1 files changed, 441 insertions, 0 deletions
diff --git a/src/pkg/runtime/darwin/thread.c b/src/pkg/runtime/darwin/thread.c
new file mode 100644
index 000000000..3a982471a
--- /dev/null
+++ b/src/pkg/runtime/darwin/thread.c
@@ -0,0 +1,441 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "runtime.h"
+#include "defs.h"
+#include "os.h"
+
+static void
+unimplemented(int8 *name)
+{
+	prints(name);
+	prints(" not implemented\n");
+	*(int32*)1231 = 1231;
+}
+
+// Thread-safe allocation of a semaphore.
+// Psema points at a kernel semaphore key.
+// It starts out zero, meaning no semaphore.
+// Fill it in, being careful of others calling initsema
+// simultaneously.
+static void
+initsema(uint32 *psema)
+{
+	uint32 sema;
+
+	if(*psema != 0)	// already have one
+		return;
+
+	sema = mach_semcreate();
+	if(!cas(psema, 0, sema)){
+		// Someone else filled it in.  Use theirs.
+		mach_semdestroy(sema);
+		return;
+	}
+}
+
+
+// Atomic add and return new value.
+static uint32
+xadd(uint32 volatile *val, int32 delta)
+{
+	uint32 oval, nval;
+
+	for(;;){
+		oval = *val;
+		nval = oval + delta;
+		if(cas(val, oval, nval))
+			return nval;
+	}
+}
+
+
+// Blocking locks.
+
+// Implement Locks, using semaphores.
+// l->key is the number of threads who want the lock.
+// In a race, one thread increments l->key from 0 to 1
+// and the others increment it from >0 to >1.  The thread
+// who does the 0->1 increment gets the lock, and the
+// others wait on the semaphore.  When the 0->1 thread
+// releases the lock by decrementing l->key, l->key will
+// be >0, so it will increment the semaphore to wake up
+// one of the others.  This is the same algorithm used
+// in Plan 9's user-level locks.
+//
+// Note that semaphores are never destroyed (the kernel
+// will clean up when the process exits).  We assume for now
+// that Locks are only used for long-lived structures like M and G.
+
+void
+lock(Lock *l)
+{
+	if(m->locks < 0)
+		throw("lock count");
+	m->locks++;
+
+	// Allocate semaphore if needed.
+	if(l->sema == 0)
+		initsema(&l->sema);
+
+	if(xadd(&l->key, 1) > 1)	// someone else has it; wait
+		mach_semacquire(l->sema);
+}
+
+void
+unlock(Lock *l)
+{
+	m->locks--;
+	if(m->locks < 0)
+		throw("lock count");
+
+	if(xadd(&l->key, -1) > 0)	// someone else is waiting
+		mach_semrelease(l->sema);
+}
+
+
+// User-level semaphore implementation:
+// try to do the operations in user space on u,
+// but when it's time to block, fall back on the kernel semaphore k.
+// This is the same algorithm used in Plan 9.
+void
+usemacquire(Usema *s)
+{
+	if((int32)xadd(&s->u, -1) < 0)
+		mach_semacquire(s->k);
+}
+
+void
+usemrelease(Usema *s)
+{
+	if((int32)xadd(&s->u, 1) <= 0)
+		mach_semrelease(s->k);
+}
+
+
+// Event notifications.
+void
+noteclear(Note *n)
+{
+	n->wakeup = 0;
+}
+
+void
+notesleep(Note *n)
+{
+	if(n->sema.k == 0)
+		initsema(&n->sema.k);
+	while(!n->wakeup)
+		usemacquire(&n->sema);
+}
+
+void
+notewakeup(Note *n)
+{
+	if(n->sema.k == 0)
+		initsema(&n->sema.k);
+	n->wakeup = 1;
+	usemrelease(&n->sema);
+}
+
+
+// BSD interface for threading.
+void
+osinit(void)
+{
+	// Register our thread-creation callback (see {amd64,386}/sys.s).
+	bsdthread_register();
+}
+
+void
+newosproc(M *m, G *g, void *stk, void (*fn)(void))
+{
+	// printf("newosproc m=%p g=%p stk=%p fn=%p\n", m, g, stk, fn);
+	m->tls[0] = m->id;	// so 386 asm can find it
+	bsdthread_create(stk, m, g, fn);
+}
+
+// Called to initialize a new m (including the bootstrap m).
