bsnes/libco/ucontext.c

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/*
libco.ucontext (2008-01-28)
author: Nach
license: public domain
*/
/*
WARNING: the overhead of POSIX ucontext is very high,
assembly versions of libco or libco_sjlj should be much faster
this library only exists for two reasons:
1: as an initial test for the viability of a ucontext implementation
2: to demonstrate the power and speed of libco over existing implementations,
such as pth (which defaults to wrapping ucontext on unix targets)
use this library only as a *last resort*
*/
#define LIBCO_C
#include "libco.h"
#define _BSD_SOURCE
#include <stdlib.h>
#include <ucontext.h>
#ifdef __cplusplus
extern "C" {
#endif
static thread_local ucontext_t co_primary;
static thread_local ucontext_t* co_running = 0;
cothread_t co_active() {
if(!co_running) co_running = &co_primary;
return (cothread_t)co_running;
}
cothread_t co_create(unsigned int heapsize, void (*coentry)(void)) {
if(!co_running) co_running = &co_primary;
ucontext_t* thread = (ucontext_t*)malloc(sizeof(ucontext_t));
if(thread) {
if((!getcontext(thread) && !(thread->uc_stack.ss_sp = 0)) && (thread->uc_stack.ss_sp = malloc(heapsize))) {
thread->uc_link = co_running;
thread->uc_stack.ss_size = heapsize;
makecontext(thread, coentry, 0);
} else {
co_delete((cothread_t)thread);
thread = 0;
}
}
return (cothread_t)thread;
}
void co_delete(cothread_t cothread) {
if(cothread) {
if(((ucontext_t*)cothread)->uc_stack.ss_sp) { free(((ucontext_t*)cothread)->uc_stack.ss_sp); }
free(cothread);
}
}
void co_switch(cothread_t cothread) {
ucontext_t* old_thread = co_running;
co_running = (ucontext_t*)cothread;
swapcontext(old_thread, co_running);
}
#ifdef __cplusplus
}
#endif