1 files changed, 82 insertions, 0 deletions
diff --git a/usb/txhandler.c b/usb/txhandler.c
new file mode 100644
index 0000000..89cd0cf
--- /dev/null
+++ b/usb/txhandler.c
@@ -0,0 +1,82 @@
+/*
+ * usb/txhandler.c -- USB Transmission Handling
+ *
+ * Copyright (C) 2017 Tomasz Kramkowski <tk@the-tk.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <reg/usbotg.h>
+#include <stdbool.h>
+#include <stddef.h>
+
+#include "bdt.h"
+#include "txhandler.h"
+
+/* puttx: place data in the current buffer descriptor */
+static bool puttx(struct tx_ctx *tx, void *data, size_t size)
+{
+	if (GET_BIT(tx->bdt[tx->odd].desc, BD_OWN))
+		return false;
+
+	tx->bdt[tx->odd].addr = data;
+	tx->bdt[tx->odd].desc = USB0_BD_INIT(size, tx->data01);
+	tx->odd = !tx->odd;
+	tx->data01 = !tx->data01;
+
+	return true;
+}
+
+/* tx_push: attempt to push rest of the current transmission into a BD */
+bool tx_push(struct tx_ctx *tx)
+{
+	size_t size = tx->size;
+
+	if (tx->data == NULL)
+		return false;
+
+	if (size > tx->max)
+		size = tx->max;
+
+	if (!puttx(tx, tx->data, size))
+		return false;
+
+	tx->data = (char *)tx->data + size;
+	tx->size -= size;
+
+	if (tx->size == 0 && size < tx->max)
+		tx->data = NULL;
+
+	return true;
+}
+
+/* tx_que: enqueue a transmission */
+void tx_que(struct tx_ctx *tx, void *data, size_t size)
+{
+	if (data == NULL || size == 0) {
+		puttx(tx, NULL, 0);
+		return;
+	}
+
+	tx->data = data;
+	tx->size = size;
+
+	while (tx_push(tx))
+		;
+}
+
+/* tx_isempty: check if there's nothing left to transmit */
+bool tx_isempty(struct tx_ctx *tx)
+{
+	return tx->data == NULL;
+}