Long()

Constructor

Defines a Long class for representing a 64-bit two’s-complement integer value, which faithfully simulates the behavior of a Java “Long”. This implementation is derived from LongLib in GWT.

class Long()
Arguments:
  • low (number) – the low (signed) 32 bits of the Long.
  • high (number) – the high (signed) 32 bits of the Long.
Returns:

long

Constructs a 64-bit two’s-complement integer, given its low and high 32-bit values as signed integers. See the from* functions below for more convenient ways of constructing Longs.

The internal representation of a Long is the two given signed, 32-bit values. We use 32-bit pieces because these are the size of integers on which Javascript performs bit-operations. For operations like addition and multiplication, we split each number into 16-bit pieces, which can easily be multiplied within Javascript’s floating-point representation without overflow or change in sign.

In the algorithms below, we frequently reduce the negative case to the positive case by negating the input(s) and then post-processing the result. Note that we must ALWAYS check specially whether those values are MIN_VALUE (-2^63) because -MIN_VALUE == MIN_VALUE (since 2^63 cannot be represented as a positive number, it overflows back into a negative). Not handling this case would often result in infinite recursion.

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