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Guymer/func_overall_index.f90

Created January 9, 2019 17:49
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a demonstration of linearizing nested do-loop indexes (for use with MPI)
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func_overall_index.f90
MODULE foo
USE ISO_FORTRAN_ENV
IMPLICIT NONE
INTERFACE func_overall_index
MODULE PROCEDURE func_overall_index_2loops
MODULE PROCEDURE func_overall_index_3loops
MODULE PROCEDURE func_overall_index_4loops
MODULE PROCEDURE func_overall_index_5loops
MODULE PROCEDURE func_overall_index_6loops
MODULE PROCEDURE func_overall_index_7loops
END INTERFACE func_overall_index
CONTAINS
ELEMENTAL FUNCTION func_overall_index_2loops(i1, i2, n1, n2) RESULT(ans)
! NOTE: Assume all indexes go from 1 to n (inclusive).
! NOTE: Assume i1 to i2 goes from the outer loop to the inner loop.
USE ISO_FORTRAN_ENV
IMPLICIT NONE
INTEGER(kind = INT64), INTENT(in) :: i1
INTEGER(kind = INT64), INTENT(in) :: i2
INTEGER(kind = INT64), INTENT(in) :: n1
INTEGER(kind = INT64), INTENT(in) :: n2
INTEGER(kind = INT64) :: ans
ans = i2 + n2 * (i1 - 1_INT64)
END FUNCTION
ELEMENTAL FUNCTION func_overall_index_3loops(i1, i2, i3, n1, n2, n3) RESULT(ans)
! NOTE: Assume all indexes go from 1 to n (inclusive).
! NOTE: Assume i1 to i3 goes from the outer loop to the inner loop.
USE ISO_FORTRAN_ENV
IMPLICIT NONE
INTEGER(kind = INT64), INTENT(in) :: i1
INTEGER(kind = INT64), INTENT(in) :: i2
INTEGER(kind = INT64), INTENT(in) :: i3
INTEGER(kind = INT64), INTENT(in) :: n1
INTEGER(kind = INT64), INTENT(in) :: n2
INTEGER(kind = INT64), INTENT(in) :: n3
INTEGER(kind = INT64) :: ans
ans = i3 + n3 * ((i2 - 1_INT64) + n2 * (i1 - 1_INT64))
END FUNCTION
ELEMENTAL FUNCTION func_overall_index_4loops(i1, i2, i3, i4, n1, n2, n3, n4) RESULT(ans)
! NOTE: Assume all indexes go from 1 to n (inclusive).
! NOTE: Assume i1 to i4 goes from the outer loop to the inner loop.
USE ISO_FORTRAN_ENV
IMPLICIT NONE
INTEGER(kind = INT64), INTENT(in) :: i1
INTEGER(kind = INT64), INTENT(in) :: i2
INTEGER(kind = INT64), INTENT(in) :: i3
INTEGER(kind = INT64), INTENT(in) :: i4
INTEGER(kind = INT64), INTENT(in) :: n1
INTEGER(kind = INT64), INTENT(in) :: n2
INTEGER(kind = INT64), INTENT(in) :: n3
INTEGER(kind = INT64), INTENT(in) :: n4
INTEGER(kind = INT64) :: ans
ans = i4 + n4 * ((i3 - 1_INT64) + n3 * ((i2 - 1_INT64) + n2 * (i1 - 1_INT64)))
END FUNCTION
ELEMENTAL FUNCTION func_overall_index_5loops(i1, i2, i3, i4, i5, n1, n2, n3, n4, n5) RESULT(ans)
! NOTE: Assume all indexes go from 1 to n (inclusive).
! NOTE: Assume i1 to i5 goes from the outer loop to the inner loop.
USE ISO_FORTRAN_ENV
IMPLICIT NONE
INTEGER(kind = INT64), INTENT(in) :: i1
INTEGER(kind = INT64), INTENT(in) :: i2
INTEGER(kind = INT64), INTENT(in) :: i3
INTEGER(kind = INT64), INTENT(in) :: i4
INTEGER(kind = INT64), INTENT(in) :: i5
INTEGER(kind = INT64), INTENT(in) :: n1
INTEGER(kind = INT64), INTENT(in) :: n2
INTEGER(kind = INT64), INTENT(in) :: n3
INTEGER(kind = INT64), INTENT(in) :: n4
INTEGER(kind = INT64), INTENT(in) :: n5
INTEGER(kind = INT64) :: ans
ans = i5 + n5 * ((i4 - 1_INT64) + n4 * ((i3 - 1_INT64) + n3 * ((i2 - 1_INT64) + n2 * (i1 - 1_INT64))))
END FUNCTION
ELEMENTAL FUNCTION func_overall_index_6loops(i1, i2, i3, i4, i5, i6, n1, n2, n3, n4, n5, n6) RESULT(ans)
! NOTE: Assume all indexes go from 1 to n (inclusive).
