<time.h>: define timespec_get, TIME_UTC, to support <threads.h> implementations

[pdclib] / platform / example / internals / _PDCLIB_config.h

#ifndef _PDCLIB_CONFIG_H
#define _PDCLIB_CONFIG_H

/* Internal PDCLib configuration <_PDCLIB_config.h>
   (Generic Template)

   This file is part of the Public Domain C Library (PDCLib).
   Permission is granted to use, modify, and / or redistribute at will.
*/

/* -------------------------------------------------------------------------- */
/* Misc                                                                       */
/* -------------------------------------------------------------------------- */

/* The character (sequence) your platform uses as newline.                    */
#define _PDCLIB_endl "\n"

/* exit() can signal success to the host environment by the value of zero or  */
/* the constant EXIT_SUCCESS. Failure is signaled by EXIT_FAILURE. Note that  */
/* any other return value is "implementation-defined", i.e. your environment  */
/* is not required to handle it gracefully. Set your definitions here.        */
#define _PDCLIB_SUCCESS 0
#define _PDCLIB_FAILURE -1

/* qsort() in <stdlib.h> requires a function that swaps two memory areas.     */
/* Below is a naive implementation that can be improved significantly for     */
/* specific platforms, e.g. by swapping int instead of char.                  */
#define _PDCLIB_memswp( i, j, size ) char tmp; do { tmp = *i; *i++ = *j; *j++ = tmp; } while ( --size );

/* The maximum value that errno can be set to. This is used to set the size   */
/* of the array in struct lconv (<locale.h>) holding error messages for the   */
/* strerror() and perror() functions. (If you change this value because you   */
/* are using additional errno values, you *HAVE* to provide appropriate error */
/* messages for *ALL* locales.)                                               */
/* Default is 4 (0, ERANGE, EDOM, EILSEQ).                                    */
#define _PDCLIB_ERRNO_MAX 4

/* -------------------------------------------------------------------------- */
/* Integers                                                                   */
/* -------------------------------------------------------------------------- */
/* Assuming 8-bit char, two's-complement architecture here. 'short' being     */
/* 16 bit, 'int' being either 16, 32 or 64 bit, 'long' being either 32 or 64  */
/* bit (but 64 bit only if 'int' is 32 bit), and 'long long' being 64 bit if  */
/* 'long' is not, 64 or 128 bit otherwise.                                    */
/* Author is quite willing to support other systems but would like to hear of */
/* interest in such support and details on the to-be-supported architecture   */
/* first, before going to lengths about it.                                   */
/* -------------------------------------------------------------------------- */

/* Comment out (or delete) the line below if your 'char' type is unsigned.    */
#define _PDCLIB_CHAR_SIGNED 1

/* Width of the integer types short, int, long, and long long, in bytes.      */
/* SHRT == 2, INT >= SHRT, LONG >= INT >= 4, LLONG >= LONG - check your       */
/* compiler manuals.                                                          */
#define _PDCLIB_SHRT_BYTES  2
#define _PDCLIB_INT_BYTES   4
#define _PDCLIB_LONG_BYTES  4
#define _PDCLIB_LLONG_BYTES 8

/* <stdlib.h> defines the div() function family that allows taking quotient   */
/* and remainder of an integer division in one operation. Many platforms      */
/* support this in hardware / opcode, and the standard permits ordering of    */
/* the return structure in any way to fit the hardware. That is why those     */
/* structs can be configured here.                                            */

struct _PDCLIB_div_t
{
    int quot;
    int rem;
};

struct _PDCLIB_ldiv_t
{
    long int quot;
    long int rem;
};

struct _PDCLIB_lldiv_t
{
    long long int quot;
    long long int rem;
};

