ethers.js/src.ts/utils/maths.ts
2023-06-01 17:42:48 -04:00

241 lines
7.3 KiB
TypeScript

/**
* Some mathematic operations.
*
* @_subsection: api/utils:Math Helpers [about-maths]
*/
import { hexlify, isBytesLike } from "./data.js";
import { assert, assertArgument } from "./errors.js";
import type { BytesLike } from "./data.js";
/**
* Any type that can be used where a numeric value is needed.
*/
export type Numeric = number | bigint;
/**
* Any type that can be used where a big number is needed.
*/
export type BigNumberish = string | Numeric;
const BN_0 = BigInt(0);
const BN_1 = BigInt(1);
//const BN_Max256 = (BN_1 << BigInt(256)) - BN_1;
// IEEE 754 support 53-bits of mantissa
const maxValue = 0x1fffffffffffff;
/**
* Convert %%value%% from a twos-compliment representation of %%width%%
* bits to its value.
*
* If the highest bit is ``1``, the result will be negative.
*/
export function fromTwos(_value: BigNumberish, _width: Numeric): bigint {
const value = getUint(_value, "value");
const width = BigInt(getNumber(_width, "width"));
assert((value >> width) === BN_0, "overflow", "NUMERIC_FAULT", {
operation: "fromTwos", fault: "overflow", value: _value
});
// Top bit set; treat as a negative value
if (value >> (width - BN_1)) {
const mask = (BN_1 << width) - BN_1;
return -(((~value) & mask) + BN_1);
}
return value;
}
/**
* Convert %%value%% to a twos-compliment representation of
* %%width%% bits.
*
* The result will always be positive.
*/
export function toTwos(_value: BigNumberish, _width: Numeric): bigint {
let value = getBigInt(_value, "value");
const width = BigInt(getNumber(_width, "width"));
const limit = (BN_1 << (width - BN_1));
if (value < BN_0) {
value = -value;
assert(value <= limit, "too low", "NUMERIC_FAULT", {
operation: "toTwos", fault: "overflow", value: _value
});
const mask = (BN_1 << width) - BN_1;
return ((~value) & mask) + BN_1;
} else {
assert(value < limit, "too high", "NUMERIC_FAULT", {
operation: "toTwos", fault: "overflow", value: _value
});
}
return value;
}
/**
* Mask %%value%% with a bitmask of %%bits%% ones.
*/
export function mask(_value: BigNumberish, _bits: Numeric): bigint {
const value = getUint(_value, "value");
const bits = BigInt(getNumber(_bits, "bits"));
return value & ((BN_1 << bits) - BN_1);
}
/**
* Gets a BigInt from %%value%%. If it is an invalid value for
* a BigInt, then an ArgumentError will be thrown for %%name%%.
*/
export function getBigInt(value: BigNumberish, name?: string): bigint {
switch (typeof(value)) {
case "bigint": return value;
case "number":
assertArgument(Number.isInteger(value), "underflow", name || "value", value);
assertArgument(value >= -maxValue && value <= maxValue, "overflow", name || "value", value);
return BigInt(value);
case "string":
try {
if (value === "") { throw new Error("empty string"); }
if (value[0] === "-" && value[1] !== "-") {
return -BigInt(value.substring(1));
}
return BigInt(value);
} catch(e: any) {
assertArgument(false, `invalid BigNumberish string: ${ e.message }`, name || "value", value);
}
}
assertArgument(false, "invalid BigNumberish value", name || "value", value);
}
/**
* Returns %%value%% as a bigint, validating it is valid as a bigint
* value and that it is positive.
*/
export function getUint(value: BigNumberish, name?: string): bigint {
const result = getBigInt(value, name);
assert(result >= BN_0, "unsigned value cannot be negative", "NUMERIC_FAULT", {
fault: "overflow", operation: "getUint", value
});
return result;
}
const Nibbles = "0123456789abcdef";
/*
* Converts %%value%% to a BigInt. If %%value%% is a Uint8Array, it
* is treated as Big Endian data.
*/
export function toBigInt(value: BigNumberish | Uint8Array): bigint {
if (value instanceof Uint8Array) {
let result = "0x0";
for (const v of value) {
result += Nibbles[v >> 4];
result += Nibbles[v & 0x0f];
}
return BigInt(result);
}
return getBigInt(value);
}
/**
* Gets a //number// from %%value%%. If it is an invalid value for
* a //number//, then an ArgumentError will be thrown for %%name%%.
*/
export function getNumber(value: BigNumberish, name?: string): number {
switch (typeof(value)) {
case "bigint":
assertArgument(value >= -maxValue && value <= maxValue, "overflow", name || "value", value);
return Number(value);
case "number":
assertArgument(Number.isInteger(value), "underflow", name || "value", value);
assertArgument(value >= -maxValue && value <= maxValue, "overflow", name || "value", value);
return value;
case "string":
try {
if (value === "") { throw new Error("empty string"); }
return getNumber(BigInt(value), name);
} catch(e: any) {
assertArgument(false, `invalid numeric string: ${ e.message }`, name || "value", value);
}
}
assertArgument(false, "invalid numeric value", name || "value", value);
}
/**
* Converts %%value%% to a number. If %%value%% is a Uint8Array, it
* is treated as Big Endian data. Throws if the value is not safe.
*/
export function toNumber(value: BigNumberish | Uint8Array): number {
return getNumber(toBigInt(value));
}
/**
* Converts %%value%% to a Big Endian hexstring, optionally padded to
* %%width%% bytes.
*/
export function toBeHex(_value: BigNumberish, _width?: Numeric): string {
const value = getUint(_value, "value");
let result = value.toString(16);
if (_width == null) {
// Ensure the value is of even length
if (result.length % 2) { result = "0" + result; }
} else {
const width = getNumber(_width, "width");
assert(width * 2 >= result.length, `value exceeds width (${ width } bits)`, "NUMERIC_FAULT", {
operation: "toBeHex",
fault: "overflow",
value: _value
});
// Pad the value to the required width
while (result.length < (width * 2)) { result = "0" + result; }
}
return "0x" + result;
}
/**
* Converts %%value%% to a Big Endian Uint8Array.
*/
export function toBeArray(_value: BigNumberish): Uint8Array {
const value = getUint(_value, "value");
if (value === BN_0) { return new Uint8Array([ ]); }
let hex = value.toString(16);
if (hex.length % 2) { hex = "0" + hex; }
const result = new Uint8Array(hex.length / 2);
for (let i = 0; i < result.length; i++) {
const offset = i * 2;
result[i] = parseInt(hex.substring(offset, offset + 2), 16);
}
return result;
}
/**
* Returns a [[HexString]] for %%value%% safe to use as a //Quantity//.
*
* A //Quantity// does not have and leading 0 values unless the value is
* the literal value `0x0`. This is most commonly used for JSSON-RPC
* numeric values.
*/
export function toQuantity(value: BytesLike | BigNumberish): string {
let result = hexlify(isBytesLike(value) ? value: toBeArray(value)).substring(2);
while (result.startsWith("0")) { result = result.substring(1); }
if (result === "") { result = "0"; }
return "0x" + result;
}