channel.c File Reference

#include "standard.h"
#include "channel.h"
#include "clock.h"
#include "input.h"

Go to the source code of this file.

Defines
#define	MAX_RAND   2147483647
#define	BUFSIZE   65536
Functions
void	apply_errors (byte *data, channel *chan)
int	channel_write_indication (channel *one)
int	channel_write (channel *one, byte m)
int	channel_read_indication (channel *one)
byte	channel_read (channel *one)
channel *	new_channel (char *name)
void	close_channel (channel *c)
Variables
int	debug

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Define Documentation

#define BUFSIZE   65536

Definition at line 18 of file channel.c. Referenced by new_channel().

#define MAX_RAND   2147483647

Definition at line 6 of file channel.c.

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Function Documentation

void apply_errors (  byte *  data, channel *  chan )

Definition at line 21 of file channel.c. References channel::bit_count, channel::bit_error_rate, byte, data, debug, channel::error, error(), channel::error_count, channel::error_file, channel::error_offset, channel::file_open, channel::filename, channel::label, and warn(). Referenced by channel_read(). { int i, j, count=0, num_bits; float r; float ber; byte b=*data; chan->bit_count += 8; if (chan->error==NoErrors) return; if (chan->error == Random) { if (chan->bit_error_rate == 0.0) return; if ((chan->bit_count/8) >= chan->error_offset) { for (j=0; j<8; j++) { r = (float) random() / MAX_RAND; if (r < chan->bit_error_rate) { b ^= (1 << j); count++; chan->error_count++; if (debug >= 2) printf("apply_errors() r=%e, bit %d flipped. \n", r, j); } } } else if (debug>=4) printf("apply_errors() - not applying errors yet\n"); } else if (chan->error == File) { if (chan->filename==NULL) { warn("apply_errors","channel's error file name is NULL"); return; } if ((chan->bit_count/8) > chan->error_offset) { if (!chan->file_open) { chan->error_file = fopen(chan->filename,"r"); if (chan->error_file == NULL) { error("apply_errors","Can't open error file"); } chan->file_open = 1; } for (j=0; j<8; j++) { if (feof(chan->error_file)) fseek(chan->error_file, 0, 0); if (fgetc(chan->error_file)=='1') { b ^= (1 << j); count++; chan->error_count++; if (debug >= 4) printf("apply_errors() bit %d flipped\n", j); } } } else if (debug>=4) printf("apply_errors() - not applying errors yet\n"); } if (debug >= 4) { printf("apply_errors() [%s] Applied %d errors to byte\n", chan->label, count); } if (debug >= 1) { printf("apply_errors() [%s] Errors %d / %d bits (BER %e)\n", chan->label, chan->error_count, chan->bit_count, (float) chan->error_count / chan->bit_count); } /* copy modified byte back to *data. cheezy way of doing this. */ *data = b; /* * Figure out the BER for this packet and log it. */ /* ber = (float) count / (float) num_bits; log_ber(ber, 0); */ return; }

byte channel_read (  channel *  one  )

Definition at line 161 of file channel.c. References apply_errors(), bread(), byte, channel::pdus, and channel::read_count. Referenced by demultiplex(). { static byte b; bread(one->pdus, &b); apply_errors(&b, one); one->read_count++; return(b); }

int channel_read_indication (  channel *  one  )

Definition at line 140 of file channel.c. References blevel(), get_clock(), channel::pdus, channel::read_count, channel::transmission_delay, and channel::transmission_speed. Referenced by demultiplex(). { /* long int pos = ((get_clock() * one->transmission_speed) / 8000) - one->transmission_delay; */ long int allowed = ((get_clock() - one->transmission_delay) * one->transmission_speed) / 8000; if (blevel(one->pdus) > 0) return (one->read_count < allowed); else return 0; }

int channel_write (  channel *  one, byte  m )

Definition at line 128 of file channel.c. References bwrite(), channel::pdus, and channel::write_count. Referenced by multiplex(). { bwrite(one->pdus, &m); one->write_count++; }

int channel_write_indication (  channel *  one  )

Definition at line 110 of file channel.c. References get_clock(), channel::transmission_speed, and channel::write_count. Referenced by multiplex(). { /* int level = (one->transmission_speed * one->transmission_delay) / 8000; */ long int allowed = (one->transmission_speed * get_clock()) / 8000; return (one->write_count < allowed); }

void close_channel (  channel *  c  )

Definition at line 205 of file channel.c. References channel::bit_count, closebuffer(), channel::error_count, channel::error_file, channel::label, and channel::pdus. Referenced by cleanup(). { if (debug) { fprintf(stdout,"Channel %s:\n",c->label); fprintf(stdout,"Number of errors: %d\nNumber of bits: %d\n",c->error_count, c->bit_count); fprintf(stdout,"BER: %f\n", (float) c->error_count/c->bit_count); } if (c->error_file!=NULL) fclose(c->error_file); closebuffer(c->pdus); free(c); }

channel* new_channel (  char *  name  )

Definition at line 178 of file channel.c. References channel::bit_count, channel::bit_error_rate, BUFSIZE, byte, DEF_CHANNEL_FILE, channel::error, error(), channel::error_count, channel::error_file, channel::error_offset, channel::file_open, channel::filename, channel::label, mkbuffer(), channel::pdus, channel::read_count, channel::transmission_delay, channel::transmission_speed, and channel::write_count. Referenced by start_config(). { char s[256]; int x; channel *one = malloc(sizeof(channel)); if (one != NULL) { strcpy(one->label, name); one->transmission_speed = DEF_CHANNEL_SPEED; one->transmission_delay = DEF_CHANNEL_DELAY; one->error = DEF_CHANNEL_ERROR; one->bit_error_rate = DEF_CHANNEL_BER; strcpy(one->filename, DEF_CHANNEL_FILE); one->pdus = mkbuffer(BUFSIZE, sizeof(byte)); one->error_count = 0; one->bit_count = 0; one->write_count=0; one->read_count=0; one->error_offset=0; one->file_open=0; one->error_file=NULL; } else error("new_channel","Can't malloc new channel"); return (one); }

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Variable Documentation

int debug

Definition at line 23 of file main.c.

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