1 files changed, 176 insertions, 0 deletions
diff --git a/assets/npyjs.js b/assets/npyjs.js
new file mode 100644
index 0000000..b474575
--- /dev/null
+++ b/assets/npyjs.js
@@ -0,0 +1,176 @@
+class npyjs {
+
+    constructor(opts) {
+        if (opts && !('convertFloat16' in opts)) {
+            console.warn([
+                "npyjs constructor now accepts {convertFloat16?: boolean}.",
+                "For usage, go to https://github.com/jhuapl-boss/npyjs."
+            ].join(" "));
+        }
+
+        this.convertFloat16 = opts?.convertFloat16 ?? true;
+
+        this.dtypes = {
+            "<u1": {
+                name: "uint8",
+                size: 8,
+                arrayConstructor: Uint8Array,
+            },
+            "|u1": {
+                name: "uint8",
+                size: 8,
+                arrayConstructor: Uint8Array,
+            },
+            "<u2": {
+                name: "uint16",
+                size: 16,
+                arrayConstructor: Uint16Array,
+            },
+            "|i1": {
+                name: "int8",
+                size: 8,
+                arrayConstructor: Int8Array,
+            },
+            "<i2": {
+                name: "int16",
+                size: 16,
+                arrayConstructor: Int16Array,
+            },
+            "<u4": {
+                name: "uint32",
+                size: 32,
+                arrayConstructor: Uint32Array,
+            },
+            "<i4": {
+                name: "int32",
+                size: 32,
+                arrayConstructor: Int32Array,
+            },
+            "<u8": {
+                name: "uint64",
+                size: 64,
+                arrayConstructor: BigUint64Array,
+            },
+            "<i8": {
+                name: "int64",
+                size: 64,
+                arrayConstructor: BigInt64Array,
+            },
+            "<f4": {
+                name: "float32",
+                size: 32,
+                arrayConstructor: Float32Array
+            },
+            "<f8": {
+                name: "float64",
+                size: 64,
+                arrayConstructor: Float64Array
+            },
+            "<f2": {
+                name: "float16",
+                size: 16,
+                arrayConstructor: Uint16Array,
+                converter: this.convertFloat16 ? this.float16ToFloat32Array : undefined
+            },
+        };
+    }
+
+    float16ToFloat32Array(float16Array) {
+        const length = float16Array.length;
+        const float32Array = new Float32Array(length);
+        
+        for (let i = 0; i < length; i++) {
+            float32Array[i] = npyjs.float16ToFloat32(float16Array[i]);
+        }
+        
+        return float32Array;
+    }
+
+    static float16ToFloat32(float16) {
+        // Extract the parts of the float16
+        const sign = (float16 >> 15) & 0x1;
+        const exponent = (float16 >> 10) & 0x1f;
+        const fraction = float16 & 0x3ff;
+
+        // Handle special cases
+        if (exponent === 0) {
+            if (fraction === 0) {
+                // Zero
+                return sign ? -0 : 0;
+            }
+            // Denormalized number
+            return (sign ? -1 : 1) * Math.pow(2, -14) * (fraction / 0x400);
+        } else if (exponent === 0x1f) {
+            if (fraction === 0) {
+                // Infinity
+                return sign ? -Infinity : Infinity;
+            }
+            // NaN
+            return NaN;
+        }
+
+        // Normalized number
+        return (sign ? -1 : 1) * Math.pow(2, exponent - 15) * (1 + fraction / 0x400);
+    }
+
+    parse(arrayBufferContents) {
+        // const version = arrayBufferContents.slice(6, 8); // Uint8-encoded
+        const headerLength = new DataView(arrayBufferContents.slice(8, 10)).getUint8(0);
+        const offsetBytes = 10 + headerLength;
+
+        const hcontents = new TextDecoder("utf-8").decode(
+            new Uint8Array(arrayBufferContents.slice(10, 10 + headerLength))
+        );
+        const header = JSON.parse(
+            hcontents
+                .toLowerCase() // True -> true
+                .replace(/'/g, '"')
+                .replace("(", "[")
+                .replace(/,*\),*/g, "]")
+        );
+        const shape = header.shape;
+        const dtype = this.dtypes[header.descr];
+
+        if (!dtype) {
+            console.error(`Unsupported dtype: ${header.descr}`);
+            return null;
+        }
+
+        const nums = new dtype.arrayConstructor(
+            arrayBufferContents,
+            offsetBytes
+        );
+
+        // Convert float16 to float32 if converter exists
+        const data = dtype.converter ? dtype.converter.call(this, nums) : nums;
+
+        return {
+            dtype: dtype.name,
+            data: data,
+            shape,
+            fortranOrder: header.fortran_order
+        };
+    }
+
+    async load(filename, callback, fetchArgs) {
+        /*
+        Loads an array from a stream of bytes.
+        */
+        fetchArgs = fetchArgs || {};
+        let arrayBuf;
+        // If filename is ArrayBuffer
+        if (filename instanceof ArrayBuffer) {
+            arrayBuf = filename;
+        }
+        // If filename is a file path
+        else {
+            const resp = await fetch(filename, { ...fetchArgs });
+            arrayBuf = await resp.arrayBuffer();
+        }
+        const result = this.parse(arrayBuf);
+        if (callback) {
+            return callback(result);
+        }
+        return result;
+    }
+}