diff --git a/espradio/osi.c b/espradio/osi.c
index 646476b..3d071a8 100644
--- a/espradio/osi.c
+++ b/espradio/osi.c
@@ -6,10 +6,6 @@
 // Documentation for these functions:
 // https://github.com/esp-rs/esp-wifi/blob/main/esp-wifi/src/wifi/os_adapter.rs
 
-// Fake task handle. Used for espradio_task_get_current_task.
-// TODO: get the real task handle somehow.
-static uint8_t current_task = 1;
-
 __attribute__((noreturn))
 void espradio_panic(char *s);
 
@@ -45,13 +41,9 @@ void *espradio_spin_lock_create(void);
 
 void espradio_spin_lock_delete(void *lock);
 
-static uint32_t espradio_wifi_int_disable(void *wifi_int_mux) {
-    espradio_panic("todo: _wifi_int_disable");
-}
+uint32_t espradio_wifi_int_disable(void *wifi_int_mux);
 
-static void espradio_wifi_int_restore(void *wifi_int_mux, uint32_t tmp) {
-    espradio_panic("todo: _wifi_int_restore");
-}
+void espradio_wifi_int_restore(void *wifi_int_mux, uint32_t tmp);
 
 static void espradio_task_yield_from_isr(void) {
     espradio_panic("todo: _task_yield_from_isr");
@@ -59,21 +51,13 @@ static void espradio_task_yield_from_isr(void) {
 
 void *espradio_semphr_create(uint32_t max, uint32_t init);
 
-static void espradio_semphr_delete(void *semphr) {
-    espradio_panic("todo: _semphr_delete");
-}
+void espradio_semphr_delete(void *semphr);
 
-static int32_t espradio_semphr_take(void *semphr, uint32_t block_time_tick) {
-    espradio_panic("todo: _semphr_take");
-}
+int32_t espradio_semphr_take(void *semphr, uint32_t block_time_tick);
 
-static int32_t espradio_semphr_give(void *semphr) {
-    espradio_panic("todo: _semphr_give");
-}
+int32_t espradio_semphr_give(void *semphr);
 
-static void *espradio_wifi_thread_semphr_get(void) {
-    espradio_panic("todo: _wifi_thread_semphr_get");
-}
+void *espradio_wifi_thread_semphr_get(void);
 
 static void *espradio_mutex_create(void) {
     espradio_panic("todo: _mutex_create");
@@ -97,9 +81,7 @@ static void espradio_queue_delete(void *queue) {
     espradio_panic("todo: _queue_delete");
 }
 
-static int32_t espradio_queue_send(void *queue, void *item, uint32_t block_time_tick) {
-    espradio_panic("todo: _queue_send");
-}
+int32_t espradio_queue_send(void *queue, void *item, uint32_t block_time_tick);
 
 static int32_t espradio_queue_send_from_isr(void *queue, void *item, void *hptw) {
     espradio_panic("todo: _queue_send_from_isr");
@@ -113,9 +95,7 @@ static int32_t espradio_queue_send_to_front(void *queue, void *item, uint32_t bl
     espradio_panic("todo: _queue_send_to_front");
 }
 
-static int32_t espradio_queue_recv(void *queue, void *item, uint32_t block_time_tick) {
-    espradio_panic("todo: _queue_recv");
-}
+int32_t espradio_queue_recv(void *queue, void *item, uint32_t block_time_tick);
 
 static uint32_t espradio_queue_msg_waiting(void *queue) {
     espradio_panic("todo: _queue_msg_waiting");
@@ -141,30 +121,24 @@ static uint32_t espradio_event_group_wait_bits(void *event, uint32_t bits_to_wai
     espradio_panic("todo: _event_group_wait_bits");
 }
 
-static int32_t espradio_task_create_pinned_to_core(void *task_func, const char *name, uint32_t stack_depth, void *param, uint32_t prio, void *task_handle, uint32_t core_id) {
-    espradio_panic("todo: _task_create_pinned_to_core");
+void espradio_run_task(void *task_func, void *task_handle) {
+    void (*fn)(void *task_handle) = task_func;
+    fn(task_handle);
 }
 
+int32_t espradio_task_create_pinned_to_core(void *task_func, const char *name, uint32_t stack_depth, void *param, uint32_t prio, void *task_handle, uint32_t core_id);
+
 static int32_t espradio_task_create(void *task_func, const char *name, uint32_t stack_depth, void *param, uint32_t prio, void *task_handle) {
     espradio_panic("todo: _task_create");
 }
 
-static void espradio_task_delete(void *task_handle) {
-    espradio_panic("todo: _task_delete");
-}
+void espradio_task_delete(void *task_handle);
 
-static void espradio_task_delay(uint32_t tick) {
-    espradio_panic("todo: _task_delay");
-}
+void espradio_task_delay(uint32_t tick);
 
-static int32_t espradio_task_ms_to_tick(uint32_t ms) {
-    espradio_panic("todo: _task_ms_to_tick");
-}
+int32_t espradio_task_ms_to_tick(uint32_t ms);
 
