.. _the-pim-system-module: The PIM system module ********************* .. code-block:: modula2 DEFINITION MODULE SYSTEM ; EXPORT QUALIFIED BITSPERBYTE, BYTESPERWORD, LOC, WORD, BYTE, ADDRESS, INTEGER8, INTEGER16, INTEGER32, INTEGER64, CARDINAL8, CARDINAL16, CARDINAL32, CARDINAL64, WORD16, WORD32, WORD64, BITSET8, BITSET16, BITSET32, REAL32, REAL64, REAL128, COMPLEX32, COMPLEX64, COMPLEX128, CSIZE_T, CSSIZE_T, ADR, TSIZE, ROTATE, SHIFT, THROW, TBITSIZE ; (* SIZE is also exported if -fpim2 is used *) CONST BITSPERBYTE (const) BITSPERBYTE = __ATTRIBUTE__ __BUILTIN__ ((BITS_PER_UNIT)) ; BYTESPERWORD (const) BYTESPERWORD = __ATTRIBUTE__ __BUILTIN__ ((UNITS_PER_WORD)) ; (* all the following types are declared internally to gm2 TYPE LOC (type) LOC ; WORD (type) WORD ; BYTE (type) BYTE ; ADDRESS (type) ADDRESS ; INTEGER8 (type) INTEGER8 ; INTEGER16 (type) INTEGER16 ; INTEGER32 (type) INTEGER32 ; INTEGER64 (type) INTEGER64 ; CARDINAL8 (type) CARDINAL8 ; CARDINAL16 (type) CARDINAL16 ; CARDINAL32 (type) CARDINAL32 ; CARDINAL64 (type) CARDINAL64 ; WORD16 (type) WORD16 ; WORD32 (type) WORD32 ; WORD64 (type) WORD64 ; BITSET8 (type) BITSET8 ; BITSET16 (type) BITSET16 ; BITSET32 (type) BITSET32 ; REAL32 (type) REAL32 ; REAL64 (type) REAL64 ; REAL128 (type) REAL128 ; COMPLEX32 (type) COMPLEX32 ; COMPLEX64 (type) COMPLEX64 ; COMPLEX128 (type) COMPLEX128 ; CSIZE_T (type) CSIZE_T ; CSSIZE_T (type) CSSIZE_T ; *) (* all the functions below are declared internally to gm2 ==================================================== ADR PROCEDURE ADR (VAR v: ): ADDRESS; (* Returns the address of variable v. *) SIZE PROCEDURE SIZE (v: ) : ZType; (* Returns the number of BYTES used to store a v of any specified . Only available if -fpim2 is used. *) TSIZE PROCEDURE TSIZE () : CARDINAL; (* Returns the number of BYTES used to store a value of the specified . *) ROTATE PROCEDURE ROTATE (val: ; num: INTEGER): ; (* Returns a bit sequence obtained from val by rotating up/right or down/right by the absolute value of num. The direction is down/right if the sign of num is negative, otherwise the direction is up/left. *) SHIFT PROCEDURE SHIFT (val: ; num: INTEGER): ; (* Returns a bit sequence obtained from val by shifting up/left or down/right by the absolute value of num, introducing zeros as necessary. The direction is down/right if the sign of num is negative, otherwise the direction is up/left. *) THROW PROCEDURE THROW (i: INTEGER) ; (* THROW is a GNU extension and was not part of the PIM or ISO standards. It throws an exception which will be caught by the EXCEPT block (assuming it exists). This is a compiler builtin function which interfaces to the GCC exception handling runtime system. GCC uses the term throw, hence the naming distinction between the GCC builtin and the Modula-2 runtime library procedure Raise. The later library procedure Raise will call SYSTEM.THROW after performing various housekeeping activities. *) TBITSIZE PROCEDURE TBITSIZE () : CARDINAL ; (* Returns the minimum number of bits necessary to represent . This procedure function is only useful for determining the number of bits used for any type field within a packed RECORD. It is not particularly useful elsewhere since might be optimized for speed, for example a BOOLEAN could occupy a WORD. *) *) (* The following procedures are invoked by GNU Modula-2 to shift non word sized set types. They are not strictly part of the core PIM Modula-2, however they are used by GNU Modula-2 to implement the SHIFT procedure defined above, which are in turn used by the Logitech compatible libraries. Users will access these procedures by using the procedure SHIFT above and GNU Modula-2 will map SHIFT onto one of the following procedures. *) (* ShiftVal - is a runtime procedure whose job is to implement the SHIFT procedure of ISO SYSTEM. GNU Modula-2 will inline a SHIFT of a single WORD sized set and will only call this routine for larger sets. *) ShiftVal PROCEDURE ShiftVal (VAR s, d: ARRAY OF BITSET; SetSizeInBits: CARDINAL; ShiftCount: INTEGER) ; (* ShiftLeft - performs the shift left for a multi word set. This procedure might be called by the back end of GNU Modula-2 depending whether amount is known at compile time. *) ShiftLeft PROCEDURE ShiftLeft (VAR s, d: ARRAY OF BITSET; SetSizeInBits: CARDINAL; ShiftCount: CARDINAL) ; (* ShiftRight - performs the shift left for a multi word set. This procedure might be called by the back end of GNU Modula-2 depending whether amount is known at compile time. *) ShiftRight PROCEDURE ShiftRight (VAR s, d: ARRAY OF BITSET; SetSizeInBits: CARDINAL; ShiftCount: CARDINAL) ; (* RotateVal - is a runtime procedure whose job is to implement the ROTATE procedure of ISO SYSTEM. GNU Modula-2 will inline a ROTATE of a single WORD (or less) sized set and will only call this routine for larger sets. *) RotateVal PROCEDURE RotateVal (VAR s, d: ARRAY OF BITSET; SetSizeInBits: CARDINAL; RotateCount: INTEGER) ; (* RotateLeft - performs the rotate left for a multi word set. This procedure might be called by the back end of GNU Modula-2 depending whether amount is known at compile time. *) RotateLeft PROCEDURE RotateLeft (VAR s, d: ARRAY OF BITSET; SetSizeInBits: CARDINAL; RotateCount: CARDINAL) ; (* RotateRight - performs the rotate right for a multi word set. This procedure might be called by the back end of GNU Modula-2 depending whether amount is known at compile time. *) RotateRight PROCEDURE RotateRight (VAR s, d: ARRAY OF BITSET; SetSizeInBits: CARDINAL; RotateCount: CARDINAL) ; END SYSTEM. The different dialects of Modula-2 PIM-[234] and ISO Modula-2 declare the function ``SIZE`` in different places. PIM-[34] and ISO Modula-2 declare ``SIZE`` as a pervasive function (declared in the base module). PIM-2 defined ``SIZE`` in the ``SYSTEM`` module (as shown above). GNU Modula-2 allows users to specify the dialect of Modula-2 by using the ``-fiso`` and ``-fpim2`` command line switches. The data types ``CSIZE_T`` and ``CSSIZE_T`` are also exported from the ``SYSTEM`` module. The type ``CSIZE_T`` is unsigned and is mapped onto the target C data type ``size_t`` whereas the type ``CSSIZE_T`` is mapped onto the signed C data type ``ssize_t``. It is anticipated that these should only be used to provide cross platform definition modules for C libraries. There are also a variety of fixed sized ``INTEGER`` and ``CARDINAL`` types. The variety of the fixed sized types will depend upon the target architecture.