view packages/language/c/libc/stdlib/current/include/div.inl @ 115:6ed91473a1cd ecos-sw-2000-08-21

Merge from eCos master repository on 2000-08-21-22:40:54-BST
author jlarmour
date Fri, 25 Aug 2000 17:32:38 +0000
parents
children e0c0827131d1
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#ifndef CYGONCE_LIBC_STDLIB_DIV_INL
#define CYGONCE_LIBC_STDLIB_DIV_INL
/*===========================================================================
//
//      div.inl
//
//      Inline implementations for the ISO standard utility functions
//      div() and ldiv()
//
//===========================================================================
//####COPYRIGHTBEGIN####
//                                                                          
// -------------------------------------------                              
// The contents of this file are subject to the Red Hat eCos Public License 
// Version 1.1 (the "License"); you may not use this file except in         
// compliance with the License.  You may obtain a copy of the License at    
// http://www.redhat.com/                                                   
//                                                                          
// Software distributed under the License is distributed on an "AS IS"      
// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See the 
// License for the specific language governing rights and limitations under 
// the License.                                                             
//                                                                          
// The Original Code is eCos - Embedded Configurable Operating System,      
// released September 30, 1998.                                             
//                                                                          
// The Initial Developer of the Original Code is Red Hat.                   
// Portions created by Red Hat are                                          
// Copyright (C) 1998, 1999, 2000 Red Hat, Inc.                             
// All Rights Reserved.                                                     
// -------------------------------------------                              
//                                                                          
//####COPYRIGHTEND####
//===========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):    jlarmour
// Contributors: 
// Date:         2000-04-28
// Purpose:     
// Description: 
// Usage:        Do not include this file directly - include <stdlib.h> instead
//
//####DESCRIPTIONEND####
//
//=========================================================================*/

// CONFIGURATION

#include <pkgconf/libc_stdlib.h>    // Configuration header

// INCLUDES

#include <cyg/infra/cyg_ass.h>      // Assertion support
#include <cyg/infra/cyg_trac.h>     // Tracing support

/* TYPE DEFINITIONS */

/* return type of the div() function */

typedef struct {
    int quot;      /* quotient  */
    int rem;       /* remainder */
} div_t;


/* return type of the ldiv() function */

typedef struct {
    long quot;     /* quotient  */
    long rem;      /* remainder */
} ldiv_t;

/* FUNCTION PROTOTYPES */

#ifdef __cplusplus
extern "C" {
#endif

extern div_t
div( int /* numerator */, int /* denominator */ ) __attribute__((__const__));

extern ldiv_t
ldiv( long /* numerator */, long /* denominator */ ) __attribute__((__const__));

#ifdef __cplusplus
} /* extern "C" */
#endif 

/* FUNCTIONS */

#ifndef CYGPRI_LIBC_STDLIB_DIV_INLINE
# define CYGPRI_LIBC_STDLIB_DIV_INLINE extern __inline__
#endif

CYGPRI_LIBC_STDLIB_DIV_INLINE div_t
div( int __numer, int __denom )
{
    div_t __ret;

    CYG_REPORT_FUNCNAMETYPE( "div", "quotient: %d");
    CYG_REPORT_FUNCARG2DV( __numer, __denom );
    // FIXME: what if they want it handled with SIGFPE? Should have option
    CYG_PRECONDITION(__denom != 0, "division by zero attempted!");
    
    __ret.quot = __numer / __denom;
    __ret.rem  = __numer % __denom;

    // But the modulo is implementation-defined for -ve numbers (ISO C 6.3.5)
    // and we are required to "round" to zero (ISO C 7.10.6.2)
    //
    // The cases we have to deal with are inexact division of:
    // a) + div +
    // b) + div -
    // c) - div +
    // d) - div -
    //
    // a) can never go wrong and the quotient and remainder are always positive
    // b) only goes wrong if the negative quotient has been "rounded" to
    //    -infinity - if so then the remainder will be negative when it
    //    should be positive or zero
    // c) only goes wrong if the negative quotient has been "rounded" to
    //    -infinity - if so then the remainder will be positive when it
    //    should be negative or zero
    // d) only goes wrong if the positive quotient has been rounded to
    //    +infinity - if so then the remainder will be positive when it
    //    should be negative or zero
    //
    // So the correct sign of the remainder corresponds to the sign of the
    // numerator. Which means we can say that the result needs adjusting
    // iff the sign of the numerator is different from the sign of the
    // remainder.
    //
    // You may be interested to know that the Berkeley version of div()
    // would get this wrong for e.g. (c) and (d) on some targets.
    // e.g. for (-5)/4 it could leave the result as -2R3

    if ((__ret.rem < 0) && (__numer > 0)) {
        ++__ret.quot;
        __ret.rem -= __denom;
    } else if ((__ret.rem > 0) && (__numer < 0)) {
        --__ret.quot;
        __ret.rem += __denom;
    } // else

    CYG_REPORT_RETVAL( __ret.quot );

    return __ret;
} // div()

CYGPRI_LIBC_STDLIB_DIV_INLINE ldiv_t
ldiv( long __numer, long __denom )
{
    ldiv_t __ret;

    CYG_REPORT_FUNCNAMETYPE( "ldiv", "quotient: %d");
    CYG_REPORT_FUNCARG2DV( __numer, __denom );
    // FIXME: what if they want it handled with SIGFPE? Should have option
    CYG_PRECONDITION(__denom != 0, "division by zero attempted!");
    
    __ret.quot = __numer / __denom;
    __ret.rem  = __numer % __denom;

    // But the modulo is implementation-defined for -ve numbers (ISO C 6.3.5)
    // and we are required to "round" to zero (ISO C 7.10.6.2)
    //
    // The cases we have to deal with are inexact division of:
    // a) + div +
    // b) + div -
    // c) - div +
    // d) - div -
    //
    // a) can never go wrong and the quotient and remainder are always positive
    // b) only goes wrong if the negative quotient has been "rounded" to
    //    -infinity - if so then the remainder will be negative when it
    //    should be positive or zero
    // c) only goes wrong if the negative quotient has been "rounded" to
    //    -infinity - if so then the remainder will be positive when it
    //    should be negative or zero
    // d) only goes wrong if the positive quotient has been rounded to
    //    +infinity - if so then the remainder will be positive when it
    //    should be negative or zero
    //
    // So the correct sign of the remainder corresponds to the sign of the
    // numerator. Which means we can say that the result needs adjusting
    // iff the sign of the numerator is different from the sign of the
    // remainder.
    //
    // You may be interested to know that the Berkeley version of ldiv()
    // would get this wrong for e.g. (c) and (d) on some targets.
    // e.g. for (-5)/4 it could leave the result as -2R3

    if ((__ret.rem < 0) && (__numer > 0)) {
        ++__ret.quot;
        __ret.rem -= __denom;
    } else if ((__ret.rem > 0) && (__numer < 0)) {
        --__ret.quot;
        __ret.rem += __denom;
    } // else

    CYG_REPORT_RETVAL( __ret.quot );

    return __ret;
} // ldiv()


#endif // CYGONCE_LIBC_STDLIB_DIV_INL multiple inclusion protection

// EOF div.inl