[sdcc-devel] [ sdcc-Bugs-1584988 ] Problem with divulong.c

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Bugs item #1584988, was opened at 2006-10-26 03:20
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Category: pic16 target
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: Problem with divulong.c

Initial Comment:
try:

  unsigned long longfoo;
  longfoo = (unsigned long) anyvariable * 13107;
  longfoo = longfoo/13107;
  

it will return completely errounous results...

if you take a closer look at divulong.c sth. seems to
be missing there!? How will reste ever be set?


#include <sdcc-lib.h>

#define MSB_SET(x) ((x >> (8*sizeof(x)-1)) & 1)

unsigned long _divulong (unsigned long a, unsigned long
b) _IL_REENTRANT
{
  unsigned long reste = 0L;
  unsigned char count = 32;
  unsigned char c;

  do
  {
    // reste: a <- 0;
    c = MSB_SET(a);
    a <<= 1;
    reste <<= 1;
    if (c)
      reste |= 1L;

    if (reste >= b)
    {
      reste -= b;
      // a <- (result = 1)
      a |= 1L;
    }
  }
  while (--count);
  return a;
}

Thanks for any explanation,

Nikias Klohr (klohni (at) eti.uni-karlsruhe.de)

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