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This commit is contained in:
Craig Everett 2026-01-07 16:48:13 +09:00
parent db48e175d0
commit e1bec6b996
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418
snippets/b58.ts Normal file
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/**
* Base58 encoding/decoding
*/
export {
encode,
decode
}
//=============================================================================
// ENCODING
//=============================================================================
/**
* Encode a Uint8Array into base58
*/
function
encode
(binary : Uint8Array)
: string
{
let num_leading_zeros : number = nlz(binary);
let rest : Uint8Array = binary.slice(num_leading_zeros);
let ones : string = encode_zeros(num_leading_zeros);
let rest_b58 : string = encode_rest(rest);
let result : string = ones + rest_b58;
return result;
}
/**
* count the number of leading zeros in a uint8array
*
* @internal
*/
function
nlz
(bytes: Uint8Array)
: number
{
let n = 0;
for (let this_byte of bytes)
{
if (0 === this_byte) { n++; }
else { break; }
}
return n;
}
/**
* Generate a bunch of '1's for however many leading zeros there are
*
* @internal
*/
function
encode_zeros
(how_many : number)
: string
{
let ones : string = '';
for (let i = 1;
i <= how_many;
i++)
{
ones += '1';
}
return ones;
}
/**
* Encode a Uint8Array that has no leading zeros
*
* @internal
*/
function
encode_rest
(bytes : Uint8Array)
: string
{
let bytes_bignum : bigint = bytes_to_bigint(bytes);
let result : string = bignum_to_base58(bytes_bignum);
return result;
}
/**
* Convert a bytestring to a bignum
*
* @internal
*/
function
bytes_to_bigint
(bytes: Uint8Array)
: bigint
{
let acc_bigint : bigint = 0n;
for(let this_byte of bytes)
{
acc_bigint <<= 8n;
acc_bigint += BigInt(this_byte);
}
return acc_bigint;
}
/**
* Convert a BigInt to Base58
*
* @internal
*/
function
bignum_to_base58
(q: bigint)
: string
{
let s = '';
while (q !== 0n)
{
let this_n : bigint = q % 58n;
q /= 58n;
let this_b58_char : string = bigint_to_char(this_n);
s = this_b58_char + s;
}
return s;
}
//=============================================================================
// DECODING
//=============================================================================
/**
* Decode a Base58 string into a Uint8Array
*/
function
decode
(base58: string)
: Uint8Array
{
let num_leading_ones : number = nlo(base58);
let rest : string = base58.slice(num_leading_ones);
let zeros : Array<number> = decode_ones(num_leading_ones);
let rest_arr : Array<number> = decode_rest(rest);
let pre_result : Array<number> = zeros.concat(rest_arr);
return new Uint8Array(pre_result);
}
/**
* count the number of leading 1 characters in a uint8array
*
* @internal
*/
function
nlo
(base58: string)
: number
{
let n = 0;
for (let this_char of base58)
{
if ('1' === this_char) { n++; }
else { break; }
}
return n;
}
/**
* Generate a bunch of '0's for however many leading ones there are
*
* @internal
*/
function
decode_ones
(how_many : number)
: Array<number>
{
let zeros : Array<number> = [];
for (let i = 1;
i <= how_many;
i++)
{
zeros.push(0);
}
return zeros;
}
/**
* Decode a string that has no leading 1s
*
* @internal
*/
function
decode_rest
(base58: string)
: Array<number>
{
let result_bignum : bigint = base58_to_bigint(base58);
let result : Array<number> = bigint_to_base256(result_bignum);
return result;
}
/**
* Convert a base58 string to a bignum
*
* @internal
*/
function
base58_to_bigint
(base58: string)
: bigint
{
let acc_bigint : bigint = 0n;
for(let this_char of base58)
{
acc_bigint *= 58n;
