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package com.cab404.fnst;
/**
* Fenechka scheme
* <p/>
* Created at 11:19 on 26/07/15
*
* @author cab404
*/
public class StandartTemplate {
public CharSequence start;
/**
* Contains knots
* 0 - first thread on top, threads swapped
* 1 - first thread on top, threads not swapped
* 2 - second thread on top, threads swapped
* 3 - second thread on top, threads not swapped
* We look only at last two bits of byte.
**/
public byte[] knots;
/**
* Used as buffer for calculations
*/
private char[] deck;
/**
* Swaps thread with one next to it in deck
*/
private void swap(int thread) {
char a = deck[thread];
deck[thread] = deck[thread + 1];
deck[thread + 1] = a;
}
/**
* Creates array of colors of knots.
*/
public char[] evaluate(char[] colors) {
if (colors.length < knots.length) throw new RuntimeException("Not enough space in colors array.");
// Number of threads
short f_len = (short) start.length();
// Current shift
short sh = 0;
// Current knot (absolute)
short knot_counter = 0;
// Type of shift
boolean even = f_len % 2 == 0;
if (deck == null || deck.length != f_len)
deck = new char[f_len];
for (int i = 0; i < start.length(); i++)
deck[i] = start.charAt(i);
for (byte knot : knots) {
char color = (knot & 2) == 0 ? deck[sh] : deck[sh + 1];
if ((knot & 1) == 0) swap(sh);
colors[knot_counter++] = color;
// odd
/* \ / \ / \
* o o )
* / \ / \ /
* ( o o
* \ / \ / \
* o o )
*/
// even
/* \ / \ / \ /
* o o o
* / \ / \ / \
* ( o o )
* \ / \ / \ /
* o o o
* / \ / \ / \
*/
sh += 2;
if (even) {
sh %= f_len - 1;
} else {
if (sh >= f_len - 1) sh = (byte) (f_len - sh);
}
}
return colors;
}
public int getRowWidth(int row) {
int length = start.length();
if (length % 2 == 1)
return (length - 1) / 2;
else
return length / 2 - (row % 2);
}
public int getRow(int knotIndex) {
int length = start.length();
int two_even_rows = length - 1;
if (length % 2 == 1)
return knotIndex / (two_even_rows / 2);
else {
int row = knotIndex / two_even_rows * 2;
if (knotIndex % two_even_rows >= length / 2) row++;
return row;
}
}
@Override
public String toString() {
StringBuilder dst = new StringBuilder("fT:");
dst.append(start.length()).append('>');
for (byte c : knots)
dst.append(c);
return dst.toString();
}
}
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