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More efficient conversion of integers to uint32s.

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library/integer.m:
    Make the bounds checks in to_int32/2 more efficient by (1) examining
    just the "sign" of the input to determine whether it is non-negative
    and (2) avoiding the creation of an integer corresponding to max_uint32.
This commit is contained in:
Julien Fischer
2018-01-18 00:39:46 -05:00
parent f205afd47d
commit 13c8fc6fae
1 changed files with 9 additions and 3 deletions
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12
library/integer.m
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@@ -1490,11 +1490,17 @@ det_to_int32(Integer) = Int32 :-
%---------------------------------------------------------------------------%
to_uint32(Integer, UInt32) :-
Integer >= integer.zero,
Integer =< integer.from_uint32(uint32.max_uint32),
Integer = i(_Sign, Digits),
Integer = i(Sign, Digits),
Sign >= 0, % i.e. Integer >= 0.
Integer =< integer_max_uint32,
UInt32 = uint32_list(Digits, 0u32).
% Return max_uint32 as an integer.
%
:- func integer_max_uint32 = integer.
integer_max_uint32 = i(3, [15, 16383, 16383]).
:- func uint32_list(list(int), uint32) = uint32.
uint32_list([], Accum) = Accum.