[m-dev.] diff: fix bug in bytecode_data.m

[Fergus Henderson]

On 27-May-1999, Simon Taylor <stayl at cs.mu.OZ.AU> wrote:
> 
> Estimated hours taken: 0.1
> 
> compiler/bytecode_data.m:
> 	Fix a bug in checking whether a negative integer
> 	fits in a certain number of bits. There isn't a
> 	test case for this because the integer sizes less than
> 	a word are only ever used for positive numbers.
> 
> Index: bytecode_data.m
> ===================================================================
> RCS file: /home/staff/zs/imp/mercury/compiler/bytecode_data.m,v
> retrieving revision 1.2
> diff -u -u -r1.2 bytecode_data.m
> --- bytecode_data.m	1999/03/10 00:01:42	1.2
> +++ bytecode_data.m	1999/03/24 03:00:16
> @@ -142,7 +142,10 @@
>  	{ int__bits_per_int(IntBits) },
>  	{ 
>  		Bits < IntBits,
> -		(IntVal /\ (\0 << Bits)) \= 0
> +		int__pow(2, Bits, MaxVal),
> +		( IntVal >= MaxVal
> +		; IntVal < -MaxVal
> +		)
>  	->
>  		string__format(
>  		"error: bytecode_data__output_int: %d does not fit in %d bits",

Shouldn't MaxVal be `2 ** (Bits - 1)' rather than `2 ** Bits'?

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>  |  of excellence is a lethal habit"
PGP: finger fjh at 128.250.37.3        |     -- the last words of T. S. Garp.
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