/* -------------------------------------------------------------------------- */
/* <stdint.h> defines a set of integer types that are of a minimum width, and */
/* "usually fastest" on the system. (If, for example, accessing a single char */
/* requires the CPU to access a complete int and then mask out the char, the  */
/* "usually fastest" type of at least 8 bits would be int, not char.)         */
/* If you do not have information on the relative performance of the types,   */
/* the standard allows you to define any type that meets minimum width and    */
/* signedness requirements.                                                   */
/* The defines below are just configuration for the real typedefs and limit   */
/* definitions done in <_PDCLIB_int.h>. The uppercase define shall be either  */
/* SHRT, INT, LONG, or LLONG (telling which values to use for the *_MIN and   */
/* *_MAX limits); the lowercase define either short, int, long, or long long  */
/* (telling the actual type to use).                                          */
/* The third define is the length modifier used for the type in printf() and  */
/* scanf() functions (used in <inttypes.h>).                                  */
/* If you require a non-standard datatype to define the "usually fastest"     */
/* types, PDCLib as-is doesn't support that. Please contact the author with   */
/* details on your platform in that case, so support can be added.            */
/* -------------------------------------------------------------------------- */

#define _PDCLIB_FAST8 INT
#define _PDCLIB_fast8 int
#define _PDCLIB_FAST8_CONV

#define _PDCLIB_FAST16 INT
#define _PDCLIB_fast16 int
#define _PDCLIB_FAST16_CONV

#define _PDCLIB_FAST32 INT
#define _PDCLIB_fast32 int
#define _PDCLIB_FAST32_CONV

#define _PDCLIB_FAST64 LLONG
#define _PDCLIB_fast64 long long
#define _PDCLIB_FAST64_CONV ll

/* -------------------------------------------------------------------------- */
/* What follows are a couple of "special" typedefs and their limits. Again,   */
/* the actual definition of the limits is done in <_PDCLIB_int.h>, and the    */
/* defines here are merely "configuration". See above for details.            */
/* -------------------------------------------------------------------------- */

/* The result type of substracting two pointers */
#define _PDCLIB_ptrdiff int
#define _PDCLIB_PTRDIFF INT
#define _PDCLIB_PTR_CONV

/* An integer type that can be accessed as atomic entity (think asynchronous
   interrupts). The type itself is not defined in a freestanding environment,
   but its limits are. (Don't ask.)
*/
#define _PDCLIB_sig_atomic int
#define _PDCLIB_SIG_ATOMIC INT

/* Result type of the 'sizeof' operator (must be unsigned) */
#define _PDCLIB_size unsigned int
#define _PDCLIB_SIZE UINT

/* Large enough an integer to hold all character codes of the largest supported
   locale.
*/
#define _PDCLIB_wchar unsigned short 
#define _PDCLIB_WCHAR USHRT

#define _PDCLIB_intptr int
#define _PDCLIB_INTPTR INT

/* Largest supported integer type. Implementation note: see _PDCLIB_atomax(). */
#define _PDCLIB_intmax long long int
#define _PDCLIB_INTMAX LLONG
#define _PDCLIB_MAX_CONV ll
/* You are also required to state the literal suffix for the intmax type      */
#define _PDCLIB_INTMAX_LITERAL ll

/* <inttypes.h> defines imaxdiv(), which is equivalent to the div() function  */
/* family (see further above) with intmax_t as basis.                         */

struct _PDCLIB_imaxdiv_t
{
    _PDCLIB_intmax quot;
    _PDCLIB_intmax rem;
};

/* <time.h>: time_t 
 * The C standard doesn't define what representation of time is stored in 
 * time_t when returned by time() , but POSIX defines it to be seconds since the
 * UNIX epoch and most appplications expect that. 
 *
 * time_t is also used as the tv_sec member of struct timespec, which *is* 
 * defined as a linear count of seconds.
 *
 * time_t is defined as a "real type", so may be a floating point type, but with
 * the presence of the nanosecond accurate struct timespec, and with the lack of
 * any functions for manipulating more accurate values of time_t, this is 
 * probably not useful.
 */
#define _PDCLIB_time  unsigned long long

/* <time.h>: clock_t
 *
 * A count of "clock ticks", where the length of a clock tick is unspecified by
 * the standard. The implementation is required to provide a macro, 
 * CLOCKS_PER_SEC, which is the number of "clock ticks" which corresponds to one
 * second.
 *
 * clock_t may be any real type (i.e. integral or floating), and its type on
 * various systems differs. 
 *
 * On XSI systems, CLOCKS_PER_SEC must be defined to 1000000
 */
#define _PDCLIB_clock double
#define _PDCLIB_CLOCKS_PER_SEC 1000000

