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Atomic Operations

## Detailed Description

These functions are used for implementing the many different varieties of atomic operations.

The compiler is at liberty to inline atomic operations that are naturally supported by the target architecture. For instance on IA-32 architecture an atomic like this can be inlined

static int s = 0;
#pragma omp atomic
s++;

using the single instruction: `lock; incl s`

However the runtime does provide entrypoints for these operations to support compilers that choose not to inline them. (For instance, `__kmpc_atomic_fixed4_add` could be used to perform the increment above.)

The names of the functions are encoded by using the data type name and the operation name, as in these tables.

Data Type | Data type encoding
--- | ---
int8_t | `fixed1`
uint8_t | `fixed1u`
int16_t | `fixed2`
uint16_t | `fixed2u`
int32_t | `fixed4`
uint32_t | `fixed4u`
int32_t | `fixed8`
uint32_t | `fixed8u`
float | `float4`
double | `float8`
float 10 (8087 eighty bit float) | `float10`
complex<float> | `cmplx4`
complex<double> | `cmplx8`
complex<float10> | `cmplx10`

Operation | Operation encoding
--- | ---
+ | add
- | sub
* | mul
/ | div
& | andb
<< | shl
>> | shr
| | orb
xor
&& | andl
|| | orl
maximum | max
minimum | min
.eqv. | eqv
.neqv. | neqv

For non-commutative operations, `_rev` can also be added for the reversed operation. For the functions that capture the result, the suffix `_cpt` is added.

# Update Functions

The general form of an atomic function that just performs an update (without a `capture`)

void __kmpc_atomic_<datatype>_<operation>( ident_t *id_ref, int gtid, TYPE *
lhs, TYPE rhs );
ident
Definition kmp.h:246

Parameters

  ident_t | a pointer to source location
  gtid | the global thread id
  lhs | a pointer to the left operand
  rhs | the right operand

# <tt>capture</tt> functions

The capture functions perform an atomic update and return a result, which is either the value before the capture, or that after. They take an additional argument to determine which result is returned. Their general form is therefore

TYPE __kmpc_atomic_<datatype>_<operation>_cpt( ident_t *id_ref, int gtid, TYPE *
lhs, TYPE rhs, int flag );

Parameters

  ident_t | a pointer to source location
  gtid | the global thread id
  lhs | a pointer to the left operand
  rhs | the right operand
  flag | one if the result is to be captured after the operation, zero if captured before.

The one set of exceptions to this is the `complex<float>` type where the value is not returned, rather an extra argument pointer is passed.

They look like

void __kmpc_atomic_cmplx4_<op>_cpt( ident_t *id_ref, int gtid, kmp_cmplx32 *
lhs, kmp_cmplx32 rhs, kmp_cmplx32 * out, int flag );

# Read and Write Operations

The OpenMP* standard now supports atomic operations that simply ensure that the value is read or written atomically, with no modification performed. In many cases on IA-32 architecture these operations can be inlined since the architecture guarantees that no tearing occurs on aligned objects accessed with a single memory operation of up to 64 bits in size.

The general form of the read operations is

TYPE __kmpc_atomic_<type>_rd ( ident_t *id_ref, int gtid, TYPE * loc );

For the write operations the form is

void __kmpc_atomic_<type>_wr ( ident_t *id_ref, int gtid, TYPE * lhs, TYPE rhs
);

# Full list of functions

This leads to the generation of 376 atomic functions, as follows.

## Functions for integers

There are versions here for integers of size 1,2,4 and 8 bytes both signed and unsigned (where that matters).