acc_bigint += char_to_bigint(this_char);
}
return acc_bigint;
}
/**
* convert a bignum into a byte array
*
* @end
*/
function
bigint_to_base256
(q: bigint)
: Array<number>
{
let arr_reverse = [];
while(q !== 0n)
{
let r: number = Number(q % 256n);
q /= 256n;
arr_reverse.push(r);
}
arr_reverse.reverse();
return arr_reverse;
}
//=============================================================================
// TRANSLATION TABLES
//=============================================================================
/**
* Base58 integer -> character conversion table
*
* @internal
*/
function
bigint_to_char
(n: bigint)
: string
{
switch(n) {
case 0n: return '1';
case 1n: return '2';
case 2n: return '3';
case 3n: return '4';
case 4n: return '5';
case 5n: return '6';
case 6n: return '7';
case 7n: return '8';
case 8n: return '9';
case 9n: return 'A';
case 10n: return 'B';
case 11n: return 'C';
case 12n: return 'D';
case 13n: return 'E';
case 14n: return 'F';
case 15n: return 'G';
case 16n: return 'H';
case 17n: return 'J';
case 18n: return 'K';
case 19n: return 'L';
case 20n: return 'M';
case 21n: return 'N';
case 22n: return 'P';
case 23n: return 'Q';
case 24n: return 'R';
case 25n: return 'S';
case 26n: return 'T';
case 27n: return 'U';
case 28n: return 'V';
case 29n: return 'W';
case 30n: return 'X';
case 31n: return 'Y';
case 32n: return 'Z';
case 33n: return 'a';
case 34n: return 'b';
case 35n: return 'c';
case 36n: return 'd';
case 37n: return 'e';
case 38n: return 'f';
case 39n: return 'g';
case 40n: return 'h';
case 41n: return 'i';
case 42n: return 'j';
case 43n: return 'k';
case 44n: return 'm';
case 45n: return 'n';
case 46n: return 'o';
case 47n: return 'p';
case 48n: return 'q';
case 49n: return 'r';
case 50n: return 's';
case 51n: return 't';
case 52n: return 'u';
case 53n: return 'v';
case 54n: return 'w';
case 55n: return 'x';
case 56n: return 'y';
case 57n: return 'z';
default:
throw new Error('invalid base58 bigint: ' + n);
}
}
/**
* Base58 character -> integer conversion table
*
* @internal
*/
function
char_to_bigint
(s: string)
: bigint
{
switch(s) {
case '1': return 0n;
case '2': return 1n;
case '3': return 2n;
case '4': return 3n;
case '5': return 4n;
case '6': return 5n;
case '7': return 6n;
case '8': return 7n;
case '9': return 8n;
case 'A': return 9n;
case 'B': return 10n;
case 'C': return 11n;
case 'D': return 12n;
case 'E': return 13n;
case 'F': return 14n;
case 'G': return 15n;
case 'H': return 16n;
case 'J': return 17n;
case 'K': return 18n;
case 'L': return 19n;
case 'M': return 20n;
case 'N': return 21n;
case 'P': return 22n;
case 'Q': return 23n;
case 'R': return 24n;
case 'S': return 25n;
case 'T': return 26n;
case 'U': return 27n;
case 'V': return 28n;
case 'W': return 29n;
case 'X': return 30n;
case 'Y': return 31n;
case 'Z': return 32n;
case 'a': return 33n;
case 'b': return 34n;
case 'c': return 35n;
case 'd': return 36n;
case 'e': return 37n;
case 'f': return 38n;
case 'g': return 39n;
case 'h': return 40n;
case 'i': return 41n;
case 'j': return 42n;
case 'k': return 43n;
case 'm': return 44n;
case 'n': return 45n;
case 'o': return 46n;
case 'p': return 47n;
case 'q': return 48n;
case 'r': return 49n;
case 's': return 50n;
case 't': return 51n;
case 'u': return 52n;
case 'v': return 53n;
case 'w': return 54n;
case 'x': return 55n;
case 'y': return 56n;
case 'z': return 57n;
default:
throw new Error('invalid base58 char: ' + s);
}
}

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/**
* Base64 Utility Functions in TypeScript
*/
export {
encode,
decode
}
/**
* Encode an array of bytes as a Uint8Array in base64 notation.
