[OpenBIOS] [PATCH 10/10] Adding filll Forth primitive

[William Hahne]

On 8/15/11, Andreas Färber <andreas.faerber at web.de> wrote:
> Am 09.08.2011 um 23:55 schrieb William Hahne:
>
>> This is a forth primitive that is required by BootX. It just fills
>> some specified memory address and length with longs.
>>
>>
>> Index: kernel/forth.c
>> ===================================================================
>> --- kernel/forth.c	(revision 1041)
>> +++ kernel/forth.c	(working copy)
>> @@ -1610,6 +1616,20 @@
>>  	memset(src, value, count);
>>  }
>>
>> +/*
>> + *  filll       ( addr len byte -- )
>> + */
>> +static void filll(void)
>> +{
>> +    ucell value = POP();
>> +	ucell count = POP();
>> +	ucell *dest = (ucell *)cell2pointer(POP());
>> +	
>> +	int i;
>> +	for (i = 0; i <= count / 4; i++) {
>> +	    dest[i] = value;	
>> +	}
>> +}
>
> This word puzzles me: The extra l in filll seems to be for "long"
> according to the patch description. But there's a hardcoded arithmetic
> with 4 and the parameter is documented as byte yet is being written
> ucell-wide. That strikes me as inconsistent.
>

Honestly, my problem is I was unable to find documentation on filll.
This suggests that it may be an non-standard addition by Apple. You
are right about the inconsistency. I will make a revised version of
the patch to address this.

> Either 4 needs to be replaced with sizeof(ucell) to fit sparc64, or
> the division by 4 dropped and uint8_t* written len times.

It seems likely that it is supposed to fill with 32bit integers, but
this would have to be checked on a 64bit platform which I do not have
access to. This may not be applicable to sparc at all but again
someone with access to the hardware would have to confirm.

William Hahne

>
> Andreas
>
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>