diff --git a/README.md b/README.md
index a9d06c4..a605aa0 100644
--- a/README.md
+++ b/README.md
@@ -41,6 +41,10 @@ The following features are present:
The library provides the `BlockDecoder` class, which can be used to decode. A new instance is created by one of the
static factory methods. You can let the library create a new buffer, or pass an existing one to save allocations.
+After construction, decoders produce no heap allocations during decoding. Internal working state is pre-allocated and
+reused across calls. Note that this also means instances are **not thread-safe**: each thread must use its own decoder
+instance.
+
Given `src` is the compressed data, starting at offset `srcPos`, the following code snippet shows how to decode a BC1
texture.
diff --git a/src/main/java/be/twofold/tinybcdec/BC1.java b/src/main/java/be/twofold/tinybcdec/BC1.java
index d765db8..0801184 100644
--- a/src/main/java/be/twofold/tinybcdec/BC1.java
+++ b/src/main/java/be/twofold/tinybcdec/BC1.java
@@ -5,6 +5,7 @@
final class BC1 extends BlockDecoder {
private static final int BPP = 4;
+ private final int[] colors = new int[4];
private final boolean bc2Or3;
private final int color3;
@@ -29,11 +30,10 @@ public void decodeBlock(ByteBuffer src, int srcPos, ByteBuffer dst, int dstPos,
int g1 = (c1 >>> +5) & 0x3F;
int b1 = (c1/* */) & 0x1F;
- int[] colors = {
- rgb(scale031(r0), scale063(g0), scale031(b0)),
- rgb(scale031(r1), scale063(g1), scale031(b1)),
- 0, 0
- };
+ int[] colors = this.colors;
+ colors[0] = rgb(scale031(r0), scale063(g0), scale031(b0));
+ colors[1] = rgb(scale031(r1), scale063(g1), scale031(b1));
+
if (c0 > c1 || bc2Or3) {
int r2 = scale093(2 * r0 + r1);
int g2 = scale189(2 * g0 + g1);
diff --git a/src/main/java/be/twofold/tinybcdec/BC2.java b/src/main/java/be/twofold/tinybcdec/BC2.java
index eec2046..3e99d31 100644
--- a/src/main/java/be/twofold/tinybcdec/BC2.java
+++ b/src/main/java/be/twofold/tinybcdec/BC2.java
@@ -4,17 +4,16 @@
final class BC2 extends BlockDecoder {
private static final int BPP = 4;
- private static final BC1 COLOR_DECODER = new BC1(BC1Mode.BC2OR3);
- static final BlockDecoder INSTANCE = new BC2();
+ private final BC1 colorDecoder = new BC1(BC1Mode.BC2OR3);
- private BC2() {
+ BC2() {
super(BPP, 16);
}
@Override
public void decodeBlock(ByteBuffer src, int srcPos, ByteBuffer dst, int dstPos, int stride) {
- COLOR_DECODER.decodeBlock(src, srcPos + 8, dst, dstPos, stride);
+ colorDecoder.decodeBlock(src, srcPos + 8, dst, dstPos, stride);
decodeAlpha(src, srcPos, dst, dstPos + 3, stride);
}
diff --git a/src/main/java/be/twofold/tinybcdec/BC3.java b/src/main/java/be/twofold/tinybcdec/BC3.java
index e034a30..e1c06b2 100644
--- a/src/main/java/be/twofold/tinybcdec/BC3.java
+++ b/src/main/java/be/twofold/tinybcdec/BC3.java
@@ -4,18 +4,17 @@
final class BC3 extends BlockDecoder {
private static final int BPP = 4;
- private static final BC1 COLOR_DECODER = new BC1(BC1Mode.BC2OR3);
- private static final BC4U ALPHA_DECODER = new BC4U(BPP);
- static final BlockDecoder INSTANCE = new BC3();
+ private final BC1 colorDecoder = new BC1(BC1Mode.BC2OR3);
+ private final BC4U alphaDecoder = new BC4U(BPP);
- private BC3() {
+ BC3() {
super(BPP, 16);
}
@Override
public void decodeBlock(ByteBuffer src, int srcPos, ByteBuffer dst, int dstPos, int stride) {
