1 files changed, 106 insertions, 0 deletions
diff --git a/firmware/src/picc/iso14443a_manchester.c b/firmware/src/picc/iso14443a_manchester.c
new file mode 100644
index 0000000..aca832c
--- /dev/null
+++ b/firmware/src/picc/iso14443a_manchester.c
@@ -0,0 +1,106 @@
+/* 
+ * ISO14443A Manchester encoder
+ * (C) 2006 by Harald Welte <hwelte@hmw-consulting.de>
+ *
+ * Definitions for 106kBps, at sampling clock 1695kHz
+ *
+ * 		bit sample pattern for one bit cycle
+ * 		MSB first		LSB first	hex LSB first
+ * Sequence D	1010101000000000	0000000001010101	0x0055
+ * Sequence E	0000000010101010	0101010100000000	0x5500
+ * Sequence F	1010101010101010	0101010101010101	0x5555
+ *
+ * Logic 1	Sequence D
+ * Logic 0	Sequence E
+ * SOF		Sequence D
+ * EOF		Sequence F
+ *
+ * 212/424/848kBps: BPSK.
+ *
+ * SOF: 32 subcarrier clocks + bit '0'
+ *
+ * SOF:		hex LSB first: 0x55555555 55555555 + bit '0'
+ *
+ * EOF:		even parity of last byte (!)
+ *
+ */
+
+#define MANCHESTER_SEQ_D	0x0055
+#define MANCHESTER_SEQ_E	0x5500
+#define MANCHESTER_SEQ_F	0x5555
+
+static u_int32_t manchester_sample_size(u_int8_t frame_bytelen)
+{
+	/* 16 bits (2 bytes) per bit => 16 bytes samples per data byte,
+	 * plus 16bit (2 bytes) parity per data byte
+	 * plus 16bit (2 bytes) SOF plus 16bit (2 bytes) EOF */
+	return (frame_bytelen*18) + 2 + 2;
+
+	/* this results in a maximum samples-per-frame size of 4612 bytes
+	 * for a 256byte frame */
+}
+
+struct manch_enc_state {
+	const char *data;
+	char *samples;
+	u_int16_t *samples16;
+};
+
+static void manchester_enc_byte(struct manch_enc_state *mencs, u_int8_t data)
+{
+	int i;
+	u_int8_t sum_1 = 0;
+
+	/* append 8 sample blobs, one for each bit */
+	for (i = 0; i < 8; i++) {
+		if (data & (1 << i)) {
+			*(mencs->samples16) = MANCHESTER_SEQ_D;
+			sum_1++;
+		} else {
+			*(mencs->samples16) = MANCHESTER_SEQ_E;
+		}
+		mencs->samples16++
+	}
+	/* append odd parity */
+	if (sum_1 & 0x01)
+		*(mencs->samples16) = MANCHESTER_SEQ_E;
+	else
+		*(mencs->samples16) = MANCHESTER_SEQ_D;
+	mencs->samples16++
+}
+ 
+int manchester_encode(char *sample_buf, u_int16_t sample_buf_len, 
+		      const char *data, u_int8_t data_len)
+{
+	int i, enc_size;
+	struct manch_enc_state mencs
+
+	enc_size = manchester_sample_size(data_len);
+
+	if (sample_buf_len < enc_size)
+		return -EINVAL;
+
+	/* SOF */
+	*(mencs.samples16++) = MANCHESTER_SEQ_D;
+
+	for (i = 0; i < data_len; i++)
+		manchester_enc_byte(mencs, data[i]);
+		
+	/* EOF */
+	*(mencs.samples16++) = MANCHESTER_SEQ_F;
+
+	return enc_size;
+}
+
+#define BPSK_SPEED_212	
+
+
+static u_int32_t bpsk_sample_size(u_int8_t frame_bytelen)
+
+int bpsk_encode(char *sample_buf, u_int16_t sample_buf_len,
+		const char *data, u_int8_t data_len)
+{
+	/* burst of 32 sub carrier cycles */	
+	memset(sample_buf, 0x55, 8);
+
+}