ICU-6.2.22.tar.gz

[apple/icu.git] / icuSources / common / putilimp.h

/*
******************************************************************************
*
*   Copyright (C) 1997-2004, International Business Machines
*   Corporation and others.  All Rights Reserved.
*
******************************************************************************
*
*  FILE NAME : putilimp.h
*
*   Date        Name        Description
*   10/17/04    grhoten     Move internal functions from putil.h to this file.
******************************************************************************
*/

#ifndef PUTILIMP_H
#define PUTILIMP_H

#include "unicode/utypes.h"
#include "unicode/putil.h"

/*==========================================================================*/
/* Platform utilities                                                       */
/*==========================================================================*/

/**
 * Platform utilities isolates the platform dependencies of the
 * libarary.  For each platform which this code is ported to, these
 * functions may have to be re-implemented.
 */

/**
 * Floating point utility to determine if a double is Not a Number (NaN).
 * @internal
 */
U_INTERNAL UBool   U_EXPORT2 uprv_isNaN(double d);
/**
 * Floating point utility to determine if a double has an infinite value.
 * @internal
 */
U_INTERNAL UBool   U_EXPORT2 uprv_isInfinite(double d);
/**
 * Floating point utility to determine if a double has a positive infinite value.
 * @internal
 */
U_INTERNAL UBool   U_EXPORT2 uprv_isPositiveInfinity(double d);
/**
 * Floating point utility to determine if a double has a negative infinite value.
 * @internal
 */
U_INTERNAL UBool   U_EXPORT2 uprv_isNegativeInfinity(double d);
/**
 * Floating point utility that returns a Not a Number (NaN) value.
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_getNaN(void);
/**
 * Floating point utility that returns an infinite value.
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_getInfinity(void);

/**
 * Floating point utility to truncate a double.
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_trunc(double d);
/**
 * Floating point utility to calculate the floor of a double.
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_floor(double d);
/**
 * Floating point utility to calculate the ceiling of a double.
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_ceil(double d);
/**
 * Floating point utility to calculate the absolute value of a double.
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_fabs(double d);
/**
 * Floating point utility to calculate the fractional and integer parts of a double.
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_modf(double d, double* pinteger);
/**
 * Floating point utility to calculate the remainder of a double divided by another double.
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_fmod(double d, double y);
/**
 * Floating point utility to calculate d to the power of exponent (d^exponent).
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_pow(double d, double exponent);
/**
 * Floating point utility to calculate 10 to the power of exponent (10^exponent).
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_pow10(int32_t exponent);
/**
 * Floating point utility to calculate the maximum value of two doubles.
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_fmax(double d, double y);
/**
 * Floating point utility to calculate the minimum value of two doubles.
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_fmin(double d, double y);
/**
 * Private utility to calculate the maximum value of two integers.
 * @internal
 */
U_INTERNAL int32_t U_EXPORT2 uprv_max(int32_t d, int32_t y);
/**
 * Private utility to calculate the minimum value of two integers.
 * @internal
 */
U_INTERNAL int32_t U_EXPORT2 uprv_min(int32_t d, int32_t y);

#if U_IS_BIG_ENDIAN
#   define uprv_isNegative(number) (*((signed char *)&(number))<0)
#else
#   define uprv_isNegative(number) (*((signed char *)&(number)+sizeof(number)-1)<0)
#endif

/**
 * Return the largest positive number that can be represented by an integer
 * type of arbitrary bit length.
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_maxMantissa(void);

/**
 * Return the floor of the log base 10 of a given double.
 * This method compensates for inaccuracies which arise naturally when
 * computing logs, and always gives the correct value.  The parameter
 * must be positive and finite.
 * (Thanks to Alan Liu for supplying this function.)
 *
 * @param d the double value to apply the common log function for.
 * @return the log of value d.
 * @internal
 */
U_INTERNAL int16_t  U_EXPORT2 uprv_log10(double d);

/**
 * Floating point utility to calculate the logarithm of a double.
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_log(double d);

/**
 * Does common notion of rounding e.g. uprv_floor(x + 0.5);
 * @param x the double number
 * @return the rounded double
 * @internal
 */
U_INTERNAL double  U_EXPORT2 uprv_round(double x);

#if 0
/**
 * Returns the number of digits after the decimal point in a double number x.
 *
 * @param x the double number
 * @return the number of digits after the decimal point in a double number x.
 * @internal
 */
/*U_INTERNAL int32_t  U_EXPORT2 uprv_digitsAfterDecimal(double x);*/
#endif

