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Replaced btest() by popcnt() in bit_count_large() #756

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merged 2 commits into from
Jan 9, 2024
Merged

Replaced btest() by popcnt() in bit_count_large() #756

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461b3a0
replaced btest() by popcnt() in bit_count_large() and added a test case
PierUgit Jan 3, 2024
67981c3
added kind= argument in size(...)
PierUgit Jan 3, 2024
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10 changes: 10 additions & 0 deletions example/bitsets/example_bitsets_bit_count.f90
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,9 @@ program example_bit_count
character(*), parameter :: &
bits_0 = '0000000000000000000'
type(bitset_64) :: set0
type(bitset_large) :: set1
logical, allocatable :: logi(:)

call set0%from_string(bits_0)
if (set0%bit_count() == 0) then
write (*, *) "FROM_STRING interpreted "// &
Expand All @@ -12,4 +15,11 @@ program example_bit_count
if (set0%bit_count() == 1) then
write (*, *) "BIT_COUNT interpreted SET0's value properly."
end if

allocate( logi(1000), source=.false.)
logi(1::7) = .true.
set1 = logi
if (set1%bit_count() == count(logi)) then
write (*, *) "BIT_COUNT interpreted SET1's value properly."
end if
end program example_bit_count
16 changes: 5 additions & 11 deletions src/stdlib_bitsets_large.fypp
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Expand Up @@ -144,19 +144,13 @@ contains
integer(bits_kind) :: bit_count
class(bitset_large), intent(in) :: self

integer(bits_kind) :: block_, pos
integer(bits_kind) :: nblocks, pos

bit_count = 0
do block_ = 1_bits_kind, size(self % blocks, kind=bits_kind) - 1
do pos = 0, block_size-1
if ( btest( self % blocks(block_), pos ) ) &
bit_count = bit_count + 1
end do

end do
nblocks = size( self % blocks, kind=bits_kind )
bit_count = sum( popcnt( self % blocks(1:nblocks-1) ) )

do pos = 0_bits_kind, self % num_bits - (block_-1)*block_size - 1
if ( btest( self % blocks(block_), pos ) ) bit_count = bit_count + 1
do pos = 0_bits_kind, self % num_bits - (nblocks-1)*block_size - 1
if ( btest( self % blocks(nblocks), pos ) ) bit_count = bit_count + 1
end do

end function bit_count_large
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