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.Dd April 11, 2013
.Dt ck_pr_cas 3
.Sh NAME
.Nm ck_pr_cas
.Nd atomic compare-and-swap operation
.Sh LIBRARY
Concurrency Kit (libck, \-lck)
.Sh SYNOPSIS
.In ck_pr.h
.Ft bool
.Fn ck_pr_cas_ptr "void *target" "void *old_value" "void *new_value"
.Ft bool
.Fn ck_pr_cas_ptr_value "void *target" "void *old_value" "void *new_value" "void *original_value"
.Ft bool
.Fn ck_pr_cas_ptr_2 "void *target" "void *old_value" "void *new_value"
.Ft bool
.Fn ck_pr_cas_ptr_2_value "void *target" "void *old_value" "void *new_value" "void *original_value"
.Ft bool
.Fn ck_pr_cas_double "double *target" "double old_value" "double new_value"
.Ft bool
.Fn ck_pr_cas_double_value "double *target" "double old_value" "double new_value" "double *original_value"
.Ft bool
.Fn ck_pr_cas_char "char *target" "char old_value" "char new_value"
.Ft bool
.Fn ck_pr_cas_char_value "char *target" "char old_value" "char new_value" "char *original_value"
.Ft bool
.Fn ck_pr_cas_uint "unsigned int *target" "unsigned int old_value" "unsigned int new_value"
.Ft bool
.Fn ck_pr_cas_uint_value "unsigned int *target" "unsigned int old_value" "unsigned int new_value" "unsigned int *original_value"
.Ft bool
.Fn ck_pr_cas_int "int *target" "int old_value" "int new_value"
.Ft bool
.Fn ck_pr_cas_int_value "int *target" "int old_value" "int new_value" "int *original_value"
.Ft bool
.Fn ck_pr_cas_64_2 "uint64_t target[static 2]" "uint64_t old_value[static 2]" "uint64_t new_value[static 2]"
.Ft bool
.Fn ck_pr_cas_64_2_value "uint64_t target[static 2]" "uint64_t old_value[static 2]" "uint64_t new_value[static 2]" "uint64_t original_value[static 2]"
.Ft bool
.Fn ck_pr_cas_64 "uint64_t *target" "uint64_t old_value" "uint64_t new_value"
.Ft bool
.Fn ck_pr_cas_64_value "uint64_t *target" "uint64_t old_value" "uint64_t new_value" "uint64_t *original_value"
.Ft bool
.Fn ck_pr_cas_64_2 "uint64_t target[static 2]" "uint64_t old_value[static 2]" "uint64_t new_value[static 2]"
.Ft bool
.Fn ck_pr_cas_64_2_value "uint64_t target[static 2]" "uint64_t old_value[static 2]" "uint64_t new_value[static 2]" "uint64_t original_value[static 2]"
.Ft bool
.Fn ck_pr_cas_32 "uint32_t *target" "uint32_t old_value" "uint32_t new_value"
.Ft bool
.Fn ck_pr_cas_32_value "uint32_t *target" "uint32_t old_value" "uint32_t new_value" "uint32_t *original_value"
.Ft bool
.Fn ck_pr_cas_16 "uint16_t *target" "uint16_t old_value" "uint16_t new_value"
.Ft bool
.Fn ck_pr_cas_16_value "uint16_t *target" "uint16_t old_value" "uint16_t new_value" "uint16_t *original_value"
.Ft bool
.Fn ck_pr_cas_8 "uint8_t *target" "uint8_t old_value" "uint8_t new_value"
.Ft bool
.Fn ck_pr_cas_8_value "uint8_t *target" "uint8_t old_value" "uint8_t new_value" "uint8_t *original_value"
.Sh DESCRIPTION
The 
.Fn ck_pr_cas 3
family of functions atomically compare the value in 
.Fa target
for equality with
.Fa old_value
and if so, replace the value pointed to by
.Fa target
with the value specified by
.Fa original_value .
If the value in
.Fa target
was not equal to the value specified by
.Fa old_value
then no modifications occur to the value in
.Fa target .
The *_value form of these functions unconditionally update
.Fa original_value .
.Sh RETURN VALUES
This family of functions return true if the value in
.Fa target
was modified as a result of the operation. Otherwise, they
return false.
.Sh SEE ALSO
.Xr ck_pr_fence_load 3 ,
.Xr ck_pr_fence_load_depends 3 ,
.Xr ck_pr_fence_store 3 ,
.Xr ck_pr_fence_memory 3 ,
.Xr ck_pr_load 3 ,
.Xr ck_pr_store 3 ,
.Xr ck_pr_fas 3 ,
.Xr ck_pr_faa 3 ,
.Xr ck_pr_inc 3 ,
.Xr ck_pr_dec 3 ,
.Xr ck_pr_neg 3 , 
.Xr ck_pr_not 3 ,
.Xr ck_pr_sub 3 ,
.Xr ck_pr_and 3 ,
.Xr ck_pr_or 3 ,
.Xr ck_pr_xor 3 ,
.Xr ck_pr_add 3 ,
.Xr ck_pr_btc 3 ,
.Xr ck_pr_bts 3 ,
.Xr ck_pr_btr 3
.Pp
Additional information available at http://concurrencykit.org/