MATLAB Programming

Accessing Files with Memory-Mapping
Property Description Data Type Default
Data
Filename
Format
Offset
Repeat
Writable
Contains the data read from the file or to be written
tothefile. (See“ReadingaMappedFile”onpage
6-54 and “Writing to a Mapped File” on page 6-59)
Path and name of the file to map into memory. (See
“SelectingtheFiletoMap”onpage6-43)
Format of the contents of the mapped region,
including data type, array shape, and variable
or field name by which to access the data. (See
“Identifying the Contents of the Mapped Region” on
page 6-45)
Number of bytes from the start of the file to the start
of the mapped region. This number is zero-based.
That is, offset 0 represents the start of the file. Must
be a nonnegative integer value. (See “Setting the
Start of the Mapped Region” on page 6-45)
Number of times to apply the specified format to the
mapped region of the file. Must be a positive integer
value or Inf. (See “Repeating a Format Scheme” on
page 6-52)
Type of access allowed to the mapped region. Must
be logical 1 or logical 0. (See “Setting the Type of
Access” on page 6-53)
Any of the
numeric
types
char array
char array
or N-by-3
cell array
double 0
double
logical
None
None
uint8
Inf
false
You can set the values for any property except for Data atthetimeyoucall
the memmapfile constructor, or at any time after that while the map is still
valid. Any properties that are not explicitly set when you construct the object
are given their default values as shown in the table above. For information on
calling the constructor, see “Constructing a memmapfile Object” on page 6-40.
Once a memmapfile object has been constructed, you can change the value of
any of its properties. Use the objname.property syntax in assigning the new
value. For example, to set a new Offset value for memory map object m, type
m.Offset = 2048;
6-39