# 
[](https://www.npmjs.com/package/@thi.ng/transducers-binary)
[](https://mastodon.thi.ng/@toxi)
> [!NOTE]
> This is one of 209 standalone projects, maintained as part
> of the [@thi.ng/umbrella](https://github.com/thi-ng/umbrella/) monorepo
> and anti-framework.
>
> 🚀 Please help me to work full-time on these projects by [sponsoring me on
> GitHub](https://github.com/sponsors/postspectacular). Thank you! ❤️
- [About](#about)
- [Status](#status)
- [Related packages](#related-packages)
- [Installation](#installation)
- [Dependencies](#dependencies)
- [Usage examples](#usage-examples)
- [API](#api)
- [Random bits](#random-bits)
- [Streaming hexdump](#streaming-hexdump)
- [Structured byte buffer construction](#structured-byte-buffer-construction)
- [Bitstream](#bitstream)
- [Base64 & UTF-8 en/decoding](#base64--utf-8-endecoding)
- [Transducers](#transducers)
- [Reducers](#reducers)
- [Authors](#authors)
- [License](#license)
## About
Binary data related transducers & reducers. This is a support package for [@thi.ng/transducers](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers).
Like the transducers and reducers defined in
[@thi.ng/transducers](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers),
all functions defined in this package too accept an optional input
iterable for direct use.
## Status
**STABLE** - used in production
[Search or submit any issues for this package](https://github.com/thi-ng/umbrella/issues?q=%5Btransducers-binary%5D+in%3Atitle)
## Related packages
- [@thi.ng/binary](https://github.com/thi-ng/umbrella/tree/develop/packages/binary) - 100+ assorted binary / bitwise operations, conversions, utilities, lookup tables
- [@thi.ng/bitstream](https://github.com/thi-ng/umbrella/tree/develop/packages/bitstream) - ES6 iterator based read/write bit streams with support for variable word widths
- [@thi.ng/unionstruct](https://github.com/thi-ng/umbrella/tree/develop/packages/unionstruct) - C-style struct, union and bitfield read/write views of ArrayBuffers
## Installation
```bash
yarn add @thi.ng/transducers-binary
```
ESM import:
```ts
import * as txb from "@thi.ng/transducers-binary";
```
Browser ESM import:
```html
```
[JSDelivr documentation](https://www.jsdelivr.com/)
For Node.js REPL:
```js
const txb = await import("@thi.ng/transducers-binary");
```
Package sizes (brotli'd, pre-treeshake): ESM: 2.50 KB
## Dependencies
- [@thi.ng/binary](https://github.com/thi-ng/umbrella/tree/develop/packages/binary)
- [@thi.ng/compose](https://github.com/thi-ng/umbrella/tree/develop/packages/compose)
- [@thi.ng/errors](https://github.com/thi-ng/umbrella/tree/develop/packages/errors)
- [@thi.ng/hex](https://github.com/thi-ng/umbrella/tree/develop/packages/hex)
- [@thi.ng/random](https://github.com/thi-ng/umbrella/tree/develop/packages/random)
- [@thi.ng/strings](https://github.com/thi-ng/umbrella/tree/develop/packages/strings)
- [@thi.ng/transducers](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers)
## Usage examples
Five projects in this repo's
[/examples](https://github.com/thi-ng/umbrella/tree/develop/examples)
directory are using this package:
| Screenshot | Description | Live demo | Source |
|:-------------------------------------------------------------------------------------------------------------------------|:-----------------------------------------------------------------------------------------|:--------------------------------------------------------|:-------------------------------------------------------------------------------------|
| 
