1 files changed, 83 insertions, 0 deletions
diff --git a/dom/webgpu/tests/cts/checkout/src/webgpu/util/texture/data_generation.ts b/dom/webgpu/tests/cts/checkout/src/webgpu/util/texture/data_generation.ts
new file mode 100644
index 0000000000..7ad7d30e08
--- /dev/null
+++ b/dom/webgpu/tests/cts/checkout/src/webgpu/util/texture/data_generation.ts
@@ -0,0 +1,83 @@
+/**
+ * A helper class that generates ranges of dummy data for buffer or texture operations
+ * efficiently. Tries to minimize allocations and data updates.
+ */
+export class DataArrayGenerator {
+  private dataBuffer = new Uint8Array(256);
+
+  private lastOffset = 0;
+  private lastStart = 0;
+  private lastByteSize = 0;
+
+  /** Find the nearest power of two greater than or equal to the input value. */
+  private nextPowerOfTwo(value: number) {
+    return 1 << (32 - Math.clz32(value - 1));
+  }
+
+  private generateData(byteSize: number, start: number = 0, offset: number = 0) {
+    const prevSize = this.dataBuffer.length;
+
+    if (prevSize < byteSize) {
+      // If the requested data is larger than the allocated buffer, reallocate it to a buffer large
+      // enough to handle the new request.
+      const newData = new Uint8Array(this.nextPowerOfTwo(byteSize));
+
+      if (this.lastOffset === offset && this.lastStart === start && this.lastByteSize) {
+        // Do a fast copy of any previous data that was generated.
+        newData.set(this.dataBuffer);
+      }
+
+      this.dataBuffer = newData;
+    } else if (this.lastOffset < offset) {
+      // Ensure all values up to the offset are zeroed out.
+      this.dataBuffer.fill(0, this.lastOffset, offset);
+    }
+
+    // If the offset or start values have changed, the whole data range needs to be regenerated.
+    if (this.lastOffset !== offset || this.lastStart !== start) {
+      this.lastByteSize = 0;
+    }
+
+    // Generate any new values that are required
+    if (this.lastByteSize < byteSize) {
+      for (let i = this.lastByteSize; i < byteSize - offset; ++i) {
+        this.dataBuffer[i + offset] = ((i ** 3 + i + start) % 251) + 1; // Ensure data is always non-zero
+      }
+
+      this.lastOffset = offset;
+      this.lastStart = start;
+      this.lastByteSize = byteSize;
+    }
+  }
+
+  /**
+   * Returns a new view into the generated data that's the correct length. Because this is a view
+   * previously returned views from the same generator will have their values overwritten as well.
+   * @param {number} byteSize - Number of bytes the returned view should contain.
+   * @param {number} [start] - The value of the first element generated in the view.
+   * @param {number} [offset] - Offset of the generated data within the view. Preceeding values will be 0.
+   * @returns {Uint8Array} A new Uint8Array view into the generated data.
+   */
+  generateView(byteSize: number, start: number = 0, offset: number = 0): Uint8Array {
+    this.generateData(byteSize, start, offset);
+
+    if (this.dataBuffer.length === byteSize) {
+      return this.dataBuffer;
+    }
+    return new Uint8Array(this.dataBuffer.buffer, 0, byteSize);
+  }
+
+  /**
+   * Returns a copy of the generated data. Note that this still changes the underlying buffer, so
+   * any previously generated views will still be overwritten, but the returned copy won't reflect
+   * future generate* calls.
+   * @param {number} byteSize - Number of bytes the returned array should contain.
+   * @param {number} [start] - The value of the first element generated in the view.
+   * @param {number} [offset] - Offset of the generated data within the view. Preceeding values will be 0.
+   * @returns {Uint8Array} A new Uint8Array copy of the generated data.
+   */
+  generateAndCopyView(byteSize: number, start: number = 0, offset: number = 0) {
+    this.generateData(byteSize, start, offset);
+    return this.dataBuffer.slice(0, byteSize);
+  }
+}