Synopsis
Allocate a 2D data buffer.
Format
MIL_ID MbufAlloc2d(SystemId, SizeX, SizeY, DataType, Attribute, BufIdPtr)
| MIL_ID SystemId | System identifier |
| long SizeX; | X dimension |
| long SizeY; | Y dimension |
| long DataType; | Pixel depth and range |
| long Attribute; | Buffer attributes |
| MIL_ID *BufIdPtr; | Storage location for buffer identifier |
Description
This function allocates a two-dimensional data buffer on the specified system.
After allocating a buffer, we recommend that you check if the operation was successful, using MappGetError or by verifying that the buffer identifier returned is not M_NULL. When a buffer is no longer required, release it, using MbufFree.
The SystemId parameter specifies the system on which the buffer will be allocated. This parameter must be set to a valid system identifier, M_DEFAULT_HOST or M_DEFAULT. To use the default Host system of the current MIL application, specify M_DEFAULT_HOST. If you specify M_DEFAULT, MIL will select the most appropriate system on which to allocate the buffer (it can be the Host system or any already allocated system).
The SizeX and SizeY parameters specify the buffer width and height, respectively, in the units appropriate for the selected buffer attribute. For example, if the buffer has an image buffer attribute, specify the width and height in pixels.
The DataType parameter specifies a combination of two values: the depth and range of the data. Express the depth in bits and give the data range as one of the following:
| Data Type | Description | Depth (in bits) |
| M_SIGNED | Signed data | 8, 16, or 32 |
| M_UNSIGNED | Unsigned data (default) | 1, 8, 16, or 32 |
| M_FLOAT | Floating point data | 32 |
For example, when allocating a 8-bit unsigned buffer, you would set the DataType parameter to (8 + M_UNSIGNED).
The Attribute parameter defines the buffer usage. The system uses this information to determine where to allocate the buffer in physical memory. This parameter should be set to one of the following:
| M_IMAGE | Image buffer. |
| M_LUT | Look up table. |
| M_KERNEL | Convolution kernel for convolution functions. |
| M_STRUCT_ELEMENT | Structuring element for morphology functions. |
When selecting an M_IMAGE attribute, it should be shown as M_IMAGE + specifier. The specifier can be one or more of the following:
Usage specifiers:
| M_DISP | An image buffer that can be displayed. |
| M_GRAB | An image buffer in which to grab data. |
| M_PROC | An image buffer that can be processed. |
For example, to allocate an image buffer that can be processed and displayed, you should set the Attribute parameter to M_IMAGE + M_PROC + M_DISP.
Board-dependent location specifiers:
| M_ON_BOARD | Force the buffer in the system memory. |
| M_OFF_BOARD | Force the buffer in the Host memory. |
| M_OVR | Force the buffer in the overlay display surface. |
| M_NON_PAGED | Force the buffer in non-pageable memory. |
| M_SINGLE | Force a unique copy of the buffer. |
Board-dependent internal storage format specifiers:
| M_DDRAW | Force the buffer to be a DDraw surface. |
| M_DIB | Force the buffer to be a DIB buffer. |
| M_FLIP | Force the buffer to be top down (DIB). |
The BufIdPtr parameter specifies the address of the variable in which the buffer identifier is to be written. Since the MbufAlloc2d function also returns the buffer identifier, you can set this parameter to M_NULL. If allocation fails, M_NULL is written as the identifier.
Returned value
The returned value is the buffer identifier. If allocation fails, M_NULL is returned.
Status
Current limitation:
- For M_KERNEL and M_LUT data buffers, the data type must be 8, 16, or 32-bit integer or floating point.
- For M_STRUCT_ELEMENT data buffers, the data type must be 32-bit integer or floating point.
See also