- COLOR_DECODER.decodeBlock(src, srcPos + 8, dst, dstPos/**/, stride);
- ALPHA_DECODER.decodeBlock(src, srcPos/**/, dst, dstPos + 3, stride);
+ colorDecoder.decodeBlock(src, srcPos + 8, dst, dstPos/**/, stride);
+ alphaDecoder.decodeBlock(src, srcPos/**/, dst, dstPos + 3, stride);
}
}
diff --git a/src/main/java/be/twofold/tinybcdec/BC4S.java b/src/main/java/be/twofold/tinybcdec/BC4S.java
index 6a7f402..02f5616 100644
--- a/src/main/java/be/twofold/tinybcdec/BC4S.java
+++ b/src/main/java/be/twofold/tinybcdec/BC4S.java
@@ -3,6 +3,8 @@
import java.nio.*;
final class BC4S extends BlockDecoder {
+ private final byte[] alphas = new byte[8];
+
BC4S(int pixelStride) {
super(pixelStride, 8);
}
@@ -14,19 +16,24 @@ public void decodeBlock(ByteBuffer src, int srcPos, ByteBuffer dst, int dstPos,
int a0 = Math.max(-127, (byte) (block/* */));
int a1 = Math.max(-127, (byte) (block >>> 8));
- byte[] alphas = {scale127(a0), scale127(a1), 0, 0, 0, 0, 0, (byte) 0xFF};
+ byte[] alphas = this.alphas;
+ alphas[0] = scale127(a0);
+ alphas[1] = scale127(a1);
+
if (a0 > a1) {
- alphas[2] = scale889(6 * a0 +/* */a1);
+ alphas[2] = scale889(6 * a0 + /**/a1);
alphas[3] = scale889(5 * a0 + 2 * a1);
alphas[4] = scale889(4 * a0 + 3 * a1);
alphas[5] = scale889(3 * a0 + 4 * a1);
alphas[6] = scale889(2 * a0 + 5 * a1);
alphas[7] = scale889(/**/a0 + 6 * a1);
} else {
- alphas[2] = scale635(4 * a0 +/* */a1);
+ alphas[2] = scale635(4 * a0 + /**/a1);
alphas[3] = scale635(3 * a0 + 2 * a1);
alphas[4] = scale635(2 * a0 + 3 * a1);
alphas[5] = scale635(/**/a0 + 4 * a1);
+ alphas[6] = (byte) 0x00;
+ alphas[7] = (byte) 0xFF;
}
long indices = block >>> 16;
diff --git a/src/main/java/be/twofold/tinybcdec/BC4U.java b/src/main/java/be/twofold/tinybcdec/BC4U.java
index 9158e12..8355c16 100644
--- a/src/main/java/be/twofold/tinybcdec/BC4U.java
+++ b/src/main/java/be/twofold/tinybcdec/BC4U.java
@@ -3,6 +3,8 @@
import java.nio.*;
final class BC4U extends BlockDecoder {
+ private final byte[] alphas = new byte[8];
+
BC4U(int pixelStride) {
super(pixelStride, 8);
}
@@ -14,19 +16,24 @@ public void decodeBlock(ByteBuffer src, int srcPos, ByteBuffer dst, int dstPos,
int a0 = (int) (block/* */) & 0xFF;
int a1 = (int) (block >>> 8) & 0xFF;
- byte[] alphas = {(byte) a0, (byte) a1, 0, 0, 0, 0, 0, (byte) 0xFF};
+ byte[] alphas = this.alphas;
+ alphas[0] = (byte) a0;
+ alphas[1] = (byte) a1;
+
if (a0 > a1) {
- alphas[2] = scale1785(6 * a0 +/* */a1);
+ alphas[2] = scale1785(6 * a0 + /**/a1);
alphas[3] = scale1785(5 * a0 + 2 * a1);
alphas[4] = scale1785(4 * a0 + 3 * a1);
alphas[5] = scale1785(3 * a0 + 4 * a1);
alphas[6] = scale1785(2 * a0 + 5 * a1);
alphas[7] = scale1785(/**/a0 + 6 * a1);
} else {
- alphas[2] = scale1275(4 * a0 +/* */a1);
+ alphas[2] = scale1275(4 * a0 + /**/a1);
alphas[3] = scale1275(3 * a0 + 2 * a1);
alphas[4] = scale1275(2 * a0 + 3 * a1);
alphas[5] = scale1275(/**/a0 + 4 * a1);
+ alphas[6] = (byte) 0x00;
+ alphas[7] = (byte) 0xFF;
}
long indices = block >>> 16;
diff --git a/src/main/java/be/twofold/tinybcdec/BC5S.java b/src/main/java/be/twofold/tinybcdec/BC5S.java
index 697f320..0fccd89 100644
--- a/src/main/java/be/twofold/tinybcdec/BC5S.java
+++ b/src/main/java/be/twofold/tinybcdec/BC5S.java
@@ -4,17 +4,16 @@
final class BC5S extends BlockDecoder {