-static void *espradio_task_get_current_task(void) {
-    int task_num = current_task;
-    return (void*)task_num;
-}
+void *espradio_task_get_current_task(void);
 
 static int32_t espradio_task_get_max_priority(void) {
     return 255; // arbitrary number
@@ -373,14 +347,12 @@ static void * espradio_wifi_calloc(size_t n, size_t size) {
 }
 
 static void * espradio_wifi_zalloc(size_t size) {
-    espradio_panic("todo: _wifi_zalloc");
+    return calloc(1, size);
 }
 
 void * espradio_wifi_create_queue(int queue_len, int item_size);
 
-static void espradio_wifi_delete_queue(void * queue) {
-    espradio_panic("todo: _wifi_delete_queue");
-}
+void espradio_wifi_delete_queue(void * queue);
 
 static int espradio_coex_init(void) {
     espradio_panic("todo: _coex_init");
diff --git a/espradio/radio.go b/espradio/radio.go
index 89fe92c..f346f65 100644
--- a/espradio/radio.go
+++ b/espradio/radio.go
@@ -14,6 +14,7 @@ import "C"
 import (
 	"runtime/interrupt"
 	"time"
+	"unsafe"
 )
 
 type LogLevel uint8
@@ -60,6 +61,14 @@ func Enable(config Config) error {
 	return nil
 }
 
+func millisecondsToTicks(ms uint32) uint32 {
+	return ms * (ticksPerSecond / 1000)
+}
+
+func ticksToMilliseconds(ticks uint32) uint32 {
+	return ticks / (ticksPerSecond / 1000)
+}
+
 //export espradio_panic
 func espradio_panic(msg *C.char) {
 	panic("espradio: " + C.GoString(msg))
@@ -69,3 +78,56 @@ func espradio_panic(msg *C.char) {
 func espradio_log_timestamp() uint32 {
 	return uint32(time.Now().UnixMilli())
 }
+
+//export espradio_run_task
+func espradio_run_task(task_func, param unsafe.Pointer)
+
+//export espradio_task_create_pinned_to_core
+func espradio_task_create_pinned_to_core(task_func unsafe.Pointer, name *C.char, stack_depth uint32, param unsafe.Pointer, prio uint32, task_handle *unsafe.Pointer, core_id uint32) int32 {
+	ch := make(chan struct{}, 1)
+	go func() {
+		*task_handle = tinygo_task_current()
+		close(ch)
+		espradio_run_task(task_func, unsafe.Pointer(task_handle))
+	}()
+	<-ch
+	return 1
+}
+
+//export espradio_task_delete
+func espradio_task_delete(task_handle unsafe.Pointer) {
+	println("espradio TODO: delete task", task_handle)
+}
+
+//export tinygo_task_current
+func tinygo_task_current() unsafe.Pointer
+
+//export espradio_task_get_current_task
+func espradio_task_get_current_task() unsafe.Pointer {
+	return tinygo_task_current()
+}
+
+//export espradio_task_delay
+func espradio_task_delay(ticks uint32) {
+	const ticksPerMillisecond = ticksPerSecond / 1000
+	// Round milliseconds up.
+	ms := (ticks + ticksPerMillisecond - 1) / ticksPerMillisecond
+	time.Sleep(time.Duration(ms) * time.Millisecond)
+}
+
+//export espradio_task_ms_to_tick
+func espradio_task_ms_to_tick(ms uint32) int32 {
+	return int32(millisecondsToTicks(ms))
+}
+
+//export espradio_wifi_int_disable
+func espradio_wifi_int_disable(wifi_int_mux unsafe.Pointer) uint32 {
+	// This is portENTER_CRITICAL (or portENTER_CRITICAL_ISR).
+	return uint32(interrupt.Disable())
+}
+
+//export espradio_wifi_int_restore
+func espradio_wifi_int_restore(wifi_int_mux unsafe.Pointer, tmp uint32) {
+	// This is portEXIT_CRITICAL (or portEXIT_CRITICAL_ISR).
+	interrupt.Restore(interrupt.State(tmp))
+}
diff --git a/espradio/radio_esp32c3.go b/espradio/radio_esp32c3.go
index f7b74ed..44f41e4 100644
--- a/espradio/radio_esp32c3.go
+++ b/espradio/radio_esp32c3.go
@@ -6,7 +6,7 @@ import "device/esp"
 
 func initHardware() error {
 	// See:
-	// https://github.com/esp-rs/esp-wifi/blob/main/esp-wifi/src/common_adapter/common_adapter_esp32c3.rs#L18
+	// https://github.com/esp-rs/esp-wifi/blob/v0.2.0/esp-wifi/src/common_adapter/common_adapter_esp32c3.rs#L18
 
 	const (
 		SYSTEM_WIFIBB_RST       = 1 << 0
@@ -35,3 +35,7 @@ func initHardware() error {
 
 	return nil
 }
+
+// This is the value used for the ESP32-C3, see:
+// https://github.com/esp-rs/esp-wifi/blob/v0.2.0/esp-wifi/src/timer/riscv.rs#L28
+const ticksPerSecond = 16_000_000
diff --git a/espradio/radio_other.go b/espradio/radio_other.go
index d00f8b5..8b72ff2 100644
--- a/espradio/radio_other.go
+++ b/espradio/radio_other.go
@@ -4,6 +4,9 @@ package espradio
 
 import "errors"
 