+void
+minit(void)
+{
+	// Initialize signal handling.
+	m->gsignal = malg(32*1024);	// OS X wants >=8K, Linux >=2K
+	signalstack(m->gsignal->stackguard, 32*1024);
+}
+
+// Mach IPC, to get at semaphores
+// Definitions are in /usr/include/mach on a Mac.
+
+static void
+macherror(int32 r, int8 *fn)
+{
+	printf("mach error %s: %d\n", fn, r);
+	throw("mach error");
+}
+
+enum
+{
+	DebugMach = 0
+};
+
+static MachNDR zerondr;
+
+#define MACH_MSGH_BITS(a, b) ((a) | ((b)<<8))
+
+static int32
+mach_msg(MachHeader *h,
+	int32 op,
+	uint32 send_size,
+	uint32 rcv_size,
+	uint32 rcv_name,
+	uint32 timeout,
+	uint32 notify)
+{
+	// TODO: Loop on interrupt.
+	return mach_msg_trap(h, op, send_size, rcv_size, rcv_name, timeout, notify);
+}
+
+// Mach RPC (MIG)
+
+enum
+{
+	MinMachMsg = 48,
+	Reply = 100,
+};
+
+#pragma pack on
+typedef struct CodeMsg CodeMsg;
+struct CodeMsg
+{
+	MachHeader h;
+	MachNDR NDR;
+	int32 code;
+};
+#pragma pack off
+
+static int32
+machcall(MachHeader *h, int32 maxsize, int32 rxsize)
+{
+	uint32 *p;
+	int32 i, ret, id;
+	uint32 port;
+	CodeMsg *c;
+
+	if((port = m->machport) == 0){
+		port = mach_reply_port();
+		m->machport = port;
+	}
+
+	h->msgh_bits |= MACH_MSGH_BITS(MACH_MSG_TYPE_COPY_SEND, MACH_MSG_TYPE_MAKE_SEND_ONCE);
+	h->msgh_local_port = port;
+	h->msgh_reserved = 0;
+	id = h->msgh_id;
+
+	if(DebugMach){
+		p = (uint32*)h;
+		prints("send:\t");
+		for(i=0; i<h->msgh_size/sizeof(p[0]); i++){
+			prints(" ");
+			sys·printpointer((void*)p[i]);
+			if(i%8 == 7)
+				prints("\n\t");
+		}
+		if(i%8)
+			prints("\n");
+	}
+
+	ret = mach_msg(h, MACH_SEND_MSG|MACH_RCV_MSG,
+		h->msgh_size, maxsize, port, 0, 0);
+	if(ret != 0){
+		if(DebugMach){
+			prints("mach_msg error ");
+			sys·printint(ret);
+			prints("\n");
+		}
+		return ret;
+	}
+
+	if(DebugMach){
+		p = (uint32*)h;
+		prints("recv:\t");
+		for(i=0; i<h->msgh_size/sizeof(p[0]); i++){
+			prints(" ");
+			sys·printpointer((void*)p[i]);
+			if(i%8 == 7)
+				prints("\n\t");
+		}
+		if(i%8)
+			prints("\n");
+	}
+
+	if(h->msgh_id != id+Reply){
+		if(DebugMach){
+			prints("mach_msg reply id mismatch ");
+			sys·printint(h->msgh_id);
+			prints(" != ");
+			sys·printint(id+Reply);
+			prints("\n");
+		}
+		return -303;	// MIG_REPLY_MISMATCH
+	}
+
+	// Look for a response giving the return value.
+	// Any call can send this back with an error,
+	// and some calls only have return values so they
+	// send it back on success too.  I don't quite see how
+	// you know it's one of these and not the full response
+	// format, so just look if the message is right.
+	c = (CodeMsg*)h;
+	if(h->msgh_size == sizeof(CodeMsg)
+	&& !(h->msgh_bits & MACH_MSGH_BITS_COMPLEX)){
+		if(DebugMach){
+			prints("mig result ");
+			sys·printint(c->code);
+			prints("\n");
+		}
+		return c->code;
+	}
+
+	if(h->msgh_size != rxsize){
+		if(DebugMach){
+			prints("mach_msg reply size mismatch ");
+			sys·printint(h->msgh_size);
+			prints(" != ");
+			sys·printint(rxsize);
+			prints("\n");
+		}
+		return -307;	// MIG_ARRAY_TOO_LARGE
+	}
+
+	return 0;
+}
+
+
+// Semaphores!
