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| Started by | Hul Tytus <ht@panix.com> |
|---|---|
| First post | 2023-08-01 21:21 +0000 |
| Last post | 2023-08-02 18:38 +0200 |
| Articles | 5 — 4 participants |
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addon functions Hul Tytus <ht@panix.com> - 2023-08-01 21:21 +0000
Re: addon functions Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2023-08-01 23:44 +0200
Re: addon functions Grant Edwards <invalid@invalid.invalid> - 2023-08-01 22:26 +0000
Re: addon functions Hul Tytus <ht@panix.com> - 2023-08-03 16:52 +0000
Re: addon functions David Brown <david.brown@hesbynett.no> - 2023-08-02 18:38 +0200
| From | Hul Tytus <ht@panix.com> |
|---|---|
| Date | 2023-08-01 21:21 +0000 |
| Subject | addon functions |
| Message-ID | <uabt18$qtu$1@reader2.panix.com> |
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
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| From | Hans-Bernhard Bröker <HBBroeker@t-online.de> |
|---|---|
| Date | 2023-08-01 23:44 +0200 |
| Message-ID | <kitcm3Fjvv7U1@mid.dfncis.de> |
| In reply to | #31974 |
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?
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| From | Grant Edwards <invalid@invalid.invalid> |
|---|---|
| Date | 2023-08-01 22:26 +0000 |
| Message-ID | <uac0ri$6n0$1@reader2.panix.com> |
| In reply to | #31974 |
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);
[...]
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| From | Hul Tytus <ht@panix.com> |
|---|---|
| Date | 2023-08-03 16:52 +0000 |
| Message-ID | <uaglvp$id9$1@reader2.panix.com> |
| In reply to | #31976 |
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); > [...]
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| From | David Brown <david.brown@hesbynett.no> |
|---|---|
| Date | 2023-08-02 18:38 +0200 |
| Message-ID | <uae0ph$5oj9$1@dont-email.me> |
| In reply to | #31974 |
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.
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