114 lines
4.7 KiB
C
114 lines
4.7 KiB
C
/*
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* bell202.h
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*
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* Copyright (c) 2005 Robert Krten. All Rights Reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This module contains the manifest constants and declarations for
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* the Bell-202 1200 baud FSK modem.
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*
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* 2005 03 20 R. Krten created
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*/
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#ifndef __FSK_H__
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#define __FSK_H__
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#include "uart.h"
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typedef struct {
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int freq_space; /* Frequency of the 0 bit */
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int freq_mark; /* Frequency of the 1 bit */
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int baud_rate; /* baud rate for the modem */
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} fsk_modem_definition_t;
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/* Must be kept in sync with fsk_modem_definitions array in fsk.c */
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/* V.23 definitions: http://www.itu.int/rec/recommendation.asp?type=folders&lang=e&parent=T-REC-V.23 */
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typedef enum {
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FSK_V23_FORWARD_MODE1 = 0, /* Maximum 600 bps for long haul */
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FSK_V23_FORWARD_MODE2, /* Standard 1200 bps V.23 */
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FSK_V23_BACKWARD, /* 75 bps return path for V.23 */
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FSK_BELL202 /* Bell 202 half-duplex 1200 bps */
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} fsk_modem_types_t;
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typedef enum {
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FSK_STATE_CHANSEIZE = 0,
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FSK_STATE_CARRIERSIG,
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FSK_STATE_DATA
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} fsk_state_t;
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typedef struct dsp_fsk_attr_s
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{
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int sample_rate; /* sample rate in HZ */
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bithandler_func_t bithandler; /* bit handler */
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void *bithandler_arg; /* arbitrary ID passed to bithandler as first argument */
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bytehandler_func_t bytehandler; /* byte handler */
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void *bytehandler_arg; /* arbitrary ID passed to bytehandler as first argument */
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} dsp_fsk_attr_t;
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typedef struct
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{
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fsk_state_t state;
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dsp_fsk_attr_t attr; /* attributes structure */
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double *correlates[4]; /* one for each of sin/cos for mark/space */
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int corrsize; /* correlate size (also number of samples in ring buffer) */
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double *buffer; /* sample ring buffer */
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int ringstart; /* ring buffer start offset */
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double cellpos; /* bit cell position */
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double celladj; /* bit cell adjustment for each sample */
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int previous_bit; /* previous bit (for detecting a transition to sync-up cell position) */
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int current_bit; /* current bit */
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int last_bit;
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int downsampling_count; /* number of samples to skip */
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int current_downsample; /* current skip count */
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int conscutive_state_bits; /* number of bits in a row that matches the pattern for the current state */
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} dsp_fsk_handle_t;
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/*
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* Function prototypes
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*
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* General calling order is:
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* a) create the attributes structure (dsp_fsk_attr_init)
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* b) initialize fields in the attributes structure (dsp_fsk_attr_set_*)
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* c) create a Bell-202 handle (dsp_fsk_create)
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* d) feed samples through the handler (dsp_fsk_sample)
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*/
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void dsp_fsk_attr_init(dsp_fsk_attr_t *attributes);
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bithandler_func_t dsp_fsk_attr_get_bithandler(dsp_fsk_attr_t *attributes, void **bithandler_arg);
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void dsp_fsk_attr_set_bithandler(dsp_fsk_attr_t *attributes, bithandler_func_t bithandler, void *bithandler_arg);
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bytehandler_func_t dsp_fsk_attr_get_bytehandler(dsp_fsk_attr_t *attributes, void **bytehandler_arg);
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void dsp_fsk_attr_set_bytehandler(dsp_fsk_attr_t *attributes, bytehandler_func_t bytehandler, void *bytehandler_arg);
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int dsp_fsk_attr_get_samplerate(dsp_fsk_attr_t *attributes);
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int dsp_fsk_attr_set_samplerate(dsp_fsk_attr_t *attributes, int samplerate);
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dsp_fsk_handle_t * dsp_fsk_create(dsp_fsk_attr_t *attributes);
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void dsp_fsk_destroy(dsp_fsk_handle_t **handle);
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void dsp_fsk_sample(dsp_fsk_handle_t *handle, double normalized_sample);
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extern fsk_modem_definition_t fsk_modem_definitions[];
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#endif
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