d8fcc8a825
The flag main purpose is to avoid race conditions between event handler and cancel_timer(). However, cancel_timer() is safe even without using gSchedulerLock. If the event is scheduled to happen on other CPU than the CPU that invokes cancel_timer() then cancel_timer() either disables the event before its handler starts executing or waits until the event handler is done. If the event is scheduled on the same CPU that calls cancel_timer() then, since cancel_timer() disables interrupts, the event is either executed before cancel_timer() or when the timer interrupt handler starts running the event is already disabled.
52 lines
1.3 KiB
C
52 lines
1.3 KiB
C
/*
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** Copyright 2003-2004, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
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** Distributed under the terms of the OpenBeOS License.
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*/
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#ifndef _KERNEL_TIMER_H
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#define _KERNEL_TIMER_H
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#include <KernelExport.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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struct kernel_args;
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#define B_TIMER_REAL_TIME_BASE 0x2000
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// For an absolute timer the given time is interpreted as a real-time, not
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// as a system time. Note that setting the real-time clock will cause the
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// timer to be updated -- it will expire according to the new clock.
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// Relative timers are unaffected by this flag.
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#define B_TIMER_USE_TIMER_STRUCT_TIMES 0x4000
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// For add_timer(): Use the timer::schedule_time (absolute time) and
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// timer::period values instead of the period parameter.
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#define B_TIMER_FLAGS \
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(B_TIMER_USE_TIMER_STRUCT_TIMES | B_TIMER_REAL_TIME_BASE)
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/* Timer info structure */
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struct timer_info {
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const char *name;
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int (*get_priority)(void);
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status_t (*set_hardware_timer)(bigtime_t timeout);
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status_t (*clear_hardware_timer)(void);
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status_t (*init)(struct kernel_args *args);
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};
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typedef struct timer_info timer_info;
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/* kernel functions */
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status_t timer_init(struct kernel_args *);
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void timer_init_post_rtc(void);
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void timer_real_time_clock_changed();
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int32 timer_interrupt(void);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _KERNEL_TIMER_H */
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