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# PetscMemoryAccessMode
Describes the intended usage of a memory region 
## Synopsis
```
#include <petscdevicetypes.h> 
typedef enum {
  PETSC_MEMORY_ACCESS_READ       = 0x1, // 01
  PETSC_MEMORY_ACCESS_WRITE      = 0x2, // 10
  PETSC_MEMORY_ACCESS_READ_WRITE = 0x3, // 11
} PetscMemoryAccessMode;
```

## Values

- ***`PETSC_MEMORY_ACCESS_READ`       -*** Read only
- ***`PETSC_MEMORY_ACCESS_WRITE`      -*** Write only
- ***`PETSC_MEMORY_ACCESS_READ_WRITE` -*** Read and write





## Notes
This `enum` is a bitmask with the following encoding (assuming 2 bit):

```none
  PETSC_MEMORY_ACCESS_READ       = 0b01
  PETSC_MEMORY_ACCESS_WRITE      = 0b10
  PETSC_MEMORY_ACCESS_READ_WRITE = 0b11

  // consequently
  PETSC_MEMORY_ACCESS_READ | PETSC_MEMORY_ACCESS_WRITE = PETSC_MEMORY_ACCESS_READ_WRITE
```


The following convenience macros are also provided:


- ***`PetscMemoryAccessRead(mode)` -*** `true` if `mode` is any kind of read, `false` otherwise
- ***`PetscMemoryAccessWrite(mode)` -*** `true` if `mode` is any kind of write, `false` otherwise



## Developer Notes
This enum uses a function (`PetscMemoryAccessModeToString()`) to convert values to string
representation, so cannot be used in `PetscOptionsEnum()`.


## See Also
 `PetscMemoryAccessModeToString()`, `PetscDevice`, `PetscDeviceContext`

## Level
beginner

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/include/petscdevicetypes.h.html#PetscMemoryAccessMode">include/petscdevicetypes.h</A>


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