*/
function
encode
(bytes: Uint8Array)
: string
{
// slice the array
// length of head is a multiple of 3
// treat the tail as a special case
let {head, tail, tail_len} = slice3k(bytes);
let head_str : string = encode_head(head);
let tail_str : string = encode_tail(tail, tail_len);
return head_str + tail_str;
}
type slice3k
= {head : Uint8Array,
tail : Uint8Array,
tail_len : number};
/**
* Take a Uint8Array, take the first 3k (k >= 0) bytes, put them in head, and
* the remaining 0,1, or 2 bytes, put them in tail
*
* @internal
*/
function
slice3k
(bytes: Uint8Array)
: slice3k
{
let len : number = bytes.length;
// too lazy to look up how to do integer division in js so this will do
let tail_len : number = len % 3;
let head_len : number = len - tail_len;
// for slice:
// first argument is the 0-index of the start
// second - first is the length of the slice
let head : Uint8Array = bytes.slice(0, head_len);
// empty second argument means go to the end
let tail : Uint8Array = bytes.slice(head_len);
return {head : head,
tail : tail,
tail_len : tail_len};
}
/**
* Encode a Uint8Array whose length is known to be a multiple of 3
*
* @internal
*/
function
encode_head
(head_bytes: Uint8Array)
: string
{
// can assume length of bytes is a multiple of 3
// start index at 0
// increment by 3
let head_bytes_len : number = head_bytes.length;
let max_idx0 : number = head_bytes_len - 1;
let head_str_acc : string = '';
for(let this_3slice_start_idx0 = 0;
this_3slice_start_idx0 <= max_idx0;
this_3slice_start_idx0 += 3)
{
let this_3slice_bytes : Uint8Array = head_bytes.slice(this_3slice_start_idx0, this_3slice_start_idx0 + 3);
let this_3slice_str : string = encode3(this_3slice_bytes);
head_str_acc += this_3slice_str;
}
return head_str_acc;
}
/**
* Encode a 3 bytes into base64 notation
*
* @internal
*/
function
encode3
(bytes: Uint8Array)
: string
{
let b0 : number = bytes[0];
let b1 : number = bytes[1];
let b2 : number = bytes[2];
// ABCDEFGH 12345678 abcdefgh
// b0 b1 b2
// ABCDEF GH1234 5678ab cdefgh
// n0 n1 n2 n3
let n0 : number = b0 >> 2;
// b0 = ABCDEFGH
// 4 = _____1__
// b0 % 4 = ______GH
// (b0 % 4) << 4 = __GH____
// b1 = 12345678
// b1 >> 4 = ____1234
// n1 = __GH1234
let n1 : number = ((b0 % 4) << 4) + (b1 >> 4);
// b1 = 12345678
// 16 = ___1____
// b1 % 16 = ____5678
// (b1 % 16) << 2 = __5678__
// b2 = abcdefgh
// b2 >> 6 = ______ab
// n2 = __5678ab
let n2 : number = ((b1 % 16) << 2) + (b2 >> 6);
// b2 = abcdefgh
// 64 = _1______
// n3 = __cdefgh
let n3 : number = b2 % 64;
// convert to chars
let s0 : string = int2char(n0);
let s1 : string = int2char(n1);
let s2 : string = int2char(n2);
let s3 : string = int2char(n3);
// retrvn
return s0 + s1 + s2 + s3;
}
/**
* Encode the final 0, 1, or 2 bytes
*
* @internal
*/
function
encode_tail
(tail_bytes : Uint8Array,
tail_len : number)
: string
{
switch(tail_len) {
case 0: return '';
case 1: return encode1(tail_bytes);
case 2: return encode2(tail_bytes);
default:
throw new Error('encode_tail with tail_len = ' + tail_len);
}
}
/**
* Encode a single byte
*
* @internal
*/
function
encode1
(bytes: Uint8Array)
: string
{
let b0 : number = bytes[0];
// n0 = __ABCDEF
// b0 = ABCDEFGH
// b0 >> 2 = __ABCDEF
let n0 : number = b0 >> 2;
// n1 = __GH____
// b0 = ABCDEFGH
// 4 = _____1__
// b0 % 4 = ______GH
// (b0 % 4) << 4 = __GH____
let n1 : number = (b0 % 4) << 4;
return int2char(n0) + int2char(n1) + '==';
}
/**
* Encode two bytes
*
* @internal
*/
function
encode2
(bytes: Uint8Array)
: string
{
let b0 : number = bytes[0];
let b1 : number = bytes[1];
// ABCDEFGH 12345678
// b0 b1
// ABCDEF GH1234 5678__
// n0 n1 n2
let n0 : number = b0 >> 2;
// b0 = ABCDEFGH
// 4 = _____1__
// b0 % 4 = ______GH
// (b0 % 4) << 4 = __GH____
// b1 = 12345678
// b1 >> 4 = ____1234
// n1 = __GH1234
let n1 : number = ((b0 % 4) << 4) + (b1 >> 4);
// b1 = 12345678
// 16 = ___1____
// b1 % 16 = ____5678
// (b1 % 16) << 2 = __5678__
// n2 = __5678__
let n2 : number = (b1 % 16) << 2;
// convert to chars
let s0 : string = int2char(n0);
let s1 : string = int2char(n1);
let s2 : string = int2char(n2);
// retrvn
return s0 + s1 + s2 + '=';
}
/**
* Decode a base64-encoded string
*/
function
decode
(base64_str : string)
: Uint8Array
{
// length of the string is guaranteed to be a multiple of 4
// if the string is empty, return the empty array
let len = base64_str.length;
// this branching contains the implicit assertion that the length is a
// multiple of 4. If this is not true, the bottom branch is triggered.
