libhw_generic: alarmclock: Use libobj instead of vcall.h

11 files changed, 84 insertions, 135 deletions

diff --git a/lib9p/tests/test_server/main.c b/lib9p/tests/test_server/main.c
index b979a4b..8df3da0 100644
--- a/lib9p/tests/test_server/main.c
+++ b/lib9p/tests/test_server/main.c
@@ -13,6 +13,7 @@
 #include <libhw/host_alarmclock.h>
 #include <libhw/host_net.h>
 #include <libmisc/macro.h>
+#include <libmisc/vcall.h>
 #include <util9p/static.h>
 
 #include "static.h"
@@ -195,10 +196,9 @@ static COROUTINE init_cr(void *) {
 
 int main() {
 	struct hostclock clock_monotonic = {
-		.vtable   = &hostclock_vtable,
 		.clock_id = CLOCK_MONOTONIC,
 	};
-	bootclock = &clock_monotonic;
+	bootclock = lo_box_hostclock_as_alarmclock(&clock_monotonic);
 	coroutine_add("init", init_cr, NULL);
 	coroutine_main();
 	return 0;
diff --git a/libdhcp/dhcp_client.c b/libdhcp/dhcp_client.c
index ea6ed28..d6b2f19 100644
--- a/libdhcp/dhcp_client.c
+++ b/libdhcp/dhcp_client.c
@@ -1,6 +1,6 @@
 /* libdhcp/dhcp_client.c - A DHCP client
  *
- * Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
  * SPDX-License-Identifier: AGPL-3.0-or-later
  *
  * -----------------------------------------------------------------------------
@@ -313,7 +313,7 @@ static bool dhcp_client_send(struct dhcp_client *client, uint8_t msgtyp, const c
 		switch (msgtyp) {
 		case DHCP_MSGTYP_DISCOVER: case DHCP_MSGTYP_INFORM:
 		case DHCP_MSGTYP_REQUEST:
-			secs = (VCALL(bootclock, get_time_ns) - client->time_ns_init)/NS_PER_S;
+			secs = (LO_CALL(bootclock, get_time_ns) - client->time_ns_init)/NS_PER_S;
 			if (!secs)
 				/* systemd's sd-dhcp-client.c asserts that some
 				 * servers are broken and require .secs to be
@@ -772,7 +772,7 @@ static void dhcp_client_setstate(struct dhcp_client *client,
 		switch (client->state) {
 		case STATE_INIT:
 			client->xid = rand_uint63n(UINT32_MAX);
-			client->time_ns_init = VCALL(bootclock, get_time_ns);
+			client->time_ns_init = LO_CALL(bootclock, get_time_ns);
 			dhcp_client_setstate(client, STATE_SELECTING, DHCP_MSGTYP_DISCOVER, NULL, scratch_msg);
 			break;
 		case STATE_SELECTING:
@@ -840,7 +840,7 @@ static void dhcp_client_setstate(struct dhcp_client *client,
 			break;
 		case STATE_RENEWING:
 			client->xid = rand_uint63n(UINT32_MAX);
-			client->time_ns_init = VCALL(bootclock, get_time_ns);
+			client->time_ns_init = LO_CALL(bootclock, get_time_ns);
 
 			VCALL(client->sock, set_read_deadline, client->lease_time_ns_t2);
 			switch ((r = dhcp_client_recv(client, scratch_msg))) {
diff --git a/libhw/host_alarmclock.c b/libhw/host_alarmclock.c
index bb1821a..19ece7c 100644
--- a/libhw/host_alarmclock.c
+++ b/libhw/host_alarmclock.c
@@ -10,7 +10,6 @@
 
 #include <libcr/coroutine.h>
 #include <libmisc/assert.h>
-#include <libmisc/vcall.h>
 
 #define IMPLEMENTATION_FOR_LIBHW_GENERIC_ALARMCLOCK_H YES
 #include <libhw/generic/alarmclock.h>
@@ -20,28 +19,9 @@
 
