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## pp_data_dump.exe for Windows
pp_data_dump.exe is a small command line tool for Windows, which dumps the content of the [Preparsed Data](https://learn.microsoft.com/en-us/windows-hardware/drivers/hid/preparsed-data) structure, provided by the Windows HID subsystem, into a file.
The generated file is in a text format, which is readable for human, as by the hid_report_reconstructor_test.exe unit test executable of the HIDAPI project. This unit test allows it to test the HIDAPIs report descriptor reconstructor - offline, without the hardware device connected.
pp_data_dump.exe has no arguments, just connect you HID device and execute pp_data_dump.exe. It will generate one file with the name
```
<vendor_id>_<product_id>_<usage>_<usage_table>.pp_data
```
for each top-level collection, of each connected HID device.
## File content
The content of such a .pp_data file looks like the struct, which HIDAPI uses internally to represent the Preparsed Data.
*NOTE:
Windows parses HID report descriptors into opaque `_HIDP_PREPARSED_DATA` objects.
The internal structure of `_HIDP_PREPARSED_DATA` is reserved for internal system use.\
Microsoft doesn't document this structure. [hid_preparsed_data.cc](https://chromium.googlesource.com/chromium/src/+/73fdaaf605bb60caf34d5f30bb84a417688aa528/services/device/hid/hid_preparsed_data.cc) is taken as a reference for its parsing.*
```
# HIDAPI device info struct:
dev->vendor_id = 0x046D
dev->product_id = 0xB010
dev->manufacturer_string = "Logitech"
dev->product_string = "Logitech Bluetooth Wireless Mouse"
dev->release_number = 0x0000
dev->interface_number = -1
dev->usage = 0x0001
dev->usage_page = 0x000C
dev->path = "\\?\hid#{00001124-0000-1000-8000-00805f9b34fb}_vid&0002046d_pid&b010&col02#8&1cf1c1b9&3&0001#{4d1e55b2-f16f-11cf-88cb-001111000030}"
# Preparsed Data struct:
pp_data->MagicKey = 0x48696450204B4452
pp_data->Usage = 0x0001
pp_data->UsagePage = 0x000C
pp_data->Reserved = 0x00000000
# Input caps_info struct:
pp_data->caps_info[0]->FirstCap = 0
pp_data->caps_info[0]->LastCap = 1
pp_data->caps_info[0]->NumberOfCaps = 1
pp_data->caps_info[0]->ReportByteLength = 2
# Output caps_info struct:
pp_data->caps_info[1]->FirstCap = 1
pp_data->caps_info[1]->LastCap = 1
pp_data->caps_info[1]->NumberOfCaps = 0
pp_data->caps_info[1]->ReportByteLength = 0
# Feature caps_info struct:
pp_data->caps_info[2]->FirstCap = 1
pp_data->caps_info[2]->LastCap = 1
pp_data->caps_info[2]->NumberOfCaps = 0
pp_data->caps_info[2]->ReportByteLength = 0
# LinkCollectionArray Offset & Size:
pp_data->FirstByteOfLinkCollectionArray = 0x0068
pp_data->NumberLinkCollectionNodes = 1
# Input hid_pp_cap struct:
pp_data->cap[0]->UsagePage = 0x0006
pp_data->cap[0]->ReportID = 0x03
pp_data->cap[0]->BitPosition = 0
pp_data->cap[0]->BitSize = 8
pp_data->cap[0]->ReportCount = 1
pp_data->cap[0]->BytePosition = 0x0001
pp_data->cap[0]->BitCount = 8
pp_data->cap[0]->BitField = 0x02
pp_data->cap[0]->NextBytePosition = 0x0002
pp_data->cap[0]->LinkCollection = 0x0000
pp_data->cap[0]->LinkUsagePage = 0x000C
pp_data->cap[0]->LinkUsage = 0x0001
pp_data->cap[0]->IsMultipleItemsForArray = 0
pp_data->cap[0]->IsButtonCap = 0
pp_data->cap[0]->IsPadding = 0
pp_data->cap[0]->IsAbsolute = 1
pp_data->cap[0]->IsRange = 0
pp_data->cap[0]->IsAlias = 0
pp_data->cap[0]->IsStringRange = 0
pp_data->cap[0]->IsDesignatorRange = 0
pp_data->cap[0]->Reserved1 = 0x000000
pp_data->cap[0]->pp_cap->UnknownTokens[0].Token = 0x00
pp_data->cap[0]->pp_cap->UnknownTokens[0].Reserved = 0x000000
pp_data->cap[0]->pp_cap->UnknownTokens[0].BitField = 0x00000000
pp_data->cap[0]->pp_cap->UnknownTokens[1].Token = 0x00
pp_data->cap[0]->pp_cap->UnknownTokens[1].Reserved = 0x000000
pp_data->cap[0]->pp_cap->UnknownTokens[1].BitField = 0x00000000
pp_data->cap[0]->pp_cap->UnknownTokens[2].Token = 0x00
pp_data->cap[0]->pp_cap->UnknownTokens[2].Reserved = 0x000000
pp_data->cap[0]->pp_cap->UnknownTokens[2].BitField = 0x00000000
pp_data->cap[0]->pp_cap->UnknownTokens[3].Token = 0x00
pp_data->cap[0]->pp_cap->UnknownTokens[3].Reserved = 0x000000
pp_data->cap[0]->pp_cap->UnknownTokens[3].BitField = 0x00000000
pp_data->cap[0]->NotRange.Usage = 0x0020
pp_data->cap[0]->NotRange.Reserved1 = 0x0020
pp_data->cap[0]->NotRange.StringIndex = 0
pp_data->cap[0]->NotRange.Reserved2 = 0
pp_data->cap[0]->NotRange.DesignatorIndex = 0
pp_data->cap[0]->NotRange.Reserved3 = 0
pp_data->cap[0]->NotRange.DataIndex = 0
pp_data->cap[0]->NotRange.Reserved4 = 0
pp_data->cap[0]->NotButton.HasNull = 0
pp_data->cap[0]->NotButton.Reserved4 = 0x000000
pp_data->cap[0]->NotButton.LogicalMin = 0
pp_data->cap[0]->NotButton.LogicalMax = 100
pp_data->cap[0]->NotButton.PhysicalMin = 0
pp_data->cap[0]->NotButton.PhysicalMax = 0
pp_data->cap[0]->Units = 0
pp_data->cap[0]->UnitsExp = 0
# Output hid_pp_cap struct:
# Feature hid_pp_cap struct:
# Link Collections:
pp_data->LinkCollectionArray[0]->LinkUsage = 0x0001
pp_data->LinkCollectionArray[0]->LinkUsagePage = 0x000C
pp_data->LinkCollectionArray[0]->Parent = 0
pp_data->LinkCollectionArray[0]->NumberOfChildren = 0
pp_data->LinkCollectionArray[0]->NextSibling = 0
pp_data->LinkCollectionArray[0]->FirstChild = 0
pp_data->LinkCollectionArray[0]->CollectionType = 1
pp_data->LinkCollectionArray[0]->IsAlias = 0
pp_data->LinkCollectionArray[0]->Reserved = 0x00000000
```
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