// general case goes first because speeeeeed
if ( (4 < len)
&& (0 === (len % 4)))
{
// split the head and tail
let tail_start_idx0 : number = len - 4;
let head_s : string = base64_str.slice(0, tail_start_idx0);
let tail_s : string = base64_str.slice(tail_start_idx0);
// Using arrays because Uint8Arrays don't have a concat operation
let head_arr : Array<number> = decode_head(head_s);
let tail_arr : Array<number> = decode_tail(tail_s);
// silly to put these in variables but this is exactly the type of
// situation where JS type insanity shows up
//
// see: i forgot
// > [1,2,3] + [4,5,6]
// '1,2,34,5,6'
//
// Originally, I used + like some sort of moron who codes in a sane
// language
//
// seriously what is this language
//
// this is some clown behavior
let total_arr : Array<number> = head_arr.concat(tail_arr);
return new Uint8Array(total_arr);
}
// special case if the length is exactly 4
else if (4 === len)
{
// it's just a tail
return new Uint8Array(decode_tail(base64_str));
}
// empty string
else if (0 === len)
{
return new Uint8Array([]);
}
else
{
throw new Error('base64 decode: invalid string length: ' + len);
}
}
/**
* Decode a string known to not have any padding
*
* @internal
*/
function
decode_head
(s: string)
: Array<number>
{
// go 4 characters at a time
let max_i0 : number = s.length - 1;
let decoded_acc : Array<number> = [];
for(let i0 = 0;
i0 <= max_i0;
i0 += 4)
{
let this_slice_s : string = s.slice(i0, i0 + 4);
let this_slice_arr : Array<number> = decode3(this_slice_s);
// update accumulator
decoded_acc = decoded_acc.concat(this_slice_arr);
}
return decoded_acc;
}
/**
* Decode 4 characters that correspond to either 3 bytes, 2, bytes, or 1 byte
*
* @internal
*/
function
decode_tail
(s: string)
: Array<number>
{
// all that matters right now is the last 2 chars
// s0, s1, s2, s3
// 0 based indexing is so annoying
let s2 = s[2];
let s3 = s[3];
// braaaaaaaaaaaaaaaaaench
// two equals signs means 1 byte
if (('=' === s3) && ('=' === s2)) {
return decode1(s);
}
// one equals sign means 2 bytes
else if (('=' === s3)) {
return decode2(s);
}
// 0 equals signs means 3 bytes
else {
return decode3(s);
}
}
/**
* Decode a 4-character long base64 string corresponding to 3 bytes
*
* @internal
*/
function
decode3
(s: string)
: Array<number>
{
// pull out strings
let s0 : string = s[0];
let s1 : string = s[1];
let s2 : string = s[2];
let s3 : string = s[3];
// convert to numbers
let n0 : number = char2int(s0);
let n1 : number = char2int(s1);
let n2 : number = char2int(s2);
let n3 : number = char2int(s3);
// abcdef gh1234 5678ab cdefgh
// n0 n1 n2 n3
// abcdefgh 12345678 abcdefgh
// b0 b1 b2
// n0 = __abcdef
// n1 = __gh1234
// n0 << 2 = abcdef__
// n1 >> 4 = ______gh
// b0 = abcdefgh
let b0 : number = (n0 << 2) + (n1 >> 4);
// n1 = __gh1234
// 16 = ___1____
// n1 % 16 = ____1234
// (n1 % 16) << 4 = 1234____
// n2 = __5678ab
// n2 >> 2 = ____5678
// b1 = 12345678
let b1 : number = ((n1 % 16) << 4) + (n2 >> 2);
// n2 = __5678ab
// 4 = _____1__
// n2 % 4 = ______ab
// (n2 % 4) << 6 = ab______
// n3 = __cdefgh
let b2 : number = ((n2 % 4) << 6) + n3;
return [b0, b1, b2];
}
/**
* Decode a 4-character long base64 string corresponding to 2 bytes
*
* @internal
*/
function
decode2
(s: string)
: Array<number>
{
// xyz=
// pull out strings
let s0 : string = s[0];
let s1 : string = s[1];
let s2 : string = s[2];
// convert to numbers
let n0 : number = char2int(s0);
let n1 : number = char2int(s1);
let n2 : number = char2int(s2);
// abcdef gh1234 5678__
// n0 n1 n2
// abcdefgh 12345678
// b0 b1
// n0 = __abcdef
// n1 = __gh1234
// n0 << 2 = abcdef__
// n1 >> 4 = ______gh
// b0 = abcdefgh
let b0 : number = (n0 << 2) + (n1 >> 4);
// n1 = __gh1234
// 16 = ___1____
// n1 % 16 = ____1234
// (n1 % 16) << 4 = 1234____
// n2 = __5678__
// n2 >> 2 = ____5678
// b1 = 12345678
let b1 : number = ((n1 % 16) << 4) + (n2 >> 2);
return [b0, b1];
}
/**
* Decode a 4-character long base64 string corresponding to 2 bytes
*
* @internal
*/
function
decode1
(s: string)
: Array<number>
{
// xy==
// pull out strings
let s0 : string = s[0];
let s1 : string = s[1];
// convert to numbers
let n0 : number = char2int(s0);
let n1 : number = char2int(s1);
// abcdef gh____
// n0 n1
