1  Expressions
   You can use expressions as parameters for some SDA commands,
   such as SEARCH and EXAMINE. To create expressions, use any of the
   following elements:

   o  Numerals

   o  Radix operators

   o  Arithmetic and logical operators

   o  Precedence operators

   o  Symbols

   Numerals are one possible component of an expression. The
   following paragraphs describe the use of the other components.

   Radix operators determine which numeric base SDA uses to evaluate
   expressions. You can use one of the three radix operators to
   specify the radix of the numeric expression that follows the
   operator:

   o  ^X (hexadecimal)

   o  ^O (octal)

   o  ^D (decimal)

   The default radix is hexadecimal. SDA displays hexadecimal
   numbers with leading zeros and decimal numbers with leading
   spaces.

   There are two types of arithmetic and logical operators:

   o  Unary operators affect the value of the expression that
      follows them.

   o  Binary operators combine the operands that precede and follow
      them.

   In evaluating expressions containing binary operators, SDA
   performs logical AND, OR, and XOR operations, and multiplication,
   division, and arithmetic shifting before addition and
   subtraction. Note that the SDA arithmetic operators perform
   integer arithmetic on 64-bit operands.
 

2  Unary_Operators
   The following table describes the unary operators.

   Operator   Action

   #          Performs a logical NOT of the expression.
   +          Makes the value of the expression positive.
   -          Makes the value of the expression negative.
   @          Evaluates the following expression as an address, then
              uses the contents of that address as its value.
   ^Q         Specifies that the size of the field to be used as an
              address is a quadword when used with the unary operator
              @.
   ^L         Specifies that the size of the field to be used as an
              address is a longword when used with the unary operator
              @.
   ^W         Specifies that the size of the field to be used as an
              address is a word when used with the unary operator @.
   ^B         Specifies that the size of the field to be used as an
              address is a byte when used with the unary operator @.
   ^P         Specifies a physical address when used with the unary
              operator @.
   ^V         Specifies a virtual address when used with the unary
              operator @.
   G          Adds FFFFFFFF 80000000(16) to the value of the
              expression. The unary operator G corresponds to the
              first virtual address in S0 system space. For example,
              the expression GD40 can be used to represent the
              address FFFFFFFF 80000D40(16).
   H          Adds 7FFE0000(16) to the value of the expression.
              The unary operator H corresponds to a convenient base
              address in P1 space (7FFE0000(16)). You can therefore
              refer to an address such as 7FFE2A64(16) as H2A64.
   I          Fills the leading digits of the following hexadecimal
              number with hex value of F. For example:

   SDA> eval i80000000
   Hex = FFFFFFFF.80000000 Decimal = -2147483648 G
                                       SYS$PUBLIC_VECTORS_NPRO
 

2  Binary_Operators
   The following table describes the binary operators.

   Operator   Action

   +          Addition
   -          Subtraction
   *          Multiplication
   &          Logical AND
   |          Logical OR
   \          Logical XOR
   /          Division - In division, SDA truncates the quotient
              to an integer, if necessary, and does not retain a
              remainder.
   @          Arithmetic shifting
   "."        Catenates two 32-bit values into a 64-bit value. For
              example:

              SDA> eval fe.50000
              Hex = 000000FE00050000   Decimal = 1090922020864
 

2  Precedence_Operators
   SDA uses parentheses as precedence operators. Expressions
   enclosed in parentheses are evaluated first. SDA evaluates nested
   parenthetical expressions from the innermost to the outermost
   pairs of parentheses.