diff 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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new file mode 100644
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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