// abcdefgh
// b0
// n0 = __abcdef
// n1 = __gh____
// n0 << 2 = abcdef__
// n1 >> 4 = ______gh
// b0 = abcdefgh
let b0 : number = (n0 << 2) + (n1 >> 4);
return [b0];
}
// FIXME: these tables would *probably* be faster if they were made into objects
/**
* Conversion table for base64 encode
*
* @internal
*/
function
int2char
(n: number)
: string
{
switch(n) {
case 0: return 'A';
case 1: return 'B';
case 2: return 'C';
case 3: return 'D';
case 4: return 'E';
case 5: return 'F';
case 6: return 'G';
case 7: return 'H';
case 8: return 'I';
case 9: return 'J';
case 10: return 'K';
case 11: return 'L';
case 12: return 'M';
case 13: return 'N';
case 14: return 'O';
case 15: return 'P';
case 16: return 'Q';
case 17: return 'R';
case 18: return 'S';
case 19: return 'T';
case 20: return 'U';
case 21: return 'V';
case 22: return 'W';
case 23: return 'X';
case 24: return 'Y';
case 25: return 'Z';
case 26: return 'a';
case 27: return 'b';
case 28: return 'c';
case 29: return 'd';
case 30: return 'e';
case 31: return 'f';
case 32: return 'g';
case 33: return 'h';
case 34: return 'i';
case 35: return 'j';
case 36: return 'k';
case 37: return 'l';
case 38: return 'm';
case 39: return 'n';
case 40: return 'o';
case 41: return 'p';
case 42: return 'q';
case 43: return 'r';
case 44: return 's';
case 45: return 't';
case 46: return 'u';
case 47: return 'v';
case 48: return 'w';
case 49: return 'x';
case 50: return 'y';
case 51: return 'z';
case 52: return '0';
case 53: return '1';
case 54: return '2';
case 55: return '3';
case 56: return '4';
case 57: return '5';
case 58: return '6';
case 59: return '7';
case 60: return '8';
case 61: return '9';
case 62: return '+';
case 63: return '/';
default: throw new Error("invalid base64 encode byte: " + n);
}
}
/**
* Conversion table for base64 decode
*
* @internal
*/
function
char2int
(s: string)
: number
{
switch(s) {
case 'A': return 0;
case 'B': return 1;
case 'C': return 2;
case 'D': return 3;
case 'E': return 4;
case 'F': return 5;
case 'G': return 6;
case 'H': return 7;
case 'I': return 8;
case 'J': return 9;
case 'K': return 10;
case 'L': return 11;
case 'M': return 12;
case 'N': return 13;
case 'O': return 14;
case 'P': return 15;
case 'Q': return 16;
case 'R': return 17;
case 'S': return 18;
case 'T': return 19;
case 'U': return 20;
case 'V': return 21;
case 'W': return 22;
case 'X': return 23;
case 'Y': return 24;
case 'Z': return 25;
case 'a': return 26;
case 'b': return 27;
case 'c': return 28;
case 'd': return 29;
case 'e': return 30;
case 'f': return 31;
case 'g': return 32;
case 'h': return 33;
case 'i': return 34;
case 'j': return 35;
case 'k': return 36;
case 'l': return 37;
case 'm': return 38;
case 'n': return 39;
case 'o': return 40;
case 'p': return 41;
case 'q': return 42;
case 'r': return 43;
case 's': return 44;
case 't': return 45;
case 'u': return 46;
case 'v': return 47;
case 'w': return 48;
case 'x': return 49;
case 'y': return 50;
case 'z': return 51;
case '0': return 52;
case '1': return 53;
case '2': return 54;
case '3': return 55;
case '4': return 56;
case '5': return 57;
case '6': return 58;
case '7': return 59;
case '8': return 60;
case '9': return 61;
case '+': return 62;
case '/': return 63;
default: throw new Error("invalid base64 character: " + s);
}
}

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@ -0,0 +1,521 @@
/**
* Ethereum Recursive-Length Prefix Encoding implementation
*
* Two reference implementations:
*
* 1. Ethereum Python implementation
* 2. My Erlang implementation (agrees with Ethereum Python in randomized
* tests)
*
* This work can be found in ../test/testgen/
*
* FIXME: need to have Safe assertions for "i am decoding a list", "i am
* decoding a binary", "I am decoding something with no remainder", etc
*
* @module
*/
export {
decoded_data,
decode_result,
decode,
encode
}
//=============================================================================
//=============================================================================
// DECODING
//=============================================================================
//=============================================================================
/**
* Data that RLP can encode. Also the result of decoding.
