Add basic atomic operations which will be used in locking-mechanisms.

arch/x86/include/asm/atomic.h

@@ -0,0 +1,167 @@
+/*
+ * Copyright (c) 2010, Stefan Lankes, RWTH Aachen University
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *    * Redistributions of source code must retain the above copyright
+ *      notice, this list of conditions and the following disclaimer.
+ *    * Redistributions in binary form must reproduce the above copyright
+ *      notice, this list of conditions and the following disclaimer in the
+ *      documentation and/or other materials provided with the distribution.
+ *    * Neither the name of the University nor the names of its contributors
+ *      may be used to endorse or promote products derived from this
+ *      software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * @author Stefan Lankes
+ * @file arch/x86/include/asm/atomic.h
+ * @brief Functions for atomic operations
+ *
+ * This file defines functions for atomic operations on int32 variables
+ * which will be used in locking-mechanisms.
+ */
+
+#ifndef __ARCH_ATOMIC_H__
+#define __ARCH_ATOMIC_H__
+
+#include <eduos/stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#if MAX_CORES > 1
+#define LOCK "lock ; "
+#else
+#define LOCK ""
+#endif
+
+/** @brief Makro for initialization of atomic_int32_t vars
+ *
+ * Whenever you use an atomic_int32_t variable, init it with 
+ * this macro first.\n
+ * Example: atomic_int32_t myAtomicVar = ATOMIC_INIT(123);
+ *
+ * @param i The number value you want to init it with.
+ */
+#define ATOMIC_INIT(i)  { (i) }
+
+/** @brief Standard-datatype for atomic operations
+ *
+ * It just consists of an int32_t variable internally, marked as volatile.
+ */
+typedef struct { volatile int32_t counter; } atomic_int32_t;
+
+/** @brief Atomic test and set operation for int32 vars.
+ *
+ * This function will atomically exchange the value of an atomic variable and
+ * return its old value. Is used in locking-operations.\n
+ * \n
+ * Intel manuals: If a memory operand is referenced, the processor's locking 
+ * protocol is automatically implemented for the duration of the exchange 
+ * operation, regardless of the presence or absence of the LOCK prefix.
+ *
+ * @param d Pointer to the atomic_int_32_t with the value you want to exchange
+ * @param ret the value you want the var test for
+ *
+ * @return The old value of the atomic_int_32_t var before exchange
+ */
+inline static int32_t atomic_int32_test_and_set(atomic_int32_t* d, int32_t ret)
+{
+	asm volatile ("xchgl %0, %1" : "=r"(ret) : "m"(d->counter), "0"(ret) : "memory");
+	return ret;
+}
+
+/** @brief Atomic addition of values to atomic_int32_t vars
+ *
+ * This function lets you add values in an atomic operation
+ *
+ * @param d Pointer to the atomit_int32_t var you want do add a value to
+ * @param i The value you want to increment by
+ *
+ * @return The mathematical result
+ */
+inline static int32_t atomic_int32_add(atomic_int32_t *d, int32_t i)
+{
+	int32_t res = i;
+	asm volatile(LOCK "xaddl %0, %1" : "=r"(i) : "m"(d->counter), "0"(i) : "memory", "cc");
+	return res+i;
+}
+
+/** @brief Atomic subtraction of values from atomic_int32_t vars
+ *
+ * This function lets you subtract values in an atomic operation.\n
+ * This function is just for convenience. It uses atomic_int32_add(d, -i)
+ *
+ * @param d Pointer to the atomic_int32_t var you want to subtract from
+ * @param i The value you want to subtract by
+ *
+ * @return The mathematical result
+ */
+inline static int32_t atomic_int32_sub(atomic_int32_t *d, int32_t i)
+{
+        return atomic_int32_add(d, -i);
+}
+
+/** @brief Atomic increment by one
+ *
+ * The atomic_int32_t var will be atomically incremented by one.\n
+ *
+ * @param d The atomic_int32_t var you want to increment
+ */
+inline static void atomic_int32_inc(atomic_int32_t* d) {
+	asm volatile(LOCK "incl %0" : "+m" (d->counter));
+}
+
+/** @brief Atomic decrement by one
+ *
+ * The atomic_int32_t var will be atomically decremented by one.\n
+ *
+ * @param d The atomic_int32_t var you want to decrement
+ */
+inline static void atomic_int32_dec(atomic_int32_t* d) {
+	asm volatile(LOCK "decl %0" : "+m" (d->counter));
+}
+
+/** @brief Read out an atomic_int32_t var
+ *
+ * This function is for convenience: It looks into the atomic_int32_t struct
+ * and returns the internal value for you.
+ *
+ * @param d Pointer to the atomic_int32_t var you want to read out
+ * @return It's number value
+ */
+inline static int32_t atomic_int32_read(atomic_int32_t *d) {
+	return d->counter;
+}
+
+/** @brief Set the value of an atomic_int32_t var
+ *
+ * This function is for convenience: It sets the internal value of 
+ * an atomic_int32_t var for you.
+ *
+ * @param d Pointer to the atomic_int32_t var you want to set
+ * @param v The value to set
+ */
+inline static void atomic_int32_set(atomic_int32_t *d, int32_t v) {
+	atomic_int32_test_and_set(d, v);
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif