DEFINITION MODULE SYSTEM ; EXPORT QUALIFIED BITSPERBYTE, BYTESPERWORD, ADDRESS, WORD, BYTE, CSIZE_T, CSSIZE_T, (* Target specific data types. *) ADR, TSIZE, ROTATE, SHIFT, THROW, TBITSIZE ; (* SIZE is also exported if -fpim2 is used. *) CONST BITSPERBYTE = __ATTRIBUTE__ __BUILTIN__ ((BITS_PER_UNIT)) ; BYTESPERWORD = __ATTRIBUTE__ __BUILTIN__ ((UNITS_PER_WORD)) ; (* Note that the full list of system and sized datatypes include: LOC, WORD, BYTE, ADDRESS, (and the non language standard target types) INTEGER8, INTEGER16, INTEGER32, INTEGER64, CARDINAL8, CARDINAL16, CARDINAL32, CARDINAL64, WORD16, WORD32, WORD64, BITSET8, BITSET16, BITSET32, REAL32, REAL64, REAL128, COMPLEX32, COMPLEX64, COMPLEX128, CSIZE_T, CSSIZE_T. Also note that the non-standard data types will move into another module in the future. *) (* The following types are supported on this target: TYPE (* Target specific data types. *) *) (* all the functions below are declared internally to gm2 ====================================================== PROCEDURE ADR (VAR v: <anytype>): ADDRESS; (* Returns the address of variable v. *) PROCEDURE SIZE (v: <type>) : ZType; (* Returns the number of BYTES used to store a v of any specified <type>. Only available if -fpim2 is used. *) PROCEDURE TSIZE (<type>) : CARDINAL; (* Returns the number of BYTES used to store a value of the specified <type>. *) PROCEDURE ROTATE (val: <a set type>; num: INTEGER): <type of first parameter>; (* 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. *) PROCEDURE SHIFT (val: <a set type>; num: INTEGER): <type of first parameter>; (* 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. *) PROCEDURE THROW (i: INTEGER) <* noreturn *> ; (* 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. *) PROCEDURE TBITSIZE (<type>) : CARDINAL ; (* Returns the minimum number of bits necessary to represent <type>. 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 <type> 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 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. *) 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. *) 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. *) 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. *) 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. *) 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. *) 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.