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Add a BitBuffer to the io package and a few tests

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This commit is contained in:
Jeff Schiller 2021-12-20 20:35:59 -08:00
parent 596a859bdc
commit 24b1603968
12 changed files with 747 additions and 25 deletions
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tests/io-bitbuffer.spec.js Normal file
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/*
* io-bitbuffer.spec.js
*
* Licensed under the MIT License
*
* Copyright(c) 2021 Google Inc.
*/
import { BitBuffer } from '../io/bitbuffer.js';
import 'mocha';
import { expect } from 'chai';
describe('bitjs.io.BitBuffer', () => {
let buffer;
describe('least-to-most-significant bit-packing', () => {
beforeEach(() => {
buffer = new BitBuffer(4);
});
it('bit/byte pointers initialized properly', () => {
expect(buffer.bytePtr).equals(0);
expect(buffer.bitPtr).equals(0);
})
it('write multiple bits', () => {
buffer.writeBits(0b01011, 5); // Should result in: 0b00001011.
expect(buffer.bytePtr).equals(0);
expect(buffer.bitPtr).equals(0 + 5);
expect(Array.from(buffer.data)).to.have.ordered.members([1 + 2 + 8, 0, 0, 0]);
});
it('write multiple bits across byte boundary', () => {
buffer.writeBits(0b01011, 5);
buffer.writeBits(0b11101, 5); // Should result in: 0b10101011 and 0b00000011.
expect(buffer.bytePtr).equals(Math.floor((5 + 5) / 8));
expect(buffer.bitPtr).equals((5 + 5) % 8);
expect(Array.from(buffer.data)).to.have.ordered.members(
[1 + 2 + 8 + 32 + 128, 1 + 2, 0, 0]);
});
it('write multiple bytes to buffer', () => {
buffer.writeBits(0, 1);
buffer.writeBits(0x1ffff, 17); // Should result in 0b111111110, 0b11111111, 0b00000011.
expect(buffer.bytePtr).equals(2);
expect(buffer.bitPtr).equals(2);
expect(Array.from(buffer.data)).to.have.ordered.members(
[0xfe, 0xff, 0x03, 0x00]);
});
});
describe('most-to-least-significant bit-packing', () => {
beforeEach(() => {
buffer = new BitBuffer(4, true);
});
it('bit/byte pointers initialized properly', () => {
expect(buffer.bytePtr).equals(0);
expect(buffer.bitPtr).equals(7);
})
it('write multiple bits', () => {
buffer.writeBits(0b01011, 5); // Should result in: 0b01011000
expect(buffer.bytePtr).equals(0);
expect(buffer.bitPtr).equals(7 - 5);
expect(Array.from(buffer.data)).to.have.ordered.members(
[64+16+8, 0, 0, 0]);
});
it('write multiple bits across byte boundary', () => {
buffer.writeBits(0b01011, 5);
buffer.writeBits(0b11101, 5); // Should result in: 0b01011111 and 0b01000000.
expect(buffer.bytePtr).equals(Math.floor((5 + 5) / 8));
expect(buffer.bitPtr).equals(7 - ((5 + 5) % 8));
expect(Array.from(buffer.data)).to.have.ordered.members(
[64+16+8+4+2+1, 64, 0, 0]);
});
it('write multiple bytes to buffer', () => {
buffer.writeBits(0, 1);
buffer.writeBits(0x1ffff, 17); // Should result in 0b011111111, 0b11111111, 0b11000000.
expect(buffer.bytePtr).equals(2);
expect(buffer.bitPtr).equals(5);
expect(Array.from(buffer.data)).to.have.ordered.members(
[0x7f, 0xff, 0xc0, 0x00]);
});
});
});