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Converted Beagle Brothers' unscrunch routine
This commit is contained in:
Denis Molony
parent
218f612877
commit
ee3b38094b
@ -7,25 +7,46 @@ import com.bytezone.diskbrowser.utilities.HexFormatter;
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public class DoubleHiResImage extends HiResImage
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{
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// private static final int BLACK = 0x000000;
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// private static final int MAGENTA = 0xFF00FF;
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// private static final int BROWN = 0x994C00;
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// private static final int ORANGE = 0xFF9933;
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// private static final int DARK_GREEN = 0x006600;
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// private static final int GRAY = 0xA0A0A0;
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// private static final int GREEN = 0x00CC00;
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// private static final int YELLOW = 0xFFFF33;
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// private static final int DARK_BLUE = 0x0066CC;
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// private static final int PURPLE = 0xCC00CC;
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// private static final int PINK = 0xFFCCE5;
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// private static final int MEDIUM_BLUE = 0x3399FF;
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// private static final int LIGHT_BLUE = 0x99CCFF;
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// private static final int AQUA = 0x99FFFF;
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// private static final int WHITE = 0xFFFFFF;
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// private static int[] palette =
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// private static int[] palette =
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// { BLACK, MAGENTA, BROWN, ORANGE, DARK_GREEN, GRAY, GREEN, YELLOW, DARK_BLUE,
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// PURPLE, GRAY, PINK, MEDIUM_BLUE, LIGHT_BLUE, AQUA, WHITE };
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private static final int BLACK = 0x000000;
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private static final int MAGENTA = 0xFF00FF;
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private static final int BROWN = 0x994C00;
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private static final int ORANGE = 0xFF9933;
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private static final int DARK_GREEN = 0x006600;
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private static final int GRAY = 0xA0A0A0;
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private static final int GREEN = 0x00CC00;
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private static final int YELLOW = 0xFFFF33;
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private static final int DARK_BLUE = 0x0066CC;
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private static final int PURPLE = 0xCC00CC;
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private static final int PINK = 0xFFCCE5;
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private static final int MEDIUM_BLUE = 0x3399FF;
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private static final int LIGHT_BLUE = 0x99CCFF;
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private static final int AQUA = 0x99FFFF;
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private static final int MAGENTA = 0xDD0033;
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private static final int BROWN = 0x885500;
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private static final int ORANGE = 0xFF6600;
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private static final int DARK_GREEN = 0x007722;
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private static final int GRAY1 = 0x555555;
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private static final int GREEN = 0x11DD00;
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private static final int YELLOW = 0xFFFF00;
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private static final int DARK_BLUE = 0x000099;
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private static final int PURPLE = 0xDD22DD;
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private static final int GRAY2 = 0xAAAAAA;
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private static final int PINK = 0xFF9988;
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private static final int MEDIUM_BLUE = 0x2222FF;
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private static final int LIGHT_BLUE = 0x66AAFF;
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private static final int AQUA = 0x44FF99;
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private static final int WHITE = 0xFFFFFF;
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private static int[] palette =
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{ BLACK, MAGENTA, BROWN, ORANGE, DARK_GREEN, GRAY, GREEN, YELLOW, DARK_BLUE, PURPLE,
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GRAY, PINK, MEDIUM_BLUE, LIGHT_BLUE, AQUA, WHITE };
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{ BLACK, MAGENTA, DARK_BLUE, PURPLE, DARK_GREEN, GRAY1, MEDIUM_BLUE, LIGHT_BLUE,
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BROWN, ORANGE, GRAY2, PINK, GREEN, YELLOW, AQUA, WHITE };
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// private static final int BLACK = 0x000000;
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// private static final int MAGENTA = 0x722640;
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@ -68,8 +89,8 @@ public class DoubleHiResImage extends HiResImage
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packedBuffer = buffer;
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doubleScrunch = new DoubleScrunch ();
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doubleScrunch.unscrunch (buffer);
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auxBuffer = doubleScrunch.auxBuffer;
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this.buffer = doubleScrunch.primaryBuffer;
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auxBuffer = doubleScrunch.memory[0];
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this.buffer = doubleScrunch.memory[1];
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createImage ();
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}
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@ -4,10 +4,10 @@ import com.bytezone.diskbrowser.utilities.CPU;
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public class DoubleScrunch extends CPU
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{
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private byte mem_71D0; // screen row index (X)
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private byte mem_71D2; // screen column index
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private byte mem_71D0; // varies 1/0/1/0 ...
