1 files changed, 78 insertions, 0 deletions
diff --git a/quantum/serial_link/protocol/triple_buffered_object.c b/quantum/serial_link/protocol/triple_buffered_object.c
new file mode 100644
index 000000000..e3e8989d3
--- /dev/null
+++ b/quantum/serial_link/protocol/triple_buffered_object.c
@@ -0,0 +1,78 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 Fred Sundvik
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
+#include "serial_link/protocol/triple_buffered_object.h"
+#include "serial_link/system/serial_link.h"
+#include <stdbool.h>
+#include <stddef.h>
+
+#define GET_READ_INDEX() object->state & 3
+#define GET_WRITE_INDEX() (object->state >> 2) & 3
+#define GET_SHARED_INDEX() (object->state >> 4) & 3
+#define GET_DATA_AVAILABLE() (object->state >> 6) & 1
+
+#define SET_READ_INDEX(i) object->state = ((object->state & ~3) | i)
+#define SET_WRITE_INDEX(i) object->state = ((object->state & ~(3 << 2)) | (i << 2))
+#define SET_SHARED_INDEX(i) object->state = ((object->state & ~(3 << 4)) | (i << 4))
+#define SET_DATA_AVAILABLE(i) object->state = ((object->state & ~(1 << 6)) | (i << 6))
+
+void triple_buffer_init(triple_buffer_object_t* object) {
+    object->state = 0;
+    SET_WRITE_INDEX(0);
+    SET_READ_INDEX(1);
+    SET_SHARED_INDEX(2);
+    SET_DATA_AVAILABLE(0);
+}
+
+void* triple_buffer_read_internal(uint16_t object_size, triple_buffer_object_t* object) {
+    serial_link_lock();
+    if (GET_DATA_AVAILABLE()) {
+        uint8_t shared_index = GET_SHARED_INDEX();
+        uint8_t read_index = GET_READ_INDEX();
+        SET_READ_INDEX(shared_index);
+        SET_SHARED_INDEX(read_index);
+        SET_DATA_AVAILABLE(false);
+        serial_link_unlock();
+        return object->buffer + object_size * shared_index;
+    }
+    else {
+        serial_link_unlock();
+        return NULL;
+    }
+}
+
+void* triple_buffer_begin_write_internal(uint16_t object_size, triple_buffer_object_t* object) {
+    uint8_t write_index = GET_WRITE_INDEX();
+    return object->buffer + object_size * write_index;
+}
+
+void triple_buffer_end_write_internal(triple_buffer_object_t* object) {
+    serial_link_lock();
+    uint8_t shared_index = GET_SHARED_INDEX();
+    uint8_t write_index = GET_WRITE_INDEX();
+    SET_SHARED_INDEX(write_index);
+    SET_WRITE_INDEX(shared_index);
+    SET_DATA_AVAILABLE(true);
+    serial_link_unlock();
+}