swapped protothreads library with custom coroutines library

This commit is contained in:
Alessandro Mauri 2026-05-27 22:19:55 +02:00
parent d9d732bb51
commit 7845689992
6 changed files with 224 additions and 844 deletions

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fw/coroutine.h Normal file
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/*
* Copyright (c) 2026, Alessandro Mauri <alemauri001@gmail.com>.
* All rights reserved.
*
* This file is a heavily modified, single-header derivative of the
* protothreads library.
*
* =============================================================================
* Original Protothreads License:
* =============================================================================
* Copyright (c) 2004-2005, Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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: Adam Dunkels <adam@sics.se>
*/
#ifndef _COROUTINE_H
#define _COROUTINE_H
/* This is an implementation of stackless coroutines that uses the labels as
* values [1] feature of GNU C, similar to protothreads [2] with the lc-addrlabels.h
* include, the only difference being better ergonomics and minimal type checking.
*
* Since coroutines implemented this way need to return to wait for a condition
* stack-local variables are NOT preserved between wait()s, as such these functions
* have to be considered stackless. Any state that has to be preserved between
* waits have to be declared static or have to be preserved outside the routine.
*
* This library's intended use is in microcontrollers and memory-constrained
* systems where having a full rtos and/or having stackful coroutines is either
* too heavy or overkill. Stackless coroutines implemented this way are an
* alternative way of expressing state machines. Since coroutines have to be
* repeatedly called to be "scheduled", the code maintains a main loop, but state
* changes can be expressed with waits on conditions, timers, semaphores and other
* more expressive constructs.
*
* A simple example program is:
*
* #include "coroutine.h"
*
* // Updates the timer when called, returns true when it expires
* static int timer_expired(struct timer *t);
* // Sets a timer in milliseconds
* static void timer_set(struct timer *t, int interval);
*
* // First coroutine, waits for 1s and prints something
* coroutine coro_1(coro_state_t *s)
* {
* static struct timer t;
* coro_begin(s);
* for (;;) {
* timer_set(&t, 1000);
* coro_wait_until(s, timer_expired(&t));
* printf("coroutine 1\n");
* }
* coro_end();
* }
*
* // Second coroutine, waits for 500ms and prints something
* coroutine coro_2(coro_state_t *s)
* {
* static struct timer t;
* coro_begin(s);
* for (;;) {
* timer_set(&t, 500);
* coro_wait_until(s, timer_expired(&t));
* printf("coroutine 2\n");
* }
* coro_end();
* }
*
* int main(void)
* {
* coro_state_t s1, s2;
* coro_init(&s1);
* coro_init(&s2);
*
* // Main loop, calls each coroutine periodically
* for (;;) {
* coro_1(&s1);
* coro_2(&s2);
* usleep(100);
* }
* }
*
* [1]: https://www.gnu.org/software/c-intro-and-ref/manual/html_node/Labels-as-Values.html
* [2]: https://dunkels.com/adam/pt/index.html
*/
// Useful macros
#define CORO_CONCAT2(s1, s2) s1##s2
#define CORO_CONCAT(s1, s2) CORO_CONCAT2(s1, s2)
#define CORO_CHECK_TYPE(var,type) { typedef void (*type_t)(type); type_t tmp = (type_t)0; if(0) tmp(var); }
// Return value of a coroutine, a coroutine should be scheduled (called) until
// it's return value becomes DONE
typedef enum {
CORO_INIT = 0,
CORO_CONT = CORO_INIT,
CORO_DONE = 1,
CORO_YIELDED = 2,
CORO_WAITING = 3,
} coroutine;
// Local continuation of the coroutine, where it left off
typedef void* coro_state_t;
/* -------------------------- COROUTINE MANAGEMENT -------------------------- */
// Initialize the coroutine state
#define coro_init(s) CORO_CHECK_TYPE(s, coro_state_t*) \
do { *s = NULL; } while (0)
