PRC (Palm OS)

PRC (Palm Resource Code) is a container format for code databases in Palm OS, Garnet OS and Access Linux Platform. Its structure is similar to PDB databases.[1] Usually, a PRC file is a flat representation of a Palm OS application that is stored as forked database[clarification needed] on the PDA. PRC files are also used by the Mobipocket e-book-reader (here sometimes referred to as MOBI format[2]). The AZW format of Amazon's Kindle reading device is in turn a DRM-restricted form of the Mobipocket format.

On Palm OS, PRC files are used for applications, localized resources (overlays) and shared libraries.[1]

## Contents

* 1 Structure of PRC file
* 1.1 PRC Header
* 1.2 PRC Resource Header
* 1.3 PRC Resources
* 2 References

## Structure of PRC file

In its essence, a PRC file is similar to a classic Mac OS application. It contains a PRC header, PRC resource headers and PRC resources.[3]

PRC Header

PRC Resource Header
PRC Resources

### PRC Header

The PRC header is located at the beginning of the file and contains meta-information on the file:[3]

Offset  | Name  | Type  | Size

|
|
|

0x00  | name  | char  | 32 Bytes
0x20  | flags  | integer  | 2 Bytes
0x22  | version  | integer  | 2 Bytes
0x24  | creation time  | 32bit integer - PDB Datetime | 4 Bytes
0x28  | modification time  | 32bit integer - PDB Datetime | 4 Bytes
0x2c  | backup time  | 32bit integer - PDB Datetime | 4 Bytes
0x30  | mod_num  | integer  | 4 Bytes
0x34  | app_info  | integer  | 4 Bytes
0x38  | sort_info  | integer  | 4 Bytes
0x3c  | type  | integer  | 4 Bytes
0x40  | creator  | integer  | 4 Bytes
0x44  | unique_id_seed  | integer  | 4 Bytes
0x48  | next_record_list  | integer  | 4 Bytes
0x4c  | num_records  | integer  | 2 Bytes

### PRC Resource Header

For every resource (specified by num_records), there is a resource header containing:[3]

name  | type  | notes  | size

|
|
|

name  | char  | Name of the resource  | 4 bytes
ID  | integer  | ID number of the resource  | 2 bytes
offset  | integer  | Pointer to resource data  | 4 bytes

### PRC Resources

Every application contains al least a Code #0 resource with size information and jump tables, a Code #1 resource with executable code and data resources containing pre-initialized values of global variables in compressed form.[3] Other resources that may be contained are forms, form objects, alerts and multimedia data, e. g. images and sounds.

## References

1. ↑ 1.0 1.1 N. Rhodes, J. McKeehan. Palm OS Programming, Second Edition, O'Reilly, 2001, ISBN 1-56592-856-3.
2. ↑ MobileRead Wiki: Reference for the MOBI format
3. ↑ 3.0 3.1 3.2 3.3 Theodore Ts'o (2000) The PRC Format. Accessed on 2009-03-07

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