node/test/simple/test-writefloat.js

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/*
 * Tests to verify we're writing floats correctly
 */
var SlowBuffer = process.binding('buffer').SlowBuffer;
var common = require('../common');
var ASSERT = require('assert');

function test(clazz) {
  var buffer = new clazz(8);

  buffer.writeFloatBE(1, 0);
  buffer.writeFloatLE(1, 4);
  ASSERT.equal(0x3f, buffer[0]);
  ASSERT.equal(0x80, buffer[1]);
  ASSERT.equal(0x00, buffer[2]);
  ASSERT.equal(0x00, buffer[3]);
  ASSERT.equal(0x00, buffer[4]);
  ASSERT.equal(0x00, buffer[5]);
  ASSERT.equal(0x80, buffer[6]);
  ASSERT.equal(0x3f, buffer[7]);

  buffer.writeFloatBE(1.793662034335766e-43, 0);
  buffer.writeFloatLE(1.793662034335766e-43, 4);
  ASSERT.equal(0x00, buffer[0]);
  ASSERT.equal(0x00, buffer[1]);
  ASSERT.equal(0x00, buffer[2]);
  ASSERT.equal(0x80, buffer[3]);
  ASSERT.equal(0x80, buffer[4]);
  ASSERT.equal(0x00, buffer[5]);
  ASSERT.equal(0x00, buffer[6]);
  ASSERT.equal(0x00, buffer[7]);

  buffer.writeFloatBE(1 / 3, 0);
  buffer.writeFloatLE(1 / 3, 4);
  ASSERT.equal(0x3e, buffer[0]);
  ASSERT.equal(0xaa, buffer[1]);
  ASSERT.equal(0xaa, buffer[2]);
  ASSERT.equal(0xab, buffer[3]);
  ASSERT.equal(0xab, buffer[4]);
  ASSERT.equal(0xaa, buffer[5]);
  ASSERT.equal(0xaa, buffer[6]);
  ASSERT.equal(0x3e, buffer[7]);

  buffer.writeFloatBE(3.4028234663852886e+38, 0);
  buffer.writeFloatLE(3.4028234663852886e+38, 4);
  ASSERT.equal(0x7f, buffer[0]);
  ASSERT.equal(0x7f, buffer[1]);
  ASSERT.equal(0xff, buffer[2]);
  ASSERT.equal(0xff, buffer[3]);
  ASSERT.equal(0xff, buffer[4]);
  ASSERT.equal(0xff, buffer[5]);
  ASSERT.equal(0x7f, buffer[6]);
  ASSERT.equal(0x7f, buffer[7]);

  buffer.writeFloatBE(0 * -1, 0);
  buffer.writeFloatLE(0 * -1, 4);
  ASSERT.equal(0x80, buffer[0]);
  ASSERT.equal(0x00, buffer[1]);
  ASSERT.equal(0x00, buffer[2]);
  ASSERT.equal(0x00, buffer[3]);
  ASSERT.equal(0x00, buffer[4]);
  ASSERT.equal(0x00, buffer[5]);
  ASSERT.equal(0x00, buffer[6]);
  ASSERT.equal(0x80, buffer[7]);
}


test(Buffer);
test(SlowBuffer);