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private byte mem_71D2; // column index * 2 (00-4F) increments every C0 bytes
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private byte mem_71D3; // byte to repeat
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private byte mem_71D4; // # of bytes to store
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private byte mem_71D4; // repetition counter
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private int src; // base address of packed buffer
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private int dst; // base address of main/aux memory
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@ -20,21 +20,77 @@ public class DoubleScrunch extends CPU
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private byte zp_E6; // hi-res page ($20 or $40)
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final byte[] auxBuffer = new byte[0x2000];
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final byte[] primaryBuffer = new byte[0x2000];
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// final byte[] auxBuffer = new byte[0x2000];
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// final byte[] primaryBuffer = new byte[0x2000];
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final byte[][] memory = new byte[2][0x2000];
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private byte[] packedBuffer;
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private final boolean debug = false;
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private int count;
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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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public DoubleScrunch ()
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{
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setDebug (debug);
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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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}
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void unscrunch (byte[] buffer)
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{
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packedBuffer = buffer;
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while (true)
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{
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int rep = packedBuffer[ptr++] & 0xFF;
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if ((rep & 0x80) == 0) // repeat same byte
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{
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byte val = packedBuffer[ptr++];
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while (rep-- > 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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rep &= 0x7F;
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while (rep-- > 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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private boolean move (byte val)
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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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// no longer needed, it was used to decipher the Beagle Bros routine
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void oldUnscrunch (byte[] buffer)
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{
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packedBuffer = buffer;
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src = 0x4000; // packed picture data
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dst = 0x2000; // main/aux picture data
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@ -48,9 +104,10 @@ public class DoubleScrunch extends CPU
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zp_27 = sta ();
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ldx ((byte) 0x01);
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mem_71D0 = stx ();
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mem_71D0 = stx (); // X and 71D0 are both set to 1
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ldy ((byte) 0x00);
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mem_71D2 = sty (); // line offset = 0
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mem_71D2 = sty (); // column index = 0
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zp_26 = sty (); // output index = 0
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while (true)
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@ -60,27 +117,27 @@ public class DoubleScrunch extends CPU
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php ();
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// prepare address to get next transfer byte (done in copy/repeat routine)
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// increment address to get next transfer byte (done in copy/repeat routine)
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zp_00 = inc (zp_00);
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if (zero)
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zp_01 = inc (zp_01);
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and ((byte) 0x7F); // remove copy/repeat flag
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mem_71D4 = sta (); // save repetition counter
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mem_71D4 = sta (); // save repetition counter (RC)
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plp ();
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// copy or repeat RC bytes
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if (negative ? copyBytes () : repeatBytes ())
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break;
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// prepare address to get next repetition counter
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// increment address to get next repetition counter
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zp_00 = inc (zp_00);
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if (zero)
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zp_01 = inc (zp_01);
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}
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}
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// $7144
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// copy a single byte $71D4 times
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// copy a single byte RC times
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private boolean repeatBytes ()
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{
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// get the byte to store
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@ -93,7 +150,7 @@ public class DoubleScrunch extends CPU
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storeByte (); // store it and decrement repetition counter
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calculateScreenLine ();
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calculateScreenColumn ();
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if (carry)
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return true; // completely finished
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@ -105,8 +162,7 @@ public class DoubleScrunch extends CPU
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}
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}
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// $717D
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// copy the next $71D4 bytes
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// copy the next RC bytes
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private boolean copyBytes ()
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{
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while (true)
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@ -117,7 +173,7 @@ public class DoubleScrunch extends CPU
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storeByte (); // store it and decrement repetition counter
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calculateScreenLine ();
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calculateScreenColumn ();
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if (carry)
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return true; // completely finished
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@ -134,33 +190,72 @@ public class DoubleScrunch extends CPU
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}
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}
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// store the byte currently in Acc
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private void storeByte ()
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{
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mem_71D4 = dec (mem_71D4); // decrement counter
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ldy (mem_71D2); // line offset
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mem_71D4 = dec (mem_71D4); // decrement repetition counter (RC)
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ldy (mem_71D2); // column index (times 2)
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php ();
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sei ();
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// sei ();
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pha ();
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tya ();
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lsr (); // divide by 2 ?
