Lead Technologies archive
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| − | '''Lead Technologies archive''' (official name unknown) is a compressed installer-archive format used in some Lead Technologies software. The file is usually named "SETUP.LTA". | + | '''Lead Technologies archive''' (official name unknown) is a compressed installer-archive format used in some Lead Technologies software. The file is usually named "SETUP.LTA". Multi-part archives are common, with multiple "SETUP.LTA" files comprising a single archive. A byte in the archive header reflects the volume number. |
| + | |||
| + | Software using LTA usually includes an LTEXPAND.DLL file, which presumably contains decompression library code. | ||
| + | |||
| + | == Identification == | ||
| + | |||
| + | File start with ASCII "{{magic|LTEC}}". | ||
== Format details == | == Format details == | ||
| − | |||
| − | The compression method | + | The format consists of an archive header and a sequence of member file headers, terminated by two null bytes, then followed by one or more compressed data blocks. A form of solid archiving is used: individual files are not packed separately, but concatenated and then compressed as a whole. Each compressed block contains a different set of files in the archive. The compression method seems to match [[LHA|LHA's lhx]] as implemented by [https://github.com/fragglet/lhasa Lhasa]. |
| − | + | Byte order is [[Endianness|little-endian]]. | |
| − | + | === Archive header === | |
| − | = | + | {| class="wikitable" |
| − | + | ! Field offset | |
| + | ! Size | ||
| + | ! Description | ||
| + | |- | ||
| + | | 0 || 4 bytes || Signature {{magic|4c 54 45 43}} | ||
| + | |- | ||
| + | | 4 || 1 byte || Volume number | ||
| + | |- | ||
| + | | 5 || 4 bytes || Start of the first compressed block | ||
| + | |} | ||
| + | |||
| + | The start of the first compressed block should equal the sum of the sizes of the archive header, all of the member file headers, and the two terminating null bytes. | ||
| + | |||
| + | === Member file header === | ||
| + | |||
| + | {| class="wikitable" | ||
| + | ! Field offset | ||
| + | ! Size | ||
| + | ! Description | ||
| + | |- | ||
| + | | 0 || 2 bytes || Length of the header (including this field) | ||
| + | |- | ||
| + | | 2 || 4 bytes || Start of the compressed stream the file is included in, relative to the third field in the archive header (i.e., files in the first compressed block have this field set to zero) | ||
| + | |- | ||
| + | | 6 || 4 bytes || Start of the file contents in the corresponding uncompressed block | ||
| + | |- | ||
| + | | 10 || 4 bytes || Size of the file contents in the corresponding uncompressed block | ||
| + | |- | ||
| + | | 14 || variable || Null-terminated file name | ||
| + | |} | ||
| + | |||
| + | The sequence of member file headers is terminated by a two-byte header with just a length field equal to zero. | ||
== Sample files == | == Sample files == | ||
| + | |||
* {{DiscMasterLink|search?detection=4c544543*&showItemName=showItemName|DiscMaster search}} | * {{DiscMasterLink|search?detection=4c544543*&showItemName=showItemName|DiscMaster search}} | ||
Latest revision as of 09:10, 3 November 2025
Lead Technologies archive (official name unknown) is a compressed installer-archive format used in some Lead Technologies software. The file is usually named "SETUP.LTA". Multi-part archives are common, with multiple "SETUP.LTA" files comprising a single archive. A byte in the archive header reflects the volume number.
Software using LTA usually includes an LTEXPAND.DLL file, which presumably contains decompression library code.
Contents |
[edit] Identification
File start with ASCII "LTEC".
[edit] Format details
The format consists of an archive header and a sequence of member file headers, terminated by two null bytes, then followed by one or more compressed data blocks. A form of solid archiving is used: individual files are not packed separately, but concatenated and then compressed as a whole. Each compressed block contains a different set of files in the archive. The compression method seems to match LHA's lhx as implemented by Lhasa.
Byte order is little-endian.
[edit] Archive header
| Field offset | Size | Description |
|---|---|---|
| 0 | 4 bytes | Signature 4c 54 45 43
|
| 4 | 1 byte | Volume number |
| 5 | 4 bytes | Start of the first compressed block |
The start of the first compressed block should equal the sum of the sizes of the archive header, all of the member file headers, and the two terminating null bytes.
[edit] Member file header
| Field offset | Size | Description |
|---|---|---|
| 0 | 2 bytes | Length of the header (including this field) |
| 2 | 4 bytes | Start of the compressed stream the file is included in, relative to the third field in the archive header (i.e., files in the first compressed block have this field set to zero) |
| 6 | 4 bytes | Start of the file contents in the corresponding uncompressed block |
| 10 | 4 bytes | Size of the file contents in the corresponding uncompressed block |
| 14 | variable | Null-terminated file name |
The sequence of member file headers is terminated by a two-byte header with just a length field equal to zero.