+
+enum
+{
+	Tmach_semcreate = 3418,
+	Rmach_semcreate = Tmach_semcreate + Reply,
+
+	Tmach_semdestroy = 3419,
+	Rmach_semdestroy = Tmach_semdestroy + Reply,
+
+	// Mach calls that get interrupted by Unix signals
+	// return this error code.  We retry them.
+	KERN_ABORTED = 14,
+};
+
+typedef struct Tmach_semcreateMsg Tmach_semcreateMsg;
+typedef struct Rmach_semcreateMsg Rmach_semcreateMsg;
+typedef struct Tmach_semdestroyMsg Tmach_semdestroyMsg;
+// Rmach_semdestroyMsg = CodeMsg
+
+#pragma pack on
+struct Tmach_semcreateMsg
+{
+	MachHeader h;
+	MachNDR ndr;
+	int32 policy;
+	int32 value;
+};
+
+struct Rmach_semcreateMsg
+{
+	MachHeader h;
+	MachBody body;
+	MachPort semaphore;
+};
+
+struct Tmach_semdestroyMsg
+{
+	MachHeader h;
+	MachBody body;
+	MachPort semaphore;
+};
+#pragma pack off
+
+uint32
+mach_semcreate(void)
+{
+	union {
+		Tmach_semcreateMsg tx;
+		Rmach_semcreateMsg rx;
+		uint8 pad[MinMachMsg];
+	} m;
+	int32 r;
+
+	m.tx.h.msgh_bits = 0;
+	m.tx.h.msgh_size = sizeof(m.tx);
+	m.tx.h.msgh_remote_port = mach_task_self();
+	m.tx.h.msgh_id = Tmach_semcreate;
+	m.tx.ndr = zerondr;
+
+	m.tx.policy = 0;	// 0 = SYNC_POLICY_FIFO
+	m.tx.value = 0;
+
+	while((r = machcall(&m.tx.h, sizeof m, sizeof(m.rx))) != 0){
+		if(r == KERN_ABORTED)	// interrupted
+			continue;
+		macherror(r, "semaphore_create");
+	}
+	if(m.rx.body.msgh_descriptor_count != 1)
+		unimplemented("mach_semcreate desc count");
+	return m.rx.semaphore.name;
+}
+
+void
+mach_semdestroy(uint32 sem)
+{
+	union {
+		Tmach_semdestroyMsg tx;
+		uint8 pad[MinMachMsg];
+	} m;
+	int32 r;
+
+	m.tx.h.msgh_bits = MACH_MSGH_BITS_COMPLEX;
+	m.tx.h.msgh_size = sizeof(m.tx);
+	m.tx.h.msgh_remote_port = mach_task_self();
+	m.tx.h.msgh_id = Tmach_semdestroy;
+	m.tx.body.msgh_descriptor_count = 1;
+	m.tx.semaphore.name = sem;
+	m.tx.semaphore.disposition = MACH_MSG_TYPE_MOVE_SEND;
+	m.tx.semaphore.type = 0;
+
+	while((r = machcall(&m.tx.h, sizeof m, 0)) != 0){
+		macherror(r, "semaphore_destroy");
+	}
+}
+
+// The other calls have simple system call traps in sys.s
+int32 mach_semaphore_wait(uint32 sema);
+int32 mach_semaphore_timedwait(uint32 sema, uint32 sec, uint32 nsec);
+int32 mach_semaphore_signal(uint32 sema);
+int32 mach_semaphore_signal_all(uint32 sema);
+
+void
+mach_semacquire(uint32 sem)
+{
+	int32 r;
+
+	while((r = mach_semaphore_wait(sem)) != 0) {
+		if(r == KERN_ABORTED)	// interrupted
+			continue;
+		macherror(r, "semaphore_wait");
+	}
+}
+
+void
+mach_semrelease(uint32 sem)
+{
+	int32 r;
+
+	while((r = mach_semaphore_signal(sem)) != 0) {
+		if(r == KERN_ABORTED)	// interrupted
+			continue;
+		macherror(r, "semaphore_signal");
+	}
+}
+