mirror of
https://github.com/merbanan/rtl_433.git
synced 2026-04-23 02:57:07 -04:00
415 lines
11 KiB
C
415 lines
11 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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#include "bitbuffer.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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void bitbuffer_clear(bitbuffer_t *bits) {
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bits->num_rows = 0;
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memset(bits->bits_per_row, 0, BITBUF_ROWS*2);
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memset(bits->bb, 0, BITBUF_ROWS * BITBUF_COLS);
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}
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void bitbuffer_add_bit(bitbuffer_t *bits, int bit) {
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if(bits->num_rows == 0) bits->num_rows++; // Add first row automatically
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uint16_t col_index = bits->bits_per_row[bits->num_rows-1] / 8;
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uint16_t bit_index = bits->bits_per_row[bits->num_rows-1] % 8;
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if((col_index < BITBUF_COLS)
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&& (bits->num_rows <= BITBUF_ROWS)
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) {
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bits->bb[bits->num_rows-1][col_index] |= (bit << (7-bit_index));
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bits->bits_per_row[bits->num_rows-1]++;
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}
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else {
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// fprintf(stderr, "ERROR: bitbuffer:: Could not add more columns\n"); // Some decoders may add many columns...
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}
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}
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void bitbuffer_add_row(bitbuffer_t *bits) {
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if(bits->num_rows == 0) bits->num_rows++; // Add first row automatically
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if(bits->num_rows < BITBUF_ROWS) {
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bits->num_rows++;
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}
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else {
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bits->bits_per_row[bits->num_rows-1] = 0; // Clear last row to handle overflow somewhat gracefully
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// fprintf(stderr, "ERROR: bitbuffer:: Could not add more rows\n"); // Some decoders may add many rows...
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}
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}
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void bitbuffer_add_sync(bitbuffer_t *bits) {
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if (bits->num_rows == 0) bits->num_rows++; // Add first row automatically
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if (bits->bits_per_row[bits->num_rows - 1]) {
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bitbuffer_add_row(bits);
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}
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bits->syncs_before_row[bits->num_rows-1]++;
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}
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void bitbuffer_invert(bitbuffer_t *bits) {
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for (unsigned row = 0; row < bits->num_rows; ++row) {
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if (bits->bits_per_row[row] > 0) {
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const unsigned last_col = (bits->bits_per_row[row]-1) / 8;
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const unsigned last_bits = ((bits->bits_per_row[row]-1) % 8) +1;
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for (unsigned col = 0; col <= last_col; ++col) {
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bits->bb[row][col] = ~bits->bb[row][col]; // Invert
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}
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bits->bb[row][last_col] ^= 0xFF >> last_bits; // Re-invert unused bits in last byte
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}
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}
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}
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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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{
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uint8_t *bits = bitbuffer->bb[row];
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if (len == 0)
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return;
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if ((pos & 7) == 0) {
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memcpy(out, bits + (pos / 8), (len + 7) / 8);
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} else {
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unsigned shift = 8 - (pos & 7);
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unsigned bytes = (len + 7) >> 3;
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uint8_t *p = out;
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uint16_t word;
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pos = pos >> 3; // Convert to bytes
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word = bits[pos];
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while (bytes--) {
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word <<= 8;
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word |= bits[++pos];
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*(p++) = word >> shift;
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}
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}
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if (len & 7)
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out[(len - 1) / 8] &= 0xff00 >> (len & 7); // mask off bottom bits
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}
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// If we make this an inline function instead of a macro, it means we don't
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// have to worry about using bit numbers with side-effects (bit++).
