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tests/include/pdclib/functions/_tzcode/_PDCLIB_mktime_tzname.c  view on Meta::CPAN

/* _PDCLIB_mktime_tzname( struct state *, struct tm *, bool )

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

#ifndef REGTEST

#include "pdclib/_PDCLIB_tzcode.h"

/* Adapted from code provided by Robert Elz, who writes:
    The "best" way to do mktime I think is based on an idea of Bob
    Kridle's (so its said...) from a long time ago.
    It does a binary search of the time_t space. Since time_t's are
    just 32 bits, its a max of 32 iterations (even at 64 bits it
    would still be very reasonable).
*/

#ifndef WRONG
#define WRONG   (-1)
#endif

/* Normalize logic courtesy Paul Eggert. */

static bool increment_overflow32( int_fast32_t * lp, int m )
{
    int_fast32_t const l = *lp;

    if ( ( l >= 0 ) ? ( m > _PDCLIB_INT_FAST32_MAX - l ) : ( m < _PDCLIB_INT_FAST32_MIN - l ) )
    {
        return true;
    }

    *lp += m;
    return false;
}

static bool normalize_overflow( int * tensptr, int * unitsptr, int base )
{
    int tensdelta;

    tensdelta = ( *unitsptr >= 0 ) ?
        ( *unitsptr / base ) :
        ( -1 - ( -1 - *unitsptr ) / base );
    *unitsptr -= tensdelta * base;
    return _PDCLIB_increment_overflow( tensptr, tensdelta );
}

static bool normalize_overflow32( int_fast32_t * tensptr, int * unitsptr, int base )
{
    int tensdelta;

    tensdelta = ( *unitsptr >= 0 ) ?
        ( *unitsptr / base ) :
        ( -1 - ( -1 - *unitsptr ) / base );
    *unitsptr -= tensdelta * base;
    return increment_overflow32( tensptr, tensdelta );
}

static int tmcomp( const struct tm * atmp, const struct tm * btmp )
{
    int result;

    if ( atmp->tm_year != btmp->tm_year )
    {
        return atmp->tm_year < btmp->tm_year ? -1 : 1;
    }

    if ( ( result = ( atmp->tm_mon - btmp->tm_mon ) ) == 0 &&
         ( result = ( atmp->tm_mday - btmp->tm_mday ) ) == 0 &&
         ( result = ( atmp->tm_hour - btmp->tm_hour ) ) == 0 &&
         ( result = ( atmp->tm_min - btmp->tm_min ) ) == 0 )
    {
        result = atmp->tm_sec - btmp->tm_sec;
    }