103 lines
4 KiB
C
103 lines
4 KiB
C
/**
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* Bit buffer
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*
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* A two-dimensional bit buffer consisting of bytes
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*
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* Copyright (C) 2015 Tommy Vestermark
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#ifndef INCLUDE_BITBUFFER_H_
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#define INCLUDE_BITBUFFER_H_
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#include <stdint.h>
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#define BITBUF_COLS 256 // Number of bytes in a column
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#define BITBUF_ROWS 25
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#define BITBUF_MAX_PRINT_BITS 50 // Maximum number of bits to print (in addition to hex values)
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typedef uint8_t bitrow_t[BITBUF_COLS];
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typedef bitrow_t bitarray_t[BITBUF_ROWS];
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/// Bit buffer
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typedef struct {
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uint16_t num_rows; // Number of active rows
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uint16_t bits_per_row[BITBUF_ROWS]; // Number of active bits per row
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uint16_t syncs_before_row[BITBUF_ROWS]; // Number of sync pulses before row
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bitarray_t bb; // The actual bits buffer
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} bitbuffer_t;
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/// Clear the content of the bitbuffer
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void bitbuffer_clear(bitbuffer_t *bits);
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/// Add a single bit at the end of the bitbuffer (MSB first)
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void bitbuffer_add_bit(bitbuffer_t *bits, int bit);
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/// Add a new row to the bitbuffer
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void bitbuffer_add_row(bitbuffer_t *bits);
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/// Increment sync counter, add new row if not empty
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void bitbuffer_add_sync(bitbuffer_t *bits);
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/// Extract (potentially unaligned) bytes from the bit buffer. Len is bits.
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void bitbuffer_extract_bytes(bitbuffer_t *bitbuffer, unsigned row,
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unsigned pos, uint8_t *out, unsigned len);
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/// Invert all bits in the bitbuffer (do not invert the empty bits)
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void bitbuffer_invert(bitbuffer_t *bits);
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/// Print the content of the bitbuffer
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void bitbuffer_print(const bitbuffer_t *bits);
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/// Parse a string into a bitbuffer
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void bitbuffer_parse(bitbuffer_t *bits, const char *code);
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// Search the specified row of the bitbuffer, starting from bit 'start', for
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// the pattern provided. Return the location of the first match, or the end
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// of the row if no match is found.
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// The pattern starts in the high bit. For example if searching for 011011
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// the byte pointed to by 'pattern' would be 0xAC. (011011xx).
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unsigned bitbuffer_search(bitbuffer_t *bitbuffer, unsigned row, unsigned start,
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const uint8_t *pattern, unsigned pattern_bits_len);
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// Manchester decoding from one bitbuffer into another, starting at the
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// specified row and start bit. Decode at most 'max' data bits (i.e. 2*max)
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// bits from the input buffer). Return the bit position in the input row
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// (i.e. returns start + 2*outbuf->bits_per_row[0]).
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unsigned bitbuffer_manchester_decode(bitbuffer_t *inbuf, unsigned row, unsigned start,
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bitbuffer_t *outbuf, unsigned max);
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// Differential Manchester decoding from one bitbuffer into another, starting at the
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// specified row and start bit. Decode at most 'max' data bits (i.e. 2*max)
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// bits from the input buffer). Return the bit position in the input row
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// (i.e. returns start + 2*outbuf->bits_per_row[0]).
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unsigned bitbuffer_differential_manchester_decode(bitbuffer_t *inbuf, unsigned row, unsigned start,
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bitbuffer_t *outbuf, unsigned max);
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// Function to compare bitbuffer rows and count repetitions
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int compare_rows(bitbuffer_t *bits, unsigned row_a, unsigned row_b);
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unsigned count_repeats(bitbuffer_t *bits, unsigned row);
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/// Find a repeated row that has a minimum count of bits.
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/// Return the row index or -1.
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int bitbuffer_find_repeated_row(bitbuffer_t *bits, unsigned min_repeats, unsigned min_bits);
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/// Return a single bit from a bitrow at bit_idx position
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static inline uint8_t bitrow_get_bit(const bitrow_t bitrow, unsigned bit_idx)
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{
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return bitrow[bit_idx >> 3] >> (7 - (bit_idx & 7)) & 1;
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}
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/// Return a single byte from a bitrow at bit_idx position (which may be unaligned)
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static inline uint8_t bitrow_get_byte(const bitrow_t bitrow, unsigned bit_idx)
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{
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return ((bitrow[(bit_idx >> 3)] << (bit_idx & 7)) |
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(bitrow[(bit_idx >> 3) + 1] >> (8 - (bit_idx & 7))));
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}
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#endif /* INCLUDE_BITBUFFER_H_ */
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