__kmpc_atomic_fixed1_add
__kmpc_atomic_fixed1_add_cpt
__kmpc_atomic_fixed1_add_fp
__kmpc_atomic_fixed1_andb
__kmpc_atomic_fixed1_andb_cpt
__kmpc_atomic_fixed1_andl
__kmpc_atomic_fixed1_andl_cpt
__kmpc_atomic_fixed1_div
__kmpc_atomic_fixed1_div_cpt
__kmpc_atomic_fixed1_div_cpt_rev
__kmpc_atomic_fixed1_div_float8
__kmpc_atomic_fixed1_div_fp
__kmpc_atomic_fixed1_div_rev
__kmpc_atomic_fixed1_eqv
__kmpc_atomic_fixed1_eqv_cpt
__kmpc_atomic_fixed1_max
__kmpc_atomic_fixed1_max_cpt
__kmpc_atomic_fixed1_min
__kmpc_atomic_fixed1_min_cpt
__kmpc_atomic_fixed1_mul
__kmpc_atomic_fixed1_mul_cpt
__kmpc_atomic_fixed1_mul_float8
__kmpc_atomic_fixed1_mul_fp
__kmpc_atomic_fixed1_neqv
__kmpc_atomic_fixed1_neqv_cpt
__kmpc_atomic_fixed1_orb
__kmpc_atomic_fixed1_orb_cpt
__kmpc_atomic_fixed1_orl
__kmpc_atomic_fixed1_orl_cpt
__kmpc_atomic_fixed1_rd
__kmpc_atomic_fixed1_shl
__kmpc_atomic_fixed1_shl_cpt
__kmpc_atomic_fixed1_shl_cpt_rev
__kmpc_atomic_fixed1_shl_rev
__kmpc_atomic_fixed1_shr
__kmpc_atomic_fixed1_shr_cpt
__kmpc_atomic_fixed1_shr_cpt_rev
__kmpc_atomic_fixed1_shr_rev
__kmpc_atomic_fixed1_sub
__kmpc_atomic_fixed1_sub_cpt
__kmpc_atomic_fixed1_sub_cpt_rev
__kmpc_atomic_fixed1_sub_fp
__kmpc_atomic_fixed1_sub_rev
__kmpc_atomic_fixed1_swp
__kmpc_atomic_fixed1_wr
__kmpc_atomic_fixed1_xor
__kmpc_atomic_fixed1_xor_cpt
__kmpc_atomic_fixed1u_add_fp
__kmpc_atomic_fixed1u_sub_fp
__kmpc_atomic_fixed1u_mul_fp
__kmpc_atomic_fixed1u_div
__kmpc_atomic_fixed1u_div_cpt
__kmpc_atomic_fixed1u_div_cpt_rev
__kmpc_atomic_fixed1u_div_fp
__kmpc_atomic_fixed1u_div_rev
__kmpc_atomic_fixed1u_shr
__kmpc_atomic_fixed1u_shr_cpt
__kmpc_atomic_fixed1u_shr_cpt_rev
__kmpc_atomic_fixed1u_shr_rev
__kmpc_atomic_fixed2_add
__kmpc_atomic_fixed2_add_cpt
__kmpc_atomic_fixed2_add_fp
__kmpc_atomic_fixed2_andb
__kmpc_atomic_fixed2_andb_cpt
__kmpc_atomic_fixed2_andl
__kmpc_atomic_fixed2_andl_cpt
__kmpc_atomic_fixed2_div
__kmpc_atomic_fixed2_div_cpt
__kmpc_atomic_fixed2_div_cpt_rev
__kmpc_atomic_fixed2_div_float8
__kmpc_atomic_fixed2_div_fp
__kmpc_atomic_fixed2_div_rev
__kmpc_atomic_fixed2_eqv
__kmpc_atomic_fixed2_eqv_cpt
__kmpc_atomic_fixed2_max
__kmpc_atomic_fixed2_max_cpt
__kmpc_atomic_fixed2_min
__kmpc_atomic_fixed2_min_cpt
__kmpc_atomic_fixed2_mul