/* <time.h>: TIME_UTC
 *
 * The TIME_UTC parameter is passed to the timespec_get function in order to get
 * the system time in UTC since an implementation defined epoch (not necessarily
 * the same as that used for time_t). That said, on POSIX the obvious 
 * implementation of timespec_get for TIME_UTC is to wrap 
 * clock_gettime(CLOCK_REALTIME, ...), which is defined as time in UTC since the
 * same epoch.
 *
 * This may be any non-zero integer value.
 */
#define _PDCLIB_TIME_UTC 1

/* -------------------------------------------------------------------------- */
/* Floating Point                                                             */
/* -------------------------------------------------------------------------- */

/* Whether the implementation rounds toward zero (0), to nearest (1), toward
   positive infinity (2), or toward negative infinity (3). (-1) signifies
   indeterminable rounding, any other value implementation-specific rounding.
*/
#define _PDCLIB_FLT_ROUNDS -1

/* Whether the implementation uses exact-width precision (0), promotes float
   to double (1), or promotes float and double to long double (2). (-1)
   signifies indeterminable behaviour, any other value implementation-specific
   behaviour.
*/
#define _PDCLIB_FLT_EVAL_METHOD -1

/* "Number of the decimal digits (n), such that any floating-point number in the
   widest supported floating type with p(max) radix (b) digits can be rounded to
   a floating-point number with (n) decimal digits and back again without change
   to the value p(max) log(10)b if (b) is a power of 10, [1 + p(max) log(10)b]
   otherwise."
   64bit IEC 60559 double format (53bit mantissa) is DECIMAL_DIG 17.
   80bit IEC 60559 double-extended format (64bit mantissa) is DECIMAL_DIG 21.
*/
#define _PDCLIB_DECIMAL_DIG 17

/* -------------------------------------------------------------------------- */
/* Platform-dependent macros defined by the standard headers.                 */
/* -------------------------------------------------------------------------- */

/* The offsetof macro
   Contract: Expand to an integer constant expression of type size_t, which
   represents the offset in bytes to the structure member from the beginning
   of the structure. If the specified member is a bitfield, behaviour is
   undefined.
   There is no standard-compliant way to do this.
   This implementation casts an integer zero to 'pointer to type', and then
   takes the address of member. This is undefined behaviour but should work on
   most compilers.
*/
#define _PDCLIB_offsetof( type, member ) ( (size_t) &( ( (type *) 0 )->member ) )

/* Variable Length Parameter List Handling (<stdarg.h>)
   The macros defined by <stdarg.h> are highly dependent on the calling
   conventions used, and you probably have to replace them with builtins of
   your compiler. The following generic implementation works only for pure
   stack-based architectures, and only if arguments are aligned to pointer
   type. Credits to Michael Moody, who contributed this to the Public Domain.
*/

/* Internal helper macro. va_round is not part of <stdarg.h>. */
#define _PDCLIB_va_round( type ) ( (sizeof(type) + sizeof(void *) - 1) & ~(sizeof(void *) - 1) )

typedef char * _PDCLIB_va_list;
#define _PDCLIB_va_arg( ap, type ) ( (ap) += (_PDCLIB_va_round(type)), ( *(type*) ( (ap) - (_PDCLIB_va_round(type)) ) ) )
#define _PDCLIB_va_copy( dest, src ) ( (dest) = (src), (void)0 )
#define _PDCLIB_va_end( ap ) ( (ap) = (void *)0, (void)0 )
#define _PDCLIB_va_start( ap, parmN ) ( (ap) = (char *) &parmN + ( _PDCLIB_va_round(parmN) ), (void)0 )

/* -------------------------------------------------------------------------- */
/* OS "glue", part 1                                                          */
/* These are values and data type definitions that you would have to adapt to */
/* the capabilities and requirements of your OS.                              */
/* The actual *functions* of the OS interface are declared in _PDCLIB_glue.h. */
/* -------------------------------------------------------------------------- */

