3 * Copyright 2007 Free Software Foundation, Inc.
5 * This file is part of GNU Radio
7 * GNU Radio is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2, or (at your option)
12 * GNU Radio is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with GNU Radio; see the file COPYING. If not, write to
19 * the Free Software Foundation, Inc., 51 Franklin Street,
20 * Boston, MA 02110-1301, USA.
24 * config.h is generated by configure. It contains the results
25 * of probing for features, options etc. It should be the first
26 * file included in your .cc file.
32 #include <cvsd_encode_sb.h>
33 #include <gr_io_signature.h>
36 * Create a new instance of cvsd_encode_sb and return
37 * a boost shared_ptr. This is effectively the public constructor.
40 cvsd_make_encode_sb (short min_step, short max_step, double step_decay,
41 double accum_decay, int K, int J,
42 short pos_accum_max, short neg_accum_max)
44 return cvsd_encode_sb_sptr (new cvsd_encode_sb (min_step, max_step,
45 step_decay, accum_decay, K, J,
46 pos_accum_max, neg_accum_max));
49 cvsd_encode_sb::cvsd_encode_sb (short min_step, short max_step, double step_decay,
50 double accum_decay, int K, int J,
51 short pos_accum_max, short neg_accum_max)
52 : gr_sync_decimator ("cvsd_encode_sb",
53 gr_make_io_signature (1, 1, sizeof (short)),
54 gr_make_io_signature (1, 1, sizeof (unsigned char)),
56 d_min_step (min_step), d_max_step(max_step), d_step_decay(step_decay),
57 d_accum_decay(accum_decay), d_K(K), d_J(J),
58 d_pos_accum_max(pos_accum_max), d_neg_accum_max(neg_accum_max),
65 assert(d_pos_accum_max <= SHRT_MAX);
66 assert(d_neg_accum_max >= -SHRT_MAX);
70 // nothing else required in this example
74 cvsd_encode_sb::~cvsd_encode_sb ()
76 // nothing else required in this example
79 unsigned char cvsd_encode_sb::cvsd_bitwise_sum (unsigned int input)
81 unsigned int temp=input;
91 int cvsd_encode_sb::cvsd_round (double input)
100 unsigned int cvsd_encode_sb::cvsd_pow (short radix, short power)
102 double d_radix = (double) radix;
103 int i_power = (int) power;
106 output=pow(d_radix,i_power);
107 return ( (unsigned int) cvsd_round(output));
113 cvsd_encode_sb::work (int noutput_items,
114 gr_vector_const_void_star &input_items,
115 gr_vector_void_star &output_items)
117 const short *in = (const short *) input_items[0];
118 unsigned char *out = (unsigned char *) output_items[0];
120 unsigned short i=0; // 2 bytes, 0 .. 65,535
121 unsigned char output_bit=0; // 1 byte, 0 .. 255
122 unsigned char output_byte=0; // 1 bytes 0.255
123 unsigned char bit_count=0; // 1 byte, 0 .. 255
124 unsigned int mask=0; // 4 bytes, 0 .. 4,294,967,295
126 // Loop through each input data point
127 for(i = 0; i < noutput_items*8; i++) {
128 if((int)in[i] >= d_accum) { // Note: sign((data(n)-accum))
135 // Update Accum (i.e. the reference value)
137 d_accum=d_accum+d_stepsize;
138 //printf("Addding %d to the accum; the result is: %d.\n", d_stepsize, d_accum);
141 d_accum=d_accum-d_stepsize;
142 //printf("Subtracting %d to the accum; the result is: %d.\n", d_stepsize, d_accum);
145 // Multiply by Accum_Decay
146 d_accum=(cvsd_round(d_accum*d_accum_decay));
148 // Check for overflow
149 if (d_accum >= ((int)d_pos_accum_max)) {
150 d_accum = (int)d_pos_accum_max;
152 else if(d_accum <= ((int) d_neg_accum_max)) {
153 d_accum = (int) d_neg_accum_max;
156 // Update runner with the last output bit
158 if (d_loop_counter >= d_J) { // Run this only if you have >= J bits in your shift register
159 mask=(cvsd_pow(2, d_J) - 1);
160 if ((cvsd_bitwise_sum(d_runner & mask) >= d_J) || (cvsd_bitwise_sum((~d_runner) & mask) >= d_J)) {
162 d_stepsize = std::min( (short)(d_stepsize + d_min_step), d_max_step);
165 // No runs of 1s and 0s
166 d_stepsize = std::max( (short)cvsd_round(d_stepsize*d_step_decay), d_min_step);
170 // Runner is a shift-register; shift left, add on newest output bit
171 d_runner = (d_runner<<1) | ((unsigned int) output_bit);
173 // Update the ouput type; shift left, add on newest output bit
174 // If you have put in 8 bits, output it as a byte
175 output_byte = (output_byte<<1) | output_bit;
178 if (d_loop_counter <= d_K) {
182 // If you have put 8 bits, output and clear.
184 // Read in short from the file
185 *(out++) = output_byte;
187 // Reset the bit_count
193 return noutput_items;