__kmpc_atomic_fixed2_mul_cpt
__kmpc_atomic_fixed2_mul_float8
__kmpc_atomic_fixed2_mul_fp
__kmpc_atomic_fixed2_neqv
__kmpc_atomic_fixed2_neqv_cpt
__kmpc_atomic_fixed2_orb
__kmpc_atomic_fixed2_orb_cpt
__kmpc_atomic_fixed2_orl
__kmpc_atomic_fixed2_orl_cpt
__kmpc_atomic_fixed2_rd
__kmpc_atomic_fixed2_shl
__kmpc_atomic_fixed2_shl_cpt
__kmpc_atomic_fixed2_shl_cpt_rev
__kmpc_atomic_fixed2_shl_rev
__kmpc_atomic_fixed2_shr
__kmpc_atomic_fixed2_shr_cpt
__kmpc_atomic_fixed2_shr_cpt_rev
__kmpc_atomic_fixed2_shr_rev
__kmpc_atomic_fixed2_sub
__kmpc_atomic_fixed2_sub_cpt
__kmpc_atomic_fixed2_sub_cpt_rev
__kmpc_atomic_fixed2_sub_fp
__kmpc_atomic_fixed2_sub_rev
__kmpc_atomic_fixed2_swp
__kmpc_atomic_fixed2_wr
__kmpc_atomic_fixed2_xor
__kmpc_atomic_fixed2_xor_cpt
__kmpc_atomic_fixed2u_add_fp
__kmpc_atomic_fixed2u_sub_fp
__kmpc_atomic_fixed2u_mul_fp
__kmpc_atomic_fixed2u_div
__kmpc_atomic_fixed2u_div_cpt
__kmpc_atomic_fixed2u_div_cpt_rev
__kmpc_atomic_fixed2u_div_fp
__kmpc_atomic_fixed2u_div_rev
__kmpc_atomic_fixed2u_shr
__kmpc_atomic_fixed2u_shr_cpt
__kmpc_atomic_fixed2u_shr_cpt_rev
__kmpc_atomic_fixed2u_shr_rev
__kmpc_atomic_fixed4_add
__kmpc_atomic_fixed4_add_cpt
__kmpc_atomic_fixed4_add_fp
__kmpc_atomic_fixed4_andb
__kmpc_atomic_fixed4_andb_cpt
__kmpc_atomic_fixed4_andl
__kmpc_atomic_fixed4_andl_cpt
__kmpc_atomic_fixed4_div
__kmpc_atomic_fixed4_div_cpt
__kmpc_atomic_fixed4_div_cpt_rev
__kmpc_atomic_fixed4_div_float8
__kmpc_atomic_fixed4_div_fp
__kmpc_atomic_fixed4_div_rev
__kmpc_atomic_fixed4_eqv
__kmpc_atomic_fixed4_eqv_cpt
__kmpc_atomic_fixed4_max
__kmpc_atomic_fixed4_max_cpt
__kmpc_atomic_fixed4_min
__kmpc_atomic_fixed4_min_cpt
__kmpc_atomic_fixed4_mul
__kmpc_atomic_fixed4_mul_cpt
__kmpc_atomic_fixed4_mul_float8
__kmpc_atomic_fixed4_mul_fp
__kmpc_atomic_fixed4_neqv
__kmpc_atomic_fixed4_neqv_cpt
__kmpc_atomic_fixed4_orb
__kmpc_atomic_fixed4_orb_cpt
__kmpc_atomic_fixed4_orl
__kmpc_atomic_fixed4_orl_cpt
__kmpc_atomic_fixed4_rd
__kmpc_atomic_fixed4_shl
__kmpc_atomic_fixed4_shl_cpt
__kmpc_atomic_fixed4_shl_cpt_rev
__kmpc_atomic_fixed4_shl_rev
__kmpc_atomic_fixed4_shr
__kmpc_atomic_fixed4_shr_cpt
__kmpc_atomic_fixed4_shr_cpt_rev
__kmpc_atomic_fixed4_shr_rev
__kmpc_atomic_fixed4_sub
__kmpc_atomic_fixed4_sub_cpt