*/
type decoded_data
= Uint8Array
| Array<decoded_data>;
/**
* Decoding can have a remainder
*/
type decode_result
= {decoded_data : decoded_data,
remainder : Uint8Array};
/**
* Decode an RLP-encoded bytestring into a `decode_result` (decoded data +
* whatever wasn't consumed)
*/
function
decode
(bytes: Uint8Array)
: decode_result
{
// check the first byte
let first_byte: number = bytes[0];
let rest : Uint8Array = bytes.slice(1);
// if the first byte is between 0 and 127, that is the data
if
(first_byte <= 127) {
return dr(new Uint8Array([first_byte]), rest);
}
// if the first byte is between 128 and 183 = 128 + 55, it is a bytestring
// and the length is Byte - 128
else if
(first_byte <= 183) {
let payload_byte_length : number = first_byte - 128;
let payload : Uint8Array = rest.slice(0, payload_byte_length);
let rest2 : Uint8Array = rest.slice(payload_byte_length);
return dr(payload, rest2);
}
// if the first byte is between 184 = 183 + 1 and 191 = 183 + 8, it is a
// bytestring. the byte length of bytestring is FirstByte - 183. Then pull
// out the actual data
else if
(first_byte <= 191) {
let byte_length_of_byte_length : number = first_byte - 183;
let bytes_of_byte_length : Uint8Array = rest.slice(0, byte_length_of_byte_length);
let byte_length : number = bytes_to_number(bytes_of_byte_length);
let bytes : Uint8Array = rest.slice(byte_length_of_byte_length,
byte_length + byte_length_of_byte_length);
let rest2 : Uint8Array = rest.slice(byte_length + byte_length_of_byte_length);
return dr(bytes, rest2);
}
// If the first byte is between 192 and 247 = 192 + 55, it is a list. The
// byte length of the list-payload is FirstByte - 192. Then the list
// payload, which needs to be decoded on its own.
else if
(first_byte <= 247) {
let byte_length_of_list : number = first_byte - 192;
let list_payload : Uint8Array = rest.slice(0, byte_length_of_list);
let list : Array<decoded_data> = decode_list(list_payload);
let rest2 : Uint8Array = rest.slice(byte_length_of_list);
return dr(list, rest2);
}
// If the first byte is between 248 = 247 + 1 and 255 = 247 + 8, it is a
// list. The byte length of the byte length of the list-payload is
// FirstByte - 247. Then the byte length of the list. Then the list
// payload, which needs to be decoded on its own.
else {
let byte_length_of_byte_length : number = first_byte - 247;
let bytes_of_byte_length : Uint8Array = rest.slice(0, byte_length_of_byte_length);
let byte_length : number = bytes_to_number(bytes_of_byte_length);
let list_bytes : Uint8Array = rest.slice(byte_length_of_byte_length,
byte_length + byte_length_of_byte_length);
let list : Array<decoded_data> = decode_list(list_bytes);
let rest2 : Uint8Array = rest.slice(byte_length + byte_length_of_byte_length);
return dr(list, rest2);
}
}
/**
* Decode a list payload (non-prefixed) into an `Array<decoded_data>`.
*
* Repeatedly decodes an element off the list until remainder is empty.