private static final int BPP = 2;
- private static final BC4S DECODER = new BC4S(BPP);
- static final BlockDecoder INSTANCE = new BC5S();
+ private final BC4S decoder = new BC4S(BPP);
- private BC5S() {
+ BC5S() {
super(BPP, 16);
}
@Override
public void decodeBlock(ByteBuffer src, int srcPos, ByteBuffer dst, int dstPos, int stride) {
- DECODER.decodeBlock(src, srcPos/**/, dst, dstPos/**/, stride);
- DECODER.decodeBlock(src, srcPos + 8, dst, dstPos + 1, stride);
+ decoder.decodeBlock(src, srcPos/**/, dst, dstPos/**/, stride);
+ decoder.decodeBlock(src, srcPos + 8, dst, dstPos + 1, stride);
}
}
diff --git a/src/main/java/be/twofold/tinybcdec/BC5U.java b/src/main/java/be/twofold/tinybcdec/BC5U.java
index 6d908b1..f4ce4d6 100644
--- a/src/main/java/be/twofold/tinybcdec/BC5U.java
+++ b/src/main/java/be/twofold/tinybcdec/BC5U.java
@@ -4,17 +4,16 @@
final class BC5U extends BlockDecoder {
private static final int BPP = 2;
- private static final BC4U DECODER = new BC4U(BPP);
- static final BlockDecoder INSTANCE = new BC5U();
+ private final BC4U decoder = new BC4U(BPP);
- private BC5U() {
+ BC5U() {
super(BPP, 16);
}
@Override
public void decodeBlock(ByteBuffer src, int srcPos, ByteBuffer dst, int dstPos, int stride) {
- DECODER.decodeBlock(src, srcPos/**/, dst, dstPos/**/, stride);
- DECODER.decodeBlock(src, srcPos + 8, dst, dstPos + 1, stride);
+ decoder.decodeBlock(src, srcPos/**/, dst, dstPos/**/, stride);
+ decoder.decodeBlock(src, srcPos + 8, dst, dstPos + 1, stride);
}
}
diff --git a/src/main/java/be/twofold/tinybcdec/BC6H.java b/src/main/java/be/twofold/tinybcdec/BC6H.java
index acbffb8..f3dec01 100644
--- a/src/main/java/be/twofold/tinybcdec/BC6H.java
+++ b/src/main/java/be/twofold/tinybcdec/BC6H.java
@@ -23,6 +23,8 @@ final class BC6H extends BPTC {
new Mode(T, F, 16, +4, +4, +4, new short[]{0x000A, 0x010A, 0x020A, 0x0404, 0x10A6, 0x0504, 0x11A6, 0x0604, 0x12A6})
);
+ private final Bits bits = new Bits();
+ private final int[] colors = new int[16];
private final boolean signed;
BC6H(boolean signed) {
@@ -32,7 +34,8 @@ final class BC6H extends BPTC {
@Override
public void decodeBlock(ByteBuffer src, int srcPos, ByteBuffer dst, int dstPos, int stride) {
- Bits bits = Bits.from(src, srcPos);
+ Bits bits = this.bits;
+ bits.read(src, srcPos);
int modeIndex = mode(bits);
if (modeIndex >= MODES.size()) {
@@ -41,7 +44,8 @@ public void decodeBlock(ByteBuffer src, int srcPos, ByteBuffer dst, int dstPos,
}
Mode mode = MODES.get(modeIndex);
- int[] colors = new int[16];
+ int[] colors = this.colors;
+ Arrays.fill(colors, 0);
for (short op : mode.ops) {
readOp(bits, op, colors);
}
@@ -89,10 +93,10 @@ public void decodeBlock(ByteBuffer src, int srcPos, ByteBuffer dst, int dstPos,
int weight = weights[(int) (indexBits & mask)];
indexBits >>>= ib;
- int pIndex = partitions & 3;
- short r = finalUnquantize(interpolate(colors[pIndex * 8/**/], colors[pIndex * 8 + 4], weight), signed);
- short g = finalUnquantize(interpolate(colors[pIndex * 8 + 1], colors[pIndex * 8 + 5], weight), signed);
- short b = finalUnquantize(interpolate(colors[pIndex * 8 + 2], colors[pIndex * 8 + 6], weight), signed);
+ int index = (partitions & 3) * 8;
+ short r = finalUnquantize(interpolate(colors[index/**/], colors[index + 4], weight), signed);
