gm2-libs-log/BitByteOps (The GNU Modula-2 Compiler)

#### 4.2.2 gm2-libs-log/BitByteOps ¶

    DEFINITION MODULE BitByteOps ;

    FROM SYSTEM IMPORT BYTE ;

    (*
       GetBits - returns the bits firstBit..lastBit from source.
                 Bit 0 of byte maps onto the firstBit of source.
    *)

    PROCEDURE GetBits (source: BYTE; firstBit, lastBit: CARDINAL) : BYTE ;

    (*
       SetBits - sets bits in, byte, starting at, firstBit, and ending at,
                 lastBit, with, pattern.  The bit zero of, pattern, will
                 be placed into, byte, at position, firstBit.
    *)

    PROCEDURE SetBits (VAR byte: BYTE; firstBit, lastBit: CARDINAL;
                       pattern: BYTE) ;

    (*
       ByteAnd - returns a bitwise (left AND right)
    *)

    PROCEDURE ByteAnd (left, right: BYTE) : BYTE ;

    (*
       ByteOr - returns a bitwise (left OR right)
    *)

    PROCEDURE ByteOr (left, right: BYTE) : BYTE ;

    (*
       ByteXor - returns a bitwise (left XOR right)
    *)

    PROCEDURE ByteXor (left, right: BYTE) : BYTE ;

    (*
       ByteNot - returns a byte with all bits inverted.
    *)

    PROCEDURE ByteNot (byte: BYTE) : BYTE ;

    (*
       ByteShr - returns a, byte, which has been shifted, count
                 bits to the right.
    *)

    PROCEDURE ByteShr (byte: BYTE; count: CARDINAL) : BYTE ;

    (*
       ByteShl - returns a, byte, which has been shifted, count
                 bits to the left.
    *)

    PROCEDURE ByteShl (byte: BYTE; count: CARDINAL) : BYTE ;

    (*
       ByteSar - shift byte arthemetic right.  Preserves the top
                 end bit and as the value is shifted right.
    *)

    PROCEDURE ByteSar (byte: BYTE; count: CARDINAL) : BYTE ;

    (*
       ByteRor - returns a, byte, which has been rotated, count
                 bits to the right.
    *)

    PROCEDURE ByteRor (byte: BYTE; count: CARDINAL) : BYTE ;

    (*
       ByteRol - returns a, byte, which has been rotated, count
                 bits to the left.
    *)

    PROCEDURE ByteRol (byte: BYTE; count: CARDINAL) : BYTE ;

    (*
       HighNibble - returns the top nibble only from, byte.
                    The top nibble of, byte, is extracted and
                    returned in the bottom nibble of the return
                    value.
    *)

    PROCEDURE HighNibble (byte: BYTE) : BYTE ;

    (*
       LowNibble - returns the low nibble only from, byte.
                   The top nibble is replaced by zeros.
    *)

    PROCEDURE LowNibble (byte: BYTE) : BYTE ;

    (*
       Swap - swaps the low and high nibbles in the, byte.
    *)

    PROCEDURE Swap (byte: BYTE) : BYTE ;

    END BitByteOps.