 #include "host_util.h" /* for host_sigrt_alloc(), ns_to_host_ns_time() */
 
-/* Globals ********************************************************************/
+LO_IMPLEMENTATION_C(alarmclock, struct hostclock, hostclock, static)
 
-static uint64_t hostclock_get_time_ns(implements_alarmclock *self);
-static bool     hostclock_add_trigger(implements_alarmclock *self,
-                                      struct alarmclock_trigger *trigger,
-                                      uint64_t   fire_at_ns,
-                                      void       (*cb)(void *),
-                                      void      *cb_arg);
-static void     hostclock_del_trigger(implements_alarmclock *self,
-                                      struct alarmclock_trigger *trigger);
-
-struct alarmclock_vtable hostclock_vtable = {
-	.get_time_ns = hostclock_get_time_ns,
-	.add_trigger = hostclock_add_trigger,
-	.del_trigger = hostclock_del_trigger,
-};
-
-/* Main implementation ********************************************************/
-
-static uint64_t hostclock_get_time_ns(implements_alarmclock *_alarmclock) {
-	struct hostclock *alarmclock =
-		VCALL_SELF(struct hostclock, implements_alarmclock, _alarmclock);
+static uint64_t hostclock_get_time_ns(struct hostclock *alarmclock) {
 	assert(alarmclock);
 
 	struct timespec ts;
@@ -76,13 +56,11 @@ static void hostclock_handle_sig_alarm(int LM_UNUSED(sig), siginfo_t *info, void
 	}
 }
 
-static bool hostclock_add_trigger(implements_alarmclock *_alarmclock,
-                                      struct alarmclock_trigger *trigger,
-                                      uint64_t   fire_at_ns,
-                                      void       (*cb)(void *),
-                                      void      *cb_arg) {
-	struct hostclock *alarmclock =
-		VCALL_SELF(struct hostclock, implements_alarmclock, _alarmclock);
+static bool hostclock_add_trigger(struct hostclock *alarmclock,
+                                  struct alarmclock_trigger *trigger,
+                                  uint64_t   fire_at_ns,
+                                  void       (*cb)(void *),
+                                  void      *cb_arg) {
 	assert(alarmclock);
 	assert(trigger);
 	assert(fire_at_ns);
@@ -133,11 +111,8 @@ static bool hostclock_add_trigger(implements_alarmclock *_alarmclock,
 	return false;
 }
 
-static void hostclock_del_trigger(implements_alarmclock *_alarmclock,
-                                      struct alarmclock_trigger *trigger) {
-	struct hostclock *alarmclock =
-		VCALL_SELF(struct hostclock, implements_alarmclock, _alarmclock);
-
+static void hostclock_del_trigger(struct hostclock *alarmclock,
+                                  struct alarmclock_trigger *trigger) {
 	assert(alarmclock);
 	assert(trigger);
 
diff --git a/libhw/host_include/libhw/host_alarmclock.h b/libhw/host_include/libhw/host_alarmclock.h
index 163fb9f..89df68a 100644
--- a/libhw/host_include/libhw/host_alarmclock.h
+++ b/libhw/host_include/libhw/host_alarmclock.h
@@ -14,7 +14,6 @@
 #include <libhw/generic/alarmclock.h>
 
 struct hostclock {
-	implements_alarmclock;
 	clockid_t                        clock_id;
 
 	BEGIN_PRIVATE(LIBHW_HOST_ALARMCLOCK_H)
@@ -23,7 +22,6 @@ struct hostclock {
 	struct alarmclock_trigger       *queue;
 	END_PRIVATE(LIBHW_HOST_ALARMCLOCK_H)
 };
-
-extern struct alarmclock_vtable hostclock_vtable;
+LO_IMPLEMENTATION_H(alarmclock, struct hostclock, hostclock)
 
