tree bb195ab649aaf85e9b608178a22289cd02e0524f
parent 3180f7b55434f19ba65f262dea450c93c769228b
author Willy Tarreau <w@1wt.eu> 1422367933 +0100
committer Willy Tarreau <w@1wt.eu> 1422369673 +0100
encoding latin1

MEDIUM: samples: provide basic arithmetic and bitwise operators

This commit introduces a new category of converters. They are bitwise and
arithmetic operators which support performing basic operations on integers.
Some bitwise operations are supported (and, or, xor, cpl) and some arithmetic
operations are supported (add, sub, mul, div, mod, neg). Some comparators
are provided (odd, even, not, bool) which make it possible to report a match
without having to write an ACL.

The detailed list of new operators as they appear in the doc is :

add(<value>)
  Adds <value> to the input value of type unsigned integer, and returns the
  result as an unsigned integer.

and(<value>)
  Performs a bitwise "AND" between <value> and the input value of type unsigned
  integer, and returns the result as an unsigned integer.

bool
  Returns a boolean TRUE if the input value of type unsigned integer is
  non-null, otherwise returns FALSE. Used in conjunction with and(), it can be
  used to report true/false for bit testing on input values (eg: verify the
  presence of a flag).

cpl
  Takes the input value of type unsigned integer, applies a twos-complement
  (flips all bits) and returns the result as an unsigned integer.

div(<value>)
  Divides the input value of type unsigned integer by <value>, and returns the
  result as an unsigned integer. If <value> is null, the largest unsigned
  integer is returned (typically 2^32-1).

even
  Returns a boolean TRUE if the input value of type unsigned integer is even
  otherwise returns FALSE. It is functionally equivalent to "not,and(1),bool".

mod(<value>)
  Divides the input value of type unsigned integer by <value>, and returns the
  remainder as an unsigned integer. If <value> is null, then zero is returned.

mul(<value>)
  Multiplies the input value of type unsigned integer by <value>, and returns
  the product as an unsigned integer. In case of overflow, the higher bits are
  lost, leading to seemingly strange values.

neg
  Takes the input value of type unsigned integer, computes the opposite value,
  and returns the remainder as an unsigned integer. 0 is identity. This
  operator is provided for reversed subtracts : in order to subtract the input
  from a constant, simply perform a "neg,add(value)".

not
  Returns a boolean FALSE if the input value of type unsigned integer is
  non-null, otherwise returns TRUE. Used in conjunction with and(), it can be
  used to report true/false for bit testing on input values (eg: verify the
  absence of a flag).

odd
  Returns a boolean TRUE if the input value of type unsigned integer is odd
  otherwise returns FALSE. It is functionally equivalent to "and(1),bool".

or(<value>)
  Performs a bitwise "OR" between <value> and the input value of type unsigned
  integer, and returns the result as an unsigned integer.

sub(<value>)
  Subtracts <value> from the input value of type unsigned integer, and returns
  the result as an unsigned integer. Note: in order to subtract the input from
  a constant, simply perform a "neg,add(value)".

xor(<value>)
  Performs a bitwise "XOR" (exclusive OR) between <value> and the input value
  of type unsigned integer, and returns the result as an unsigned integer.