181 lines
6.9 KiB
Ada
181 lines
6.9 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- S Y S T E M . A T O M I C _ P R I M I T I V E S --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 2012, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This package contains both atomic primitives defined from gcc built-in
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-- functions and operations used by the compiler to generate the lock-free
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-- implementation of protected objects.
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package System.Atomic_Primitives is
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pragma Preelaborate;
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type uint is mod 2 ** Long_Integer'Size;
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type uint8 is mod 2**8
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with Size => 8;
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type uint16 is mod 2**16
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with Size => 16;
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type uint32 is mod 2**32
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with Size => 32;
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type uint64 is mod 2**64
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with Size => 64;
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Relaxed : constant := 0;
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Consume : constant := 1;
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Acquire : constant := 2;
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Release : constant := 3;
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Acq_Rel : constant := 4;
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Seq_Cst : constant := 5;
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Last : constant := 6;
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subtype Mem_Model is Integer range Relaxed .. Last;
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------------------------------------
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-- GCC built-in atomic primitives --
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------------------------------------
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function Atomic_Load_8
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(Ptr : Address;
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Model : Mem_Model := Seq_Cst) return uint8;
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pragma Import (Intrinsic, Atomic_Load_8, "__atomic_load_1");
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function Atomic_Load_16
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(Ptr : Address;
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Model : Mem_Model := Seq_Cst) return uint16;
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pragma Import (Intrinsic, Atomic_Load_16, "__atomic_load_2");
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function Atomic_Load_32
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(Ptr : Address;
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Model : Mem_Model := Seq_Cst) return uint32;
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pragma Import (Intrinsic, Atomic_Load_32, "__atomic_load_4");
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function Atomic_Load_64
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(Ptr : Address;
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Model : Mem_Model := Seq_Cst) return uint64;
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pragma Import (Intrinsic, Atomic_Load_64, "__atomic_load_8");
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function Sync_Compare_And_Swap_8
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(Ptr : Address;
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Expected : uint8;
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Desired : uint8) return uint8;
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pragma Import (Intrinsic,
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Sync_Compare_And_Swap_8,
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"__sync_val_compare_and_swap_1");
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-- ??? Should use __atomic_compare_exchange_1 (doesn't work yet):
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-- function Sync_Compare_And_Swap_8
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-- (Ptr : Address;
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-- Expected : Address;
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-- Desired : uint8;
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-- Weak : Boolean := False;
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-- Success_Model : Mem_Model := Seq_Cst;
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-- Failure_Model : Mem_Model := Seq_Cst) return Boolean;
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-- pragma Import (Intrinsic,
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-- Sync_Compare_And_Swap_8,
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-- "__atomic_compare_exchange_1");
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function Sync_Compare_And_Swap_16
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(Ptr : Address;
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Expected : uint16;
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Desired : uint16) return uint16;
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pragma Import (Intrinsic,
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Sync_Compare_And_Swap_16,
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"__sync_val_compare_and_swap_2");
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function Sync_Compare_And_Swap_32
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(Ptr : Address;
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Expected : uint32;
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Desired : uint32) return uint32;
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pragma Import (Intrinsic,
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Sync_Compare_And_Swap_32,
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"__sync_val_compare_and_swap_4");
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function Sync_Compare_And_Swap_64
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(Ptr : Address;
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Expected : uint64;
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Desired : uint64) return uint64;
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pragma Import (Intrinsic,
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Sync_Compare_And_Swap_64,
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"__sync_val_compare_and_swap_8");
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--------------------------
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-- Lock-free operations --
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--------------------------
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-- The lock-free implementation uses two atomic instructions for the
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-- expansion of protected operations:
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-- * Lock_Free_Read_N atomically loads the value of the protected component
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-- accessed by the current protected operation.
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-- * Lock_Free_Try_Write_N tries to write the Desired value into Ptr only
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-- if Expected and Desired mismatch.
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function Lock_Free_Read_8 (Ptr : Address) return uint8;
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function Lock_Free_Read_16 (Ptr : Address) return uint16;
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function Lock_Free_Read_32 (Ptr : Address) return uint32;
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function Lock_Free_Read_64 (Ptr : Address) return uint64;
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function Lock_Free_Try_Write_8
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(Ptr : Address;
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Expected : in out uint8;
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Desired : uint8) return Boolean;
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function Lock_Free_Try_Write_16
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(Ptr : Address;
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Expected : in out uint16;
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Desired : uint16) return Boolean;
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function Lock_Free_Try_Write_32
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(Ptr : Address;
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Expected : in out uint32;
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Desired : uint32) return Boolean;
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function Lock_Free_Try_Write_64
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(Ptr : Address;
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Expected : in out uint64;
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Desired : uint64) return Boolean;
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pragma Inline (Lock_Free_Read_8);
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pragma Inline (Lock_Free_Read_16);
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pragma Inline (Lock_Free_Read_32);
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pragma Inline (Lock_Free_Read_64);
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pragma Inline (Lock_Free_Try_Write_8);
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pragma Inline (Lock_Free_Try_Write_16);
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pragma Inline (Lock_Free_Try_Write_32);
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pragma Inline (Lock_Free_Try_Write_64);
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end System.Atomic_Primitives;
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