*
* @internal
*/
function
decode_list
(bytes: Uint8Array)
: Array<decoded_data>
{
let arr : Array<decoded_data> = [];
while (bytes.length > 0) {
// grab an item off the bytes
let {decoded_data, remainder} = decode(bytes);
// push it
arr.push(decoded_data);
// update bytes
bytes = remainder;
}
return arr;
}
/**
* Convert bytestring to number
*
* @internal
*/
function
bytes_to_number
(bytes: Uint8Array)
: number
{
let n : number = 0;
for (let b of bytes)
{
n <<= 8;
n += b;
}
return n;
}
/**
* Make a `decode_result` containing the two arguments
*
* @internal
*/
function
dr
(x : decoded_data,
y : Uint8Array)
: decode_result
{
return {decoded_data : x,
remainder : y};
}
//=============================================================================
//=============================================================================
// ENCODING
//=============================================================================
//=============================================================================
/**
* Encode some decoded data
*/
function
encode
(data: decoded_data)
: Uint8Array
{
// is it an array or data
if
(is_binary(data)) {
return encode_binary(data as Uint8Array);
}
else if
(is_list(data)) {
return encode_list(data as Array<decoded_data>);
}
else {
throw new Error('encode told to encode something that is not an array or a binary: ' + data);
}
}
/**
* Encode a binary into RLP
*
* @internal
*/
function
encode_binary
(bytes: Uint8Array)
: Uint8Array
{
let len: number = bytes.length;
// single byte case when the byte is between 0..127
// result is the bytestring containing the byte itself
if
((len === 1) &&
(bytes[0] <= 127)){
return bytes;
}
// if the bytestring is 0..55 bytes long, the first byte in the result is
// 128 + Length, the rest of the result bytestring is the input string
else if
(len <= 55) {
// construct the result
// <<128 + Len, Bytes/binary>>
let result : Uint8Array = new Uint8Array(len + 1);
// first byte is 128 + length
result[0] = 128 + len;
// copy input bytes into result
for (let input_idx0 = 0;
input_idx0 < len;
input_idx0++)
{
let result_idx0 : number = input_idx0 + 1;
result[result_idx0] = bytes[input_idx0];
}
return result;
}
// if the bytestring is more than 55 bytes long, the first byte is 183 +
// ByteLengthOfByteLength, followed by the byte length, followed by the
// bytes
else {
let len_bytes : Uint8Array = encode_unsigned(len);
let len_bytes_length : number = len_bytes.length;
// total array is
// <<183 + len_bytes_length, len_bytes, Bytes>>
// 1 byte len_bytes_length bytes len bytes
let result : Uint8Array = new Uint8Array(1 + len_bytes_length + len);
// <<183 + len_bytes_length, len_bytes, Bytes>>
// 1 byte len_bytes_length bytes len bytes
//
// ^ YOU ARE HERE
result[0] = 183 + len_bytes_length;
// copy len_bytes into result
for (let len_bytes_idx0 = 0;
len_bytes_idx0 < len_bytes_length;
len_bytes_idx0++)
{
// <<183 + len_bytes_length, len_bytes, Bytes>>
// 1 byte len_bytes_length bytes len bytes
//
// ^ YOU ARE HERE
let result_idx0: number = len_bytes_idx0 + 1;
result[result_idx0] = len_bytes[len_bytes_idx0];
}
// copy original byte array into result
for (let input_idx0 = 0;
input_idx0 < len;
input_idx0++)
{
// <<183 + len_bytes_length, len_bytes, Bytes>>
// 1 byte len_bytes_length bytes len bytes
//
// ^ YOU ARE HERE
let result_idx0: number = input_idx0 + (1 + len_bytes_length);
result[result_idx0] = bytes[input_idx0];
}
// finally, return the result
return result;
}
}
/**
* Encode a list
*
* @internal
*/
function
encode_list
(list: Array<decoded_data>)
: Uint8Array
{
// first encode every element in the list, then branch
let payloads : Array<Uint8Array> = list.map(encode);
let payload : Uint8Array = uint8arr_concat(payloads);
let payload_size : number = payload.length;
// if the payload size is in 0..55, then the first byte is 192 + payload
// size, followed by the payload
if
(payload_size <= 55) {
// result: <<(192 + Payload_Size), Payload/binary >>;
// 1 byte payload_size bytes
let result : Uint8Array = new Uint8Array(1 + payload_size);
// result: <<(192 + Payload_Size), Payload/binary >>;
// 1 byte payload_size bytes
//
