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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 | 5x 5x 5x 5x 33x 5x 5x 22x 22x 38x 24x 24x 24x 24x 24x 24x 2x 2x 2x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x 3x | import {Writer} from '@jsonjoy.com/buffers/lib/Writer';
import type {IWriter, IWriterGrowable} from '@jsonjoy.com/buffers';
const RM_HEADER_SIZE = 4;
const MAX_SINGLE_FRAME_SIZE = 0x7fffffff;
export class RmRecordEncoder<W extends IWriter & IWriterGrowable = IWriter & IWriterGrowable> {
constructor(public readonly writer: W = new Writer() as any) {}
public encodeHdr(fin: 0 | 1, length: number): Uint8Array {
this.writeHdr(fin, length);
return this.writer.flush();
}
public encodeRecord(record: Uint8Array): Uint8Array {
this.writeRecord(record);
return this.writer.flush();
}
public writeHdr(fin: 0 | 1, length: number): void {
this.writer.u32((fin ? 0b10000000_00000000_00000000_00000000 : 0) + length);
}
public writeRecord(record: Uint8Array): void {
const length = record.length;
Eif (length <= 2147483647) {
const writer = this.writer;
writer.u32(0b10000000_00000000_00000000_00000000 + length);
writer.buf(record, length);
return;
}
let offset = 0;
while (offset < length) {
const fragmentLength = Math.min(length - offset, 0x7fffffff);
const fin = fragmentLength + offset >= length ? 1 : 0;
this.writeFragment(record, offset, fragmentLength, fin);
offset += fragmentLength;
}
}
public writeFragment(record: Uint8Array, offset: number, length: number, fin: 0 | 1): void {
this.writeHdr(fin, length);
const fragment = record.subarray(offset, offset + length);
this.writer.buf(fragment, length);
}
/**
* To write an RM record in one pass this method reserves space for the RM
* header, and returns the state, which needs to passed to `endRmRecord` to
* finalize the RM header.
*/
public startRecord(): number {
const writer = this.writer;
const rmHeaderPosition = writer.x - writer.x0;
writer.x += RM_HEADER_SIZE;
return rmHeaderPosition;
}
/**
* Finalize the RM header started by `startRmRecord`.
*
* @param rmHeaderPosition The position returned by `startRmRecord`
* @remarks This method will check if the data written after `startRmRecord`
* fits into a single RM frame. If it does, it will write the RM header in
* place. If it doesn't, it will move the data to a new location and write
* it as multiple RM frames.
*/
public endRecord(rmHeaderPosition: number): void {
const writer = this.writer;
const rmFrameStart = writer.x0 + rmHeaderPosition;
const totalSize = writer.x - rmFrameStart - RM_HEADER_SIZE;
if (totalSize <= MAX_SINGLE_FRAME_SIZE) {
const currentX = writer.x;
writer.x = rmFrameStart;
this.writeHdr(1, totalSize);
writer.x = currentX;
} else E{
const currentX = writer.x;
writer.x = rmFrameStart;
const data = writer.uint8.subarray(rmFrameStart + RM_HEADER_SIZE, currentX);
writer.reset();
this.writeRecord(data);
}
}
}
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