// Jump to the previous state where the coroutine left off, __yield flag indicates
// wether the coroutine should yield this cycle
#define coro_begin(s) CORO_CHECK_TYPE(s, coro_state_t*) \
unsigned char __yield = 0; \
do { if(*s != NULL) goto *(*s); } while (0)
#define coro_end()
// Set a jump with a gcc label as value feature, this is a GNU C extension
#define CORO_SET_JUMP(s) CORO_CHECK_TYPE(s, coro_state_t*) \
do { \
CORO_CONCAT(LC_LABEL, __LINE__): \
*s = &&CORO_CONCAT(LC_LABEL, __LINE__); \
} while (0)
// Yield from a coroutine
#define coro_yield(s) CORO_CHECK_TYPE(s, coro_state_t*) \
do { \
__yield = 1; \
CORO_SET_JUMP(s); \
if (__yield == 1) return CORO_YIELDED; \
} while (0)
// Wait until a condition is met (becomes true)
#define coro_wait_until(s, cond) CORO_CHECK_TYPE(s, coro_state_t*) \
do { \
CORO_SET_JUMP(s); \
if (!(cond)) return CORO_WAITING; \
} while (0)
// Shorthand for wait_until
#define coro_wait(s, cond) coro_wait_until(s, cond)
// Wait while a condition remains true
#define coro_wait_while(s, cond) coro_wait_until(s, !(cond))
// Exit from the coroutine, resets the state
#define coro_exit(s) CORO_CHECK_TYPE(s, coro_state_t*) \
do { \
coro_init(s); \
return CORO_DONE; \
} while (0)
// Restart a coroutine, when called it will not resume from where it left off,
// instead it will start from the beginning, the only difference with exit is
// the return value. To determine wether a coroutine has exited or restarted
// is to check it's return value
#define coro_restart(s) CORO_CHECK_TYPE(s, coro_state_t*) \
do { \
coro_init(s); \
return CORO_INIT; \
} while(0)
/* ------------------------- SEMAPHORE IMPLEMENTATION ----------------------- */
// Implements a basic semaphore type with the classic wait and signal operations
// semaphores are not bound checked
typedef int coro_semaphore_t;
// Initializes a semaphore with a starting value of "count"
#define coro_sem_init(sem, count) CORO_CHECK_TYPE(sem, coro_semaphore_t*) \
do { \
*sem = (int)count; \
} while (0)
// Wait until a semaphore has a value other than zero
#define coro_sem_wait(state, sem) \
CORO_CHECK_TYPE(state, coro_state_t*) \
CORO_CHECK_TYPE(sem, coro_semaphore_t*) \
do { \
coro_wait_until(state, *(sem) > 0); \
--(*sem); \
} while (0)
// Signal a semaphore
#define coro_sem_signal(state, sem) \
CORO_CHECK_TYPE(state, coro_state_t*) \
CORO_CHECK_TYPE(sem, coro_semaphore_t*) \
++(*sem)
#endif

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/*
* Copyright (c) 2004-2005, Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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.
*
* This file is part of the Contiki operating system.
*
* Author: Adam Dunkels <adam@sics.se>
*
* $Id: lc-addrlabels.h,v 1.4 2006/06/03 11:29:43 adam Exp $
*/
/**
* \addtogroup lc
* @{
*/
/**
* \file
* Implementation of local continuations based on the "Labels as
* values" feature of gcc
* \author
* Adam Dunkels <adam@sics.se>
*
* This implementation of local continuations is based on a special
* feature of the GCC C compiler called "labels as values". This
* feature allows assigning pointers with the address of the code
* corresponding to a particular C label.
*
* For more information, see the GCC documentation:
* http://gcc.gnu.org/onlinedocs/gcc/Labels-as-Values.html
*
*/
#ifndef __LC_ADDRLABELS_H__
#define __LC_ADDRLABELS_H__
/** \hideinitializer */
typedef void * lc_t;
#define LC_INIT(s) s = NULL
#define LC_RESUME(s) \
do { \
if(s != NULL) { \
goto *s; \
} \
} while(0)
#define LC_CONCAT2(s1, s2) s1##s2
#define LC_CONCAT(s1, s2) LC_CONCAT2(s1, s2)
#define LC_SET(s) \
do { \
LC_CONCAT(LC_LABEL, __LINE__): \
(s) = &&LC_CONCAT(LC_LABEL, __LINE__); \
} while(0)
#define LC_END(s)
#endif /* __LC_ADDRLABELS_H__ */
/** @} */

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/*
* Copyright (c) 2004-2005, Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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.