 #endif /* _LIBHW_HOST_ALARMCLOCK_H_ */
diff --git a/libhw/host_net.c b/libhw/host_net.c
index bf79480..3352b87 100644
--- a/libhw/host_net.c
+++ b/libhw/host_net.c
@@ -267,7 +267,7 @@ static ssize_t hostnet_tcp_read(implements_net_stream_conn *_conn, void *buf, si
 		.ret          = &ret,
 	};
 	if (conn->read_deadline_ns) {
-		uint64_t now_ns = VCALL(bootclock, get_time_ns);
+		uint64_t now_ns = LO_CALL(bootclock, get_time_ns);
 		if (conn->read_deadline_ns < now_ns)
 			return -NET_ERECV_TIMEOUT;
 		args.timeout = ns_to_host_us_time(conn->read_deadline_ns-now_ns);
@@ -534,7 +534,7 @@ static ssize_t hostnet_udp_recvfrom(implements_net_packet_conn *_conn, void *buf
 		.ret_port     = ret_port,
 	};
 	if (conn->read_deadline_ns) {
-		uint64_t now_ns = VCALL(bootclock, get_time_ns);
+		uint64_t now_ns = LO_CALL(bootclock, get_time_ns);
 		if (conn->read_deadline_ns < now_ns)
 			return -NET_ERECV_TIMEOUT;
 		args.timeout = ns_to_host_us_time(conn->read_deadline_ns-now_ns);
diff --git a/libhw/rp2040_hwtimer.c b/libhw/rp2040_hwtimer.c
index 6c871a3..ada6246 100644
--- a/libhw/rp2040_hwtimer.c
+++ b/libhw/rp2040_hwtimer.c
@@ -9,10 +9,10 @@
 
 #include <libcr/coroutine.h>
 #include <libmisc/assert.h>
-#include <libmisc/vcall.h>
 
 #define IMPLEMENTATION_FOR_LIBHW_GENERIC_ALARMCLOCK_H YES
 #include <libhw/generic/alarmclock.h>
+
 #include <libhw/rp2040_hwtimer.h>
 
 /******************************************************************************/
@@ -23,46 +23,32 @@ void add_alarm_at(void) {};
 /* Types **********************************************************************/
 
 struct rp2040_hwtimer {
-	implements_alarmclock;
 	enum rp2040_hwalarm_instance     alarm_num;
 	bool                             initialized;
 	struct alarmclock_trigger       *queue;
 };
+LO_IMPLEMENTATION_H(alarmclock, struct rp2040_hwtimer, rp2040_hwtimer);
+LO_IMPLEMENTATION_C(alarmclock, struct rp2040_hwtimer, rp2040_hwtimer, static);
 
 /* Globals ********************************************************************/
 
-static uint64_t rp2040_hwtimer_get_time_ns(implements_alarmclock *self);
-static bool     rp2040_hwtimer_add_trigger(implements_alarmclock *self,
-                                           struct alarmclock_trigger *trigger,
-                                           uint64_t   fire_at_ns,
-                                           void       (*cb)(void *),
-                                           void      *cb_arg);
-static void     rp2040_hwtimer_del_trigger(implements_alarmclock *self,
-                                           struct alarmclock_trigger *trigger);
-
-static struct alarmclock_vtable rp2040_hwtimer_vtable = {
-	.get_time_ns = rp2040_hwtimer_get_time_ns,
-	.add_trigger = rp2040_hwtimer_add_trigger,
-	.del_trigger = rp2040_hwtimer_del_trigger,
-};
-
 static struct rp2040_hwtimer hwtimers[] = {
-	{ .vtable = &rp2040_hwtimer_vtable, .alarm_num = 0 },
-	{ .vtable = &rp2040_hwtimer_vtable, .alarm_num = 1 },
-	{ .vtable = &rp2040_hwtimer_vtable, .alarm_num = 2 },
-	{ .vtable = &rp2040_hwtimer_vtable, .alarm_num = 3 },
+	{ .alarm_num = 0 },
+	{ .alarm_num = 1 },
+	{ .alarm_num = 2 },
+	{ .alarm_num = 3 },
 };
 static_assert(sizeof(hwtimers)/sizeof(hwtimers[0]) == _RP2040_HWALARM_NUM);
 
