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For ../dm5dm6_ex3
  Run on Tue Feb 24 07:41:47 2015
Reported on Tue Feb 24 07:41:51 2015

Filename/usr/lib/perl5/5.20.1/integer.pm
StatementsExecuted 23 statements in 73µs
Subroutines
Calls P F Exclusive
Time
Inclusive
Time
Subroutine
1616317µs17µsinteger::::unimportinteger::unimport
4424µs4µsinteger::::importinteger::import
Call graph for these subroutines as a Graphviz dot language file.
Line State
ments
Time
on line
Calls Time
in subs
Code
1package integer;
2
31200nsour $VERSION = '1.01';
4
5=head1 NAME
6
7integer - Perl pragma to use integer arithmetic instead of floating point
8
9=head1 SYNOPSIS
10
11 use integer;
12 $x = 10/3;
13 # $x is now 3, not 3.33333333333333333
14
15=head1 DESCRIPTION
16
17This tells the compiler to use integer operations from here to the end
18of the enclosing BLOCK. On many machines, this doesn't matter a great
19deal for most computations, but on those without floating point
20hardware, it can make a big difference in performance.
21
22Note that this only affects how most of the arithmetic and relational
23B<operators> handle their operands and results, and B<not> how all
24numbers everywhere are treated. Specifically, C<use integer;> has the
25effect that before computing the results of the arithmetic operators
26(+, -, *, /, %, +=, -=, *=, /=, %=, and unary minus), the comparison
27operators (<, <=, >, >=, ==, !=, <=>), and the bitwise operators (|, &,
28^, <<, >>, |=, &=, ^=, <<=, >>=), the operands have their fractional
29portions truncated (or floored), and the result will have its
30fractional portion truncated as well. In addition, the range of
31operands and results is restricted to that of familiar two's complement
32integers, i.e., -(2**31) .. (2**31-1) on 32-bit architectures, and
33-(2**63) .. (2**63-1) on 64-bit architectures. For example, this code
34
35 use integer;
36 $x = 5.8;
37 $y = 2.5;
38 $z = 2.7;
39 $a = 2**31 - 1; # Largest positive integer on 32-bit machines
40 $, = ", ";
41 print $x, -$x, $x+$y, $x-$y, $x/$y, $x*$y, $y==$z, $a, $a+1;
42
43will print: 5.8, -5, 7, 3, 2, 10, 1, 2147483647, -2147483648
44
45Note that $x is still printed as having its true non-integer value of
465.8 since it wasn't operated on. And note too the wrap-around from the
47largest positive integer to the largest negative one. Also, arguments
48passed to functions and the values returned by them are B<not> affected
49by C<use integer;>. E.g.,
50
51 srand(1.5);
52 $, = ", ";
53 print sin(.5), cos(.5), atan2(1,2), sqrt(2), rand(10);
54
55will give the same result with or without C<use integer;> The power
56operator C<**> is also not affected, so that 2 ** .5 is always the
57square root of 2. Now, it so happens that the pre- and post- increment
58and decrement operators, ++ and --, are not affected by C<use integer;>
59either. Some may rightly consider this to be a bug -- but at least it's
60a long-standing one.
61
62Finally, C<use integer;> also has an additional affect on the bitwise
63operators. Normally, the operands and results are treated as
64B<unsigned> integers, but with C<use integer;> the operands and results
65are B<signed>. This means, among other things, that ~0 is -1, and -2 &
66-5 is -6.
67
68Internally, native integer arithmetic (as provided by your C compiler)
69is used. This means that Perl's own semantics for arithmetic
70operations may not be preserved. One common source of trouble is the
71modulus of negative numbers, which Perl does one way, but your hardware
72may do another.
73
74 % perl -le 'print (4 % -3)'
75 -2
76 % perl -Minteger -le 'print (4 % -3)'
77 1
78
79See L<perlmodlib/"Pragmatic Modules">, L<perlop/"Integer Arithmetic">
80
81=cut
82
831100ns$integer::hint_bits = 0x1;
84
85
# spent 4µs within integer::import which was called 4 times, avg 1µs/call: # once (2µs+0s) by Date::Manip::Date::BEGIN@1318 at line 1318 of Date/Manip/Date.pm # once (1µs+0s) by Date::Manip::Date::BEGIN@20 at line 20 of Date/Manip/Date.pm # once (900ns+0s) by Date::Manip::Date::BEGIN@3551 at line 3551 of Date/Manip/Date.pm # once (600ns+0s) by Date::Manip::Base::BEGIN@21 at line 21 of Date/Manip/Base.pm
sub import {
86410µs $^H |= $integer::hint_bits;
87}
88
89
# spent 17µs within integer::unimport which was called 16 times, avg 1µs/call: # once (2µs+0s) by Date::Manip::Delta::BEGIN@902 at line 902 of Date/Manip/Delta.pm # once (2µs+0s) by Date::Manip::Date::BEGIN@1288 at line 1288 of Date/Manip/Date.pm # once (1µs+0s) by Date::Manip::Base::BEGIN@232 at line 232 of Date/Manip/Base.pm # once (1µs+0s) by Date::Manip::Delta::BEGIN@971 at line 971 of Date/Manip/Delta.pm # once (1µs+0s) by Date::Manip::Date::BEGIN@3130 at line 3130 of Date/Manip/Date.pm # once (1µs+0s) by Date::Manip::Base::BEGIN@1782 at line 1782 of Date/Manip/Base.pm # once (1µs+0s) by Date::Manip::Date::BEGIN@3541 at line 3541 of Date/Manip/Date.pm # once (1µs+0s) by Date::Manip::Base::BEGIN@392 at line 392 of Date/Manip/Base.pm # once (1µs+0s) by Date::Manip::Base::BEGIN@577 at line 577 of Date/Manip/Base.pm # once (1µs+0s) by Date::Manip::Base::BEGIN@2194 at line 2194 of Date/Manip/Base.pm # once (900ns+0s) by Date::Manip::Base::BEGIN@2207 at line 2207 of Date/Manip/Base.pm # once (700ns+0s) by Date::Manip::Delta::BEGIN@979 at line 979 of Date/Manip/Delta.pm # once (600ns+0s) by Date::Manip::Base::BEGIN@2238 at line 2238 of Date/Manip/Base.pm # once (600ns+0s) by Date::Manip::Base::BEGIN@2256 at line 2256 of Date/Manip/Base.pm # once (600ns+0s) by Date::Manip::Base::BEGIN@2218 at line 2218 of Date/Manip/Base.pm # once (600ns+0s) by Date::Manip::Base::BEGIN@2272 at line 2272 of Date/Manip/Base.pm
sub unimport {
901661µs $^H &= ~$integer::hint_bits;
91}
92
9311µs1;