*
* This file is part of the Contiki operating system.
*
* Author: Adam Dunkels <adam@sics.se>
*
* $Id: lc-switch.h,v 1.4 2006/06/03 11:29:43 adam Exp $
*/
/**
* \addtogroup lc
* @{
*/
/**
* \file
* Implementation of local continuations based on switch() statment
* \author Adam Dunkels <adam@sics.se>
*
* This implementation of local continuations uses the C switch()
* statement to resume execution of a function somewhere inside the
* function's body. The implementation is based on the fact that
* switch() statements are able to jump directly into the bodies of
* control structures such as if() or while() statmenets.
*
* This implementation borrows heavily from Simon Tatham's coroutines
* implementation in C:
* http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html
*/
#ifndef __LC_SWITCH_H__
#define __LC_SWITCH_H__
/* WARNING! lc implementation using switch() does not work if an
LC_SET() is done within another switch() statement! */
/** \hideinitializer */
typedef unsigned short lc_t;
#define LC_INIT(s) s = 0;
#define LC_RESUME(s) switch(s) { case 0:
#define LC_SET(s) s = __LINE__; case __LINE__:
#define LC_END(s) }
#endif /* __LC_SWITCH_H__ */
/** @} */

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/*
* Copyright (c) 2004-2005, Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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.
*
* This file is part of the protothreads library.
*
* Author: Adam Dunkels <adam@sics.se>
*
* $Id: lc.h,v 1.2 2005/02/24 10:36:59 adam Exp $
*/
/**
* \addtogroup pt
* @{
*/
/**
* \defgroup lc Local continuations
* @{
*
* Local continuations form the basis for implementing protothreads. A
* local continuation can be <i>set</i> in a specific function to
* capture the state of the function. After a local continuation has
* been set can be <i>resumed</i> in order to restore the state of the
* function at the point where the local continuation was set.
*
*
*/
/**
* \file lc.h
* Local continuations
* \author
* Adam Dunkels <adam@sics.se>
*
*/
#ifdef DOXYGEN
/**
* Initialize a local continuation.
*
* This operation initializes the local continuation, thereby
* unsetting any previously set continuation state.
*
* \hideinitializer
*/
#define LC_INIT(lc)
/**
* Set a local continuation.
*
* The set operation saves the state of the function at the point
* where the operation is executed. As far as the set operation is
* concerned, the state of the function does <b>not</b> include the
* call-stack or local (automatic) variables, but only the program
* counter and such CPU registers that needs to be saved.
*
* \hideinitializer
*/
#define LC_SET(lc)
/**
* Resume a local continuation.
*
* The resume operation resumes a previously set local continuation, thus
* restoring the state in which the function was when the local
* continuation was set. If the local continuation has not been
* previously set, the resume operation does nothing.
*
* \hideinitializer
*/
#define LC_RESUME(lc)
/**
* Mark the end of local continuation usage.
*
* The end operation signifies that local continuations should not be
* used any more in the function. This operation is not needed for
* most implementations of local continuation, but is required by a
* few implementations.
*
* \hideinitializer
*/
#define LC_END(lc)
/**
* \var typedef lc_t;
*
* The local continuation type.
*
* \hideinitializer
*/
#endif /* DOXYGEN */
#ifndef __LC_H__
#define __LC_H__
#ifdef LC_INCLUDE
#include LC_INCLUDE
#else
#include "lc-switch.h"
#endif /* LC_INCLUDE */
#endif /* __LC_H__ */
/** @} */
/** @} */

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/*
* Copyright (c) 2004, Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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.