| Figlet-style bitmap font creation with transducers | [Demo](https://demo.thi.ng/umbrella/bitmap-font/) | [Source](https://github.com/thi-ng/umbrella/tree/develop/examples/bitmap-font) |
| 
| 2D transducer based cellular automata | [Demo](https://demo.thi.ng/umbrella/cellular-automata/) | [Source](https://github.com/thi-ng/umbrella/tree/develop/examples/cellular-automata) |
| 
| Parser grammar livecoding editor/playground & codegen | [Demo](https://demo.thi.ng/umbrella/parse-playground/) | [Source](https://github.com/thi-ng/umbrella/tree/develop/examples/parse-playground) |
| 
| Procedural stochastic text generation via custom DSL, parse grammar & AST transformation | [Demo](https://demo.thi.ng/umbrella/procedural-text/) | [Source](https://github.com/thi-ng/umbrella/tree/develop/examples/procedural-text) |
| 
| 1D Wolfram automata with OBJ point cloud export | [Demo](https://demo.thi.ng/umbrella/wolfram/) | [Source](https://github.com/thi-ng/umbrella/tree/develop/examples/wolfram) |
## API
[Generated API docs](https://docs.thi.ng/umbrella/transducers-binary/)
### Random bits
```ts
import { take } from "@thi.ng/transducers";
import { randomBits } from "@thi.ng/transducers-binary";
// 10 samples with 50% probability of drawing a 1
[...randomBits(0.5, 10)]
// [ 1, 0, 1, 1, 0, 1, 0, 1, 1, 0 ]
// infinite iterator without 2nd arg, so limit with `take()`
[...take(10, randomBits(0.1))]
// [ 0, 0, 0, 0, 0, 0, 1, 0, 0, 0 ]
import { Smush32 } from "@thi.ng/random";
// with seeded PRNG
[...randomBits(0.5, 10, new Smush32(12345678))]
// [ 0, 0, 1, 1, 0, 0, 0, 0, 1, 0 ]
```
### Streaming hexdump
This is a higher-order transducer, purely composed from other
transducers. [See code
here](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers-binary/src/hex-dump.ts).
```ts
import { hexDump } from "@thi.ng/transducers-binary";
src = [65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 33, 48, 49, 50, 51, 126, 122, 121, 120]
[...hexDump({ cols: 8, address: 0x100 }, src)]
// [ '00000100 | 41 42 43 44 45 46 47 48 | ABCDEFGH',
// '00000108 | 49 4a 21 30 31 32 33 7e | IJ!0123~',
// '00000110 | 7a 79 78 00 00 00 00 00 | zyx.....' ]
```
### Structured byte buffer construction
The
[`bytes()`](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers-binary/src/bytes.ts)
reducer transforms a stream of declarative data definitions (optionally
with Little-Endian encoding) into an `Uint8Array`.
```ts
import * as tx from "@thi.ng/transducers";
import * as txb from "@thi.ng/transducers-binary";
const bytes = txb.bytes(
// initial buffer capacity (grows on demand)
32,
// structured data
[
// default order is Big-Endian
txb.u32(0xdecafbad),
// force Little-endian (also works for floats)
txb.u32(0x44332211, true),
// all strings will be utf-8 encoded
txb.str("vec4"),
// use little-endian for each of these array vals
txb.f32array([1, 2, 3, 4], true),
txb.u8(0x2a)
]
);
console.log(tx.str("\n", txb.hexDump({}, bytes)));
// 00000000 | de ca fb ad 11 22 33 44 76 65 63 34 00 00 80 3f | ....."3Dvec4...?
// 00000010 | 00 00 00 40 00 00 40 40 00 00 80 40 2a 00 00 00 | ...@..@@...@*...
```
### Bitstream
Decompose / transform a stream of fixed size words into their bits:
```ts
import { comp, map, partition, str, transduce } from "@thi.ng/transducers";
import { bits } from "@thi.ng/transducers-binary";
[...bits(8, [0xf0, 0xaa])];
// [ 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0 ]
console.log(
transduce(
comp(
bits(8),
map((x) => (x ? "#" : ".")),
partition(8),
map((x) => x.join(""))
),
str("\n"),
[0x00, 0x18, 0x3c, 0x66, 0x66, 0x7e, 0x66, 0x00]
)
);
// ........
// ...##...
// ..####..
// .##..##.
// .##..##.
// .######.
// .##..##.
// ........
