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Enum member std.bitmanip.bitfields

Allows creating bit fields inside structs and classes.

enum bitfields(T...) = createStorageAndFields!T.result;

The type of a bit field can be any integral type or enumerated type. The most efficient type to store in bitfields is bool, followed by unsigned types, followed by signed types.

See Also

BitFlags

Example

Create a bitfield pack of eight bits, which fit in one ubyte. The bitfields are allocated starting from the least significant bit, i.e. x occupies the two least significant bits of the bitfields storage. 

struct A
{
    int a;
    mixin(bitfields!(
        uint, "x",    2,
        int,  "y",    3,
        uint, "z",    2,
        bool, "flag", 1));
}

A obj;
obj.x = 2;
obj.z = obj.x;

writeln(obj.x); // 2
writeln(obj.y); // 0
writeln(obj.z); // 2

Example

The sum of all bit lengths in one bitfield instantiation must be exactly 8, 16, 32, or 64. If padding is needed, just allocate one bitfield with an empty name. 

struct A
{
    mixin(bitfields!(
        bool, "flag1",    1,
        bool, "flag2",    1,
        uint, "",         6));
}

Example

enums can be used too 

enum ABC { A, B, C }
struct EnumTest
{
    mixin(bitfields!(
              ABC, "x", 2,
              bool, "y", 1,
              ubyte, "z", 5));
}

Example

Creates a bitfield pack of eight bits, which fit in one ubyte. The bitfields are allocated starting from the least significant bit, i.e. x occupies the two least significant bits of the bitfields storage. 

struct A
{
    int a;
    mixin(bitfields!(
        uint, "x",    2,
        int,  "y",    3,
        uint, "z",    2,
        bool, "flag", 1));
}
A obj;
obj.x = 2;
obj.z = obj.x;

writeln(obj.x); // 2
writeln(obj.y); // 0
writeln(obj.z); // 2
writeln(obj.flag); // false

Example

Add empty fields for padding to have a total bit length of 8, 16, 32, or 64 

struct A
{
    mixin(bitfields!(
        bool, "flag1",    1,
        bool, "flag2",    1,
        uint, "",         6));
}
A a;
writeln(a.flag1); // 0
a.flag1 = 1;
writeln(a.flag1); // 1
a.flag1 = 0;
writeln(a.flag1); // 0

Authors

Walter Bright, Andrei Alexandrescu, Jonathan M Davis, Alex Rønne Petersen, Damian Ziemba, Amaury SECHET

License

Boost License 1.0.