Re: [PATCH 1/3] notes: move hex_to_bytes() to hex.c and export it

[Kevin Daudt <me@ikke.info>]

On Sun, Nov 05, 2017 at 05:47:47PM +0100, René Scharfe wrote:
> Am 05.11.2017 um 03:56 schrieb Kevin Daudt:
> > On Tue, Oct 31, 2017 at 02:46:49PM +0100, René Scharfe wrote:
> >> Make the function for converting pairs of hexadecimal digits to binary
> >> available to other call sites.
> >>
> >> Signed-off-by: Rene Scharfe <l.s.r@web.de>
> >> ---
> >>   cache.h |  7 +++++++
> >>   hex.c   | 12 ++++++++++++
> >>   notes.c | 17 -----------------
> >>   3 files changed, 19 insertions(+), 17 deletions(-)
> >>
> >> diff --git a/cache.h b/cache.h
> >> index 6440e2bf21..f06bfbaf32 100644
> >> --- a/cache.h
> >> +++ b/cache.h
> >> @@ -1317,6 +1317,13 @@ extern int set_disambiguate_hint_config(const char *var, const char *value);
> >>   extern int get_sha1_hex(const char *hex, unsigned char *sha1);
> >>   extern int get_oid_hex(const char *hex, struct object_id *sha1);
> >>   
> >> +/*
> >> + * Read `len` pairs of hexadecimal digits from `hex` and write the
> >> + * values to `binary` as `len` bytes. Return 0 on success, or -1 if
> > 
> > Is it correct to call the result binary? I would say that it's the value
> > that gets stored. To me, this value does not really have a base.
> 
> Here's the full context:
> 
>   /*
>    * Read `len` pairs of hexadecimal digits from `hex` and write the
>    * values to `binary` as `len` bytes. Return 0 on success, or -1 if
>    * the input does not consist of hex digits).
>    */
>   extern int hex_to_bytes(unsigned char *binary, const char *hex, size_t len);
> 
> The patch moves the comment verbatim.  Words in backticks (`binary`,
> `hex`, `len`) are parameter names.
> 
> The function converts pairs of hexadecimal digits (base 16, ASCII
> encoded) to bytes (base 256).  A byte can be seen as an array of bits;
> thus the output is also binary (base 2) without requiring further
> conversion.
> 
> Calling the variable "binary" may seem unspecific, but makes sense in
> the context of this function.
> 
> Does any of that help?
> 
> Thanks,
> René

Thanks, I have been thinking about it more, and I agree, it does make
sense. 

I had a binary representation in mind, but this is refering to binary
data (just like you can have binary files).

Kevin