CSCoroutine.m

#ifndef MAC_OS_X_VERSION_MIN_REQUIRED
#define MAC_OS_X_VERSION_MIN_REQUIRED MAC_OS_X_VERSION_10_1
#endif
#ifndef MAC_OS_X_VERSION_MAX_ALLOWED
#define MAC_OS_X_VERSION_MAX_ALLOWED MAC_OS_X_VERSION_10_4
#endif
#import "CSCoroutine.h"
#import <pthread.h>
#import <objc/objc-runtime.h>


@interface NSProxy (Hidden)
-(void)doesNotRecognizeSelector:(SEL)sel;
@end

static pthread_key_t currkey,mainkey;

static void CSCoroutineFreeMain(CSCoroutine *main) { [main release]; }

static CSCoroutine *CSMainCoroutine()
{
	CSCoroutine *main=(CSCoroutine *)pthread_getspecific(mainkey);
	if(!main)
	{
		main=[[CSCoroutine alloc] initWithTarget:nil stackSize:0];
		pthread_setspecific(mainkey,main);
	}
	return main;
}

static CSCoroutine *CSCurrentCoroutine()
{
	CSCoroutine *curr=(CSCoroutine *)pthread_getspecific(currkey);
	if(curr) return curr;
	else return CSMainCoroutine();
}

static CSCoroutine *CSSetCurrentCoroutine(CSCoroutine *new)
{
	CSCoroutine *curr=CSCurrentCoroutine();
	pthread_setspecific(currkey,new);
	return curr;
}

static void CSSetEntryPoint(jmp_buf env,void (*entry)(),void *stack,int stacksize)
{
	#if defined(__i386__)
	env[9]=(((int)stack+stacksize)&~15)-4; // -4 to pretend that a return address has just been pushed onto the stack
	env[12]=(int)entry;
	#else
	env[0]=((int)stack+stacksize-64)&~3;
	env[21]=(int)entry;
	#endif
}

@implementation CSCoroutine

+(void)initialize
{
	pthread_key_create(&currkey,NULL);
	pthread_key_create(&mainkey,(void (*)())CSCoroutineFreeMain);
}

+(CSCoroutine *)mainCoroutine { return CSMainCoroutine(); }

+(CSCoroutine *)currentCoroutine { return CSCurrentCoroutine(); }

+(void)setCurrentCoroutine:(CSCoroutine *)curr { CSSetCurrentCoroutine(curr); }

+(void)returnFromCurrent { [CSCurrentCoroutine() returnFrom]; }

-(id)initWithTarget:(id)targetobj stackSize:(size_t)stackbytes
{
	target=targetobj;
	stacksize=stackbytes;
	if(stacksize) stack=malloc(stacksize);
	fired=target?NO:YES;

	caller=nil;
	inv=nil;

	return self;
}

-(void)dealloc
{
	free(stack);
	[inv release];
	[super dealloc];
}

-(void)switchTo
{
	CSCoroutine *curr=CSSetCurrentCoroutine(self);
	caller=curr;
	if(_setjmp(curr->env)==0) _longjmp(env,1);
}

-(void)returnFrom
{
	/*CSCoroutine *curr=*/CSSetCurrentCoroutine(caller);
	if(_setjmp(env)==0) _longjmp(caller->env,1);
}



static void CSTigerCoroutineStart()
{
	CSCoroutine *coro=CSCurrentCoroutine();
	objc_msgSendv(coro->target,coro->selector,coro->argsize,coro->arguments);
	[coro returnFrom];
	[NSException raise:@"CSCoroutineException" format:@"Attempted to switch to a coroutine that has ended"];
}

-forward:(SEL)sel :(marg_list)args // Tiger forwarding
{
	if(fired) [NSException raise:@"CSCoroutineException" format:@"Attempted to start a coroutine that is already running"];
	fired=YES;

	selector=sel;
	arguments=args;
	Method method=class_getInstanceMethod([target class],sel);
	if(!method) { [self doesNotRecognizeSelector:sel]; return nil; }
	argsize=method_getSizeOfArguments(method);

	_setjmp(env);
	CSSetEntryPoint(env,CSTigerCoroutineStart,stack,stacksize);

	[self switchTo];
	return nil;
}



-(NSMethodSignature *)methodSignatureForSelector:(SEL)sel { return [target methodSignatureForSelector:sel]; }

static void CSLeopardCoroutineStart()
{
	CSCoroutine *coro=CSCurrentCoroutine();
	[coro->inv invoke];
	[coro returnFrom];
	[NSException raise:@"CSCoroutineException" format:@"Attempted to switch to a coroutine that has ended"];
}

-(void)forwardInvocation:(NSInvocation *)invocation
{
	if(fired) [NSException raise:@"CSCoroutineException" format:@"Attempted to start a coroutine that is already running"];
	fired=YES;

	inv=[invocation retain];
	[inv setTarget:target];

	_setjmp(env);
	CSSetEntryPoint(env,CSLeopardCoroutineStart,stack,stacksize);

	[self switchTo];
}

@end



@implementation NSObject (CSCoroutine)

-(CSCoroutine *)newCoroutine
{ return [[CSCoroutine alloc] initWithTarget:self stackSize:1024*1024]; }

-(CSCoroutine *)newCoroutineWithStackSize:(size_t)stacksize
{ return [[CSCoroutine alloc] initWithTarget:self stackSize:stacksize]; }

@end