+ short g = finalUnquantize(interpolate(colors[index + 1], colors[index + 5], weight), signed);
+ short b = finalUnquantize(interpolate(colors[index + 2], colors[index + 6], weight), signed);
partitions >>>= 2;
int o = dstPos + x * BPP;
diff --git a/src/main/java/be/twofold/tinybcdec/BC7.java b/src/main/java/be/twofold/tinybcdec/BC7.java
index 8162c4b..c0b7732 100644
--- a/src/main/java/be/twofold/tinybcdec/BC7.java
+++ b/src/main/java/be/twofold/tinybcdec/BC7.java
@@ -17,9 +17,10 @@ final class BC7 extends BPTC {
new Mode(2, 6, F, F, 5, 5, T, F, 2, 0)
);
- static final BC7 INSTANCE = new BC7();
+ private final Bits bits = new Bits();
+ private final int[] colors = new int[3 * 2 * 4];
- private BC7() {
+ BC7() {
super(BPP);
}
@@ -31,14 +32,16 @@ public void decodeBlock(ByteBuffer src, int srcPos, ByteBuffer dst, int dstPos,
return;
}
- Bits bits = Bits.from(src, srcPos);
+ Bits bits = this.bits;
+ bits.read(src, srcPos);
+
bits.get(modeIndex + 1); // Skip mode bits
Mode mode = MODES.get(modeIndex);
int partition = mode.pb != 0 ? bits.get(mode.pb) : 0;
int rotation = mode.rb ? bits.get(2) : 0;
boolean selection = mode.isb && bits.get1() != 0;
- int[] colors = new int[6 * 4];
+ int[] colors = this.colors;
// Read colors
int numColors = mode.ns * 2;
diff --git a/src/main/java/be/twofold/tinybcdec/BPTC.java b/src/main/java/be/twofold/tinybcdec/BPTC.java
index 62029cb..c1ae789 100644
--- a/src/main/java/be/twofold/tinybcdec/BPTC.java
+++ b/src/main/java/be/twofold/tinybcdec/BPTC.java
@@ -119,15 +119,12 @@ static final class Bits {
private long lo;
private long hi;
- private Bits(long lo, long hi) {
- this.lo = lo;
- this.hi = hi;
+ Bits() {
}
- static Bits from(ByteBuffer buffer, int index) {
- long lo = ByteIO.getLong(buffer, index);
- long hi = ByteIO.getLong(buffer, index + 8);
- return new Bits(lo, hi);
+ void read(ByteBuffer buffer, int index) {
+ lo = ByteIO.getLong(buffer, index);
+ hi = ByteIO.getLong(buffer, index + 8);
}
int get(int count) {
diff --git a/src/main/java/be/twofold/tinybcdec/BlockDecoder.java b/src/main/java/be/twofold/tinybcdec/BlockDecoder.java
index 8bf26fd..fe0deb8 100644
--- a/src/main/java/be/twofold/tinybcdec/BlockDecoder.java
+++ b/src/main/java/be/twofold/tinybcdec/BlockDecoder.java
@@ -11,6 +11,8 @@
* Depending on if you want to allocate a new byte array or use an existing one.
*
* To decode a single block, use the {@link #decodeBlock(ByteBuffer, int, ByteBuffer, int, int)} method.
+ *
+ * Thread safety: instances are not thread-safe. Each thread should use its own decoder instance.
*/
public abstract class BlockDecoder {
static final int BLOCK_WIDTH = 4;
@@ -41,7 +43,7 @@ public static BlockDecoder bc1(boolean opaque) {
* @return The block decoder.
*/
public static BlockDecoder bc2() {
- return BC2.INSTANCE;
+ return new BC2();
}
/**
@@ -50,7 +52,7 @@ public static BlockDecoder bc2() {
* @return The block decoder.
*/
public static BlockDecoder bc3() {
- return BC3.INSTANCE;
+ return new BC3();
}
/**
@@ -70,7 +72,7 @@ public static BlockDecoder bc4(boolean signed) {
* @return The block decoder.
*/
public static BlockDecoder bc5(boolean signed) {
- return signed ? BC5S.INSTANCE : BC5U.INSTANCE;
+ return signed ? new BC5S() : new BC5U();
}
/**
@@ -89,7 +91,7 @@ public static BlockDecoder bc6h(boolean signed) {
* @return The block decoder.