__kmpc_atomic_fixed4_sub_cpt_rev
__kmpc_atomic_fixed4_sub_fp
__kmpc_atomic_fixed4_sub_rev
__kmpc_atomic_fixed4_swp
__kmpc_atomic_fixed4_wr
__kmpc_atomic_fixed4_xor
__kmpc_atomic_fixed4_xor_cpt
__kmpc_atomic_fixed4u_add_fp
__kmpc_atomic_fixed4u_sub_fp
__kmpc_atomic_fixed4u_mul_fp
__kmpc_atomic_fixed4u_div
__kmpc_atomic_fixed4u_div_cpt
__kmpc_atomic_fixed4u_div_cpt_rev
__kmpc_atomic_fixed4u_div_fp
__kmpc_atomic_fixed4u_div_rev
__kmpc_atomic_fixed4u_shr
__kmpc_atomic_fixed4u_shr_cpt
__kmpc_atomic_fixed4u_shr_cpt_rev
__kmpc_atomic_fixed4u_shr_rev
__kmpc_atomic_fixed8_add
__kmpc_atomic_fixed8_add_cpt
__kmpc_atomic_fixed8_add_fp
__kmpc_atomic_fixed8_andb
__kmpc_atomic_fixed8_andb_cpt
__kmpc_atomic_fixed8_andl
__kmpc_atomic_fixed8_andl_cpt
__kmpc_atomic_fixed8_div
__kmpc_atomic_fixed8_div_cpt
__kmpc_atomic_fixed8_div_cpt_rev
__kmpc_atomic_fixed8_div_float8
__kmpc_atomic_fixed8_div_fp
__kmpc_atomic_fixed8_div_rev
__kmpc_atomic_fixed8_eqv
__kmpc_atomic_fixed8_eqv_cpt
__kmpc_atomic_fixed8_max
__kmpc_atomic_fixed8_max_cpt
__kmpc_atomic_fixed8_min
__kmpc_atomic_fixed8_min_cpt
__kmpc_atomic_fixed8_mul
__kmpc_atomic_fixed8_mul_cpt
__kmpc_atomic_fixed8_mul_float8
__kmpc_atomic_fixed8_mul_fp
__kmpc_atomic_fixed8_neqv
__kmpc_atomic_fixed8_neqv_cpt
__kmpc_atomic_fixed8_orb
__kmpc_atomic_fixed8_orb_cpt
__kmpc_atomic_fixed8_orl
__kmpc_atomic_fixed8_orl_cpt
__kmpc_atomic_fixed8_rd
__kmpc_atomic_fixed8_shl
__kmpc_atomic_fixed8_shl_cpt
__kmpc_atomic_fixed8_shl_cpt_rev
__kmpc_atomic_fixed8_shl_rev
__kmpc_atomic_fixed8_shr
__kmpc_atomic_fixed8_shr_cpt
__kmpc_atomic_fixed8_shr_cpt_rev
__kmpc_atomic_fixed8_shr_rev
__kmpc_atomic_fixed8_sub
__kmpc_atomic_fixed8_sub_cpt
__kmpc_atomic_fixed8_sub_cpt_rev
__kmpc_atomic_fixed8_sub_fp
__kmpc_atomic_fixed8_sub_rev
__kmpc_atomic_fixed8_swp
__kmpc_atomic_fixed8_wr
__kmpc_atomic_fixed8_xor
__kmpc_atomic_fixed8_xor_cpt
__kmpc_atomic_fixed8u_add_fp
__kmpc_atomic_fixed8u_sub_fp
__kmpc_atomic_fixed8u_mul_fp
__kmpc_atomic_fixed8u_div
__kmpc_atomic_fixed8u_div_cpt
__kmpc_atomic_fixed8u_div_cpt_rev
__kmpc_atomic_fixed8u_div_fp
__kmpc_atomic_fixed8u_div_rev
__kmpc_atomic_fixed8u_shr
__kmpc_atomic_fixed8u_shr_cpt
__kmpc_atomic_fixed8u_shr_cpt_rev
__kmpc_atomic_fixed8u_shr_rev