 /* Main implementation ********************************************************/
 
-implements_alarmclock *rp2040_hwtimer(enum rp2040_hwalarm_instance alarm_num) {
+lo_interface alarmclock rp2040_hwtimer(enum rp2040_hwalarm_instance alarm_num) {
 	assert(alarm_num < _RP2040_HWALARM_NUM);
-	return &hwtimers[alarm_num];
+	return lo_box_rp2040_hwtimer_as_alarmclock(&hwtimers[alarm_num]);
 }
 
 
-static uint64_t rp2040_hwtimer_get_time_ns(implements_alarmclock *) {
+static uint64_t rp2040_hwtimer_get_time_ns(struct rp2040_hwtimer *) {
 	return timer_time_us_64(timer_hw) * (NS_PER_S/US_PER_S);
 }
 
@@ -91,13 +77,11 @@ static void rp2040_hwtimer_intrhandler(void) {
 		timer_hw->alarm[alarm_num] = (uint32_t)NS_TO_US_ROUNDUP(alarmclock->queue->fire_at_ns);
 }
 
-static bool rp2040_hwtimer_add_trigger(implements_alarmclock     *_alarmclock,
+static bool rp2040_hwtimer_add_trigger(struct rp2040_hwtimer     *alarmclock,
                                        struct alarmclock_trigger *trigger,
                                        uint64_t                   fire_at_ns,
                                        void                       (*cb)(void *),
                                        void                      *cb_arg) {
-	struct rp2040_hwtimer *alarmclock =
-		VCALL_SELF(struct rp2040_hwtimer, implements_alarmclock, _alarmclock);
 	assert(alarmclock);
 	assert(trigger);
 	assert(fire_at_ns);
@@ -147,10 +131,8 @@ static bool rp2040_hwtimer_add_trigger(implements_alarmclock     *_alarmclock,
 	return false;
 }
 
-static void rp2040_hwtimer_del_trigger(implements_alarmclock     *_alarmclock,
+static void rp2040_hwtimer_del_trigger(struct rp2040_hwtimer     *alarmclock,
                                        struct alarmclock_trigger *trigger) {
-	struct rp2040_hwtimer *alarmclock =
-		VCALL_SELF(struct rp2040_hwtimer, implements_alarmclock, _alarmclock);
 	assert(alarmclock);
 	assert(trigger);
 
diff --git a/libhw/rp2040_include/libhw/rp2040_hwtimer.h b/libhw/rp2040_include/libhw/rp2040_hwtimer.h
index 645ba20..40e4172 100644
--- a/libhw/rp2040_include/libhw/rp2040_hwtimer.h
+++ b/libhw/rp2040_include/libhw/rp2040_hwtimer.h
@@ -20,6 +20,6 @@ enum rp2040_hwalarm_instance {
 	_RP2040_HWALARM_NUM,
 };
 
-implements_alarmclock *rp2040_hwtimer(enum rp2040_hwalarm_instance alarm_num);
+lo_interface alarmclock rp2040_hwtimer(enum rp2040_hwalarm_instance alarm_num);
 
 #endif /* _LIBHW_RP2040_HWTIMER_H_ */
diff --git a/libhw/w5500.c b/libhw/w5500.c
index cebcf8e..5a9a718 100644
--- a/libhw/w5500.c
+++ b/libhw/w5500.c
@@ -1,6 +1,6 @@
 /* libhw/w5500.c - <libhw/generic/net.h> implementation for the WIZnet W5500 chip
  *
- * Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
  * SPDX-License-Identifier: AGPL-3.0-or-later
  *
  * -----------------------------------------------------------------------------
@@ -744,7 +744,7 @@ static ssize_t w5500_tcp_read(implements_net_stream_conn *_socket, void *buf, si
 
