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digitalmars.D - core.math.rndtonl: invalid return type or description?

reply ketmar <ketmar ketmar.no-ip.org> writes:
core.math.rndtonl is declared as this:

	extern (C) real rndtonl(real x);

yet it's description says: "...If the integer value of x is greater than 
long.max, the result is indeterminate."

it looks like it either should return `long`, or this part of description 
was copypasted from `rndtol`. and if it *really* has such limitation, but 
returns `real`, i think it should be clarified in documentation, 'cause 
right now it is somewhat confusing.
Jun 19 2017
parent reply ag0aep6g <anonymous example.com> writes:
On 06/19/2017 10:04 AM, ketmar wrote:

 core.math.rndtonl is declared as this:
 
      extern (C) real rndtonl(real x);


Is rndtonl a Digital Mars C thing? It has no implementation in druntime, 
and I get an undefined reference  when I try to call it on Linux.

It compiles on Windows (wine, -m32), but only ever returns -nan.

If this is the same function: 
<http://www.digitalmars.com/rtl/fltpnt.html#rndtol>, then it should 
return a C long, which I guess is a D int on 32 bits. And surprise: that 
works.
Jun 19 2017
next sibling parent reply ketmar <ketmar ketmar.no-ip.org> writes:
ag0aep6g wrote:


 On 06/19/2017 10:04 AM, ketmar wrote:

 core.math.rndtonl is declared as this:
 extern (C) real rndtonl(real x);


 Is rndtonl a Digital Mars C thing?


yes, it looks like DMC library function. thus, is should be versioned out 
on non-DMC builds. another bug. ;-)


 It has no implementation in druntime, and I get an undefined reference  
 when I try to call it on Linux.

 It compiles on Windows (wine, -m32), but only ever returns -nan.



 If this is the same function: 
 <http://www.digitalmars.com/rtl/fltpnt.html#rndtol>, then it should 
 return a C long, which I guess is a D int on 32 bits. And surprise: that 
 works.


no, there is `rndtol()` and `rndtonl()` in `core.math`,  they are different
functions.

also, `rndtol()` should return D `long` (i.e. 64 bit value). at least this 
is what `core.math` says.
Jun 19 2017
parent reply ag0aep6g <anonymous example.com> writes:
On 06/19/2017 12:45 PM, ketmar wrote:

 ag0aep6g wrote:


[...]

 If this is the same function: 
 <http://www.digitalmars.com/rtl/fltpnt.html#rndtol>, then it should 
 return a C long, which I guess is a D int on 32 bits. And surprise: 
 that works.


 
 no, there is `rndtol()` and `rndtonl()` in `core.math`,  they are 
 different functions.


The link covers both. See the Prototype and Description sections.


 also, `rndtol()` should return D `long` (i.e. 64 bit value). at least 
 this is what `core.math` says.


Sure, but it doesn't work with D long. It works with D int, which makes 
sense when the function actually returns a C long (assuming that DMC's 
long has 32 bits).
Jun 19 2017
parent ketmar <ketmar ketmar.no-ip.org> writes:
ag0aep6g wrote:


 On 06/19/2017 12:45 PM, ketmar wrote:

 ag0aep6g wrote:


 [...]

 If this is the same function: 
 <http://www.digitalmars.com/rtl/fltpnt.html#rndtol>, then it should 
 return a C long, which I guess is a D int on 32 bits. And surprise: 
 that works.


 no, there is `rndtol()` and `rndtonl()` in `core.math`,  they are 
 different functions.


 The link covers both. See the Prototype and Description sections.


ah, sorry, i should really read linked text instead of guessing from the 
name only. ;-)



 also, `rndtol()` should return D `long` (i.e. 64 bit value). at least 
 this is what `core.math` says.


 Sure, but it doesn't work with D long. It works with D int, which makes 
 sense when the function actually returns a C long (assuming that DMC's 
 long has 32 bits).


then it is yet another bug in `core.math`...
Jun 19 2017
prev sibling parent ketmar <ketmar ketmar.no-ip.org> writes:
p.s.: it is *important* to use `core.math.rndtonl`! this is compiler 
intrinsic (or at least it should be), and it won't be detected as intrinsic 
outside of `core.math`.
Jun 19 2017