Re: udigits_to_I

[Sam S. <sd...@gn...>]

> * Bruno Haible <oe...@py...t> [2005-01-25 20:28:06 +0100]:
>
> