@ledgerhq/hw-app-btc/lib-es/buffertools.js

Ledger Hardware Wallet Bitcoin Application API

import varuint from "varuint-bitcoin";
export function unsafeTo64bitLE(n) {
    // we want to represent the input as a 8-bytes array
    if (n > Number.MAX_SAFE_INTEGER) {
        throw new Error("Can't convert numbers > MAX_SAFE_INT");
    }
    const byteArray = Buffer.alloc(8, 0);
    for (let index = 0; index < byteArray.length; index++) {
        const byte = n & 0xff;
        byteArray[index] = byte;
        n = (n - byte) / 256;
    }
    return byteArray;
}
export function unsafeFrom64bitLE(byteArray) {
    let value = 0;
    if (byteArray.length != 8) {
        throw new Error("Expected Bufffer of lenght 8");
    }
    if (byteArray[7] != 0) {
        throw new Error("Can't encode numbers > MAX_SAFE_INT");
    }
    if (byteArray[6] > 0x1f) {
        throw new Error("Can't encode numbers > MAX_SAFE_INT");
    }
    for (let i = byteArray.length - 1; i >= 0; i--) {
        value = value * 256 + byteArray[i];
    }
    return value;
}
export class BufferWriter {
    bufs = [];
    write(alloc, fn) {
        const b = Buffer.alloc(alloc);
        fn(b);
        this.bufs.push(b);
    }
    writeUInt8(i) {
        this.write(1, b => b.writeUInt8(i, 0));
    }
    writeInt32(i) {
        this.write(4, b => b.writeInt32LE(i, 0));
    }
    writeUInt32(i) {
        this.write(4, b => b.writeUInt32LE(i, 0));
    }
    writeUInt64(i) {
        const bytes = unsafeTo64bitLE(i);
        this.writeSlice(bytes);
    }
    writeVarInt(i) {
        this.bufs.push(varuint.encode(i));
    }
    writeSlice(slice) {
        this.bufs.push(Buffer.from(slice));
    }
    writeVarSlice(slice) {
        this.writeVarInt(slice.length);
        this.writeSlice(slice);
    }
    buffer() {
        return Buffer.concat(this.bufs);
    }
}
export class BufferReader {
    buffer;
    offset;
    constructor(buffer, offset = 0) {
        this.buffer = buffer;
        this.offset = offset;
    }
    available() {
        return this.buffer.length - this.offset;
    }
    readUInt8() {
        const result = this.buffer.readUInt8(this.offset);
        this.offset++;
        return result;
    }
    readInt32() {
        const result = this.buffer.readInt32LE(this.offset);
        this.offset += 4;
        return result;
    }
    readUInt32() {
        const result = this.buffer.readUInt32LE(this.offset);
        this.offset += 4;
        return result;
    }
    readUInt64() {
        const buf = this.readSlice(8);
        const n = unsafeFrom64bitLE(buf);
        return n;
    }
    readVarInt() {
        const vi = varuint.decode(this.buffer, this.offset);
        this.offset += varuint.decode.bytes;
        return vi;
    }
    readSlice(n) {
        if (this.buffer.length < this.offset + n) {
            throw new Error("Cannot read slice out of bounds");
        }
        const result = this.buffer.slice(this.offset, this.offset + n);
        this.offset += n;
        return result;
    }
    readVarSlice() {
        return this.readSlice(this.readVarInt());
    }
    readVector() {
        const count = this.readVarInt();
        const vector = [];
        for (let i = 0; i < count; i++)
            vector.push(this.readVarSlice());
        return vector;
    }
}
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