Add load modulation and encoding/decoding code from harald

git-svn-id: https://svn.openpcd.org:2342/trunk@351 6dc7ffe9-61d6-0310-9af1-9938baff3ed1

1 files changed, 81 insertions, 0 deletions

diff --git a/openpicc/application/decoder.c b/openpicc/application/decoder.c
new file mode 100644
index 0000000..a4287fd
--- /dev/null
+++ b/openpicc/application/decoder.c
@@ -0,0 +1,81 @@
+/* Decoder Core for OpenPICC
+ * (C) 2006 by Harald Welte <hwelte@hmw-consulting.de>
+ *
+ *  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 2 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, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include <errno.h>
+#include <sys/types.h>
+
+#include "openpicc.h"
+#include "dbgu.h"
+#include "decoder.h"
+
+static struct decoder_algo *decoder_algo[DECODER_NUM_ALGOS];
+
+static int get_next_data(struct decoder_state *st, u_int8_t *data)
+{
+	u_int8_t parity_sample;
+	u_int32_t bytesample;
+
+	bytesample = st->algo->get_next_bytesample(st, &parity_sample);
+
+	return st->algo->decode_sample(bytesample, data);
+}
+
+/* iterate over sample buffer (size N bytes) and decode data */
+int decoder_decode(u_int8_t algo, const char *sample_buf,
+	  	   int sample_buf_size, unsigned char *data_buf)
+{
+	int i, ret;
+	struct decoder_state st;
+
+	if (algo >= DECODER_NUM_ALGOS)
+		return -EINVAL;
+
+	st.buf = sample_buf;
+	st.buf32 = (u_int32_t *) st.buf;
+	st.bit_ofs = 0;
+	st.algo = decoder_algo[algo];
+
+	for (i = 0; i < (sample_buf_size*8)/st.algo->bits_per_sampled_char;
+	     i++) {
+		ret = get_next_data(&st, &data_buf[i]);
+		if (ret < 0) {
+			DEBUGPCR("decoder error %d at data byte %u",
+				 ret, i);
+			return ret;
+		}
+	}
+
+	return i+1;
+}
+
+int decoder_register(int algnum, struct decoder_algo *algo)
+{
+	if (algnum >= DECODER_NUM_ALGOS)
+		return -EINVAL;
+
+	decoder_algo[algnum] = algo;
+
+	return 0;
+}
+
+void decoder_init(void)
+{
+	decoder_register(DECODER_MILLER, &miller_decoder);
+	decoder_register(DECODER_NRZL, &nrzl_decoder);
+}