+// This is the value used for the ESP32-C3.
+const ticksPerSecond = 16_000_000
+
 var errUnsupportedChip = errors.New("espradio: unsupported chip")
 
 func initHardware() error {
diff --git a/espradio/sync.go b/espradio/sync.go
index 3c205b7..a16f94e 100644
--- a/espradio/sync.go
+++ b/espradio/sync.go
@@ -2,9 +2,15 @@ package espradio
 
 // Various functions related to locks, mutexes, semaphores, and queues.
 
+/*
+#include "include.h"
+*/
+import "C"
+
 import (
 	"sync"
 	"sync/atomic"
+	"time"
 	"unsafe"
 )
 
@@ -57,25 +63,101 @@ func espradio_mutex_unlock(cmut unsafe.Pointer) int32 {
 	return 1
 }
 
-var semaphores [1]uint32
+type semaphore chan struct{}
+
+var semaphores [2]semaphore
 var semaphoreIndex uint32
+var wifiSemaphore semaphore
 
 //export espradio_semphr_create
 func espradio_semphr_create(max, init uint32) unsafe.Pointer {
 	newIndex := atomic.AddUint32(&semaphoreIndex, 1)
 	sem := &semaphores[newIndex-1]
+	ch := make(semaphore, max)
+	for i := uint32(0); i < init; i++ {
+		ch <- struct{}{}
+	}
+	*sem = ch
 	return unsafe.Pointer(sem)
 }
 
+//export espradio_semphr_take
+func espradio_semphr_take(semphr unsafe.Pointer, block_time_tick uint32) int32 {
+	sem := (*semaphore)(semphr)
+	if block_time_tick != C.OSI_FUNCS_TIME_BLOCKING {
+		panic("espradio: todo: semphr_take with timeout")
+	}
+	<-*sem
+	return 1
+}
+
+//export espradio_semphr_give
+func espradio_semphr_give(semphr unsafe.Pointer) int32 {
+	// Note: we might need to return 0 when sending isn't possible (e.g. using a
+	// non-blocking send). According to the documentation of xSemaphoreGive:
+	//
+	// > pdTRUE if the semaphore was released. pdFALSE if an error occurred.
+	// > Semaphores are implemented using queues. An error can occur if there is
+	// > no space on the queue to post a message - indicating that the semaphore
+	// > was not first obtained correctly.
+	sem := (*semaphore)(semphr)
+	*sem <- struct{}{}
+	return 1
+}
+
+//export espradio_semphr_delete
+func espradio_semphr_delete(semphr unsafe.Pointer) {
+	sem := (*semaphore)(semphr)
+	close(*sem)
+}
+
+//export espradio_wifi_thread_semphr_get
+func espradio_wifi_thread_semphr_get() unsafe.Pointer {
+	if wifiSemaphore == nil {
+		wifiSemaphore = make(semaphore, 1)
+	}
+	return unsafe.Pointer(&wifiSemaphore)
+}
+
 type queueElementType [8]byte
 
-// TODO: I think the return type results in undefined behavior (but it's still a
-// pointer so I hope LLVM won't use that fact).
-//
 //export espradio_wifi_create_queue
 func espradio_wifi_create_queue(queue_len, item_size int) chan queueElementType {
-	if item_size > len(queueElementType{}) {
-		panic("espradio: queue item_size too large")
+	if item_size != len(queueElementType{}) {
+		panic("espradio: unexpected queue item_size")
 	}
 	return make(chan queueElementType, item_size)
 }
+
+//export espradio_wifi_delete_queue
+func espradio_wifi_delete_queue(queue chan queueElementType) {
+	// We can't really delete a channel, but we can close it.
+	close(queue)
+}
+
+//export espradio_queue_recv
+func espradio_queue_recv(queue chan queueElementType, item unsafe.Pointer, block_time_tick uint32) int32 {
+	// This is xQueueReceive.
+	if block_time_tick != C.OSI_FUNCS_TIME_BLOCKING {
+		panic("espradio: todo: queue_recv with timeout")
+	}
+	*(*[8]byte)(item) = <-queue
+	return 1
+}
+
+//export espradio_queue_send
+func espradio_queue_send(queue chan queueElementType, item unsafe.Pointer, block_time_tick uint32) int32 {
+	// This is xQueueSend.
+	if block_time_tick != C.OSI_FUNCS_TIME_BLOCKING {
+		duration := time.Duration(ticksToMilliseconds(block_time_tick)) * time.Millisecond
+		// TODO: reuse the timer to avoid allocating a new timer on each queue send
+		select {
+		case <-time.After(duration):
+			return 0
+		case queue <- *(*[8]byte)(item):
+			return 1
+		}
+	}
+	queue <- *(*[8]byte)(item)
+	return 1
+}