*
* This file is part of the protothreads library.
*
* Author: Adam Dunkels <adam@sics.se>
*
* $Id: pt-sem.h,v 1.2 2005/02/24 10:36:59 adam Exp $
*/
/**
* \addtogroup pt
* @{
*/
/**
* \defgroup ptsem Protothread semaphores
* @{
*
* This module implements counting semaphores on top of
* protothreads. Semaphores are a synchronization primitive that
* provide two operations: "wait" and "signal". The "wait" operation
* checks the semaphore counter and blocks the thread if the counter
* is zero. The "signal" operation increases the semaphore counter but
* does not block. If another thread has blocked waiting for the
* semaphore that is signalled, the blocked thread will become
* runnable again.
*
* Semaphores can be used to implement other, more structured,
* synchronization primitives such as monitors and message
* queues/bounded buffers (see below).
*
* The following example shows how the producer-consumer problem, also
* known as the bounded buffer problem, can be solved using
* protothreads and semaphores. Notes on the program follow after the
* example.
*
\code
#include "pt-sem.h"
#define NUM_ITEMS 32
#define BUFSIZE 8
static struct pt_sem mutex, full, empty;
PT_THREAD(producer(struct pt *pt))
{
static int produced;
PT_BEGIN(pt);
for(produced = 0; produced < NUM_ITEMS; ++produced) {
PT_SEM_WAIT(pt, &full);
PT_SEM_WAIT(pt, &mutex);
add_to_buffer(produce_item());
PT_SEM_SIGNAL(pt, &mutex);
PT_SEM_SIGNAL(pt, &empty);
}
PT_END(pt);
}
PT_THREAD(consumer(struct pt *pt))
{
static int consumed;
PT_BEGIN(pt);
for(consumed = 0; consumed < NUM_ITEMS; ++consumed) {
PT_SEM_WAIT(pt, &empty);
PT_SEM_WAIT(pt, &mutex);
consume_item(get_from_buffer());
PT_SEM_SIGNAL(pt, &mutex);
PT_SEM_SIGNAL(pt, &full);
}
PT_END(pt);
}
PT_THREAD(driver_thread(struct pt *pt))
{
static struct pt pt_producer, pt_consumer;
PT_BEGIN(pt);
PT_SEM_INIT(&empty, 0);
PT_SEM_INIT(&full, BUFSIZE);
PT_SEM_INIT(&mutex, 1);
PT_INIT(&pt_producer);
PT_INIT(&pt_consumer);
PT_WAIT_THREAD(pt, producer(&pt_producer) &
consumer(&pt_consumer));
PT_END(pt);
}
\endcode
*
* The program uses three protothreads: one protothread that
* implements the consumer, one thread that implements the producer,
* and one protothread that drives the two other protothreads. The
* program uses three semaphores: "full", "empty" and "mutex". The
* "mutex" semaphore is used to provide mutual exclusion for the
* buffer, the "empty" semaphore is used to block the consumer is the
* buffer is empty, and the "full" semaphore is used to block the
* producer is the buffer is full.
*
* The "driver_thread" holds two protothread state variables,
* "pt_producer" and "pt_consumer". It is important to note that both
* these variables are declared as <i>static</i>. If the static
* keyword is not used, both variables are stored on the stack. Since
* protothreads do not store the stack, these variables may be
* overwritten during a protothread wait operation. Similarly, both
* the "consumer" and "producer" protothreads declare their local
* variables as static, to avoid them being stored on the stack.
*
*
*/
/**
* \file
* Couting semaphores implemented on protothreads
* \author
* Adam Dunkels <adam@sics.se>
*
*/
#ifndef __PT_SEM_H__
#define __PT_SEM_H__
#include "pt.h"
struct pt_sem {
unsigned int count;
};
/**
* Initialize a semaphore
*
* This macro initializes a semaphore with a value for the
* counter. Internally, the semaphores use an "unsigned int" to
* represent the counter, and therefore the "count" argument should be
* within range of an unsigned int.
