Use inter-core API for pycardium IO

epicardium/api/caller.c

+#include <stdlib.h>
+#include "sema.h"
+#include "api/caller.h"
+
+void*_api_call_start(api_id_t id, uintptr_t size)
+{
+	while (SEMA_GetSema(_API_SEMAPHORE) == E_BUSY) {}
+
+	/* TODO: Check flag */
+
+	API_CALL_MEM->id = id;
+	return API_CALL_MEM->buffer;
+}
+
+void*_api_call_transact(void*buffer)
+{
+	API_CALL_MEM->call_flag = _API_FLAG_CALLING;
+	SEMA_FreeSema(_API_SEMAPHORE);
+
+	/* Notify the dispather of the new call */
+	__SEV();
+	__WFE();
+
+	while (1) {
+		/* Wait for the dispather to return */
+		__WFE();
+
+		while (SEMA_GetSema(_API_SEMAPHORE) == E_BUSY) {}
+		if (API_CALL_MEM->call_flag == _API_FLAG_RETURNED) {
+			break;
+		}
+		SEMA_FreeSema(_API_SEMAPHORE);
+	}
+
+	API_CALL_MEM->call_flag = _API_FLAG_IDLE;
+	SEMA_FreeSema(_API_SEMAPHORE);
+
+	return API_CALL_MEM->buffer;
+}