/* Memory management -------------------------------------------------------- */

/* Set this to the page size of your OS. If your OS does not support paging, set
   to an appropriate value. (Too small, and malloc() will call the kernel too
   often. Too large, and you will waste memory.)
*/
#define _PDCLIB_MALLOC_PAGESIZE 4096
#define _PDCLIB_MALLOC_ALIGN 16
#define _PDCLIB_MALLOC_GRANULARITY 64*1024
#define _PDCLIB_MALLOC_TRIM_THRESHOLD 2*1024*1024
#define _PDCLIB_MALLOC_MMAP_THRESHOLD 256*1024
#define _PDCLIB_MALLOC_RELEASE_CHECK_RATE 4095

/* TODO: Better document these */

/* I/O ---------------------------------------------------------------------- */

/* The type of the file descriptor returned by _PDCLIB_open(). */
typedef int _PDCLIB_fd_t;

/* The value (of type _PDCLIB_fd_t) returned by _PDCLIB_open() if the operation
   failed.
*/
#define _PDCLIB_NOHANDLE ( (_PDCLIB_fd_t) -1 )

/* The default size for file buffers. Must be at least 256. */
#define _PDCLIB_BUFSIZ 1024

/* The minimum number of files the implementation can open simultaneously. Must
   be at least 8. Depends largely on how the bookkeeping is done by fopen() /
   freopen() / fclose(). The example implementation limits the number of open
   files only by available memory.
*/
#define _PDCLIB_FOPEN_MAX 8

/* Length of the longest filename the implementation guarantees to support. */
#define _PDCLIB_FILENAME_MAX 128

/* Maximum length of filenames generated by tmpnam(). (See tmpfile.c.) */
#define _PDCLIB_L_tmpnam 46

/* Number of distinct file names that can be generated by tmpnam(). */
#define _PDCLIB_TMP_MAX 50

/* The values of SEEK_SET, SEEK_CUR and SEEK_END, used by fseek().
   Since at least one platform (POSIX) uses the same symbols for its own "seek"
   function, we use whatever the host defines (if it does define them).
*/
#define _PDCLIB_SEEK_SET 0
#define _PDCLIB_SEEK_CUR 1
#define _PDCLIB_SEEK_END 2

/* The number of characters that can be buffered with ungetc(). The standard
   guarantees only one (1); anything larger would make applications relying on
   this capability dependent on implementation-defined behaviour (not good).
*/
#define _PDCLIB_UNGETCBUFSIZE 1

/* errno -------------------------------------------------------------------- */

/* These are the values that _PDCLIB_errno can be set to by the library.

   By keeping PDCLib's errno in the _PDCLIB_* namespace, the library is capable
   to "translate" between errno values used by the hosting operating system and
   those used and passed out by the library.

   Example: In the example platform, the remove() function uses the unlink()
   system call as backend. Linux sets its errno to EISDIR if you try to unlink()
   a directory, but POSIX demands EPERM. Within the remove() function, you can
   catch the 'errno == EISDIR', and set '_PDCLIB_errno = _PDCLIB_EPERM'. Anyone
   using PDCLib's <errno.h> will "see" EPERM instead of EISDIR (the _PDCLIB_*
   prefix removed by <errno.h> mechanics).

   If you do not want that kind of translation, you might want to "match" the
   values used by PDCLib with those used by the host OS, as to avoid confusion.

   The C standard only defines three distinct errno values: ERANGE, EDOM, and
   EILSEQ. The standard leaves it up to "the implementation" whether there are
   any more beyond those three. There is some controversy as to whether errno is
   such a good idea at all, so you might want to come up with a different error
   reporting facility for your platform. 

   Things used to say "Since errno values beyond the three defined by the 
   standard are not portable anyway (unless you look at POSIX), having your own
   error reporting facility would not hurt anybody either." at this point. 
   However, then somebody birthed C++11 into the world, which copied POSIX's 
   errno values into C++. Yes, even EINTR. Therefore, this library defines 
   them. That said, thats nothing stopping you from using your own error 
   reporting facility for things outside the C library.

