X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=blobdiff_plain;f=src%2Fcore%2Fao_fec_tx.c;h=4941d74581254ec26402218b9ed952cdbc03138b;hp=bf32c506a90f54410dc051aa388da42b2282b429;hb=46abd248fb2eb84f161672ffce121b2203d42be0;hpb=75e4521ec42a368cebc67a07f8713d7a854ea265

diff --git a/src/core/ao_fec_tx.c b/src/core/ao_fec_tx.c
index bf32c506..4941d745 100644
--- a/src/core/ao_fec_tx.c
+++ b/src/core/ao_fec_tx.c
@@ -18,10 +18,11 @@
 #include <ao_fec.h>
 #include <stdio.h>
 
+#if AO_FEC_DEBUG
 void
-ao_fec_dump_bytes(uint8_t *bytes, uint8_t len, char *name)
+ao_fec_dump_bytes(const uint8_t *bytes, uint16_t len, const char *name)
 {
-	uint8_t	i;
+	uint16_t	i;
 
 	printf ("%s (%d):", name, len);
 	for (i = 0; i < len; i++) {
@@ -31,67 +32,57 @@ ao_fec_dump_bytes(uint8_t *bytes, uint8_t len, char *name)
 	}
 	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;
-}
+#endif
 
 uint16_t
-ao_fec_crc(uint8_t *bytes, uint8_t len)
+ao_fec_crc(const uint8_t *bytes, uint8_t len)
 {
 	uint16_t	crc = AO_FEC_CRC_INIT;
 
 	while (len--)
-		crc = crc_byte(*bytes++, crc);
+		crc = ao_fec_crc_byte(*bytes++, crc);
 	return crc;
 }
 
+/*
+ * len is the length of the data; the crc will be
+ * the fist two bytes after that
+ */
+
 uint8_t
-ao_fec_prepare(uint8_t *in, uint8_t len, uint8_t *out)
+ao_fec_check_crc(const uint8_t *bytes, uint8_t len)
+{
+	uint16_t	computed_crc = ao_fec_crc(bytes, len);
+	uint16_t	received_crc = (bytes[len] << 8) | (bytes[len+1]);
+
+	return computed_crc == received_crc;
+}
+
+/*
+ * Compute CRC and trellis-terminator/interleave-pad bytes
+ */
+static uint8_t
+ao_fec_prepare(const uint8_t *in, uint8_t len, uint8_t *extra)
 {
 	uint16_t	crc = ao_fec_crc (in, len);
-	uint8_t		i;
+	uint8_t		i = 0;
 	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;
+	extra[i++] = crc >> 8;
+	extra[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;
+		extra[i++] = AO_FEC_TRELLIS_TERMINATOR;
 	return i;
 }
 
-static const uint8_t whiten[] = {
+const uint8_t ao_fec_whiten_table[] = {
 #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] = {
 /* next 0  1	  state */
 	0, 3,	/* 000 */
@@ -105,40 +96,39 @@ static const uint8_t ao_fec_encode_table[16] = {
 };
 
 uint8_t
-ao_fec_encode(uint8_t *in, uint8_t len, uint8_t *out)
+ao_fec_encode(const 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;
+	uint8_t		extra[AO_FEC_PREPARE_EXTRA];
+	uint8_t 	extra_len;
+	uint32_t	encode, interleave;
+	uint8_t		pair, byte, bit;
+	uint16_t	fec = 0;
+	const uint8_t	*whiten = ao_fec_whiten_table;
+
+	extra_len = ao_fec_prepare(in, len, extra);
+	for (pair = 0; pair < len + extra_len; pair += 2) {
+		encode = 0;
+		for (byte = 0; byte < 2; byte++) {
+			if (pair + byte == len)
+				in = extra;
+			fec |= *in++ ^ *whiten++;
+			for (bit = 0; bit < 8; bit++) {
+				encode = encode << 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;
+		interleave = 0;
+		for (bit = 0; bit < 4 * 4; bit++) {
+			uint8_t	byte_shift = (bit & 0x3) << 3;
+			uint8_t	bit_shift = (bit & 0xc) >> 1;
 
-		for (j = 0; j < 4 * 4; j++) {
-			interleaved <<= 2;
-			interleaved |= (in[i + (~j & 0x3)] >> (2 * ((j & 0xc) >> 2))) & 0x03;
+			interleave = (interleave << 2) | ((encode >> (byte_shift + bit_shift)) & 0x3);
 		}
-		out[i+0] = interleaved >> 24;
-		out[i+1] = interleaved >> 16;
-		out[i+2] = interleaved >> 8;
-		out[i+3] = interleaved;
+		*out++ = interleave >> 24;
+		*out++ = interleave >> 16;
+		*out++ = interleave >> 8;
+		*out++ = interleave >> 0;
 	}
-	return len;
+	return (len + extra_len) * 2;
 }