Re: [Groff] Using C with glib instead of C++ for groff

[Doug Royer]

> > This is incorrect.  ANSI C does not mandate `int' has 16 bits.
>
> In my version of the ANSI C book of Kernighan/Ritchie, chapter B.11
> on <limits.h> says
>
> INT_MAX     +32767
> INT_MIN     -32767
> UINT_MAX     65535
>
> This makes int and uint 16 bits types in ANSI C.

POSIX (&ANSI) system and C standards have a matrix
that describes the size.

It's not that simple.

           |         System Model
Data Type  |LP32 ILP32  ILP64  LLP64 LP64 |
-----------+----+-----+-------+-----+-----+
char       | 8  | 8   |  8    |  8  |  8  |
-----------+----+-----+-------+-----+-----+
short      | 16 | 16  | 16    |  16 |  16 |
-----------+----+-----+-------+-----+-----+
int32      |    |     | 32    |     |     |
-----------+----+-----+-------+-----+-----+
int        | 16 | 32  | 64    |  32 |  32 |
-----------+----+-----+-------+-----+-----+
long       | 32 | 32  | 64    |  32 |  64 |
-----------+----+-----+-------+-----+-----+
long long  |    |     |       |  64 |     |
  (int64)  |    |     |       |     |     |
-----------+----+-----+-------+-----+-----+
pointer    | 32 | 32  | 64    |  64 |  64 |
-----------+----+-----+-------+-----+-----+

And the [u]int{16,32,64}_t are obvious size.

And the [u]intptr_t == [un]signed int large enought to hold any pointer.

And readup on the POSIX sysconf() for c89 values:

  sysconf() value  |  int  | long  | pointer  | off_t
-------------------+-------+-------+----------+------+
_XBS5_ILP32_OFF32  |   32  |   32  |      32  |  32  |
-------------------+-------+-------+----------+------+
_XSB5_ILP32_OFFBIG |   32  |   32  |      32  | >=64 |
-------------------+-------+-------+----------+------+
_XBS5_LP64_OFF64   |   32  |   64  |      64  |   64 |
-------------------+-------+-------+----------+------+
_XSB5_LPBIG_OFFBIG | >=32  | >=64  |    >=64  | >=64 |
-------------------+-------+-------+----------+------+

In addition there are standard corrosponding C, LD, and LIB flags
that are defined to use/select/detect the standard sizes.
This works for CONFORMING C compilers and systems.

On Unix'OS there is often a nice explanation in <unistd.h>


--

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