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stream.c
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stream.c
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/**
* Common stream library.
*/
#include "stream.h"
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
/** Allocates a new stream */
stream_t *stream_new()
{
stream_t *stream = malloc( sizeof( stream[0] ) );
if( stream )
{
stream->pos = 0;
stream->size = 32;
stream->s = calloc( stream->size, sizeof( stream->s[0] ) );
}
return( stream );
}
/** Creates a stream from a string of 0's and 1's. */
stream_t *stream_string( char *str )
{
stream_t *stream = NULL;
if( str )
{
stream = stream_new();
if( stream )
{
while( *str != '\0' )
{
char c = *str - '0';
if( c != 0 && c != 1 )
{
printf( "Invalid character '%c'.", *str );
}
else
{
add( stream, c );
}
str++;
}
}
}
return( stream );
}
/** Generates a random stream of 'size' bits. */
stream_t *
stream_random( int size )
{
stream_t *stream = stream_new();
srand( time( NULL ) );
for( int i = 0; i < size; i++ )
{
char r = (char) rand() % 2;
add( stream, r );
}
return( stream );
}
/** Prints a bit stream to the screen for debugging. */
void stream_print( stream_t *stream )
{
//printf( "pos=%d, size=%d, s: ", stream->pos, stream->size );
for( int i = 0; i < stream->pos; i++ )
{
char c = get( stream->s[i/NBITS], ( NBITS - 1 ) - ( i % NBITS ) );
printf( "%d ", c );
}
}
/** Gets a bit at a position in the stream. (Leftmost bit is pos = 0). */
char
getbit( stream_t *stream, int pos )
{
return( get( stream->s[ pos / NBITS ], ( NBITS - 1 ) - ( pos % NBITS ) ) );
}
/** Sets the bit at a position in the stream. */
char
setbit( stream_t *stream, int pos, char bit )
{
if( 0 == bit )
{
stream->s[ pos / NBITS ] &= ~( 1 << ( ( NBITS - 1 ) - ( pos % NBITS ) ) );
}
else
{
stream->s[ pos / NBITS ] |= 1 << ( ( NBITS - 1 ) - ( pos % NBITS ) );
}
return getbit( stream, pos );
}
/** Adds a bit to the stream. */
void add( stream_t *stream, char bit )
{
// Mem location
int i = stream->pos / NBITS;
// Bit location
int ibit =
( NBITS - 1 )
- ( stream->pos % NBITS );
// Double the size if we reached the end
if( i == stream->size )
{
stream->size *= 2;
stream->s = (char *) reallocf(
stream->s,
sizeof( stream->s[0] ) * stream->size
);
// Zero the allocated space
for( int j = i; j < stream->size; j++ )
{
stream->s[j] = 0;
}
}
// Add bit
stream->s[i] |= bit << ibit;
// Inc position
stream->pos++;
}
/** Get a bit at position i in c. */
char get( char c, int i )
{
return ( c & ( 1 << i ) ) >> i;
}
/** Print a bit from left (MSB or index 7) to right (LSB or index 0) */
int print( char c )
{
int i;
for( i = NBITS - 1; i >= 0; i-- )
{
printf( "%d ", get( c, i ) );
}
return( 0 );
}