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lsr (); // divide by 2, put odd/even value in carry (bank)
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tay ();
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pla ();
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// switch page
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byte[] target = carry ? primaryBuffer : auxBuffer;
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// store byte
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sta (target, indirectY (dst, zp_26, zp_27));
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if (false)
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System.out.printf (
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"%04X D0: %02X D2: %02X xReg: %02X bank: %d %02X -> %02X %02X + %02X%n",
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count++, mem_71D0, mem_71D2, stx (), carry ? 0 : 1, sta (), zp_27, zp_26,
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sty ());
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sta (memory[carry ? 1 : 0], indirectY (dst, zp_26, zp_27));
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plp ();
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}
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// $70E8
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// $71B1
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private void calculateScreenColumn ()
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{
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// increment X by 2 - X varies 01, 03, 05 -> BF, then 00, 02, 04 -> BE
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inx ();
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inx ();
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cpx ((byte) 0xC0); // # screen lines
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if (!carry) // X < $C0
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return; // continue current phase
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// carry is now set, current phase is finished
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// change phase
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mem_71D0 = dec (mem_71D0); // either 1 -> 0, or 0 -> -1
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if (!negative) //
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{
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assert mem_71D0 == 0;
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// start second phase of screen column
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ldx ((byte) 0x00); // start X at 0
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// mem_71D0 = stx (); // phase 2 (not necessary, was already 0)
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clc ();
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return; // start phase 2
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}
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// start a new screen column (and start phase 1)
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mem_71D2 = inc (mem_71D2); // increment column index
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ldy (mem_71D2);
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cpy ((byte) 0x50); // test for end of line (2 x 0x28)
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if (carry) // Y >= $50
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return; // program finished
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ldx ((byte) 0x01); // start X at 1
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mem_71D0 = stx (); // start phase 1
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clc ();
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}
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// set locations $26-27 (address of first location in screen line)
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private void calculateNextScreenAddress ()
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{
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txa ();
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and ((byte) 0xC0); // clear bits 5-0
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and ((byte) 0xC0); // get 2 hi bits - 00/40/80
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zp_26 = sta ();
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lsr ();
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@ -188,39 +283,6 @@ public class DoubleScrunch extends CPU
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zp_27 = sta ();
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}
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// $71B1
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private void calculateScreenLine ()
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{
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inx ();
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inx ();
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cpx ((byte) 0xC0);
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if (!carry) // BCC $71CE
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{
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clc ();
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return;
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}
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mem_71D0 = dec (mem_71D0);
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if (!negative) // BPL $71C9
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{
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ldx ((byte) 0);
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mem_71D0 = stx ();
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clc ();
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return;
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}
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mem_71D2 = inc (mem_71D2); // increment line offset
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ldy (mem_71D2);
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cpy ((byte) 0x50);
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if (carry) // BCS $71CF
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return; // program finished
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ldx ((byte) 0x01);
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// bit ((byte) 0xA2); // ??
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mem_71D0 = stx ();
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clc ();
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}
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@Override
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protected String debugString ()
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{
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