   Sometimes the standard says to set errno to indicate an error, but does not 
   prescribe a value. We will use a value from the following list. If POSIX 
   defines a value, we use that; otherwise, we use as seems suitable.

   If porting to a system which uses an errno-like reporting system (e.g. a 
   UNIX), you'll probably want to define them to match what the OS uses
*/
/* C errno values */
#define _PDCLIB_ERANGE 1
#define _PDCLIB_EDOM   2
#define _PDCLIB_EILSEQ 3

/* C++11/POSIX errno values */
#define _PDCLIB_E2BIG 4
#define _PDCLIB_ECONNRESET 5
#define _PDCLIB_EISCONN 6
#define _PDCLIB_ENOENT 7
#define _PDCLIB_ENOTRECOVERABLE 8
#define _PDCLIB_EROFS 9
#define _PDCLIB_EACCES 10
#define _PDCLIB_EDEADLK 11
#define _PDCLIB_EISDIR 12
#define _PDCLIB_ENOEXEC 13
#define _PDCLIB_ENOTSOCK 14
#define _PDCLIB_ESPIPE 15
#define _PDCLIB_EADDRINUSE 16
#define _PDCLIB_EDESTADDRREQ 17
#define _PDCLIB_ELOOP 18
#define _PDCLIB_ENOLCK 19
#define _PDCLIB_ENOTSUPP 20
#define _PDCLIB_ESRCH 21
#define _PDCLIB_EADDRNOTAVAIL 22
#define _PDCLIB_EMFILE 23
#define _PDCLIB_ENOLINK 24
#define _PDCLIB_ENOTTY 25
#define _PDCLIB_ETIME 26
#define _PDCLIB_EAFNOSUPPORT 27
#define _PDCLIB_EEXIST 28
#define _PDCLIB_EMLINK 29
#define _PDCLIB_ENOMEM 30
#define _PDCLIB_ENXIO 31
#define _PDCLIB_ETIMEDOUT 32
#define _PDCLIB_EAGAIN 33
#define _PDCLIB_EFAULT 34
#define _PDCLIB_EMSGSIZE 35
#define _PDCLIB_ENOMSG 36
#define _PDCLIB_EOPNOTSUPP 37
#define _PDCLIB_ETXTBSY 38
#define _PDCLIB_EALREADY 39
#define _PDCLIB_EFBIG 40
#define _PDCLIB_ENAMETOOLONG 41
#define _PDCLIB_ENOPROTOOPT 42
#define _PDCLIB_EOVERFLOW 43
#define _PDCLIB_EWOULDBLOCK _PDCLIB_EAGAIN
#define _PDCLIB_EBADF 44
#define _PDCLIB_EHOSTUNREACH 45
#define _PDCLIB_ENETDOWN 46
#define _PDCLIB_ENOSPC 47
#define _PDCLIB_EOWNERDEAD 48
#define _PDCLIB_EXDEV 49
#define _PDCLIB_EBADMSG 50
#define _PDCLIB_EIDRM 51
#define _PDCLIB_ENETRESET 52
#define _PDCLIB_ENOSR 53
#define _PDCLIB_EPERM 54
#define _PDCLIB_EBUSY 55
#define _PDCLIB_ENETUNREACH 56
#define _PDCLIB_ENOSTR 57
#define _PDCLIB_EPIPE 58
#define _PDCLIB_ECANCELED 59
#define _PDCLIB_EINPROGRESS 60
#define _PDCLIB_ENFILE 61
#define _PDCLIB_ENOSYS 62
#define _PDCLIB_EPROTO 63
#define _PDCLIB_ECHILD 64
#define _PDCLIB_EINTR 65
#define _PDCLIB_ENOBUFS 66
#define _PDCLIB_ENOTCONN 67
#define _PDCLIB_EPROTONOSUPPORT 68
#define _PDCLIB_ECONNABORTED 69
#define _PDCLIB_EINVAL 70
#define _PDCLIB_ENODATA 71
#define _PDCLIB_ENOTDIR 72
#define _PDCLIB_EPROTOTYPE 73

#endif