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static inline int bit(const uint8_t *bytes, unsigned bit)
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{
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return bytes[bit >> 3] >> (7 - (bit & 7)) & 1;
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}
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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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{
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uint8_t *bits = bitbuffer->bb[row];
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unsigned len = bitbuffer->bits_per_row[row];
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unsigned ipos = start;
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unsigned ppos = 0; // cursor on init pattern
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while (ipos < len && ppos < pattern_bits_len) {
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if (bit(bits, ipos) == bit(pattern, ppos)) {
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ppos++;
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ipos++;
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if (ppos == pattern_bits_len)
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return ipos - pattern_bits_len;
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} else {
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ipos -= ppos;
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ipos++;
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ppos = 0;
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}
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}
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// Not found
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return len;
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}
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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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{
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uint8_t *bits = inbuf->bb[row];
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unsigned int len = inbuf->bits_per_row[row];
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unsigned int ipos = start;
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if (max && len > start + (max * 2))
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len = start + (max * 2);
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while (ipos < len) {
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uint8_t bit1, bit2;
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bit1 = bit(bits, ipos++);
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bit2 = bit(bits, ipos++);
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if (bit1 == bit2)
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break;
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bitbuffer_add_bit(outbuf, bit2);
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}
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return ipos;
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}
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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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{
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uint8_t *bits = inbuf->bb[row];
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unsigned int len = inbuf->bits_per_row[row];
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unsigned int ipos = start;
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uint8_t bit1, bit2=0, bit3;
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if (max && len > start + (max * 2))
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len = start + (max * 2);
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// the first long pulse will determine the clock
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// if needed skip one short pulse to get in synch
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while (ipos < len) {
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bit1 = bit(bits, ipos++);
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bit2 = bit(bits, ipos++);
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bit3 = bit(bits, ipos);
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if (bit1 != bit2) {
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if (bit2 != bit3) {
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bitbuffer_add_bit(outbuf, 0);
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} else {
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bit2 = bit1;
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ipos -= 1;
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break;
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}
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} else {
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bit2 = 1 - bit1;
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ipos -= 2;
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break;
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}
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}
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while (ipos < len) {
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bit1 = bit(bits, ipos++);
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if (bit1 == bit2)
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break; // clock missing, abort
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bit2 = bit(bits, ipos++);
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if (bit1 == bit2)
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bitbuffer_add_bit(outbuf, 1);
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else
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bitbuffer_add_bit(outbuf, 0);
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}
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return ipos;
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}
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static void print_bitrow(bitrow_t const bitrow, unsigned bit_len, unsigned highest_indent, int always_binary)
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{
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unsigned row_len = 0;
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fprintf(stderr, "{%2d} ", bit_len);
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for (unsigned col = 0; col < (bit_len + 7) / 8; ++col) {
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row_len += fprintf(stderr, "%02x ", bitrow[col]);
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}
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// Print binary values also?
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if (always_binary || bit_len <= BITBUF_MAX_PRINT_BITS) {
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fprintf(stderr, "%-*s: ", highest_indent > row_len ? highest_indent - row_len : 0, "");
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for (unsigned bit = 0; bit < bit_len; ++bit) {
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if (bitrow[bit / 8] & (0x80 >> (bit % 8))) {
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fprintf(stderr, "1");
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} else {
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fprintf(stderr, "0");
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}
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if ((bit % 8) == 7) // Add byte separators
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fprintf(stderr, " ");
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}
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}
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fprintf(stderr, "\n");
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}
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static void print_bitbuffer(const bitbuffer_t *bits, int always_binary)
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{
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unsigned highest_indent, indent_this_col, indent_this_row;
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unsigned col, row;
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/* Figure out the longest row of bit to get the highest_indent
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*/
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highest_indent = sizeof("[dd] {dd} ") - 1;
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for (row = indent_this_row = 0; row < bits->num_rows; ++row) {
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for (col = indent_this_col = 0; col < (unsigned)(bits->bits_per_row[row] + 7) / 8; ++col) {
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indent_this_col += 2 + 1;
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}
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indent_this_row = indent_this_col;
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if (indent_this_row > highest_indent)
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highest_indent = indent_this_row;
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}
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fprintf(stderr, "bitbuffer:: Number of rows: %d \n", bits->num_rows);
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for (row = 0; row < bits->num_rows; ++row) {
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fprintf(stderr, "[%02d] ", row);
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print_bitrow(bits->bb[row], bits->bits_per_row[row], highest_indent, always_binary);
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}
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if (bits->num_rows >= BITBUF_ROWS) {
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fprintf(stderr, "... Maximum number of rows reached. Message is likely truncated.\n");
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}
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}
