Benchmark: Bytes to BigInt64

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

function bytesToBigIntLoop(bytes) {
    let value = 0n;
    let bits = 8n;
    for (let i = 0; i < bytes.length; i++) {
        value = (value << bits) + BigInt(bytes[i]);
    }
    return value;
}

function bytesToBigIntDataView(bytes) {
    const view = new DataView(bytes.buffer);
    return view.getBigInt64(0);
}

function bytesToBigIntHex(bytes) {
    return BigInt('0x' + bytes.map(byte => byte.toString(16).padStart(2, '0')).join(''))
}

function bytesToBigIntLoop2(data) {
    let encoded = 0n;

    for (let i = 0, l = data.length; i < l; i++) {

        encoded |= BigInt(data[i]) << BigInt((l - i - 1) * 8);

    }

    return encoded;

}

function bytesToBigIntSplit(data) {
    let high = 0;
    high = (high << 8) | data[0];
    high = (high << 8) | data[1];
    high = (high << 8) | data[2];
    high = (high << 8) | data[3];

    let low = 0;
    low = (low << 8) | data[4];
    low = (low << 8) | data[5];
    low = (low << 8) | data[6];
    low = (low << 8) | data[7];

    return (BigInt(low) << 32n) | BigInt(high);
}

Tests:

Loop
bytesToBigIntLoop(new Uint8Array([255,255,255,0,0,0,0,0]))
DataView
bytesToBigIntDataView(new Uint8Array([255,255,255,0,0,0,0,0]))
Hex
bytesToBigIntHex(new Uint8Array([255,255,255,0,0,0,0,0]))
Loop2
bytesToBigIntLoop2(new Uint8Array([255,255,255,0,0,0,0,0]))
Split
bytesToBigIntSplit(new Uint8Array([255,255,255,0,0,0,0,0]))

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Loop
DataView
Hex
Loop2
Split

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 126 on Android

View result in a separate tab

Test name	Executions per second
Loop	3259180.8 Ops/sec
DataView	1374523.1 Ops/sec
Hex	923228.0 Ops/sec
Loop2	2321812.2 Ops/sec
Split	9455548.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 4 months ago):

LLMs can make mistakes. Check important info.

The benchmark you provided tests five different JavaScript functions for converting an array of bytes (specifically a `Uint8Array`) into a `BigInt64` value. Each function employs a different approach to achieve the same goal, allowing for a comparative analysis of performance based on how the conversion is implemented.

### Test Cases and Their Approaches:

1. **Loop:**
   ```javascript
   function bytesToBigIntLoop(bytes) {
       let value = 0n;
       let bits = 8n;
       for (let i = 0; i < bytes.length; i++) {
           value = (value << bits) + BigInt(bytes[i]);
       }
       return value;
   }
   ```
   - **Description:** Iteratively shifts the accumulated value left by 8 bits for each byte, then adds the byte's value converted to a `BigInt`.
   - **Pros:** Simple and straightforward to understand; directly processes each byte in a loop.
   - **Cons:** Performance may be lower due to repeated bitwise operations and continuous accumulation.

2. **DataView:**
   ```javascript
   function bytesToBigIntDataView(bytes) {
       const view = new DataView(bytes.buffer);
       return view.getBigInt64(0);
   }
   ```
   - **Description:** Uses the `DataView` API, which provides methods for reading multiple number types from an `ArrayBuffer` in a byte order-aware manner.
   - **Pros:** Fast and optimized for reading data in a specific format (i.e., `BigInt64`); works efficiently for properly formatted buffers.
   - **Cons:** Limited to specific buffer structures; requires a complete and correctly sized `ArrayBuffer`.

3. **Hex:**
   ```javascript
   function bytesToBigIntHex(bytes) {
       return BigInt('0x' + bytes.map(byte => byte.toString(16).padStart(2, '0')).join(''));
   }
   ```
   - **Description:** Converts each byte to a hexadecimal string, concatenates them, and finally converts that string into a `BigInt`.
   - **Pros:** Relatively concise and leverages JavaScript's built-in string manipulation features.
   - **Cons:** May have overhead due to string operations and the conversion from string to `BigInt`.

4. **Loop2:**
   ```javascript
   function bytesToBigIntLoop2(data) {
       let encoded = 0n;
       for (let i = 0, l = data.length; i < l; i++) {
           encoded |= BigInt(data[i]) << BigInt((l - i - 1) * 8);
       }
       return encoded;
   }
   ```
   - **Description:** Similar to the first loop method but uses a bitwise OR operation to combine the values, calculating shifts based on their position.
   - **Pros:** In some JavaScript engines, this might be optimized better due to use of bitwise operations.
   - **Cons:** Could still be slower than `DataView` and involves more complex operations.

5. **Split:**
   ```javascript
   function bytesToBigIntSplit(data) {
       let high = 0;
       high = (high << 8) | data[0];
       // ... (repeated for all bytes)
       return (BigInt(low) << 32n) | BigInt(high);
   }
   ```
   - **Description:** This method manually splits the byte array into high and low parts and combines them into a `BigInt`.
   - **Pros:** This could be faster when the byte array always consists of exactly 8 bytes; direct control over byte manipulation.
   - **Cons:** Hardcoded for 8-byte (64-bit) input; lacks flexibility for varying sizes.

### Benchmark Results:

The results show the number of executions per second for each approach:
- **Split:** 6,696,320.5 executions/second (Fastest)
- **Loop:** 1,836,954.375 executions/second
- **Loop2:** 1,732,851.875 executions/second
- **Hex:** 1,355,990.125 executions/second
- **DataView:** 1,259,076.5 executions/second

### Other Considerations:

- **Performance:** The fastest method (`Split`) suggests that directly manipulating the byte array for a fixed size is more efficient in this case; however, it sacrifices generality.
- **Robustness:** While `DataView` may offer speed advantages, it is important to ensure that the input is in the required format (buffer of at least 8 bytes).
- **Use Case:** In scenarios requiring a conversion from byte arrays (especially when dealing with network protocols or binary file formats), the chosen method will critically affect performance based on the data size and structure.

### Alternatives:

Other alternatives outside these methods could include:
- **Typed Arrays:** Utilizing other typed arrays (e.g., `Int8Array` or `Uint32Array`) if lower precision is acceptable.
- **WebAssembly:** For performance-critical applications, implementing this logic in WebAssembly could yield performance gains as it is more optimized than JavaScript in many scenarios.
- **Native Modules:** If this will be run in an environment like Node.js, native modules that handle binary data might be leveraged to achieve even better performance.

In conclusion, the best choice among these methods heavily depends on the specific use case, input size, and runtime environment.

Related benchmarks:

Bytes to BigInt64 (version: 7)

Comparing performance of: Loop vs DataView vs Hex vs Loop2 vs Split

Created: 4 months ago by: Registered User

Jump to the latest result

Loop

DataView

Hex

Loop2

Split

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 4 months ago):