```
Extended to transform longer strings (taken from the [bitmap-font
example](https://github.com/thi-ng/umbrella/tree/develop/examples/bitmap-font),
[live demo](https://demo.thi.ng/umbrella/bitmap-font/)):
```js
import * as tx from "@thi.ng/transducers";
import { bits } from "@thi.ng/transducers-binary";
// font lookup table
const chars = {
a: [0x00, 0x18, 0x3c, 0x66, 0x66, 0x7e, 0x66, 0x00],
b: [0x00, 0x7c, 0x66, 0x7c, 0x66, 0x66, 0x7c, 0x00]
};
// re-usable transducer
const xfJoin = tx.map((x) => x.join(""));
// higher order transducer to transform single char from string
const xfChar = (i) =>
tx.comp(
tx.pluck(i),
bits(8),
tx.map((x) => (x ? "#" : ".")),
tx.partition(8),
xfJoin
);
// transform entire string
const banner = (src) =>
tx.transduce(
tx.comp(
// dynamically create `xfChar` transducers for each char
// and run them in parallel via `multiplex()`
tx.multiplex(...tx.map((i) => xfChar(i), tx.range(src.length))),
// then join the results for each line
xfJoin
),
// use `str()` reducer to build string result
tx.str("\n"),
// convert input string into stream of row-major bitmap font tuples
tx.zip(...tx.map((x) => chars[x], src))
);
console.log(banner("abba"));
// ................................
// ...##....#####...#####.....##...
// ..####...##..##..##..##...####..
// .##..##..#####...#####...##..##.
// .##..##..##..##..##..##..##..##.
// .######..##..##..##..##..######.
// .##..##..#####...#####...##..##.
// ................................
```
### Base64 & UTF-8 en/decoding
Unlike JS default `btoa()` / `atob()` functions which operate on
strings, these transducers stepwise convert byte values to base64 and
back.
```ts
import * as tx from "@thi.ng/transducers";
import {
base64Decode, base64Encode,
utf8Decode, utf8Encode
} from "@thi.ng/transducers-binary";
// here we first add an offset (0x80) to allow negative values to be encoded
// (URL safe results can be produced via opt arg to `base64Encode`)
enc = tx.transduce(
tx.comp(tx.map((x) => x + 0x80), base64Encode()),
tx.str(),
tx.range(-8, 8)
);
// "eHl6e3x9fn+AgYKDhIWGhw=="
// remove offset again during decoding, but (for example) only decode while val < 0
[
...tx.iterator(
tx.comp(
txb.base64Decode(),
tx.map((x) => x - 0x80),
tx.takeWhile((x) => x < 0)
),
enc
)
];
// [ -8, -7, -6, -5, -4, -3, -2, -1 ]
buf = tx.transduce(
tx.comp(utf8Encode(), base64Encode()),
tx.str(),
"beer (🍺) or hot beverage (☕️)"
);
// "YmVlciAo8J+Nuikgb3IgaG90IGJldmVyYWdlICjimJXvuI4p"
tx.transduce(tx.comp(base64Decode(), utf8Decode()), tx.str(), buf);
// "beer (🍺) or hot beverage (☕️)"
```
### Transducers
- [base64Decode](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers-binary/src/base64.ts)
- [base64Encode](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers-binary/src/base64.ts)
- [bits](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers-binary/src/bits.ts)
- [hexDump](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers-binary/src/hex-dump.ts)
- [partitionBits](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers-binary/src/partition-bits.ts)
- [utf8Decode](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers-binary/src/utf8.ts)
- [utf8Encode](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers-binary/src/utf8.ts)
### Reducers
- [bytes](https://github.com/thi-ng/umbrella/tree/develop/packages/transducers-binary/src/bytes.ts)
## Authors
- [Karsten Schmidt](https://thi.ng)
If this project contributes to an academic publication, please cite it as:
```bibtex
@misc{thing-transducers-binary,
title = "@thi.ng/transducers-binary",
author = "Karsten Schmidt",
note = "https://thi.ng/transducers-binary",
year = 2018
}
```
## License
© 2018 - 2025 Karsten Schmidt // Apache License 2.0