 	struct alarmclock_trigger trigger = {0};
 	if (socket->read_deadline_ns)
-		VCALL(bootclock, add_trigger, &trigger,
+		LO_CALL(bootclock, add_trigger, &trigger,
 		      socket->read_deadline_ns,
 		      w5500_tcp_alarm_handler,
 		      socket);
@@ -753,12 +753,12 @@ static ssize_t w5500_tcp_read(implements_net_stream_conn *_socket, void *buf, si
 	uint16_t avail = 0;
 	for (;;) {
 		if (!socket->read_open) {
-			VCALL(bootclock, del_trigger, &trigger);
+			LO_CALL(bootclock, del_trigger, &trigger);
 			debugf(" => soft closed");
 			return -NET_ECLOSED;
 		}
-		if (socket->read_deadline_ns && socket->read_deadline_ns <= VCALL(bootclock, get_time_ns)) {
-			VCALL(bootclock, del_trigger, &trigger);
+		if (socket->read_deadline_ns && socket->read_deadline_ns <= LO_CALL(bootclock, get_time_ns)) {
+			LO_CALL(bootclock, del_trigger, &trigger);
 			debugf(" => recv timeout");
 			return -NET_ERECV_TIMEOUT;
 		}
@@ -770,7 +770,7 @@ static ssize_t w5500_tcp_read(implements_net_stream_conn *_socket, void *buf, si
 		case STATE_TCP_FIN_WAIT:
 			break; /* OK */
 		default:
-			VCALL(bootclock, del_trigger, &trigger);
+			LO_CALL(bootclock, del_trigger, &trigger);
 			cr_mutex_unlock(&chip->mu);
 			debugf(" => hard closed");
 			return -NET_ECLOSED;
@@ -781,7 +781,7 @@ static ssize_t w5500_tcp_read(implements_net_stream_conn *_socket, void *buf, si
 			/* We have data to read.  */
 			break;
 		if (state == STATE_TCP_CLOSE_WAIT) {
-			VCALL(bootclock, del_trigger, &trigger);
+			LO_CALL(bootclock, del_trigger, &trigger);
 			cr_mutex_unlock(&chip->mu);
 			debugf(" => EOF");
 			return 0;
@@ -801,7 +801,7 @@ static ssize_t w5500_tcp_read(implements_net_stream_conn *_socket, void *buf, si
 	w5500ll_write_sock_reg(chip->spidev, socknum, rx_read_pointer, uint16be_marshal(ptr+avail));
 	w5500_socket_cmd(socket, CMD_RECV);
 	/* Return.  */
-	VCALL(bootclock, del_trigger, &trigger);
+	LO_CALL(bootclock, del_trigger, &trigger);
 	cr_mutex_unlock(&chip->mu);
 	return avail;
 }
@@ -916,23 +916,23 @@ static ssize_t w5500_udp_recvfrom(implements_net_packet_conn *_socket, void *buf
 
 	struct alarmclock_trigger trigger = {0};
 	if (socket->read_deadline_ns)
-		VCALL(bootclock, add_trigger, &trigger,
-		      socket->read_deadline_ns,
-		      w5500_udp_alarm_handler,
-		      socket);
+		LO_CALL(bootclock, add_trigger, &trigger,
+		        socket->read_deadline_ns,
+		        w5500_udp_alarm_handler,
+		        socket);
 