*
* \param s (struct pt_sem *) A pointer to the pt_sem struct
* representing the semaphore
*
* \param c (unsigned int) The initial count of the semaphore.
* \hideinitializer
*/
#define PT_SEM_INIT(s, c) (s)->count = c
/**
* Wait for a semaphore
*
* This macro carries out the "wait" operation on the semaphore. The
* wait operation causes the protothread to block while the counter is
* zero. When the counter reaches a value larger than zero, the
* protothread will continue.
*
* \param pt (struct pt *) A pointer to the protothread (struct pt) in
* which the operation is executed.
*
* \param s (struct pt_sem *) A pointer to the pt_sem struct
* representing the semaphore
*
* \hideinitializer
*/
#define PT_SEM_WAIT(pt, s) \
do { \
PT_WAIT_UNTIL(pt, (s)->count > 0); \
--(s)->count; \
} while(0)
/**
* Signal a semaphore
*
* This macro carries out the "signal" operation on the semaphore. The
* signal operation increments the counter inside the semaphore, which
* eventually will cause waiting protothreads to continue executing.
*
* \param pt (struct pt *) A pointer to the protothread (struct pt) in
* which the operation is executed.
*
* \param s (struct pt_sem *) A pointer to the pt_sem struct
* representing the semaphore
*
* \hideinitializer
*/
#define PT_SEM_SIGNAL(pt, s) ++(s)->count
#endif /* __PT_SEM_H__ */
/** @} */
/** @} */

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/*
* Copyright (c) 2004-2005, Swedish Institute of Computer Science.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the Institute 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 INSTITUTE 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 INSTITUTE 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.
*
* This file is part of the Contiki operating system.
*
* Author: Adam Dunkels <adam@sics.se>
*
* $Id: pt.h,v 1.7 2006/10/02 07:52:56 adam Exp $
*/
/**
* \addtogroup pt
* @{
*/
/**
* \file
* Protothreads implementation.
* \author
* Adam Dunkels <adam@sics.se>
*
*/
#ifndef __PT_H__
#define __PT_H__
#include "lc.h"
struct pt {
lc_t lc;
};
#define PT_WAITING 0
#define PT_YIELDED 1
#define PT_EXITED 2
#define PT_ENDED 3
/**
* \name Initialization
* @{
*/
/**
* Initialize a protothread.
*
* Initializes a protothread. Initialization must be done prior to
* starting to execute the protothread.
*
* \param pt A pointer to the protothread control structure.
*
* \sa PT_SPAWN()
*
* \hideinitializer
*/
#define PT_INIT(pt) LC_INIT((pt)->lc)
/** @} */
/**
* \name Declaration and definition
* @{
*/
/**
* Declaration of a protothread.
*
* This macro is used to declare a protothread. All protothreads must
* be declared with this macro.
*
* \param name_args The name and arguments of the C function
* implementing the protothread.
*
* \hideinitializer
*/
#define PT_THREAD(name_args) char name_args
/**
* Declare the start of a protothread inside the C function
* implementing the protothread.
*
* This macro is used to declare the starting point of a
* protothread. It should be placed at the start of the function in
* which the protothread runs. All C statements above the PT_BEGIN()
* invokation will be executed each time the protothread is scheduled.
*
* \param pt A pointer to the protothread control structure.
*
* \hideinitializer
*/
#define PT_BEGIN(pt) { char PT_YIELD_FLAG = 1; LC_RESUME((pt)->lc)
/**
* Declare the end of a protothread.
*
* This macro is used for declaring that a protothread ends. It must
* always be used together with a matching PT_BEGIN() macro.
*
* \param pt A pointer to the protothread control structure.
*
* \hideinitializer
*/
#define PT_END(pt) LC_END((pt)->lc); PT_YIELD_FLAG = 0; \
PT_INIT(pt); return PT_ENDED; }
/** @} */
/**
* \name Blocked wait
* @{
*/
/**
* Block and wait until condition is true.
*
* This macro blocks the protothread until the specified condition is
* true.
*
* \param pt A pointer to the protothread control structure.
