[MinGW-notify] [ mingw-Bugs-2965184 ] Unsigned 64bit Attribution from negative floating number

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Bugs item #2965184, was opened at 2010-03-07 14:32
Message generated for change (Comment added) made by earnie
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Category: gcc
>Group: Aged issue
>Status: Closed
>Resolution: Out of Date
Priority: 5
Private: No
Submitted By: https://www.google.com/accounts ()
Assigned to: Nobody/Anonymous (nobody)
Summary: Unsigned 64bit Attribution from negative floating number

Initial Comment:
Accidentally I came across the strage behaviour when attributing a negative floating point number to a unsigned 64bit integer.  For example, when attributing the value -1.0 to a 64bit integer instead of having the expected value (0xFFFF FFFF FFFF FFFF) the integer is attributed with the equivalent value if I used a 32bit value (0xFFFF FFFF).  The attached file for test purposes is shown below:

#include <stdio.h>

int main ( )
{
  unsigned long long i;
  unsigned char* p;
  float f;
  int i2;

  p = ( unsigned char* ) &i;
  f = -1.0;
  i2 = -1;
  
  i = ( unsigned long long ) f;
  
  printf ( "From floating point: " );
  
  for ( int k = 0; k < sizeof ( i ); ++ k )
  {
    printf ( "%02X ", ( unsigned int ) p [k] );
  }
  
  printf ( "\r\n" );
  
  i = ( unsigned long long ) i2;
  
  printf ( "From signed integer: " );
  
  for ( int k = 0; k < sizeof ( i ); ++ k )
  {
    printf ( "%02X ", ( unsigned int ) p [k] );
  }
  
  printf ( "\r\n" );  
}

The output of this test is:

From floating point: FF FF FF FF 00 00 00 00
From signed integer: FF FF FF FF FF FF FF FF

Thank you,
I hope it helps
Denis

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>Comment By: Earnie Boyd (earnie)
Date: 2012-10-22 10:45

Message:
Works for me with GCC 4.7.0.

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You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=102435&aid=2965184&group_id=2435