c.md

C

OpenCL C is a C99 variant in which kernels must be written.

https://en.wikipedia.org/wiki/OpenCL#OpenCL_C_language

C99 extensions:

• new qualifiers
• new types, in particular short vector types and image types: https://www.khronos.org/registry/cl/sdk/2.1/docs/man/xhtml/dataTypes.html
• new built-in functions

C99 restrictions: https://www.khronos.org/registry/cl/sdk/2.1/docs/man/xhtml/restrictions.html

• pointers to functions are not allowed

Qualifiers

https://www.khronos.org/registry/cl/sdk/1.1/docs/man/xhtml/qualifiers.html

__global

__local

Shared across the work group.

__constant

__private

Default qualifier for arguments and local function variables: https://www.khronos.org/registry/cl/sdk/2.1/docs/man/xhtml/global.html

__kernel

Marks a function that can be called from the host.

Must return void, https://www.khronos.org/registry/cl/sdk/2.1/docs/man/xhtml/restrictions.html

https://www.khronos.org/registry/cl/sdk/2.1/docs/man/xhtml/restrictions.html:

Arguments to kernel functions declared in a program that are pointers must be declared with the __global, __constant, or __local qualifier.

Built-in functions

• https://www.khronos.org/registry/cl/sdk/2.1/docs/man/xhtml/integerFunctions.html
• https://www.khronos.org/registry/cl/sdk/2.1/docs/man/xhtml/workItemFunctions.html
• synchronization, e.g. work_group_barrier (ex barrier)

Those may in particular take vector type arguments.