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Thread security added
jonroach 2 Sep 2025 09:44
1 contributor
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8 months ago
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 #include "coroutine.h"
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 #include <assert.h>
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 #include <setjmp.h>
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 #include <stdbool.h>
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 #include <stddef.h>
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 #include <stdio.h>
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 #include <pthread.h>
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 #include <stdlib.h>
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 #include "cor_thread_local.h"
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 static void *mustmalloc(size_t size){
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 void *p = malloc(size);
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 assert(p);
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 return p;
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 }
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 #define New(type, ...) (type##_ctor((type *)mustmalloc(sizeof(type), ## __VA_ARGS__)))
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 #define Delete(ptr, type) ((ptr) ? (type##_dtor(ptr), free(ptr), (ptr) = NULL) : (void)0)
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 ///////////////////////////////////////////////////////////////////////////////
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 // Semaphore built from mutex & condition variables...
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 //
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 // Using pthread.h (more widely available than the C standard library thread.h)
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 ///////////////////////////////////////////////////////////////////////////////
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 typedef struct Semaphore {
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 pthread_mutex_t mutex;
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 pthread_cond_t cond;
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 int count;
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 } Semaphore;
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 static void Semaphore_ctor(Semaphore *sem, int initial_count){
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 sem->count = initial_count;
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 int r = pthread_mutex_init(&sem->mutex, NULL);
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 assert(r == 0);
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 r = pthread_cond_init(&sem->cond, NULL);
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 assert(r == 0);
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 }
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 static void Semaphore_dtor(Semaphore *sem){
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 int r = pthread_mutex_destroy(&sem->mutex);
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 assert(r == 0);
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 r = pthread_cond_destroy(&sem->cond);
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 assert(r == 0);
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 }
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 static void Semaphore_Claim(Semaphore *sem){
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 int r = pthread_mutex_lock(&sem->mutex);
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 assert(r == 0);
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 while (sem->count <= 0) {
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 r = pthread_cond_wait(&sem->cond, &sem->mutex);
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 assert(r == 0);
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 }
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 sem->count--;
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 r = pthread_mutex_unlock(&sem->mutex);
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 assert(r == 0);
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 }
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 static void Semaphore_Release(Semaphore *sem){
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 int r = pthread_mutex_lock(&sem->mutex);
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 assert(r == 0);
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 sem->count++;
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 r = pthread_cond_broadcast(&sem->cond);
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 assert(r == 0);
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 r = pthread_mutex_unlock(&sem->mutex);
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 assert(r == 0);
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 }
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 ///////////////////////////////////////////////////////////////////////////////
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 // ...semaphore built from mutex
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 ///////////////////////////////////////////////////////////////////////////////
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 ///////////////////////////////////////////////////////////////////////////////
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 // 2-way linked lists...
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 //
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 // Brought inline here to avoid namespace polution
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 ///////////////////////////////////////////////////////////////////////////////
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 typedef struct List_Link List_Link;
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 struct List_Link {
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 List_Link *next;
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 List_Link *prev;
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 };
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 typedef struct List_Head List_Head;
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 struct List_Head {
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 union {
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 struct {
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 List_Link link;
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 List_Link *filler;
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 } fwd;
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 struct {
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 List_Link *filler;
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 List_Link link;
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 } back;
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 };
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 };
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 static inline bool List_IsEmpty(const List_Head *list) {
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 return list->fwd.link.next == &list->back.link;
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 }
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 static inline List_Link *List_GetHead(const List_Head *list) {
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 return List_IsEmpty(list) ? NULL : list->fwd.link.next;
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 }
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 static inline List_Link *List_GetTail(const List_Head *list) {
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 return List_IsEmpty(list) ? NULL : list->back.link.prev;
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 }
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 #define OFFSETOF(Container, Field) ((char *)&((Container *)4)->Field - (char *)(Container *)4)
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 #define List_Link_Container(Container, Link, link) ((Container *)((char *)(link) - OFFSETOF(Container, Link)))