// ^ YOU ARE HERE
result[0] = 192 + payload_size;
// copy the rest of the payload into result
for (let payload_idx0 = 0;
payload_idx0 < payload_size;
payload_idx0++)
{
// result: <<(192 + Payload_Size), Payload/binary >>;
// 1 byte payload_size bytes
//
// ^ YOU ARE HERE
let result_idx0: number = payload_idx0 + 1;
result[result_idx0] = payload[payload_idx0];
}
return result;
}
// if the payload size is greater than 55, the first byte is 247 +
// size_of_payload_size, followed by the payload size, followed by the
// payload
else {
// compute the payload size size
let payload_size_bytes : Uint8Array = encode_unsigned(payload_size);
let payload_size_size : number = payload_size_bytes.length;
// result = <<(247 + payload_size_size), payload_size_bytes/binary, payload/binary >>
// 1 byte payload_size_size bytes payload_size bytes
let result: Uint8Array = new Uint8Array(1 + payload_size_size + payload_size);
// result = <<(247 + payload_size_size), payload_size_bytes/binary, payload/binary >>
// 1 byte payload_size_size bytes payload_size bytes
//
// ^ YOU ARE HERE
// first byte is 247 + payload_size_size
result[0] = 247 + payload_size_size;
// copy the payload_size_bytes into result
for (let psb_idx0 = 0;
psb_idx0 < payload_size_size;
psb_idx0++)
{
// result = <<(247 + payload_size_size), payload_size_bytes/binary, payload/binary >>
// 1 byte payload_size_size bytes payload_size bytes
//
// ^ YOU ARE HERE
// offset is 1 byte for this
let result_idx0 : number = psb_idx0 + 1;
result[result_idx0] = payload_size_bytes[psb_idx0];
}
// copy the payload into result
for (let pb_idx0 = 0;
pb_idx0 < payload_size;
pb_idx0++)
{
// result = <<(247 + payload_size_size), payload_size_bytes/binary, payload/binary >>
// 1 byte payload_size_size bytes payload_size bytes
//
// ^ YOU ARE HERE
// offset is 1 + payload_size_size bytes for this
let result_idx0 : number = pb_idx0 + (1 + payload_size_size);
result[result_idx0] = payload[pb_idx0];
}
// finally, return result
return result;
}
}
/**
* Encode a number as a bytestring
*
* Not for general use, this assumes the input number is greater than 55
*
* @internal
*/
function
encode_unsigned
(n: number)
: Uint8Array
{
// can assume that n initially is greater than 55
// have to encode it in reverse order
let arr : Array<number> = [];
// repeated division by 256 with remainder
//
// example: suppose bign was 1234 and we were dividing by 10
//
// iteration 0:
// bign = 1234
// arr = []
// ---
// bign / 10 = 123
// bign % 10 = 4
// ---
// bign = 123
// arr = [4]
//
// iteration 1:
// bign = 123
// arr = [4]
// ---
// bign / 10 = 12
// bign % 10 = 3
// ---
// bign = 12
// arr = [4, 3]
//
// iteration 2:
// bign = 12
// arr = [4, 3]
// ---
// bign / 10 = 1
// bign % 10 = 2
// ---
// bign = 1
// arr = [4, 3, 2]
//
// iteration 3:
// bign = 1
// arr = [4, 3, 2]
// ---
// bign / 10 = 0
// bign % 10 = 1
// ---
// bign = 0
// arr = [4, 3, 2, 1]
//
// iteration 4:
// bign = 0
// arr = [4, 3, 2, 1]
// ---
// DONE
while (n > 0) {
arr.push(n % 256);
n >>= 8;
}
// reverse and make into Uint8Array
arr.reverse();
return new Uint8Array(arr);
}
/**
* concatenate an array of `Uint8Array`s into a single Uint8Array
*
* @internal
*/
function
uint8arr_concat
(arrs: Array<Uint8Array>)
: Uint8Array
{
// total length
let total_len = arrs.reduce(// fold
function (acc_len: number, this_uint8array: Uint8Array): number {
return acc_len + this_uint8array.length;
},
// initial accumulator
0);
// start up result
let result : Uint8Array = new Uint8Array(total_len);
let result_idx0 : number = 0;
// concatenate
for (let this_uint8arr of arrs) {
// bytewise copy of this uint8array
for (let this_uint8arr_idx0 = 0;
this_uint8arr_idx0 < this_uint8arr.length;
this_uint8arr_idx0++)
{
// copy byte and increment result idx0
result[result_idx0] = this_uint8arr[this_uint8arr_idx0];
result_idx0++;
}
}
return result;
}
/**
* returns true if input is `instanceof Uint8Array`
*
* @internal
*/
function
is_binary
(x: any)
: boolean
{
return (x instanceof Uint8Array);
}
/**
* returns true if input is `instanceof Array`
*
* @internal
*/
function
is_list
(x: any)
: boolean
{
return (x instanceof Array);
}