Add T/C based receiver code with integrated miller decoder

Integrate T/C receiver into iso14443 layer 2a
Add state field to iso14443_frame, rename ssc buffer state constants
Sniffer seems to work with the new code


git-svn-id: https://svn.openpcd.org:2342/trunk@452 6dc7ffe9-61d6-0310-9af1-9938baff3ed1

1 files changed, 213 insertions, 0 deletions

diff --git a/openpicc/application/tc_recv.c b/openpicc/application/tc_recv.c
new file mode 100644
index 0000000..fa6b510
--- /dev/null
+++ b/openpicc/application/tc_recv.c
@@ -0,0 +1,213 @@
+/***************************************************************
+ *
+ * OpenPICC - ISO 14443 Layer 2 Type A  T/C based receiver code
+ * Implements a receiver using FDT Timer/Counter (TC2) and the
+ * FIQ to measure the number of carrier cycles between modulation
+ * pauses.
+ * 
+ * The timing measurements are given to the differential miller
+ * decoder on the fly to interleave reception and decoding. This
+ * means two things: a) The CPU will be held in an IRQ handler
+ * with IRQs disabled for the time of reception and b) The frame
+ * will already have been fully decoded to a iso14443_frame
+ * structure when reception ends.
+ * 
+ * Copyright 2008 Henryk Plötz <henryk@ploetzli.ch>
+ *
+ ***************************************************************
+
+    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.
+
+    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.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+*/
+
+#include <FreeRTOS.h>
+#include <openpicc.h>
+#include <errno.h>
+#include <string.h>
+
+#include <task.h>
+#include <queue.h>
+
+#include "tc_recv.h"
+
+#include "iso14443a_diffmiller.h"
+#include "usb_print.h"
+#include "pio_irq.h"
+#include "led.h"
+#include "cmd.h"
+
+struct tc_recv_handle {
+	u_int8_t initialized;
+	u_int8_t pauses_count;
+	struct diffmiller_state *decoder;
+	int current, next;
+	tc_recv_callback_t callback;
+	iso14443_frame *current_frame;
+	xQueueHandle rx_queue;
+};
+
+static struct tc_recv_handle _tc;
+
+#define BUFSIZE 1024
+typedef struct {
+	u_int32_t count;
+	u_int32_t data[BUFSIZE];
+} fiq_buffer_t;
+fiq_buffer_t fiq_buffers[2];
+
+fiq_buffer_t *tc_sniffer_next_buffer_for_fiq = 0;
+
+iso14443_frame rx_frames[TC_RECV_NUMBER_OF_FRAME_BUFFERS];
+
+#define REAL_FRAME_END 333 
+
+static int tc_recv_buffer_overruns = 0;
+
+static inline iso14443_frame *get_frame_buffer(tc_recv_handle_t th)
+{
+	if(th->current_frame) return th->current_frame;
+	unsigned int i; iso14443_frame *result;
+	for(i=0; i<sizeof(rx_frames)/sizeof(rx_frames[0]); i++) {
+		if(rx_frames[i].state == FRAME_FREE) {
+			result = &rx_frames[i];
+			result->state = FRAME_PENDING;
+			th->current_frame = result;
+			return result;
+		}
+	}
+	tc_recv_buffer_overruns++;
+	return NULL;
+}
+
+static portBASE_TYPE handle_frame(iso14443_frame *frame, portBASE_TYPE task_woken)
+{
+	if(_tc.callback) _tc.callback(TC_RECV_CALLBACK_RX_FRAME_ENDED, frame);
+	if(frame->state != FRAME_FREE) {
+		task_woken = xQueueSendFromISR(_tc.rx_queue, &frame, task_woken);
+	}
+	_tc.current_frame = NULL;
+	return task_woken;
+}
+
+static portBASE_TYPE handle_buffer(u_int32_t data[], unsigned int count, portBASE_TYPE task_woken)
+{
+	unsigned int offset = 0;