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 static inline void List_Init(List_Head *list)
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 {
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 list->fwd.link.next = &list->back.link;
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 list->fwd.link.prev = NULL;
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 list->back.link.prev = &list->fwd.link;
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 }
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 static inline void List_AddHead(List_Head *list, List_Link *link)
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 {
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 List_Link *first = list->fwd.link.next;
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 link->next = first;
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 link->prev = &list->fwd.link;
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 first->prev = link;
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 list->fwd.link.next = link;
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 }
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 static inline void List_AddTail(List_Head *list, List_Link *link)
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 {
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 List_Link *last = list->back.link.prev;
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 link->prev = last;
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 link->next = &list->back.link;
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 last->next = link;
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 list->back.link.prev = link;
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 }
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 static inline void List_Remove(List_Link *link)
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 {
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 link->prev->next = link->next;
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 link->next->prev = link->prev;
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 }
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 ///////////////////////////////////////////////////////////////////////////////
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 // ...2-way linked lists
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 ///////////////////////////////////////////////////////////////////////////////
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 typedef struct Coroutines Coroutines;
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 enum {
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 Coroutines_Idle,
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 Coroutines_Starting,
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 Coroutines_Started,
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 Coroutines_Active,
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 Coroutines_Stopping
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 };
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 enum {
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 Chunk_Initial,
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 Chunk_Create,
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 Chunk_Enter
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 };
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 enum {
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 Coroutine_Constructing,
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 Coroutine_Free,
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 Coroutine_Idle,
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 Coroutine_Running,
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 Coroutine_Waiting,
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 Coroutine_Complete
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 };
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 enum {
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 Coroutines_Init,
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 Coroutines_AllocatedChunk,
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 Coroutines_CoroutineComplete,
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 };
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 struct Coroutine {
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 Coroutines *coroutines;
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 List_Link link;
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 jmp_buf buf;
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 void *this;
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 Coroutine_Start start;
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 void *entry_param;
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 void *value;
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 char state;
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 char action;
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 };
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 struct Coroutines {
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 pthread_mutex_t mutex;
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 jmp_buf controller;
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 jmp_buf chunk_allocated;
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 // singletons
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 Coroutine *tip; // top of stack chunk
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 Coroutine *active; // currently running coroutine
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 Coroutine *primary; // Coroutine_Run coroutine
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 // lists
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 List_Head free;
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 List_Head inactive; // idle or complete
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 List_Head runable; // running or waiting to run
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 List_Head waiting; // yielded / waiting to run
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 Semaphore waiting_sem;
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 // state
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 char state;
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 };
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 _Cor_thread_local Coroutines *g_c;
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 static void stack_chunk_chunk(Coroutine *parent);
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 static void stack_chunk_base(Coroutine *parent);
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 static void Coroutine_PrimeStackChunks()
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 {
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 unsigned char chunk_of_stack[COROUTINE_STACK_SIZE];
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 chunk_of_stack[0] = 0xde;
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 chunk_of_stack[1] = 0xad;
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 chunk_of_stack[2] = 0xbe;
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 chunk_of_stack[3] = 0xef;
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 chunk_of_stack[COROUTINE_STACK_SIZE - 4] = 0xde;
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 chunk_of_stack[COROUTINE_STACK_SIZE - 3] = 0xad;
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 chunk_of_stack[COROUTINE_STACK_SIZE - 2] = 0xbe;
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 chunk_of_stack[COROUTINE_STACK_SIZE - 1] = 0xef;
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 stack_chunk_base(NULL);
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 }
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 static void stack_chunk_chunk(
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 Coroutine *parent
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 ){
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 unsigned char chunk_of_stack[COROUTINE_STACK_SIZE];