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void bitbuffer_print(const bitbuffer_t *bits)
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{
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print_bitbuffer(bits, 0);
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}
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void bitbuffer_debug(const bitbuffer_t *bits)
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{
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print_bitbuffer(bits, 1);
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}
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void bitrow_print(bitrow_t const bitrow, unsigned bit_len)
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{
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print_bitrow(bitrow, bit_len, 0, 0);
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}
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void bitrow_debug(bitrow_t const bitrow, unsigned bit_len)
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{
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print_bitrow(bitrow, bit_len, 0, 1);
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}
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void bitbuffer_parse(bitbuffer_t *bits, const char *code)
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{
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const char *c;
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int data = 0;
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int width = -1;
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bitbuffer_clear(bits);
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for (c = code; *c; ++c) {
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if (*c == ' ') {
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continue;
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} else if (*c == '0' && (*(c + 1) == 'x' || *(c + 1) == 'X')) {
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++c;
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continue;
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} else if (*c == '{') {
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if (bits->num_rows == 0) {
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bits->num_rows++;
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} else {
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bitbuffer_add_row(bits);
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}
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if (width >= 0) {
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bits->bits_per_row[bits->num_rows - 2] = width;
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}
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width = strtol(c + 1, (char **)&c, 0);
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continue;
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} else if (*c == '/') {
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bitbuffer_add_row(bits);
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if (width >= 0) {
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bits->bits_per_row[bits->num_rows - 2] = width;
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width = -1;
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}
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continue;
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} else if (*c >= '0' && *c <= '9') {
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data = *c - '0';
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} else if (*c >= 'A' && *c <= 'F') {
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data = *c - 'A' + 10;
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} else if (*c >= 'a' && *c <= 'f') {
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data = *c - 'a' + 10;
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}
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bitbuffer_add_bit(bits, data >> 3 & 0x01);
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bitbuffer_add_bit(bits, data >> 2 & 0x01);
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bitbuffer_add_bit(bits, data >> 1 & 0x01);
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bitbuffer_add_bit(bits, data >> 0 & 0x01);
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}
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if (width >= 0) {
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if (bits->num_rows == 0) {
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bits->num_rows++;
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}
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bits->bits_per_row[bits->num_rows - 1] = width;
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}
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}
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int compare_rows(bitbuffer_t *bits, unsigned row_a, unsigned row_b) {
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return (bits->bits_per_row[row_a] == bits->bits_per_row[row_b] &&
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!memcmp(bits->bb[row_a], bits->bb[row_b],
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(bits->bits_per_row[row_a] + 7) / 8));
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}
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unsigned count_repeats(bitbuffer_t *bits, unsigned row) {
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unsigned cnt = 0;
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for (int i = 0; i < bits->num_rows; ++i) {
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if (compare_rows(bits, row, i)) {
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++cnt;
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}
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}
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return cnt;
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}
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int bitbuffer_find_repeated_row(bitbuffer_t *bits, unsigned min_repeats, unsigned min_bits) {
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for (int i = 0; i < bits->num_rows; ++i) {
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if (bits->bits_per_row[i] >= min_bits &&
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count_repeats(bits, i) >= min_repeats) {
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return i;
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}
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}
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return -1;
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}
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// Test code
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// gcc -I include/ -std=gnu11 -D _TEST src/bitbuffer.c
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#ifdef _TEST
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int main(int argc, char **argv) {
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fprintf(stderr, "bitbuffer:: test\n");
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bitbuffer_t bits = {0};
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fprintf(stderr, "TEST: bitbuffer:: The empty buffer\n");
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bitbuffer_print(&bits);
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fprintf(stderr, "TEST: bitbuffer:: Add 1 bit\n");
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bitbuffer_add_bit(&bits, 1);
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bitbuffer_print(&bits);
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fprintf(stderr, "TEST: bitbuffer:: Add 1 new row\n");
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bitbuffer_add_row(&bits);
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bitbuffer_print(&bits);
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fprintf(stderr, "TEST: bitbuffer:: Fill row\n");
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for (int i=0; i < BITBUF_COLS*8; ++i) {
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bitbuffer_add_bit(&bits, i%2);
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}
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bitbuffer_print(&bits);
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fprintf(stderr, "TEST: bitbuffer:: Add row and fill 1 column too many\n");
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bitbuffer_add_row(&bits);
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for (int i=0; i <= BITBUF_COLS*8; ++i) {
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bitbuffer_add_bit(&bits, i%2);
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}
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bitbuffer_print(&bits);
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fprintf(stderr, "TEST: bitbuffer:: invert\n");
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bitbuffer_invert(&bits);
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bitbuffer_print(&bits);
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fprintf(stderr, "TEST: bitbuffer:: Clear\n");
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bitbuffer_clear(&bits);
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bitbuffer_print(&bits);
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fprintf(stderr, "TEST: bitbuffer:: Add 1 row too many\n");
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for (int i=0; i <= BITBUF_ROWS; ++i) {
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bitbuffer_add_row(&bits);
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}
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bitbuffer_add_bit(&bits, 1);
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bitbuffer_print(&bits);
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return 0;
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}
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#endif /* _TEST */
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