bitstream readers and writers in impls. Thus, if you do not specify a value for the parameter RP/WP, you will obtain automatically the blanket implementations for parameterless traits contained in this module.

However, you can also create new selector types implementing ReadParams/WriteParams and write blanket implementations for the bitstream readers and writers in crate::impls where RP/WP is set to your selector types. Then, by specifying your type as value of the parameter RP/WP when creating such readers and writers you will use automatically your blanket implementations instead of the ones provided by this module.

Note that the default implementations provided by this module are targeted at u32 read words and u64 write words. If you use different word sizes, you may want to write your own selector types.

Table peek-bits checks

The read_*_param methods in each code module (e.g., GammaReadParam::read_gamma_param) verify at compile time, via const { } blocks using BitRead::PEEK_BITS, that the reader’s peek word is large enough for the table when the corresponding USE_TABLE const parameter is true. These checks are short-circuited when the table is not used, so they are only triggered for the tables actually selected.

Structs

DefaultReadParams

A selector type for read parameters providing reasonable defaults.

DefaultWriteParams

A selector type for write parameters providing reasonable defaults.

Traits

ReadParams

Marker trait for read-parameters selector types.

WriteParams

Marker trait for write-parameters selector types.