001package org.dcm4che3.image;
002
003public class ShortLookupTable extends LookupTable {
004
005    private final short[] lut;
006
007    ShortLookupTable(StoredValue inBits, int outBits, int offset, short[] lut) {
008        super(inBits, outBits, offset);
009        this.lut = lut;
010    }
011
012    ShortLookupTable(StoredValue inBits, int outBits, int offset, int size, boolean flip) {
013       this(inBits, outBits, offset, new short[size]);
014       int maxOut = (1<<outBits)-1;
015       int maxIndex = size - 1;
016       int midIndex = size / 2;
017       if (flip)
018           for (int i = 0; i < size; i++)
019               lut[maxIndex-i] = (short) ((i * maxOut + midIndex) / maxIndex);
020       else
021           for (int i = 0; i < size; i++)
022               lut[i] = (short) ((i * maxOut + midIndex) / maxIndex);
023    }
024
025    @Override
026    public int length() {
027        return lut.length;
028    }
029
030    @Override
031    public void lookup(byte[] src, int srcPos, byte[] dest, int destPos, int length) {
032        for (int i = srcPos, endPos = srcPos + length, j = destPos; i < endPos;)
033            dest[j++] = (byte) lut[index(src[i++] & 0xff)];
034    }
035
036    private int index(int pixel) {
037        int index = inBits.valueOf(pixel) - offset;
038        return Math.min(Math.max(0, index), lut.length-1);
039    }
040
041    @Override
042    public void lookup(short[] src, int srcPos, byte[] dest, int destPos, int length) {
043        for (int i = srcPos, endPos = srcPos + length, j = destPos; i < endPos;)
044            dest[j++] = (byte) lut[index(src[i++] & 0xffff)];
045    }
046
047    @Override
048    public void lookup(byte[] src, int srcPos, short[] dest, int destPos, int length) {
049        for (int i = srcPos, endPos = srcPos + length, j = destPos; i < endPos;)
050            dest[j++] = lut[index(src[i++] & 0xff)];
051    }
052
053    @Override
054    public void lookup(short[] src, int srcPos, short[] dest, int destPos, int length) {
055        for (int i = srcPos, endPos = srcPos + length, j = destPos; i < endPos;)
056            dest[j++] = lut[index(src[i++] & 0xffff)];
057    }
058
059    @Override
060    public LookupTable adjustOutBits(int outBits) {
061        int diff = outBits - this.outBits;
062        if (diff != 0) {
063            short[] lut = this.lut;
064            if (diff < 0) {
065                diff = -diff;
066                for (int i = 0; i < lut.length; i++)
067                    lut[i] = (short) ((lut[i] & 0xffff) >> diff);
068            } else
069                for (int i = 0; i < lut.length; i++)
070                    lut[i] <<= diff;
071            this.outBits = outBits;
072        }
073        return this;
074    }
075
076    @Override
077    public void inverse() {
078        short[] lut = this.lut;
079        int maxOut = (1<<outBits)-1;
080        for (int i = 0; i < lut.length; i++)
081            lut[i] = (short) (maxOut - lut[i]); 
082     }
083
084    @Override
085    public LookupTable combine(LookupTable other) {
086        short[] lut = this.lut;
087        other.lookup(lut, 0, lut, 0, lut.length);
088        this.outBits = other.outBits;
089        return this;
090    }
091}