Vulkan-Docs/doc/specs/vulkan/man/vkGetPipelineCacheData.txt

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// Copyright (c) 2014-2016 Khronos Group. This work is licensed under a
// Creative Commons Attribution 4.0 International License; see
// http://creativecommons.org/licenses/by/4.0/
vkGetPipelineCacheData(3)
=========================
Name
----
vkGetPipelineCacheData - Get the data store from a pipeline cache
C Specification
---------------
// refBegin vkGetPipelineCacheData Get the data store from a pipeline cache
Data can: be retrieved from a pipeline cache object using the command:
include::../api/protos/vkGetPipelineCacheData.txt[]
Parameters
----------
* pname:device is the logical device that owns the pipeline cache.
* pname:pipelineCache is the pipeline cache to retrieve data from.
* pname:pDataSize is a pointer to a value related to the amount of data in
the pipeline cache, as described below.
* pname:pData is either `NULL` or a pointer to a buffer.
Description
-----------
If pname:pData is `NULL`, then the maximum size of the data that can: be
retrieved from the pipeline cache, in bytes, is returned in pname:pDataSize.
Otherwise, pname:pDataSize must: point to a variable set by the user to the
size of the buffer, in bytes, pointed to by pname:pData, and on return the
variable is overwritten with the amount of data actually written to
pname:pData.
If pname:pDataSize is less than the maximum size that can: be
retrieved by the pipeline cache, at most pname:pDataSize bytes will be
written to pname:pData, and fname:vkGetPipelineCacheData will return
ename:VK_INCOMPLETE. Any data written to pname:pData is valid and can: be
provided as the pname:pInitialData member of the
sname:VkPipelineCacheCreateInfo structure passed to
fname:vkCreatePipelineCache.
[[pipelines-cache-header]]
Applications can: store the data retrieved from the pipeline cache, and use
these data, possibly in a future run of the application, to populate new
pipeline cache objects. The results of pipeline compiles, however,
may: depend on the vendor ID, device ID, driver version, and other details
of the device. To enable applications to detect when previously retrieved
data is incompatible with the device, the initial bytes written to
pname:pData must: be a header consisting of the following members:
.Layout for pipeline cache header version VK_PIPELINE_CACHE_HEADER_VERSION_ONE
[width="85%",cols="8%,21%,71%",options="header"]
|=====
| Offset | Size | Meaning
| 0 | 4 | length in bytes of the entire pipeline cache header
written as a stream of bytes, with the least
significant byte first
| 4 | 4 | a elink:VkPipelineCacheHeaderVersion value
written as a stream of bytes, with the least
significant byte first
| 8 | 4 | a vendor ID equal to
sname:VkPhysicalDeviceProperties::pname:vendorID
written as a stream of bytes, with the least
significant byte first
| 12 | 4 | a device ID equal to
sname:VkPhysicalDeviceProperties::pname:deviceID
written as a stream of bytes, with the least
significant byte first
| 16 | ename:VK_UUID_SIZE | a pipeline cache ID equal to
sname:VkPhysicalDeviceProperties::pname:pipelineCacheUUID
|=====
The first four bytes encode the length of the entire pipeline header, in
bytes. This value includes all fields in the header including the pipeline
cache version field and the size of the length field.
// refBegin VkPipelineCacheHeaderVersion Encode pipeline cache version
The next four bytes encode the pipeline cache version. This field is
interpreted as a elink:VkPipelineCacheHeaderVersion value, and must:
have one of the following values:
include::../api/enums/VkPipelineCacheHeaderVersion.txt[]
A consumer of the pipeline cache should use the cache version to interpret
the remainder of the cache header.
// refEnd VkPipelineCacheHeaderVersion vkCreatePipelineCache vkGetPipelineCacheData
If pname:pDataSize is less than what is necessary to store this
header, nothing will be written to pname:pData and zero will be written to
pname:pDataSize.
include::../validity/protos/vkGetPipelineCacheData.txt[]
See Also
--------
slink:VkDevice, slink:VkPipelineCache
Document Notes
--------------
For more information, see the Vulkan Specification at URL
https://www.khronos.org/registry/vulkan/specs/1.0/xhtml/vkspec.html#vkGetPipelineCacheData
This page is extracted from the Vulkan Specification.
Fixes and changes should be made to the Specification,not directly.
include::footer.txt[]