 	/* Wait until there is data to read.  */
 	uint16_t avail = 0;
 	for (;;) {
-		if (socket->read_deadline_ns && socket->read_deadline_ns <= VCALL(bootclock, get_time_ns)) {
-			VCALL(bootclock, del_trigger, &trigger);
+		if (socket->read_deadline_ns && socket->read_deadline_ns <= LO_CALL(bootclock, get_time_ns)) {
+			LO_CALL(bootclock, del_trigger, &trigger);
 			debugf(" => recv timeout");
 			return -NET_ERECV_TIMEOUT;
 		}
 		cr_mutex_lock(&chip->mu);
 		uint8_t state = w5500ll_read_sock_reg(chip->spidev, socknum, state);
 		if (state != STATE_UDP) {
-			VCALL(bootclock, del_trigger, &trigger);
+			LO_CALL(bootclock, del_trigger, &trigger);
 			debugf(" => hard closed");
 			return -NET_ECLOSED;
 		}
@@ -970,7 +970,7 @@ static ssize_t w5500_udp_recvfrom(implements_net_packet_conn *_socket, void *buf
 	w5500ll_write_sock_reg(chip->spidev, socknum, rx_read_pointer, uint16be_marshal(ptr+8+len));
 	w5500_socket_cmd(socket, CMD_RECV);
 	/* Return.  */
-	VCALL(bootclock, del_trigger, &trigger);
+	LO_CALL(bootclock, del_trigger, &trigger);
 	cr_mutex_unlock(&chip->mu);
 	return len;
 }
diff --git a/libhw_generic/CMakeLists.txt b/libhw_generic/CMakeLists.txt
index 0356770..e38fbe9 100644
--- a/libhw_generic/CMakeLists.txt
+++ b/libhw_generic/CMakeLists.txt
@@ -1,12 +1,13 @@
 # libhw_generic/CMakeLists.txt - UAPI device interfaces
 #
-# Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
+# Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
 add_library(libhw_generic INTERFACE)
 target_include_directories(libhw_generic SYSTEM INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}/include)
 target_link_libraries(libhw_generic INTERFACE
 	libmisc
+	libobj
 	libcr
 )
 
diff --git a/libhw_generic/alarmclock.c b/libhw_generic/alarmclock.c
index d501f51..7fd049e 100644
--- a/libhw_generic/alarmclock.c
+++ b/libhw_generic/alarmclock.c
@@ -5,22 +5,21 @@
  */
 
 #include <libcr/coroutine.h>
-#include <libmisc/vcall.h>
 
 #include <libhw/generic/alarmclock.h>
 
-implements_alarmclock *bootclock = NULL;
+lo_interface alarmclock bootclock = {0};
 
 static void alarmclock_sleep_intrhandler(void *_arg) {
 	cid_t cid = *(cid_t *)_arg;
 	cr_unpause_from_intrhandler(cid);
 }
 
-void alarmclock_sleep_until_ns(implements_alarmclock *clock, uint64_t abstime_ns) {
+void alarmclock_sleep_until_ns(lo_interface alarmclock clock, uint64_t abstime_ns) {
 	bool saved = cr_save_and_disable_interrupts();
 	cid_t cid = cr_getcid();
 	struct alarmclock_trigger trigger;
-	VCALL(clock, add_trigger, &trigger, abstime_ns, alarmclock_sleep_intrhandler, &cid);
+	LO_CALL(clock, add_trigger, &trigger, abstime_ns, alarmclock_sleep_intrhandler, &cid);
 	cr_pause_and_yield();
 	cr_restore_interrupts(saved);
 }
diff --git a/libhw_generic/include/libhw/generic/alarmclock.h b/libhw_generic/include/libhw/generic/alarmclock.h
index a9d816b..3817b4b 100644
--- a/libhw_generic/include/libhw/generic/alarmclock.h
+++ b/libhw_generic/include/libhw/generic/alarmclock.h
@@ -1,6 +1,6 @@
 /* libhw/generic/alarmclock.h - Device-independent alarmclock definitions
  *
- * Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
  * SPDX-License-Identifier: AGPL-3.0-or-later
  */
 
@@ -11,7 +11,7 @@
 #include <stdint.h>  /* for uint{n}_t and UINT{n}_C */
 
 #include <libmisc/private.h>
-#include <libmisc/vcall.h>
+#include <libobj/obj.h>
 
