implement i128/u128 types (credit goes to @Jabolol)

src/non-standard-numbers/big_numbers.ts

@@ -0,0 +1,116 @@
+import { type Options, SizedType } from "../types/mod.ts";
+import { isLittleEndian } from "../util.ts";
+
+export class U128 extends SizedType<bigint> {
+  constructor(
+    readonly littleEndian: boolean = isLittleEndian,
+    /**
+     * Clang, GCC and rust 1.78 (with LLVM 18) say 16 byte alignment.
+     *
+     * Older rust versions (or rust with older LLVM versions) say 8 byte alignment.
+     *
+     * Due to compatiblity reason we allow 8 byte alignment with these older versions.
+     *
+     * But by default it uses the now correct 16 byte alignment.
+     *
+     * See [Rust's blogpost](https://blog.rust-lang.org/2024/03/30/i128-layout-update.html) for more details
+     */
+    alignment: 8 | 16 = 16,
+  ) {
+    super(16, alignment);
+  }
+
+  override readPacked(
+    dt: DataView,
+    options: Options = { byteOffset: 0 },
+  ): bigint {
+    const partOne = dt.getBigUint64(options.byteOffset, this.littleEndian);
+    const partTwo = dt.getBigUint64(options.byteOffset + 8, this.littleEndian);
+    super.incrementOffset(options);
+    // deno-fmt-ignore
+    return this.littleEndian
+        ? (partTwo << 64n) | partOne
+        : (partOne << 64n) | partTwo;
+  }
+
+  override writePacked(
+    value: bigint,
+    dt: DataView,
+    options: Options = { byteOffset: 0 },
+  ): void {
+    const hi = value >> 64n;
+    dt.setBigUint64(
+      options.byteOffset,
+      this.littleEndian ? hi : value,
+      this.littleEndian,
+    );
+    dt.setBigUint64(
+      options.byteOffset + 8,
+      this.littleEndian ? value : hi,
+      this.littleEndian,
+    );
+
+    super.incrementOffset(options);
+  }
+}
+
+export class I128 extends SizedType<bigint> {
+  constructor(
+    readonly littleEndian: boolean = isLittleEndian,
+    /**
+     * Clang, GCC and rust 1.78 (with LLVM 18) say 16 byte alignment.
+     *
+     * Older rust versions (or rust with older LLVM versions) say 8 byte alignment.
+     *
+     * Due to compatiblity reason we allow 8 byte alignment with these older versions.
+     *
+     * But by default it uses the now correct 16 byte alignment.
+     *
+     * See [Rust's blogpost](https://blog.rust-lang.org/2024/03/30/i128-layout-update.html) for more details
+     */
+    alignment: 8 | 16 = 16,
+  ) {
+    super(16, alignment);
+  }
+
+  override readPacked(
+    dt: DataView,
+    options: Options = { byteOffset: 0 },
+  ): bigint {
+    const partOne = dt.getBigInt64(options.byteOffset, this.littleEndian);
+    const partTwo = dt.getBigInt64(options.byteOffset + 8, this.littleEndian);
+    super.incrementOffset(options);
+    // deno-fmt-ignore
+    return this.littleEndian
+        ? (partTwo << 64n) | partOne
+        : (partOne << 64n) | partTwo;
+  }
+
+  override writePacked(
+    value: bigint,
+    dt: DataView,
+    options: Options = { byteOffset: 0 },
+  ): void {
+    const hi = value >> 64n;
+    dt.setBigInt64(
+      options.byteOffset,
+      this.littleEndian ? hi : value,
+      this.littleEndian,
+    );
+    dt.setBigInt64(
+      options.byteOffset + 8,
+      this.littleEndian ? value : hi,
+      this.littleEndian,
+    );
+
+    super.incrementOffset(options);
+  }
+}
+
+export const u128le: U128 = new U128(true);
+export const u128be: U128 = new U128(false);
+export const u128: U128 = new U128();
+
+export const i128le: I128 = new I128(true);
+export const i128be: I128 = new I128(false);
+export const i128: I128 = new I128();

src/non-standard-numbers/big_numbers_test.ts

@@ -0,0 +1,78 @@
+import { assertEquals, assertThrows } from "../../test_deps.ts";
+import { i128be, i128le, u128be, u128le } from "./big_numbers.ts";
+
+Deno.test("u128", async (t) => {
+  const buff = new ArrayBuffer(16);
+  const dt = new DataView(buff);
+  const value = 12n;
+
+  await t.step("read", () => {
+    // Little endian
+    const lo = value & 0xffffffffffffffffn;
+    const hi = value >> 64n;
+    dt.setBigUint64(0, lo, true);
+    dt.setBigUint64(8, hi, true);
+    assertEquals(value, u128le.read(dt));
+    // Big endian
+    dt.setBigUint64(0, hi, false);
+    dt.setBigUint64(8, lo, false);
+    assertEquals(value, u128be.read(dt));
+  });
+
+  await t.step("write", () => {
+    // Little endian
+    u128le.write(value, dt);
+    let lo = dt.getBigInt64(0, true);
+    let hi = dt.getBigInt64(8, true);
+    assertEquals(value, (lo << 64n) | hi);
+    // Big endian
+    u128be.write(value, dt);
+    lo = dt.getBigInt64(8, false);
+    hi = dt.getBigInt64(0, false);
+    assertEquals(value, (lo << 64n) | hi);
+  });
+
+  await t.step("OOB Read", () => {
+    assertThrows(() => {
+      u128le.read(dt, { byteOffset: 9 });
+    }, RangeError);
+  });
+});
+
+Deno.test("i128", async (t) => {
+  const buff = new ArrayBuffer(16);
+  const dt = new DataView(buff);
+  const value = 12n;
+
+  await t.step("read", () => {
+    // Little endian
+    const lo = value & 0xffffffffffffffffn;
+    const hi = value >> 64n;
+    dt.setBigUint64(0, lo, true);
+    dt.setBigUint64(8, hi, true);
+    assertEquals(value, i128le.read(dt));
+    // Big endian
+    dt.setBigUint64(0, hi, false);
+    dt.setBigUint64(8, lo, false);
+    assertEquals(value, i128be.read(dt));
+  });
+
+  await t.step("write", () => {
+    // Little endian
+    i128le.write(value, dt);
+    let lo = dt.getBigInt64(0, true);
+    let hi = dt.getBigInt64(8, true);
+    assertEquals(value, (lo << 64n) | hi);
+    // Big endian
+    i128be.write(value, dt);
+    lo = dt.getBigInt64(8, false);
+    hi = dt.getBigInt64(0, false);
+    assertEquals(value, (lo << 64n) | hi);
+  });
+
+  await t.step("OOB Read", () => {
+    assertThrows(() => {
+      i128le.read(dt, { byteOffset: 9 });
+    }, RangeError);
+  });
+});

src/non-standard-numbers/mod.ts

@@ -0,0 +1,2 @@
+export * from "./small_numbers.ts";
+export * from "./big_numbers.ts";