Windows x64 Software Conventions

1. Type and storage

Scalar data types

• Byte-8 bit

• Word-16 bit

• Double Word-32 Bit

• Quad Word-64 Bit

• Octa Word-128 Bit

Symbol types and their sizes in programs

Aggregation and Union

Other types, such as arrays, structs, and unions, have stricter alignment requirements to ensure consistent storage and data retrieval for aggregations and unions. The following are definitions of arrays, structs, and unions:

Array
An ordered group that contains adjacent data objects. Each object is called an element. All elements in the array have the same size and data type.

Structure
An ordered group that contains data objects. Unlike elements of an array, a data object in a structure can have different data types and sizes. Each data object in the structure is called a member.

Union
An object that can hold any named member set. The members of a named set can be of any type. The storage allocated for the union equals the storage required for the largest member of the union, plus all the white space required for alignment.

The following table shows the highly recommended alignment of the union and struct scalar members.

Not to be continued ....

Windows x64 Software Conventions