/**
 * Time zone utilities
 *
 * Wrappers for C runtime library functions relating to timezones.
 * The t_tzset() function (similar to tzset) uses the current setting 
 * of the environment variable TZ to assign values to three global 
 * variables: daylight, timezone, and tzname. These variables have the 
 * following meanings, and are declared in &lt;time.h&gt;.
 *
 *   daylight   Nonzero if daylight-saving-time zone (DST) is specified
 *              in TZ; otherwise, 0. Default value is 1.
 *   timezone   Difference in seconds between coordinated universal
 *              time and local time. E.g., -28,800 for PST (GMT-8hrs)
 *   tzname(0)  Three-letter time-zone name derived from TZ environment
 *              variable. E.g., "PST".
 *   tzname(1)  Three-letter DST zone name derived from TZ environment
 *              variable.  E.g., "PDT". If DST zone is omitted from TZ,
 *              tzname(1) is an empty string.
 *
 * Notes: For example, to set the TZ environment variable to correspond
 * to the current time zone in Germany, you can use one of the
 * following statements:
 *
 *   set TZ=GST1GDT
 *   set TZ=GST+1GDT
 *
 * If the TZ value is not set, t_tzset() attempts to use the time zone
 * information specified by the operating system. Under Windows NT
 * and Windows 95, this information is specified in the Control Panel's
 * Date/Time application.
 * @internal
 */
U_INTERNAL void     U_EXPORT2 uprv_tzset(void);

/**
 * Difference in seconds between coordinated universal
 * time and local time. E.g., -28,800 for PST (GMT-8hrs)
 * @return the difference in seconds between coordinated universal time and local time.
 * @internal
 */
U_INTERNAL int32_t  U_EXPORT2 uprv_timezone(void);

/**
 *   tzname(0)  Three-letter time-zone name derived from TZ environment
 *              variable. E.g., "PST".
 *   tzname(1)  Three-letter DST zone name derived from TZ environment
 *              variable.  E.g., "PDT". If DST zone is omitted from TZ,
 *              tzname(1) is an empty string.
 * @internal
 */
U_INTERNAL const char* U_EXPORT2 uprv_tzname(int n);

/**
 * Get UTC (GMT) time measured in milliseconds since 0:00 on 1/1/1970.
 * @return the UTC time measured in milliseconds 
 * @internal
 */
U_INTERNAL UDate U_EXPORT2 uprv_getUTCtime(void);

/**
 * Determine whether a pathname is absolute or not, as defined by the platform.
 * @param path Pathname to test
 * @return TRUE if the path is absolute
 * @internal (ICU 3.0)
 */
U_INTERNAL UBool U_EXPORT2 uprv_pathIsAbsolute(const char *path);

/**
 * Maximum value of a (void*) - use to indicate the limit of an 'infinite' buffer.
 * In fact, buffer sizes must not exceed 2GB so that the difference between
 * the buffer limit and the buffer start can be expressed in an int32_t.
 *
 * The definition of U_MAX_PTR must fulfill the following conditions:
 * - return the largest possible pointer greater than base
 * - return a valid pointer according to the machine architecture (AS/400, 64-bit, etc.)
 * - avoid wrapping around at high addresses
 * - make sure that the returned pointer is not farther from base than 0x7fffffff
 *
 * @param base The beginning of a buffer to find the maximum offset from
 * @internal
 */
#ifndef U_MAX_PTR
#  ifdef OS390
#    define U_MAX_PTR(base) ((void *)0x7fffffff)
#  elif defined(OS400)
/*
 * With the provided macro we should never be out of range of a given segment
 * (a traditional/typical segment that is).  Our segments have 5 bytes for the id
 * and 3 bytes for the offset.  The key is that the casting takes care of only
 * retrieving the offset portion minus x1000.  Hence, the smallest offset seen in
 * a program is x001000 and when casted to an int would be 0.  That's why we can
 * only add 0xffefff.  Otherwise, we would exceed the segment.
 *
 * Currently, 16MB is the current addressing limitation on as/400.  This macro
 * may eventually be changed to use 2GB addressability for the newer version of
 * as/400 machines.
 */
#    define U_MAX_PTR(base) ((void *)(((char *)base)-((int32_t)(base))+((int32_t)0xffefff)))
#  else
#    define U_MAX_PTR(base) ((void *)(((char *)(base)+0x7fffffffu) > (char *)(base) ? ((char *)(base)+0x7fffffffu) : (char *)-1))
#  endif
#endif

#endif