write-unaligned.js

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// Test unaligned write access.

load(libdir + "dataview.js");

// Create a new test function for each scalar type.

function createWrite(data) {

  const name = typeName(data.type);

  const offset = 1;

  return Function("data", `

    const {values, littleEndian, bigEndian} = data;

    // Load from array so that Ion doesn't treat as constants.

    const True = [true, 1];

    const False = [false, 0];

    const src = new ${data.type.name}(values);

    const ab = new ArrayBuffer(${data.type.BYTES_PER_ELEMENT + offset});

    const dv = new DataView(ab);

    const srcUint8 = new Uint8Array(src.buffer);

    const dstUint8 = new Uint8Array(ab);

    function assertSameContents(idx, msg) {

      for (let i = 0; i < ${data.type.BYTES_PER_ELEMENT}; ++i) {

        assertEq(dstUint8[i + ${offset}], srcUint8[i + idx * ${data.type.BYTES_PER_ELEMENT}]);

    for (let i = 0; i < 100; ++i) {

      let j = i % values.length;

      // Skip over NaNs to avoid false-negatives due to NaN canonicalisation.

      if (${name === "Float16" || name === "Float32" || name === "Float64"}) {

        if (Number.isNaN(bigEndian[j]) || Number.isNaN(littleEndian[j])) {

          continue;

      dstUint8.fill(0);

      dv.set${name}(${offset}, bigEndian[j]);

      assertSameContents(j, "default");

      dstUint8.fill(0);

      dv.set${name}(${offset}, littleEndian[j], true);

      assertSameContents(j, "little");

      dstUint8.fill(0);

      dv.set${name}(${offset}, bigEndian[j], false);

      assertSameContents(j, "big");

      dstUint8.fill(0);

      dv.set${name}(${offset}, littleEndian[j], True[i & 1]);

      assertSameContents(j, "little, dynamic");

      dstUint8.fill(0);

      dv.set${name}(${offset}, bigEndian[j], False[i & 1]);

      assertSameContents(j, "big, dynamic");

`);

for (let data of createTestData()) {

  let f = createWrite(data);

  for (let i = 0; i < 2; ++i) {

    f(data);