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 chunk_of_stack[0] = 0xde;
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 chunk_of_stack[1] = 0xad;
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 chunk_of_stack[2] = 0xbe;
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 chunk_of_stack[3] = 0xef;
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 chunk_of_stack[COROUTINE_STACK_SIZE - 4] = 0xde;
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 chunk_of_stack[COROUTINE_STACK_SIZE - 3] = 0xad;
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 chunk_of_stack[COROUTINE_STACK_SIZE - 2] = 0xbe;
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 chunk_of_stack[COROUTINE_STACK_SIZE - 1] = 0xef;
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 stack_chunk_base(parent);
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 }
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 static void Coroutine_RunNext()
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 {
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 // arrvie here with mutex unlocked
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 Semaphore_Claim(&g_c->waiting_sem);
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 int r = pthread_mutex_lock(&g_c->mutex);
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 assert(r == 0);
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 assert(!List_IsEmpty(&g_c->runable));
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 Coroutine *next = List_Link_Container(Coroutine, link, List_GetHead(&g_c->runable));
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 assert(next->state == Coroutine_Running);
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 longjmp(next->buf, Chunk_Enter);
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 assert(false);
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 }
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 static void stack_chunk_base(
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 Coroutine *parent
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 ){
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 Coroutine here;
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 here.state = Coroutine_Constructing;
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 switch (setjmp(here.buf)) {
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 case Chunk_Initial:
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 // got here for the first time
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 // parent now has a chunk_of_stack - add it to the free list
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 if (parent) {
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 assert(parent->state == Coroutine_Constructing);
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 parent->state = Coroutine_Free;
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 List_AddHead(&g_c->free, &parent->link);
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 }
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 // note that here is the tip of the chunk-claim stack
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 here.coroutines = g_c;
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 g_c->tip = &here;
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 // return to the coroutine allocator
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 longjmp(g_c->chunk_allocated, 1);
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 case Chunk_Create:
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 // request to create a new chunk on the stack
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 assert(here.state == Coroutine_Constructing);
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 stack_chunk_chunk(&here);
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 assert(false);
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 case Chunk_Enter:
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 // request to start a coroutine (ie use the chunk for a coroutine)
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 // arrive here with mutex locked
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 assert(here.state == Coroutine_Running);
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 g_c->active = &here;
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 int r = pthread_mutex_unlock(&g_c->mutex);
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 assert(r == 0);
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 here.value = here.start(here.entry_param);
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 r = pthread_mutex_lock(&g_c->mutex);
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 assert(r == 0);
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 g_c->active = NULL;
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 assert(here.state == Coroutine_Running);
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 List_Remove(&here.link);
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 here.state = Coroutine_Complete;
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 List_AddTail(&g_c->inactive, &here.link);
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 // coroutine has completed
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 if (g_c->primary == &here) {
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 // if primary coroutine - return to Coroutine_Run
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 longjmp(g_c->controller, Coroutines_CoroutineComplete);
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 }
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 r = pthread_mutex_unlock(&g_c->mutex);
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 assert(r == 0);
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 Coroutine_RunNext();
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 assert(false);
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 }
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 }
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 void Coroutine_StartSystem()
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 {
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 assert(!g_c);
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 g_c = mustmalloc(sizeof(Coroutines));
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 g_c->state = Coroutines_Starting;
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 pthread_mutexattr_t attr;
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 int r = pthread_mutexattr_init(&attr);
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 assert(r == 0);
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 r = pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
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 assert(r == 0);
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 r = pthread_mutex_init(&g_c->mutex, &attr);
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 assert(r == 0);
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 r = pthread_mutexattr_destroy(&attr);
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 assert(r == 0);
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 g_c->tip = NULL;
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 g_c->active = NULL;
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 List_Init(&g_c->free);
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 List_Init(&g_c->inactive);
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 List_Init(&g_c->runable);
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 List_Init(&g_c->waiting);
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 Semaphore_ctor(&g_c->waiting_sem, 0);
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 // prime the chunk system
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 if (!setjmp(g_c->chunk_allocated)){
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 Coroutine_PrimeStackChunks();
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 assert(false);
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 }
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 assert(g_c->state == Coroutines_Starting);
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 g_c->state = Coroutines_Started;