 /* Useful constants ***********************************************************/
 
@@ -35,59 +35,53 @@ struct alarmclock_trigger {
 
 /* Interface ******************************************************************/
 
-struct alarmclock_vtable;
-
-typedef struct {
-	struct alarmclock_vtable     *vtable;
-} implements_alarmclock;
-
-struct alarmclock_vtable {
-	/**
-	 * (2⁶⁴-1 nanoseconds is more than 500 years; there is little
-	 * risk of this overflowing)
-	 */
-	uint64_t (*get_time_ns)(implements_alarmclock *self);
-
-	/**
-	 * Returns true on error.
-	 *
-	 * Implementations may return an error if fire_at_ns is more
-	 * than UINT32_MAX µs (72 minutes) in the future.
-	 *
-	 * If fire_at_ns is in the past, then it will fire
-	 * immediately.
-	 */
-	bool     (*add_trigger)(implements_alarmclock *self, struct alarmclock_trigger *trigger,
-	                        uint64_t   fire_at_ns,
-	                        void       (*cb)(void *),
-	                        void      *cb_arg);
-
-	void     (*del_trigger)(implements_alarmclock *self, struct alarmclock_trigger *trigger);
-};
+#define alarmclock_LO_IFACE                                            \
+	/**                                                            \
+	 * (2⁶⁴-1 nanoseconds is more than 500 years; there is little  \
+	 * risk of this overflowing)                                   \
+	 */                                                            \
+	LO_FUNC(uint64_t, get_time_ns)                                 \
+                                                                       \
+	/**                                                            \
+	 * Returns true on error.                                      \
+	 *                                                             \
+	 * Implementations may return an error if fire_at_ns is more   \
+	 * than UINT32_MAX µs (72 minutes) in the future.              \
+	 *                                                             \
+	 * If fire_at_ns is in the past, then it will fire             \
+	 * immediately.                                                \
+	 */                                                            \
+	LO_FUNC(bool, add_trigger, struct alarmclock_trigger *trigger, \
+	                           uint64_t   fire_at_ns,              \
+	                           void       (*cb)(void *),           \
+	                           void      *cb_arg)                  \
+                                                                       \
+	LO_FUNC(void, del_trigger, struct alarmclock_trigger *trigger)
+LO_INTERFACE(alarmclock)
 
 /* Utilities ******************************************************************/
 
-void alarmclock_sleep_until_ns(implements_alarmclock *clock, uint64_t abstime_ns);
+void alarmclock_sleep_until_ns(lo_interface alarmclock clock, uint64_t abstime_ns);
 
-static inline void alarmclock_sleep_for_ns(implements_alarmclock *clock, uint64_t delta_ns) {
-	alarmclock_sleep_until_ns(clock, VCALL(clock, get_time_ns) + delta_ns);
+static inline void alarmclock_sleep_for_ns(lo_interface alarmclock clock, uint64_t delta_ns) {
+	alarmclock_sleep_until_ns(clock, LO_CALL(clock, get_time_ns) + delta_ns);
 }
 
-static inline void alarmclock_sleep_for_us(implements_alarmclock *clock, uint64_t delta_us) {
+static inline void alarmclock_sleep_for_us(lo_interface alarmclock clock, uint64_t delta_us) {
 	alarmclock_sleep_for_ns(clock, delta_us * (NS_PER_S/US_PER_S));
 }
 
-static inline void alarmclock_sleep_for_ms(implements_alarmclock *clock, uint64_t delta_ms) {
+static inline void alarmclock_sleep_for_ms(lo_interface alarmclock clock, uint64_t delta_ms) {
 	alarmclock_sleep_for_ns(clock, delta_ms * (NS_PER_S/MS_PER_S));
 }
 
-static inline void alarmclock_sleep_for_s(implements_alarmclock *clock, uint64_t delta_s) {
+static inline void alarmclock_sleep_for_s(lo_interface alarmclock clock, uint64_t delta_s) {
 	alarmclock_sleep_for_ns(clock, delta_s * NS_PER_S);
 }
 
 /* Globals ********************************************************************/
 
-extern implements_alarmclock *bootclock;
+extern lo_interface alarmclock bootclock;
 
 #define sleep_until_ns(t) alarmclock_sleep_until_ns(bootclock, t)
 #define sleep_for_ns(t)   alarmclock_sleep_for_ns(bootclock, t)