190 lines
6.8 KiB
C
Executable file
190 lines
6.8 KiB
C
Executable file
/** @file */
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// xos_semaphore.h - XOS Semaphore API interface and data structures.
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// Copyright (c) 2003-2015 Cadence Design Systems, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining
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// a copy of this software and associated documentation files (the
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// "Software"), to deal in the Software without restriction, including
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// without limitation the rights to use, copy, modify, merge, publish,
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// distribute, sublicense, and/or sell copies of the Software, and to
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// permit persons to whom the Software is furnished to do so, subject to
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// the following conditions:
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//
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// The above copyright notice and this permission notice shall be included
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// in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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// NOTE: Do not include this file directly in your application. Including
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// xos.h will automatically include this file.
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#ifndef __XOS_SEMAPHORE_H__
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#define __XOS_SEMAPHORE_H__
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#include "xos_types.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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//-----------------------------------------------------------------------------
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// Semaphore flags.
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//-----------------------------------------------------------------------------
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#define XOS_SEM_WAIT_PRIORITY 0x0000 ///< Wake waiters in priority order (default)
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#define XOS_SEM_WAIT_FIFO 0x0001 ///< Wake waiters in FIFO order
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#define XOS_SEM_PRIORITY_INV 0x0004 // Protect against priority inversion
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//-----------------------------------------------------------------------------
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///
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/// XosSem object.
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///
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//-----------------------------------------------------------------------------
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typedef struct XosSem {
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uint32_t count; ///< Current count
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XosThreadQueue waitq; ///< Queue of waiters.
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uint32_t flags; ///< Properties.
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#if XOS_SEM_DEBUG
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uint32_t sig; // Valid signature indicates inited.
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#endif
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} XosSem;
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//-----------------------------------------------------------------------------
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///
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/// Initialize a semaphore object before first use.
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///
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/// \param sem Pointer to semaphore object.
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///
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/// \param flags Creation flags:
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/// - XOS_SEM_WAIT_FIFO -- queue waiting threads in
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/// fifo order.
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/// - XOS_SEM_WAIT_PRIORITY -- queue waiting threads
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/// by priority. This is the default.
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/// - XOS_SEM_PRIORITY_INV -- protect against priority
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/// inversion.
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///
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/// \param initial_count Initial count for semaphore on creation.
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///
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/// \return Returns XOS_OK on success, else error code.
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///
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/// NOTE: XOS_SEM_PRIORITY_INV is NOT supported in the current release. It will
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/// be supported in a future release.
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///
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//-----------------------------------------------------------------------------
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int32_t
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xos_sem_create(XosSem * sem, uint32_t flags, uint32_t initial_count);
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//-----------------------------------------------------------------------------
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///
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/// Destroy a semaphore object. Must have been previously created by calling
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/// xos_sem_create().
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///
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/// \param sem Pointer to semaphore object.
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///
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/// \return Returns XOS_OK on success, else error code.
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///
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//-----------------------------------------------------------------------------
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int32_t
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xos_sem_delete(XosSem * sem);
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//-----------------------------------------------------------------------------
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///
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/// Decrement the semaphore count: block until the decrement is possible.
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/// The semaphore must have been initialized.
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///
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/// \param sem Pointer to semaphore object.
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///
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/// \return Returns XOS_OK on success, else error code.
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///
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//-----------------------------------------------------------------------------
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int32_t
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xos_sem_get(XosSem * sem);
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//-----------------------------------------------------------------------------
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///
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/// Decrement the semaphore count: block until the decrement is possible or
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/// the timeout expires. The semaphore must have been initialized.
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///
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/// \param sem Pointer to semaphore object.
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///
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/// \param to_cycles Timeout in cycles. Convert from time to cycles
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/// using the helper functions provided in xos_timer.
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/// A value of zero indicates no timeout.
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///
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/// \return Returns XOS_OK on success, XOS_ERR_TIMEOUT on timeout, else error code.
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///
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/// NOTE: If XOS_OPT_WAIT_TIMEOUT is not enabled, then the timeout value is
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/// ignored, and no timeout will occur.
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///
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//-----------------------------------------------------------------------------
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int32_t
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xos_sem_get_timeout(XosSem * sem, uint64_t to_cycles);
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//-----------------------------------------------------------------------------
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///
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/// Increment the semaphore count. The semaphore must have been initialized.
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/// Remember that this action may wake up a waiting thread, and if that thread
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/// is higher priority then there will be an immediate context switch.
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///
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/// \param sem Pointer to semaphore object.
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///
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/// \return Returns XOS_OK on success, else error code.
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///
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//-----------------------------------------------------------------------------
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int32_t
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xos_sem_put(XosSem * sem);
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//-----------------------------------------------------------------------------
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///
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/// Try to decrement the semaphore, but do not block if the semaphore count is
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/// zero. Return immediately. The semaphore must have been initialized.
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///
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/// \param sem Pointer to semaphore object.
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///
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/// \return Returns XOS_OK on success (semaphore decremented), else error code.
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///
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//-----------------------------------------------------------------------------
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int32_t
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xos_sem_tryget(XosSem * sem);
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//-----------------------------------------------------------------------------
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///
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/// Return the count of the semaphore but do not attempt to decrement it.
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/// The semaphore must have been initialized.
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///
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/// \param sem Pointer to semaphore object.
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///
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/// \return Returns semaphore count, -1 on error.
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///
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//-----------------------------------------------------------------------------
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static inline int32_t
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xos_sem_test(XosSem * sem)
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{
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XOS_ASSERT(sem);
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return sem ? sem->count : -1;
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}
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#ifdef __cplusplus
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}
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#endif
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#endif // __XOS_SEMAPHORE_H__
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