bit-* functions don't check for overflow
Description
The bit* functions, in contrast to the other numerical functions, don't appear to check for overflow, i.e. (bit-test 13 200000) returns true.
It would be nice if the behaviour would fit the other numerical operators, i.e. throw on overflow and provide a variant that doesn't, and one that works with arbitrary precision, also not currently supported:
(bit-test (bigint 13) 20000), (bit-test (biginteger 13) 20000) throw IllegalArgumentException.
Environment
Activity
Reporter is import as it was imported from a prior jira system and the user was not imported, but all of the info should be here. What did you want to chat about?
Hi, Alex. Wasn’t sure who to ping on this –
”Reporter” is “import”, so guessing this issue was submitted on a non-git repo before it was imported to “git”
Do you know who I might chat with about this issue?
Thanks.
-- Harmon
I have a patch that allows bit operations to be applied to BigInts (long + BigInteger).
(previous content deleted)
From the description of this issue, and “overflow” for a bit operation on a long-integer is when a specified bit position is greater than 64 (i.e. 1 << 6, the bit-length of a length of a long integer). In Java, if such a bit-position is specified, it is truncated to its first 6 bits.
As such, the behavior of bit-test is consistent with the java language, so I don’t think this behavior should change.
However, in my patch, each bit-operation on long-integers that specifies a bit-position (i.e. bit-set, bit-clear, bit-flip, bit-test, bit-shift-left, bit-shift-right) have corresponding companion bit-operations that do not truncate the bit-position to the first 6 bits (bit-set', bit-clear', bit-flip', bit-test', bit-shift-left', bit-shift-right' . Instead, if needed, they convert the result of the operation to a BigInt (that uses a BigInteger under the hood).
The convention of adding an apostrophe to the end of the operation name come from arithmetic operations like + and +', and * and *'.
