util.java

J2ME编写的完整国际象棋程序

package chess;

import java.io.IOException;
import java.io.InputStream;

public class Util {
	public static int MIN_MAX(int min, int mid, int max) {
		return mid < min ? min : mid > max ? max : mid;
	}

	private static byte[] POP_COUNT_16 = new byte[65536];

	static {
		for (int i = 0; i < 65536; i ++) {
			int n = ((i >> 1) & 0x5555) + (i & 0x5555);
			n = ((n >> 2) & 0x3333) + (n & 0x3333);
			n = ((n >> 4) & 0x0f0f) + (n & 0x0f0f);
			POP_COUNT_16[i] = (byte) ((n >> 8) + (n & 0x00ff));
		}
	}

	public static int POP_COUNT_16(int data) {
		return POP_COUNT_16[data];
	}

	public static int readShort(InputStream in) throws IOException {
		int b0 = in.read();
		int b1 = in.read();
		if (b0 == -1 || b1 == -1) {
			throw new IOException();
		}
		return b0 | (b1 << 8);
	}

	public static int readInt(InputStream in) throws IOException {
		int b0 = in.read();
		int b1 = in.read();
		int b2 = in.read();
		int b3 = in.read();
		if (b0 == -1 || b1 == -1 || b2 == -1 || b3 == -1) {
			throw new IOException();
		}
		return b0 | (b1 << 8) | (b2 << 16) | (b3 << 24);
	}

	public static class RC4 {
		public int[] state = new int[256];
		public int x, y;

		public void swap(int i, int j) {
			int t = state[i];
			state[i] = state[j];
			state[j] = t;
		}

		public RC4(byte[] key) {
			x = 0;
			y = 0;
			for (int i = 0; i < 256; i ++) {
				state[i] = i;
			}
			int j = 0;
			for (int i = 0; i < 256; i ++) {
				j = (j + state[i] + key[i % key.length]) & 0xff;
				swap(i, j);
			}
		}

		public int nextByte() {
			x = (x + 1) & 0xff;
			y = (y + state[x]) & 0xff;
			swap(x, y);
			int t = (state[x] + state[y]) & 0xff;
			return state[t];
		}

		public int nextLong() {
			int n0, n1, n2, n3;
			n0 = nextByte();
			n1 = nextByte();
			n2 = nextByte();
			n3 = nextByte();
			return n0 + (n1 << 8) + (n2 << 16) + (n3 << 24);
		}
	}

	public static int binarySearch(int vl, int[] vls, int from, int to) {
		int low = from;
		int high = to - 1;
		while (low <= high) {
			int mid = (low + high) / 2;
			if (vls[mid] < vl) {
				low = mid + 1;
			} else if (vls[mid] > vl) {
				high = mid - 1;
			} else {
				return mid;
			}
		}
		return -1;
	}

	private static final int[] SHELL_STEP = {0, 1, 4, 13, 40, 121, 364, 1093};

	public static void shellSort(int[] mvs, int[] vls, int from, int to) {
		int stepLevel = 1;
		while (SHELL_STEP[stepLevel] < to - from) {
			stepLevel ++;
		}
		stepLevel --;
		while (stepLevel > 0) {
			int step = SHELL_STEP[stepLevel];
			for (int i = from + step; i < to; i ++) {
				int mvBest = mvs[i];
				int vlBest = vls[i];
				int j = i - step;
				while (j >= from && vlBest > vls[j]) {
					mvs[j + step] = mvs[j];
					vls[j + step] = vls[j];
					j -= step;
				}
				mvs[j + step] = mvBest;
				vls[j + step] = vlBest;
			}
			stepLevel --;
		}
	}
}