! NOTE: Assume i1 to i6 goes from the outer loop to the inner loop.
USE ISO_FORTRAN_ENV
IMPLICIT NONE
INTEGER(kind = INT64), INTENT(in) :: i1
INTEGER(kind = INT64), INTENT(in) :: i2
INTEGER(kind = INT64), INTENT(in) :: i3
INTEGER(kind = INT64), INTENT(in) :: i4
INTEGER(kind = INT64), INTENT(in) :: i5
INTEGER(kind = INT64), INTENT(in) :: i6
INTEGER(kind = INT64), INTENT(in) :: n1
INTEGER(kind = INT64), INTENT(in) :: n2
INTEGER(kind = INT64), INTENT(in) :: n3
INTEGER(kind = INT64), INTENT(in) :: n4
INTEGER(kind = INT64), INTENT(in) :: n5
INTEGER(kind = INT64), INTENT(in) :: n6
INTEGER(kind = INT64) :: ans
ans = i6 + n6 * ((i5 - 1_INT64) + n5 * ((i4 - 1_INT64) + n4 * ((i3 - 1_INT64) + n3 * ((i2 - 1_INT64) + n2 * (i1 - 1_INT64)))))
END FUNCTION
ELEMENTAL FUNCTION func_overall_index_7loops(i1, i2, i3, i4, i5, i6, i7, n1, n2, n3, n4, n5, n6, n7) RESULT(ans)
! NOTE: Assume all indexes go from 1 to n (inclusive).
! NOTE: Assume i1 to i7 goes from the outer loop to the inner loop.
USE ISO_FORTRAN_ENV
IMPLICIT NONE
INTEGER(kind = INT64), INTENT(in) :: i1
INTEGER(kind = INT64), INTENT(in) :: i2
INTEGER(kind = INT64), INTENT(in) :: i3
INTEGER(kind = INT64), INTENT(in) :: i4
INTEGER(kind = INT64), INTENT(in) :: i5
INTEGER(kind = INT64), INTENT(in) :: i6
INTEGER(kind = INT64), INTENT(in) :: i7
INTEGER(kind = INT64), INTENT(in) :: n1
INTEGER(kind = INT64), INTENT(in) :: n2
INTEGER(kind = INT64), INTENT(in) :: n3
INTEGER(kind = INT64), INTENT(in) :: n4
INTEGER(kind = INT64), INTENT(in) :: n5
INTEGER(kind = INT64), INTENT(in) :: n6
INTEGER(kind = INT64), INTENT(in) :: n7
INTEGER(kind = INT64) :: ans
ans = i7 + n7 * ((i6 - 1_INT64) + n6 * ((i5 - 1_INT64) + n5 * ((i4 - 1_INT64) + n4 * ((i3 - 1_INT64) + n3 * ((i2 - 1_INT64) + n2 * (i1 - 1_INT64))))))
END FUNCTION
END MODULE foo
PROGRAM bar
USE ISO_FORTRAN_ENV
USE foo
IMPLICIT NONE
INTEGER(kind = INT64), PARAMETER :: n1 = 2
INTEGER(kind = INT64), PARAMETER :: n2 = 4
INTEGER(kind = INT64), PARAMETER :: n3 = 6
INTEGER(kind = INT64), PARAMETER :: n4 = 8
INTEGER(kind = INT64), PARAMETER :: n5 = 10
INTEGER(kind = INT64), PARAMETER :: n6 = 12
INTEGER(kind = INT64), PARAMETER :: n7 = 14
INTEGER(kind = INT64) :: i1
INTEGER(kind = INT64) :: i2
INTEGER(kind = INT64) :: i3
INTEGER(kind = INT64) :: i4
INTEGER(kind = INT64) :: i5
INTEGER(kind = INT64) :: i6
INTEGER(kind = INT64) :: i7
DO i1 = 1_INT64, n1
DO i2 = 1_INT64, n2
DO i3 = 1_INT64, n3
WRITE(fmt = '(3(1x, i2, "/", i2), i9)', unit = OUTPUT_UNIT) i1, n1, i2, n2, i3, n3, func_overall_index(i1, i2, i3, n1, n2, n3)
END DO
END DO
END DO
DO i1 = 1_INT64, n1
DO i2 = 1_INT64, n2
DO i3 = 1_INT64, n3
DO i4 = 1_INT64, n4
DO i5 = 1_INT64, n5
DO i6 = 1_INT64, n6
DO i7 = 1_INT64, n7
WRITE(fmt = '(7(1x, i2, "/", i2), i9)', unit = OUTPUT_UNIT) i1, n1, i2, n2, i3, n3, i4, n4, i5, n5, i6, n6, i7, n7, func_overall_index(i1, i2, i3, i4, i5, i6, i7, n1, n2, n3, n4, n5, n6, n7)
END DO
END DO
END DO
END DO
END DO
END DO
END DO
END PROGRAM bar
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