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Integer Data Types in MDSplus

MDSplus supports several formats of integers including 8-bit, 16-bit, 32-bit, 64-bit and 128-bit signed and unsigned integers. The data is stored in 2's complement representation and little endian format. The endian is converted to big or little endian depending on the computer platform being used to reference the data. Like most programming languages, when operations are performed with values of different size, the values are converted to a common size (the largest of the values being operated on) before performing the operation. For example, if you were to add a 16-bit integer with a 32-bit integer the 16-bit integer would first be converted to a 32-bit integer before performing the add operation.

Integers can be simple scalar values or regular arrays with one to seven dimensions. When loaded into MDSplus trees, integer arrays may be compressed using a non-destructive delta compression algorithm automatically depending on the characteristics of the node in the tree where the data is being stored. Decompression of this data occurs automatically when the data is referenced. Raw data from data acquisition hardware is often stored in integer format and often compresses to one third or less of its orginal size requiring less disk space for storage and network bandwidth when accessing the data remotely.

Expression evaluator (TDI) operations used on Integer Data Types

The following table lists some of the more common operations performed on integer datatypes:

Function Description
ABS Absolute Value
ABSSQ Absolute Value Squared
ADD (+) Add
ALL Determine if all values are true
AND Logical And
AND_NOT Logical And with negation of second
ANY Determine if any values are true
ARRAY Construct array (uninitialized values)
BIT_SIZE Size in bits of data type
BSEARCH Binary search in sorted table
BTEST Test a bit of a number
BYTE Convert to 8-bit signed data type
BYTE_UNSIGNED Convert to 8-bit unsigned data type
CHAR Convert to text character
CONDITIONAL (test ? a : b) Select from 2 sources based on test value
COUNT Count number of true elements
CVT Convert to other data type
DATE_TIME Convert 64-bit internal date format to ascii date and time string
DBLE Double the precision, 8-bit values become 16-bit etc.
DECOMPILE Convert to text representation
DIAGONAL Create a diagonal matrix
DIGITS Number of significant digits
DIVIDE (/) Divide
DOT_PRODUCT Dot-product multiplication
ELBOUND Lower bound of array
EQ (==) Tests for equality
EQV Tests for logical equality
ESHAPE Return shape of array or scalar
ESIZE Total number of elements of array
EUBOUND Upper bound of array
FLOAT Convert to floating point
GE (>=) Test for first greater or equal to second
GT (>) Test for first greater than second
HUGE Largest value of this data type
IAND (&) Bit-by-bit intersection
IAND_NOT Bit-by-bit intersection with complement of second
IBCLR Clear one bit to zero
IBSET Set one bit to one
IEOR Bit-by-bit exclusive or
IEOR_NOT Bit-by-bit exclusive or with complement of second
IF IF statement
INAND Complement of bit-by-bit intersection
INAND_NOT Complement of bit-by-bit intersection with complement of second
INOR Complement of bit-by-bit union
INOR_NOT Complement of bit-by-bit union with complement of second
INOT Complement bit-by-bit
INT Convert to signed integer
INT_UNSIGNED Convert to unsigned integer
IOR (|) Bit-by-bit inclusive or
IOR_NOT Bit-by-bit union with complement of second
ISHFT Logical shift
LASTLOC Locate trailing edges of a set of true elements of a logical mask
LBOUND Lower bound of array
LE (<=) Test for first less than or equal to second
LOGICAL Convert to logical
LONG Convert to 32-bit signed integer
LONG_UNSIGNED Convert to 32-bit unsigned integer
LT (<) Test for first less than second
MAP Element selection from an array
MAX Maximum of argument list
MAXLOC Determine location of maximum value
MAXVAL Maximum value in an array
MEAN Average value of the elements of an array
MERGE Merge two arrays
MIN Minimum of argument list
MINLOC Determine location of minimum value
MINVAL Minimum value in an array
MOD Remainder
MULTIPLY (*) Multiply
NAND Negation of logical intersection
NAND_NOT Negation of logical intersection with negation of second
NE (!=) Test for inequality
NEQV Test inequality of logical values
NOR Negation of logical union of elements
NOR_NOT Negation of logical union with negation of second
NOT (!) Negate a logical
OCTAWORD Convert to 128-bit value
OCTAWORD_UNSIGNED Convert to 128-bit unsigned value
OR (||) Logical union
OR_NOT Logical union with negation of second
PACK Pack and array under control of mask
PRODUCT Product of all elements of an array
QUADWORD Convert to 64-bit integer
QUADWORD_UNSIGNED Convert to 64-bit unsigned integer
SET_RANGE Set array bounds
SHAPE Shape of array
SHIFT_LEFT (<<) Bitwise shift of value
SHIFT_RIGHT (>>) Bitwise shift of value
SIGNED Convert to signed integer
SIZE Total number of elements in an array
SIZEOF Total number of bytes
SORT Make index list of ascending array
SORTVAL Rearrange array in ascending order
SPREAD Replicate an array by adding a dimension
SQUARE Product of number with itself
SUBSCRIPT Pick certain elements of array
SUBTRACT (-) Subtract
SUM Sum all elements of array
TEXT Convert to text
UBOUND Upper bound of array
UNION Union of sets keeping only unique values
UNSIGNED Convert to unsigned value
WORD Convert to 16-bit integer
WORD_UNSIGNED Convert to 16-bit unsigned integer
ZERO Create array initialized to zero