BigMathMinified

Git Source

the number is divided into two parts: a coefficient and an exponent. This comes at a cost of losing some precision at the end of the number because the exponent simply fills it with zeroes. This precision is oftentimes negligible and can result in significant gas cost reduction due to storage space reduction. Also note, a valid big number is as follows: if the exponent is > 0, then coefficient last bits should be occupied to have max precision.

roundUp is more like a increase 1, which happens everytime for the same number. roundDown simply sets trailing digits after coefficientSize to zero (floor), only once for the same number.

State Variables

ROUND_DOWN

constants to use for roundUp input param to increase readability

bool internal constant ROUND_DOWN = false;

ROUND_UP

bool internal constant ROUND_UP = true;

Functions

toBigNumber

converts normal number to BigNumber with exponent and coefficient (or precision). e.g.: 5035703444687813576399599 (normal) = (coefficient32bits, exponent8bits)40bits 5035703444687813576399599 (decimal) => 10000101010010110100000011111011110010100110100000000011100101001101001101011101111 (binary) => 10000101010010110100000011111011000000000000000000000000000000000000000000000000000 ^-------------------- 51(exponent) -------------- ^ coefficient = 1000,0101,0100,1011,0100,0000,1111,1011 (2236301563) exponent = 0011,0011 (51) bigNumber = 1000,0101,0100,1011,0100,0000,1111,1011,0011,0011 (572493200179)

function toBigNumber(uint256 normal, uint256 coefficientSize, uint256 exponentSize, bool roundUp)
    internal
    pure
    returns (uint256 bigNumber);

Parameters

NameTypeDescription
normaluint256number which needs to be converted into Big Number
coefficientSizeuint256at max how many bits of precision there should be (64 = uint64 (64 bits precision))
exponentSizeuint256at max how many bits of exponent there should be (8 = uint8 (8 bits exponent))
roundUpboolsignals if result should be rounded down or up

Returns

NameTypeDescription
bigNumberuint256converted bigNumber (coefficient << exponent)

fromBigNumber

get normal number from bigNumber, exponentSize and exponentMask

function fromBigNumber(uint256 bigNumber, uint256 exponentSize, uint256 exponentMask)
    internal
    pure
    returns (uint256 normal);

mostSignificantBit

gets the most significant bit lastBit of a normal number (length of given number of binary format). e.g. 5035703444687813576399599 = 10000101010010110100000011111011110010100110100000000011100101001101001101011101111 lastBit = ^--------------------------------- 83 ----------------------------------------^

function mostSignificantBit(uint256 normal) internal pure returns (uint256 lastBit);
Table of Contents