+	while(offset < count) {
+		iso14443_frame *rx_frame = get_frame_buffer(&_tc);
+		if(rx_frame == NULL) return task_woken;
+		int ret = iso14443a_decode_diffmiller(_tc.decoder, rx_frame, data, &offset, count);
+		if(ret == 0) {
+			task_woken = handle_frame(rx_frame, task_woken);
+		}
+	}
+	return task_woken;
+}
+
+static inline portBASE_TYPE flush_buffer(fiq_buffer_t *buffer, portBASE_TYPE task_woken)
+{
+	if(buffer->count > 0) {
+		if(buffer->count >= BUFSIZE) {
+			usb_print_string_f("Warning: Possible buffer overrun detected\n\r",0);
+			//overruns++;
+		}
+		buffer->count = MIN(buffer->count, BUFSIZE);
+		task_woken = handle_buffer(buffer->data, buffer->count, task_woken);
+		buffer->count = 0;
+	}
+	return task_woken;
+}
+
+#define NEXT_BUFFER(a) ((a+1)%(sizeof(fiq_buffers)/sizeof(fiq_buffers[0])))
+
+static portBASE_TYPE switch_buffers(portBASE_TYPE task_woken)
+{
+	_tc.next = NEXT_BUFFER(_tc.current);
+	task_woken = flush_buffer( &fiq_buffers[_tc.next] , task_woken);
+	
+	tc_sniffer_next_buffer_for_fiq = &fiq_buffers[_tc.current=_tc.next];
+	return task_woken;
+}
+
+static portBASE_TYPE tc_recv_irq(u_int32_t pio, portBASE_TYPE task_woken)
+{
+	(void)pio;
+	/* TODO There should be some emergency exit here to prevent the CPU from
+	 * spinning in the IRQ for excessive amounts of time. (Maximum transmission
+	 * time for 256 Byte frame is something like 21ms.)
+	 */ 
+	while(*AT91C_TC2_CV <= REAL_FRAME_END || 
+			fiq_buffers[NEXT_BUFFER(_tc.current)].count > 0 || 
+			fiq_buffers[_tc.current].count > 0) 
+		task_woken = switch_buffers(task_woken);
+	
+	if(*AT91C_TC2_CV > REAL_FRAME_END) {
+		iso14443_frame *rx_frame = get_frame_buffer(&_tc);
+		if(rx_frame == NULL) return task_woken;
+		int ret = iso14443a_diffmiller_assert_frame_ended(_tc.decoder, rx_frame);
+		if(ret == 0) {
+			task_woken = handle_frame(rx_frame, task_woken);
+		}
+	}
+	return task_woken;
+}
+
+
+int tc_recv_init(tc_recv_handle_t *_th, int pauses_count, tc_recv_callback_t callback)
+{
+	if(_tc.initialized) return -EBUSY;
+	tc_recv_handle_t th = &_tc;
+	
+	memset(fiq_buffers, 0, sizeof(fiq_buffers));
+	th->current = th->next = 0;
+	
+	memset(rx_frames, 0, sizeof(rx_frames));
+	th->current_frame = NULL;
+	
+	if(th->rx_queue == NULL) {
+		th->rx_queue = xQueueCreate(TC_RECV_NUMBER_OF_FRAME_BUFFERS, sizeof(iso14443_frame*));
+		if(th->rx_queue == NULL)
+			return -ENOMEM;
+	}
+	
+	th->pauses_count = pauses_count;
+	th->decoder = iso14443a_init_diffmiller(th->pauses_count);
+	if(!th->decoder) return -EBUSY;
+
+	// The change interrupt is going to be handled by the FIQ and our secondary IRQ handler 
+	AT91F_PIO_CfgInput(AT91C_BASE_PIOA, OPENPICC_SSC_DATA);
+	if( pio_irq_register(OPENPICC_SSC_DATA, &tc_recv_irq) < 0) 
+		return -EBUSY;
+	pio_irq_enable(OPENPICC_SSC_DATA);
+	
+	th->initialized = 1;
+	*_th = th;
+	
+	th->callback = callback;
+	if(th->callback) th->callback(TC_RECV_CALLBACK_SETUP, th);
+	
+	return 0;
+}
+
+int tc_recv_receive(tc_recv_handle_t th, iso14443_frame* *frame, unsigned int timeout)
+{
+	if(th == NULL) return -EINVAL;
+	if(!th->initialized) return -EINVAL;
+	
+	if(xQueueReceive(th->rx_queue, frame, timeout)){
+		if(*frame != NULL) return 0;
+		else return -EINTR;
+	}
+	
+	return -ETIMEDOUT;
+}