69 lines
2.0 KiB
Java
69 lines
2.0 KiB
Java
package com.bytezone.diskbrowser.applefile;
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// -----------------------------------------------------------------------------------//
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public class DoubleScrunch
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// -----------------------------------------------------------------------------------//
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{
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final byte[][] memory = new byte[2][0x2000];
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private byte[] packedBuffer;
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private final int[] rows = new int[192];
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private int ptr;
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private int bank;
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private int outPtr;
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private int column;
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// ---------------------------------------------------------------------------------//
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public DoubleScrunch (byte[] buffer)
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// ---------------------------------------------------------------------------------//
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{
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int row = 0;
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for (int a = 0x400; a >= 0; a -= 0x400) // reversed!
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for (int b = 0; b < 0x78; b += 0x28)
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for (int c = 0; c < 0x400; c += 0x80)
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for (int d = 0; d < 0x2000; d += 0x800)
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rows[row++] = a + b + c + d;
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packedBuffer = buffer;
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while (true)
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{
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int repeat = packedBuffer[ptr++] & 0xFF;
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if ((repeat & 0x80) == 0) // repeat same byte
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{
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byte val = packedBuffer[ptr++];
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while (repeat-- > 0)
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if (move (val))
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return;
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}
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else // copy bytes
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{
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repeat &= 0x7F;
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while (repeat-- > 0)
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if (move (packedBuffer[ptr++]))
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return;
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}
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}
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}
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// ---------------------------------------------------------------------------------//
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private boolean move (byte val)
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// ---------------------------------------------------------------------------------//
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{
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memory[bank][rows[outPtr++] + column] = val;
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if (outPtr % 192 == 0) // screen column for this bank is finished
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{
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outPtr = 0;
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if (++bank > 1) // both banks are finished
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{
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bank = 0;
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if (++column >= 40) // whole screen is finished
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return true;
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}
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}
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return false;
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}
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} |