1 files changed, 139 insertions, 0 deletions
diff --git a/src/drivers/ao_fec_tx.c b/src/drivers/ao_fec_tx.c
new file mode 100644
index 00000000..b8933956
--- /dev/null
+++ b/src/drivers/ao_fec_tx.c
@@ -0,0 +1,139 @@
+/*
+ * Copyright © 2012 Keith Packard <keithp@keithp.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; version 2 of the License.
+ *
+ * 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, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao_fec.h>
+#include <stdio.h>
+
+void
+ao_fec_dump_bytes(uint8_t *bytes, uint8_t len, char *name)
+{
+	uint8_t	i;
+
+	printf ("%s (%d):", name, len);
+	for (i = 0; i < len; i++) {
+		if ((i & 7) == 0)
+			printf ("\n\t%02x:", i);
+		printf(" %02x", bytes[i]);
+	}
+	printf ("\n");
+}
+
+static uint16_t inline
+crc_byte(uint8_t byte, uint16_t crc)
+{
+	uint8_t	bit;
+
+	for (bit = 0; bit < 8; bit++) {
+		if (((crc & 0x8000) >> 8) ^ (byte & 0x80))
+			crc = (crc << 1) ^ 0x8005;
+		else
+			crc = (crc << 1);
+		byte <<= 1;
+	}
+	return crc;
+}
+
+uint16_t
+ao_fec_crc(uint8_t *bytes, uint8_t len)
+{
+	uint16_t	crc = AO_FEC_CRC_INIT;
+
+	while (len--)
+		crc = crc_byte(*bytes++, crc);
+	return crc;
+}
+
+uint8_t
+ao_fec_prepare(uint8_t *in, uint8_t len, uint8_t *out)
+{
+	uint16_t	crc = ao_fec_crc (in, len);
+	uint8_t		i;
+	uint8_t		num_fec;
+
+	/* Copy data */
+	for (i = 0; i < len; i++)
+		out[i] = in[i];
+
+	/* Append CRC */
+	out[i++] = crc >> 8;
+	out[i++] = crc;
+
+	/* Append FEC -- 1 byte if odd, two bytes if even */
+	num_fec = 2 - (i & 1);
+	while (num_fec--)
+		out[i++] = AO_FEC_TRELLIS_TERMINATOR;
+	return i;
+}
+
+static const uint8_t whiten[] = {
+#include "ao_whiten.h"
+};
+
+uint8_t
+ao_fec_whiten(uint8_t *in, uint8_t len, uint8_t *out)
+{
+	const uint8_t	*w = whiten;
+
+	while (len--)
+		*out++ = *in++ ^ *w++;
+}
+
+static const uint8_t ao_fec_encode_table[16] = {
+	0, 3, 1, 2,
+	3, 0, 2, 1,
+	3, 0, 2, 1,
+	0, 3, 1, 2
+};
+
+uint8_t
+ao_fec_encode(uint8_t *in, uint8_t len, uint8_t *out)
+{
+	uint16_t	fec = 0, output;
+	uint8_t		byte, bit;
+
+	for (byte = 0; byte < len; byte++) {
+		fec = (fec & 0x700) | in[byte];
+		output = 0;
+		for (bit = 0; bit < 8; bit++) {
+			output = output << 2 | ao_fec_encode_table[fec >> 7];
+			fec = (fec << 1) & 0x7ff;
+		}
+		out[byte * 2] = output >> 8;
+		out[byte * 2 + 1] = output;
+	}
+	return len * 2;
+}
+
+uint8_t
+ao_fec_interleave(uint8_t *in, uint8_t len, uint8_t *out)
+{
+	uint8_t	i, j;
+
+	for (i = 0; i < len; i += 4) {
+		uint32_t	interleaved = 0;
+
+		for (j = 0; j < 4 * 4; j++) {
+			interleaved <<= 2;
+			interleaved |= (in[i + (~j & 0x3)] >> (2 * ((j & 0xc) >> 2))) & 0x03;
+		}
+		out[i+0] = interleaved >> 24;
+		out[i+1] = interleaved >> 16;
+		out[i+2] = interleaved >> 8;
+		out[i+3] = interleaved;
+	}
+	return len;
+}