## Functions for floating point

There are versions here for floating point numbers of size 4, 8, 10 and 16 bytes. (Ten byte floats are used by X87, but are now rare).

__kmpc_atomic_float4_add
__kmpc_atomic_float4_add_cpt
__kmpc_atomic_float4_add_float8
__kmpc_atomic_float4_add_fp
__kmpc_atomic_float4_div
__kmpc_atomic_float4_div_cpt
__kmpc_atomic_float4_div_cpt_rev
__kmpc_atomic_float4_div_float8
__kmpc_atomic_float4_div_fp
__kmpc_atomic_float4_div_rev
__kmpc_atomic_float4_max
__kmpc_atomic_float4_max_cpt
__kmpc_atomic_float4_min
__kmpc_atomic_float4_min_cpt
__kmpc_atomic_float4_mul
__kmpc_atomic_float4_mul_cpt
__kmpc_atomic_float4_mul_float8
__kmpc_atomic_float4_mul_fp
__kmpc_atomic_float4_rd
__kmpc_atomic_float4_sub
__kmpc_atomic_float4_sub_cpt
__kmpc_atomic_float4_sub_cpt_rev
__kmpc_atomic_float4_sub_float8
__kmpc_atomic_float4_sub_fp
__kmpc_atomic_float4_sub_rev
__kmpc_atomic_float4_swp
__kmpc_atomic_float4_wr
__kmpc_atomic_float8_add
__kmpc_atomic_float8_add_cpt
__kmpc_atomic_float8_add_fp
__kmpc_atomic_float8_div
__kmpc_atomic_float8_div_cpt
__kmpc_atomic_float8_div_cpt_rev
__kmpc_atomic_float8_div_fp
__kmpc_atomic_float8_div_rev
__kmpc_atomic_float8_max
__kmpc_atomic_float8_max_cpt
__kmpc_atomic_float8_min
__kmpc_atomic_float8_min_cpt
__kmpc_atomic_float8_mul
__kmpc_atomic_float8_mul_cpt
__kmpc_atomic_float8_mul_fp
__kmpc_atomic_float8_rd
__kmpc_atomic_float8_sub
__kmpc_atomic_float8_sub_cpt
__kmpc_atomic_float8_sub_cpt_rev
__kmpc_atomic_float8_sub_fp
__kmpc_atomic_float8_sub_rev
__kmpc_atomic_float8_swp
__kmpc_atomic_float8_wr
__kmpc_atomic_float10_add
__kmpc_atomic_float10_add_cpt
__kmpc_atomic_float10_add_fp
__kmpc_atomic_float10_div
__kmpc_atomic_float10_div_cpt
__kmpc_atomic_float10_div_cpt_rev
__kmpc_atomic_float10_div_fp
__kmpc_atomic_float10_div_rev
__kmpc_atomic_float10_mul
__kmpc_atomic_float10_mul_cpt
__kmpc_atomic_float10_mul_fp
__kmpc_atomic_float10_rd
__kmpc_atomic_float10_sub
__kmpc_atomic_float10_sub_cpt
__kmpc_atomic_float10_sub_cpt_rev
__kmpc_atomic_float10_sub_fp
__kmpc_atomic_float10_sub_rev
__kmpc_atomic_float10_swp
__kmpc_atomic_float10_wr
__kmpc_atomic_float16_add
__kmpc_atomic_float16_add_cpt
__kmpc_atomic_float16_div
__kmpc_atomic_float16_div_cpt
__kmpc_atomic_float16_div_cpt_rev
__kmpc_atomic_float16_div_rev
__kmpc_atomic_float16_max
__kmpc_atomic_float16_max_cpt
__kmpc_atomic_float16_min
__kmpc_atomic_float16_min_cpt
__kmpc_atomic_float16_mul
__kmpc_atomic_float16_mul_cpt
__kmpc_atomic_float16_rd
__kmpc_atomic_float16_sub
__kmpc_atomic_float16_sub_cpt
__kmpc_atomic_float16_sub_cpt_rev
__kmpc_atomic_float16_sub_rev
__kmpc_atomic_float16_swp
__kmpc_atomic_float16_wr

## Functions for Complex types

Functions for complex types whose component floating point variables are of size 4,8,10 or 16 bytes. The names here are based on the size of the component float, not* the size of the complex type. So `__kmpc_atomic_cmplx8_add` is an operation on a `complex<double>` or `complex(kind=8)`, not `complex<float>`.