*/
public static BlockDecoder bc7() {
- return BC7.INSTANCE;
+ return new BC7();
}
/**
@@ -197,12 +199,17 @@ public void decode(
throw new IndexOutOfBoundsException("Not enough data in dst buffer");
}
+ ByteOrder srcOrder = src.order();
+ ByteOrder dstOrder = dst.order();
+ src.order(ByteOrder.LITTLE_ENDIAN);
+ dst.order(ByteOrder.LITTLE_ENDIAN);
+
int srcBlocksW = (srcWidth + (BLOCK_WIDTH - 1)) / BLOCK_WIDTH;
int srcLineStride = srcBlocksW * bytesPerBlock;
int dstLineStride = dstWidth * bytesPerPixel;
- var srcBuf = src.slice().order(ByteOrder.LITTLE_ENDIAN);
- var dstBuf = dst.slice().order(ByteOrder.LITTLE_ENDIAN);
+ int srcBase = src.position();
+ int dstBase = dst.position();
for (int y = 0; y < height; ) {
int srcRowStart = ((srcY + y) / BLOCK_HEIGHT * srcLineStride);
int dstRowStart = ((dstY + y) * dstLineStride);
@@ -210,23 +217,25 @@ public void decode(
int blockH = Math.min(BLOCK_HEIGHT - blockY, height - y);
for (int x = 0; x < width; ) {
- int srcPosStart = srcRowStart + ((srcX + x) / BLOCK_WIDTH * bytesPerBlock);
- int dstPosStart = dstRowStart + ((dstX + x) * bytesPerPixel);
+ int srcPosStart = srcBase + srcRowStart + ((srcX + x) / BLOCK_WIDTH * bytesPerBlock);
+ int dstPosStart = dstBase + dstRowStart + ((dstX + x) * bytesPerPixel);
int blockX = (srcX + x) % BLOCK_WIDTH;
int blockW = Math.min(BLOCK_WIDTH - blockX, width - x);
if (blockX == 0 && x + BLOCK_WIDTH <= width && blockY == 0 && y + BLOCK_HEIGHT <= height) {
- decodeBlock(srcBuf, srcPosStart, dstBuf, dstPosStart, dstLineStride);
+ decodeBlock(src, srcPosStart, dst, dstPosStart, dstLineStride);
x += BLOCK_WIDTH;
} else {
partialBlock(
- srcBuf, srcPosStart, dstBuf, dstPosStart, dstLineStride,
+ src, srcPosStart, dst, dstPosStart, dstLineStride,
blockX, blockY, blockW, blockH);
x += blockW;
}
}
y += blockH;
}
+ src.order(srcOrder);
+ dst.order(dstOrder);
}
/**
@@ -269,8 +278,8 @@ private void partialBlock(
int offset = blockY * stride + blockX * bytesPerPixel;
for (int row = 0; row < blockH; row++) {
- var srcOff = offset + (row * stride);
- var dstOff = dstPos + (row * lineStride);
+ int srcOff = offset + (row * stride);
+ int dstOff = dstPos + (row * lineStride);
ByteIO.copy(scratch, srcOff, dst, dstOff, blockW * bytesPerPixel);
}
}
diff --git a/src/test/java/be/twofold/tinybcdec/BlockDecoderTest.java b/src/test/java/be/twofold/tinybcdec/BlockDecoderTest.java
index bc3bd93..07514a5 100644
--- a/src/test/java/be/twofold/tinybcdec/BlockDecoderTest.java
+++ b/src/test/java/be/twofold/tinybcdec/BlockDecoderTest.java
@@ -31,7 +31,7 @@ void testPartialBlockCrop() throws IOException {
int dstOffset = 31;
ByteBuffer dst = ByteBuffer.allocate(8 * 8 + dstOffset);
- var decoder = BlockDecoder.bc4(false);
+ BlockDecoder decoder = BlockDecoder.bc4(false);
for (int h = 1; h <= 8; h++) {
for (int w = 1; w <= 8; w++) {
decoder.decode(src.position(BCTestUtils.DDS_HEADER_SIZE), srcWidth, srcHeight, dst.position(dstOffset), w, h);
@@ -55,7 +55,7 @@ void testPartialBlockCropExtra() throws IOException {
int dstOffset = 31;
ByteBuffer dst = ByteBuffer.allocate(8 * 8 + dstOffset);
- var decoder = BlockDecoder.bc4(false);
+ BlockDecoder decoder = BlockDecoder.bc4(false);
// Test all offsets between 0 and 8
for (int srcY = 1; srcY < 8; srcY++) {