* \param condition The condition.
*
* \hideinitializer
*/
#define PT_WAIT_UNTIL(pt, condition) \
do { \
LC_SET((pt)->lc); \
if(!(condition)) { \
return PT_WAITING; \
} \
} while(0)
/**
* Block and wait while condition is true.
*
* This function blocks and waits while condition is true. See
* PT_WAIT_UNTIL().
*
* \param pt A pointer to the protothread control structure.
* \param cond The condition.
*
* \hideinitializer
*/
#define PT_WAIT_WHILE(pt, cond) PT_WAIT_UNTIL((pt), !(cond))
/** @} */
/**
* \name Hierarchical protothreads
* @{
*/
/**
* Block and wait until a child protothread completes.
*
* This macro schedules a child protothread. The current protothread
* will block until the child protothread completes.
*
* \note The child protothread must be manually initialized with the
* PT_INIT() function before this function is used.
*
* \param pt A pointer to the protothread control structure.
* \param thread The child protothread with arguments
*
* \sa PT_SPAWN()
*
* \hideinitializer
*/
#define PT_WAIT_THREAD(pt, thread) PT_WAIT_WHILE((pt), PT_SCHEDULE(thread))
/**
* Spawn a child protothread and wait until it exits.
*
* This macro spawns a child protothread and waits until it exits. The
* macro can only be used within a protothread.
*
* \param pt A pointer to the protothread control structure.
* \param child A pointer to the child protothread's control structure.
* \param thread The child protothread with arguments
*
* \hideinitializer
*/
#define PT_SPAWN(pt, child, thread) \
do { \
PT_INIT((child)); \
PT_WAIT_THREAD((pt), (thread)); \
} while(0)
/** @} */
/**
* \name Exiting and restarting
* @{
*/
/**
* Restart the protothread.
*
* This macro will block and cause the running protothread to restart
* its execution at the place of the PT_BEGIN() call.
*
* \param pt A pointer to the protothread control structure.
*
* \hideinitializer
*/
#define PT_RESTART(pt) \
do { \
PT_INIT(pt); \
return PT_WAITING; \
} while(0)
/**
* Exit the protothread.
*
* This macro causes the protothread to exit. If the protothread was
* spawned by another protothread, the parent protothread will become
* unblocked and can continue to run.
*
* \param pt A pointer to the protothread control structure.
*
* \hideinitializer
*/
#define PT_EXIT(pt) \
do { \
PT_INIT(pt); \
return PT_EXITED; \
} while(0)
/** @} */
/**
* \name Calling a protothread
* @{
*/
/**
* Schedule a protothread.
*
* This function shedules a protothread. The return value of the
* function is non-zero if the protothread is running or zero if the
* protothread has exited.
*
* \param f The call to the C function implementing the protothread to
* be scheduled
*
* \hideinitializer
*/
#define PT_SCHEDULE(f) ((f) < PT_EXITED)
/** @} */
/**
* \name Yielding from a protothread
* @{
*/
/**
* Yield from the current protothread.
*
* This function will yield the protothread, thereby allowing other
* processing to take place in the system.
*
* \param pt A pointer to the protothread control structure.
*
* \hideinitializer
*/
#define PT_YIELD(pt) \
do { \
PT_YIELD_FLAG = 0; \
LC_SET((pt)->lc); \
if(PT_YIELD_FLAG == 0) { \
return PT_YIELDED; \
} \
} while(0)
/**
* \brief Yield from the protothread until a condition occurs.
* \param pt A pointer to the protothread control structure.
* \param cond The condition.
*
* This function will yield the protothread, until the
* specified condition evaluates to true.
*
*
* \hideinitializer
*/
#define PT_YIELD_UNTIL(pt, cond) \
do { \
PT_YIELD_FLAG = 0; \
LC_SET((pt)->lc); \
if((PT_YIELD_FLAG == 0) || !(cond)) { \
return PT_YIELDED; \
} \
} while(0)
/** @} */
#endif /* __PT_H__ */
/** @} */