symbian 2.12.1.4Rationale ruct thi 2.12.2 Alignment a 32 bit zero bytes (at the memory.on processors which only allow 32-bit aligned access. 2.12.3 Notation The following notation is used to describe the data-structures used by the SIS file format: Structure Name Name of Field 1 Type of Field Size of Field Name of Field N Type of Field Size of Field 6oernaeByneemeh0teshe6spe6meeeP6gegpoeg8a The Structu name is the name of the str which e field The should appear in the value part of the structure. 3 SIS File Structure e e file escoiCat tai ng 32-bit UIDs and a 32-bit checksum. Symbian File Header SISContents 3.1 File Header Structure Field Name Field Size UID 1 4 Bytes UID2 4 Bytes UID3 4 Bytes UID Checksum 4 Bytes www.symbian.com 8 2.12.1.4 Rationale The reason for this format is that it makes it makes it very easy to construct a C++ class instance from a SISField. It is also possible to construct this instance by giving only the SISField data and no other part of the SIS file. 2.12.2 Alignment The SIS file is padded with zero bytes (at the end of each SISField) where necessary so each SISField begins on a 32 bit word boundary. This is to enable efficient parsing of the format from memory, on processors which only allow 32-bit aligned access. 2.12.3 Notation The following notation is used to describe the data-structures used by the SIS file format: Structure Name Name of Field 1 Type of Field Size of Field … … … Name of Field N Type of Field Size of Field The Structure name is the name of the structure, which determines the ID stored in the type field. The length is determined by the length of all the fields specified. The fields 1 to N, specify the data which should appear in the value part of the structure. 3 SIS File Structure All of the actual data of the SIS file is contained in the SISContents SISField. However Symbian OS uses a header, to associate files with applications. This header is a flat data structure consisting of three 32-bit UIDs and a 32-bit checksum. SISContents Symbian File Header 3.1 File Header Structure Field Name Field Size UID 1 4 Bytes UID 2 4 Bytes UID 3 4 Bytes UID Checksum 4 Bytes