read-unaligned.js - mozsearch

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// Test unaligned read access.

load(libdir + "dataview.js");

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

function createRead(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 ab = new ArrayBuffer(${data.values.length * data.type.BYTES_PER_ELEMENT + offset});

    const dv = new DataView(ab);

    new ${data.type.name}(ab, 0, ${data.values.length}).set(values);

    new Uint8Array(ab).copyWithin(${offset}, 0);

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

      let j = i % values.length;

      let index = j * ${data.type.BYTES_PER_ELEMENT} + ${offset};

      let v1 = dv.get${name}(index);

      assertEq(v1, bigEndian[j]);

      let v2 = dv.get${name}(index, true);

      assertEq(v2, littleEndian[j]);

      let v3 = dv.get${name}(index, false);

      assertEq(v3, bigEndian[j]);

      let v4 = dv.get${name}(index, True[i & 1]);

      assertEq(v4, littleEndian[j]);

      let v5 = dv.get${name}(index, False[i & 1]);

      assertEq(v5, bigEndian[j]);

`);

for (let data of createTestData()) {

  let f = createRead(data);

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

    f(data);