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/*
libco.sjlj (2008-01-28)
author: Nach
license: public domain
*/
/*
* Note this was designed for UNIX systems. Based on ideas expressed in a paper
* by Ralf Engelschall.
* For SJLJ on other systems, one would want to rewrite springboard() and
* co_create() and hack the jmb_buf stack pointer.
*/
#define LIBCO_C
#include <libco.h>
#include <stdlib.h>
#include <signal.h>
#include <setjmp.h>
#ifdef __cplusplus
extern "C" {
#endif
typedef struct
{
sigjmp_buf context;
void (*coentry)(void);
void *stack;
} cothread_struct;
static thread_local cothread_struct co_primary;
static thread_local cothread_struct *creating, *co_running = 0;
static void springboard(int ignored)
{
if(sigsetjmp(creating->context, 0))
co_running->coentry();
}
cothread_t co_active(void)
{
if (!co_running)
co_running = &co_primary;
return (cothread_t)co_running;
}
cothread_t co_create(unsigned int size, void (*coentry)(void))
{
if(!co_running)
co_running = &co_primary;
cothread_struct *thread = (cothread_struct*)malloc(sizeof(cothread_struct));
if(thread)
{
struct sigaction handler;
struct sigaction old_handler;
stack_t stack;
stack_t old_stack;
thread->coentry = thread->stack = 0;
stack.ss_flags = 0;
stack.ss_size = size;
thread->stack = stack.ss_sp = malloc(size);
if(stack.ss_sp && !sigaltstack(&stack, &old_stack))
{
handler.sa_handler = springboard;
handler.sa_flags = SA_ONSTACK;
sigemptyset(&handler.sa_mask);
creating = thread;
if(!sigaction(SIGUSR1, &handler, &old_handler))
{
if(!raise(SIGUSR1))
thread->coentry = coentry;
sigaltstack(&old_stack, 0);
sigaction(SIGUSR1, &old_handler, 0);
}
}
if(thread->coentry != coentry)
{
co_delete(thread);
thread = 0;
}
}
return (cothread_t)thread;
}
void co_delete(cothread_t cothread)
{
if(cothread)
{
if(((cothread_struct*)cothread)->stack)
free(((cothread_struct*)cothread)->stack);
free(cothread);
}
}
void co_switch(cothread_t cothread)
{
if(!sigsetjmp(co_running->context, 0))
{
co_running = (cothread_struct*)cothread;
siglongjmp(co_running->context, 1);
}
}
#ifdef __cplusplus
}
#endif
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