diff options
Diffstat (limited to 'openpicc/application/tc_recv.c')
| -rw-r--r-- | openpicc/application/tc_recv.c | 213 |
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; +} |