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libhermit/arch/x86/include/asm/irqflags.h

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/*
* 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/irqflags.h
* @brief Functions related to IRQ configuration
*
* This file contains definitions of inline functions
* for enabling and disabling IRQ handling.
*/
#ifndef __ARCH_IRQFLAGS_H__
#define __ARCH_IRQFLAGS_H__
#ifdef __cplusplus
extern "C" {
#endif
/** @brief Determines, if the interrupt flags (IF) is set
*
* @return
* - 1 interrupt flag is set
* - 0 interrupt flag is cleared
*/
inline static uint8_t is_irq_enabled(void)
{
size_t flags;
asm volatile("pushf; pop %0": "=r"(flags) : : "memory");
if (flags & (1 << 9))
return 1;
return 0;
}
/** @brief Disable IRQs
*
* This inline function just clears out the interrupt bit
*/
inline static void irq_disable(void) {
asm volatile("cli" ::: "memory");
}
/** @brief Enable IRQs
*
* This inline function just sets the interrupt bit
*/
inline static void irq_enable(void) {
asm volatile("sti" ::: "memory");
}
/** @brief Disable IRQs (nested)
*
* Disable IRQs when unsure if IRQs were enabled at all.
* This function together with irq_nested_enable can be used
* in situations when interrupts shouldn't be activated if they
* were not activated before calling this function.
*
* @return Whether IRQs had been enabled or not before disabling
*/
inline static uint8_t irq_nested_disable(void) {
uint8_t was_enabled = is_irq_enabled();
irq_disable();
return was_enabled;
}
/** @brief Enable IRQs (nested)
*
* Can be used in conjunction with irq_nested_disable() to only enable
* interrupts again if they were enabled before.
*
* @param was_enabled Whether IRQs should be enabled or not
*/
inline static void irq_nested_enable(uint8_t was_enabled) {
if (was_enabled)
irq_enable();
}
#ifdef __cplusplus
}
#endif
#endif