__kmpc_atomic_cmplx4_add
__kmpc_atomic_cmplx4_add_cmplx8
__kmpc_atomic_cmplx4_add_cpt
__kmpc_atomic_cmplx4_div
__kmpc_atomic_cmplx4_div_cmplx8
__kmpc_atomic_cmplx4_div_cpt
__kmpc_atomic_cmplx4_div_cpt_rev
__kmpc_atomic_cmplx4_div_rev
__kmpc_atomic_cmplx4_mul
__kmpc_atomic_cmplx4_mul_cmplx8
__kmpc_atomic_cmplx4_mul_cpt
__kmpc_atomic_cmplx4_rd
__kmpc_atomic_cmplx4_sub
__kmpc_atomic_cmplx4_sub_cmplx8
__kmpc_atomic_cmplx4_sub_cpt
__kmpc_atomic_cmplx4_sub_cpt_rev
__kmpc_atomic_cmplx4_sub_rev
__kmpc_atomic_cmplx4_swp
__kmpc_atomic_cmplx4_wr
__kmpc_atomic_cmplx8_add
__kmpc_atomic_cmplx8_add_cpt
__kmpc_atomic_cmplx8_div
__kmpc_atomic_cmplx8_div_cpt
__kmpc_atomic_cmplx8_div_cpt_rev
__kmpc_atomic_cmplx8_div_rev
__kmpc_atomic_cmplx8_mul
__kmpc_atomic_cmplx8_mul_cpt
__kmpc_atomic_cmplx8_rd
__kmpc_atomic_cmplx8_sub
__kmpc_atomic_cmplx8_sub_cpt
__kmpc_atomic_cmplx8_sub_cpt_rev
__kmpc_atomic_cmplx8_sub_rev
__kmpc_atomic_cmplx8_swp
__kmpc_atomic_cmplx8_wr
__kmpc_atomic_cmplx10_add
__kmpc_atomic_cmplx10_add_cpt
__kmpc_atomic_cmplx10_div
__kmpc_atomic_cmplx10_div_cpt
__kmpc_atomic_cmplx10_div_cpt_rev
__kmpc_atomic_cmplx10_div_rev
__kmpc_atomic_cmplx10_mul
__kmpc_atomic_cmplx10_mul_cpt
__kmpc_atomic_cmplx10_rd
__kmpc_atomic_cmplx10_sub
__kmpc_atomic_cmplx10_sub_cpt
__kmpc_atomic_cmplx10_sub_cpt_rev
__kmpc_atomic_cmplx10_sub_rev
__kmpc_atomic_cmplx10_swp
__kmpc_atomic_cmplx10_wr
__kmpc_atomic_cmplx16_add
__kmpc_atomic_cmplx16_add_cpt
__kmpc_atomic_cmplx16_div
__kmpc_atomic_cmplx16_div_cpt
__kmpc_atomic_cmplx16_div_cpt_rev
__kmpc_atomic_cmplx16_div_rev
__kmpc_atomic_cmplx16_mul
__kmpc_atomic_cmplx16_mul_cpt
__kmpc_atomic_cmplx16_rd
__kmpc_atomic_cmplx16_sub
__kmpc_atomic_cmplx16_sub_cpt
__kmpc_atomic_cmplx16_sub_cpt_rev
__kmpc_atomic_cmplx16_swp
__kmpc_atomic_cmplx16_wr