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 }
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 void Coroutine_StopSystem()
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 {
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 int r = pthread_mutex_lock(&g_c->mutex);
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 assert(r == 0);
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 assert(g_c->state == Coroutines_Started);
359
 g_c->state = Coroutines_Stopping;
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 assert(List_IsEmpty(&g_c->inactive));
362
 Semaphore_dtor(&g_c->waiting_sem);
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 assert(g_c->state == Coroutines_Stopping);
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 pthread_mutex_unlock(&g_c->mutex);
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 assert(r == 0);
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 g_c->state = Coroutines_Idle;
368
 r = pthread_mutex_destroy(&g_c->mutex);
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 assert(r == 0);
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 free(g_c);
371
 g_c = NULL;
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372
 }
373
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375
 void *Coroutine_Run(
376
 Coroutine *cor,
377
 void *value
378
 ){
379
 Coroutines *cors = cor->coroutines;
380
 assert(g_c == cors);
381
 int r = pthread_mutex_lock(&cors->mutex);
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 assert(r == 0);
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 assert(cors->state == Coroutines_Started);
384
 cors->state = Coroutines_Active;
385
 cors->primary = cor;
386
 Coroutine_Continue(cors->primary, value, true);
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 if (!setjmp(cors->controller)){
389
 pthread_mutex_unlock(&cors->mutex);
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 assert(r == 0);
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391
 // start the first coroutine
392
 Coroutine_RunNext();
393
 }
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 // arrive here with mutex locked
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 assert(List_IsEmpty(&cors->runable));
396
 assert(List_IsEmpty(&cors->waiting));
397
 assert(cors->state == Coroutines_Active);
398
 cors->state = Coroutines_Started;
399
 pthread_mutex_unlock(&cors->mutex);
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 assert(r == 0);
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401
 return Coroutine_GetValue(cor);
402
 }
403
404
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 Coroutine *Coroutine_New(
406
 Coroutine_Start start
407
 ){
408
 assert(g_c->state == Coroutines_Started || g_c->state == Coroutines_Active);
409
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 // if none free - add one
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 if (List_IsEmpty(&g_c->free)){
412
 if (!setjmp(g_c->chunk_allocated)){
413
 longjmp(g_c->tip->buf, Chunk_Create);
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414
 }
415
 }
416
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417
 Coroutine *cor = List_Link_Container(Coroutine, link, List_GetHead(&g_c->free));
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418
 assert(cor->state == Coroutine_Free);
419
 cor->state = Coroutine_Idle;
420
 cor->start = start;
421
 cor->value = NULL;
422
 List_Remove(&cor->link);
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 List_AddHead(&g_c->inactive, &cor->link);
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424
425
 return cor;
426
 }
427
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429
 void Coroutine_Delete(
430
 Coroutine *cor
431
 ){
432
 Coroutines *cors = cor->coroutines;
433
 int r = pthread_mutex_lock(&cors->mutex);
434
 assert(r == 0);
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435
 assert(cor->state == Coroutine_Idle || cor->state == Coroutine_Complete);
436
 cor->state = Coroutine_Free;
437
 List_Remove(&cor->link);
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 List_AddTail(&cors->free, &cor->link);
439
 r = pthread_mutex_unlock(&cors->mutex);
440
 assert(r == 0);
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441
 }
442
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444
 void Coroutine_Continue(
445
 Coroutine *cor,
446
 void *value,
447
 bool early
448
 ){
449
 Coroutines *cors = cor->coroutines;
450
 int r = pthread_mutex_lock(&cors->mutex);
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 assert(r == 0);
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 assert(cor->state == Coroutine_Idle || cor->state == Coroutine_Waiting);
453
 cor->entry_param = value;
454
 cor->state = Coroutine_Running;
455
 List_Remove(&cor->link);
456
 if ( early ) {
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 List_AddHead(&cors->runable, &cor->link);
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458
 } else {
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 List_AddTail(&cors->runable, &cor->link);
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460
 }
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 r = pthread_mutex_unlock(&cors->mutex);
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462
 assert(r == 0);
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 Semaphore_Release(&cors->waiting_sem);
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464
 }
465
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467
 void *Coroutine_Yield(
468
 void *value,
469
 Coroutine_YieldCallback on_yield,
470
 void *this
471
 ){
472
 int r = pthread_mutex_lock(&g_c->mutex);
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473
 assert(r == 0);
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 Coroutine *me = g_c->active;
475
 Coroutines *cors = me->coroutines;
476
 assert(me && me->state == Coroutine_Running && cors == g_c);
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477
 me->value = value;
478
 me->state = Coroutine_Waiting;
479
 List_Remove(&me->link);
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 List_AddTail(&cors->waiting, &me->link);
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481
 switch (setjmp(me->buf)){
482
 case Chunk_Initial:
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 r = pthread_mutex_unlock(&cors->mutex);
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484
 assert(r == 0);
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485
 on_yield(this);
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486
 Coroutine_RunNext();
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 case Chunk_Create:
488
 assert(false);
489
 case Chunk_Enter:
490
 // arrive here with mutex locked
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 cors->active = me;
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 // when we return here - we are running again
493
 assert(me->state == Coroutine_Running);
494
 void *res = me->entry_param;
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 r = pthread_mutex_unlock(&cors->mutex);
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496
 assert(r == 0);
497
 return res;
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498
 }
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 return NULL;
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500
 }
501
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503
 void *Coroutine_GetValue(
504
 Coroutine *cor
505
 ){
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506
 return cor->value;
507
 }
508
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509
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510
 Coroutine *Coroutine_GetActive()
511
 {
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 return g_c->active;
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513
 }
514
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516
 bool Coroutine_IsRunning(
517
 Coroutine *cor
518
 )
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519
 {
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 int state = cor->state;
521
 return state == Coroutine_Running || state == Coroutine_Waiting;
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522
 }
523