MPSMatrix(3)

NAME
MPSMatrix

SYNOPSIS

#import <MPSMatrixTypes.h>

Inherits NSObject.

Inherited by MPSTemporaryMatrix.

  Instance Methods
(nonnull instancetype) - initWithBuffer:descriptor:
(nonnull instancetype) - initWithDevice:descriptor:
(nonnull instancetype) - init
(void) - synchronizeOnCommandBuffer:
(NSUInteger) - resourceSize

  Properties
id< MTLDevice > device
NSUInteger rows
NSUInteger columns
NSUInteger matrices
MPSDataType dataType
NSUInteger rowBytes
NSUInteger matrixBytes
id< MTLBuffer > data

Detailed Description

This depends on Metal.framework

A MPSMatrix object describes a set of 2-dimensional arrays of data and provides storage for its values. MPSMatrix objects serve as inputs and outputs of MPSMatrixKernel objects.

Implementation note: A MPSMatrix object maintains its internal storage using a MTLBuffer object and thus the same rules for maintaining coherency of a MTLBuffer's data between CPU memory and GPU memory apply to a MPSMatrix. An MPSMatrix object's data refers to an array of matrices. Data is assumed to be ordered by matrix first, followed by row, followed by column.

For example, index [i,j] of the k'th matrix of an MPSMatrix is located at byte offset: k * matrixBytes + i * rowBytes + j * sizeof(dataType)

Where matrixBytes is a multiple of rowBytes at least equal to rows * rowBytes.

Method Documentation

  - (nonnull instancetype) init

  - (nonnull instancetype) initWithBuffer: (nonnull id< MTLBuffer >) buffer(nonnull MPSMatrixDescriptor *) descriptor
Initialize a MPSMatrix object with a MTLBuffer.

Parameters:
    buffer The MTLBuffer object which contains the data to use for the MPSMatrix. May not be NULL.
    descriptor The MPSMatrixDescriptor. May not be NULL.

Returns:
    A valid MPSMatrix object or nil, if failure.

This function returns a MPSMatrix object which uses the supplied MTLBuffer. The dimensions and stride of the matrix are specified by the MPSMatrixDescriptor object.

The provided MTLBuffer must have enough storage to hold

(descriptor.matrices-1) * descriptor.matrixBytes +
(descriptor.rows-1) * descriptor.rowBytes +
 descriptor.columns * (element size) bytes.

Reimplemented in MPSTemporaryMatrix.

  - (nonnull instancetype) initWithDevice: (nonnull id< MTLDevice >) device(MPSMatrixDescriptor *__nonnull) descriptor
Initialize a MPSMatrix object with a descriptor. Allocate the buffer.

Parameters:
    device The device with which it will be used
    descriptor The shape and style of the matrix

Returns:
    A valid MPSMatrix object or nil The matrix object will be created, but the storage to hold the matrix data will only be allocated when it is needed, typically when the data property is invoked. In conjunction with -resourceSize, this will allow you to estimate storage needs without actually creating the backing store for the matrix.

  - (NSUInteger) resourceSize
Get the number of bytes used to allocate underyling MTLResources This is the size of the backing store of underlying MTLResources. It does not include all storage used by the object, for example the storage used to hold the MPSMatrix instantiation and MTLBuffer is not included. It only measures the size of the allocation used to hold the matrix data in the buffer. This value is subject to change between different devices and operating systems.

Except when -initWithBuffer:descriptor: is used, most MPSMatrixes are allocated without a backing store. The backing store is allocated lazily when it is needed, typically when the .texture property is called. Consequently, in most cases, it should be inexpensive to make a MPSImage to see how much memory it will need, and release it if it is too large.

This method may fail in certain circumstances, such as when the MPSImage is created with -initWithTexture:featureChannels:. In such cases, 0 will be returned.

  - (void) synchronizeOnCommandBuffer: (__nonnull id< MTLCommandBuffer >) commandBuffer
Flush the underlying MTLBuffer from the device's caches, and invalidate any CPU caches if needed. This will call [id <MTLBlitEncoder> synchronizeResource: ] on the matrix's MTLBuffer, if any. This is necessary for all MTLStorageModeManaged resources. For other resources, including temporary resources (these are all MTLStorageModePrivate), and buffers that have not yet been allocated, nothing is done. It is more efficient to use this method than to attempt to do this yourself with the data property.

Parameters:
    commandBuffer The commandbuffer on which to synchronize

Property Documentation

  - columns [read], [nonatomic], [assign]
The number of columns in a matrix in the MPSMatrix.

  - data [read], [nonatomic], [assign]
An MTLBuffer to store the data.

  - dataType [read], [nonatomic], [assign]
The type of the MPSMatrix data.

  - device [read], [nonatomic], [retain]
The device on which the MPSMatrix will be used.

  - matrices [read], [nonatomic], [assign]
The number of matrices in the MPSMatrix.

  - matrixBytes [read], [nonatomic], [assign]
The stride, in bytes, between corresponding elements of consecutive matrices.

  - rowBytes [read], [nonatomic], [assign]
The stride, in bytes, between corresponding elements of consecutive rows.

  - rows [read], [nonatomic], [assign]
The number of rows in a matrix in the MPSMatrix.

Author

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