[m-rev.] for review: fix float_to_string so that roundtripping works

[Fergus Henderson]

On 20-Nov-2002, Peter Ross <pro at missioncriticalit.com> wrote:
> +++ library/string.m	20 Nov 2002 16:42:19 -0000
> @@ -1826,45 +1826,21 @@
>  :- pragma foreign_proc("C",
>  	string__float_to_string(Flt::in, Str::uo),
>  		[will_not_call_mercury, promise_pure, thread_safe], "{
> +	char buf[ML_SPRINTF_FLOAT_BUF_SIZE];
> +	ML_sprintf_float(buf, Flt);
> +	MR_make_aligned_string(Str, buf);

That needs to be MR_make_aligned_string_copy().

> +:- pragma foreign_code(c, "
> +void
> +ML_sprintf_float(char *buf, MR_Float f)
> +{
> +	MR_Float round;
> +	int 	 i = ML_MIN_PRECISION;
> +
> +	do {
> +		sprintf(buf, ""%#.*g"", i, f);
> +		if (i >= ML_MAX_PRECISION) {
> +			/*
> +			** This should be sufficient precision to
> +			** round-trip any value.  Don't bother checking
> +			** whether it can actually be round-tripped,
> +			** since if it can't, this is a bug in the C
> +			** implementation.
> +			*/
> +			break;
> +		}
> +		sscanf(buf, ML_FMT, &round);
> +		i++;
> +	} while (round != f);
> +}
> +").

This routine should be documented.

Otherwise the interdiff looks good.
But I'd like to double-check the full diff.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
--------------------------------------------------------------------------
mercury-reviews mailing list
post:  mercury-reviews at cs.mu.oz.au
administrative address: owner-mercury-reviews at cs.mu.oz.au
unsubscribe: Address: mercury-reviews-request at cs.mu.oz.au Message: unsubscribe
subscribe:   Address: mercury-reviews-request at cs.mu.oz.au Message: subscribe
--------------------------------------------------------------------------