addon functions

Lewin Edwards in his dosfs file system uses the ldiv() functions shown below:
	sector = ldiv(offset, SECTOR_SIZE).quot  and
	offset = ldiv(offset, SECTOR_SIZE).rem
Anybody know how this is declared or, maybe, defined?

Hul

Am 01.08.2023 um 23:21 schrieb Hul Tytus:
> Lewin Edwards in his dosfs file system uses the ldiv() functions shown below:
> 	sector = ldiv(offset, SECTOR_SIZE).quot  and
> 	offset = ldiv(offset, SECTOR_SIZE).rem
> Anybody know how this is declared or, maybe, defined?

Seriously?  Does every C compiler you use come without a manual?

How else could you possibly find it hard to discover the declaration and 
semantics of a 33+ years old C standard library function like that?

On 2023-08-01, Hul Tytus <ht@panix.com> wrote:
> Lewin Edwards in his dosfs file system uses the ldiv() functions shown below:
> 	sector = ldiv(offset, SECTOR_SIZE).quot  and
> 	offset = ldiv(offset, SECTOR_SIZE).rem
> Anybody know how this is declared or, maybe, defined?

$ man ldiv

------------------------------------------------------------------------------
div(3)                     Library Functions Manual                     div(3)

NAME
       div,  ldiv, lldiv, imaxdiv - compute quotient and remainder of an inte&#8208;
       ger division

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <stdlib.h>

       div_t div(int numerator, int denominator);
       ldiv_t ldiv(long numerator, long denominator);
       lldiv_t lldiv(long long numerator, long long denominator);

       #include <inttypes.h>

       imaxdiv_t imaxdiv(intmax_t numerator, intmax_t denominator);


[...]

On 01/08/2023 23:21, Hul Tytus wrote:
> Lewin Edwards in his dosfs file system uses the ldiv() functions shown below:
> 	sector = ldiv(offset, SECTOR_SIZE).quot  and
> 	offset = ldiv(offset, SECTOR_SIZE).rem
> Anybody know how this is declared or, maybe, defined?
> 
> Hul
> 

It's a standard C library function.  You can see its definition in the C 
standards (draft versions of all modern C standards are freely available 
online).  A good reference for C is the "cppreference" site, with the 
exact page here being:

<https://en.cppreference.com/w/c/numeric/math/div>

The "div" functions are almost never used these days - any decent 
compiler will do as good or better when the code is expressed simply as:

	sector = offset / SECTOR_SIZE;
	offset = offset % SECTOR_SIZE;

But the "div" functions made sense with older and poorer compilers.

Thanks Grant. I'd never seen those before and assumed they were Lewin's creation.

Hul

Grant Edwards <invalid@invalid.invalid> wrote:
> On 2023-08-01, Hul Tytus <ht@panix.com> wrote:
> > Lewin Edwards in his dosfs file system uses the ldiv() functions shown below:
> >       sector = ldiv(offset, SECTOR_SIZE).quot  and
> >       offset = ldiv(offset, SECTOR_SIZE).rem
> > Anybody know how this is declared or, maybe, defined?

> $ man ldiv

> ------------------------------------------------------------------------------
> div(3)                     Library Functions Manual                     div(3)

> NAME
>        div,  ldiv, lldiv, imaxdiv - compute quotient and remainder of an inte???
>        ger division

> LIBRARY
>        Standard C library (libc, -lc)

> SYNOPSIS
>        #include <stdlib.h>

>        div_t div(int numerator, int denominator);
>        ldiv_t ldiv(long numerator, long denominator);
>        lldiv_t lldiv(long long numerator, long long denominator);

>        #include <inttypes.h>

>        imaxdiv_t imaxdiv(intmax_t numerator, intmax_t denominator);


> [...]