fpt and WinFPT Reference Manual - Command-line Commands

| SimCon Home | Ref Manual Home |

ALIGNMENT GRANULARITY

Syntax:

ALIGNMENT GRANULARITY [:] <integer> [BYTE[S]]

Function:

Most systems access memory more efficiently if objects occupy aligned addresses, addresses which are multiples of 4 or 8 bytes. The command ALIGNMENT GRANULARITY specifies the spacing of aligned addresses for local variables and for variables in COMMON blocks. The command STRUCTURE ALIGNMENT GRANULARITY specifies the spacing of aligned addresses of the fields within Fortran structures. The alignment rules used by most compilers, and by fpt, are that:

• the alignment granularity of a numeric object is the data size of the object, or the system alignment granularity, whichever is the smaller;
• the alignment granularity of character variables and arrays is one byte when assigning COMMON block addresses, but access is more efficient if variables and array elements start on aligned addresses;
• the alignment granularity of a record or of a user-defined compound type is the granularity of the largest object in the structure or type, or the system granularity, whichever is the smaller.

Where to Use this Command

Note that the alignment granularity used by the command ALIGN OBJECTS IN COMMON BLOCKS cannot be specified interactively because addresses within COMMON blocks are computed before fpt enters interactive mode.

Default

ALIGNMENT GRANULARITY : 4 BYTES

Examples:

In an FSP file for Compaq Visual Fortran under Windows 7:

%alignment granularity: 8 %check alignment

See Also:

ALIGN OBJECTS IN COMMON BLOCKS

CHECK ALIGNMENT

Copyright ©1995 to 2024 Software Validation Ltd. All rights reserved.