User`s guide

Cray XMT™ Programming Environment User’s Guide
The Cray XMT compiler recognizes the following generic write functions.
writeef(&v, value)
Writes value in variable v when v is in an empty state and sets v to
a full state. This allows one or more threads waiting for v to change
to a full state to resume execution. If v is in a full state, the write
operation is blocked until v changes to an empty state. This generic
function behaves like a write access to a sync variable.
writeff(&v, value)
Writes value in variable v when v is in a full state and leaves v
in a full state. If v is in an empty state, the write is blocked until v
changes to a full state. This generic function behaves like a write
access to a future variable that occurs outside the body of a future
statement.
writexf(&v, value)
Writes value in variable v and sets v to a full state. This allows
one or more threads waiting for v to change to a full state to resume
execution. This generic function behaves like the write of a return
value that occurs at the end of the body of a future statement but is
not like a write access to a variable declared with the future qualifier.
int_fetch_add(&v, i)
Atomically adds integer i to the value at address v, stores the sum at
v, and returns the original value from v (setting v to a full state).
Regardless of its type, i is cast as an 8-byte integer. Neither
parameter can be a multiword object. If v is less than the size of a
word, the compiler generates a warning diagnostic. If v is an empty
sync or future variable, the operation is blocked until v changes to
a full state.
purge(&v)
Writes 0, using the appropriate data type, to variable v and sets v to
an empty state.
For more information, see the generics(1) man page.
3.2.1.2 Generic Read Functions
Generic read functions return the value for a variable, depending upon the full-empty
state of the variable. When you invoke these functions, the data type of the return
value is determined by the type of the first argument in the function call.
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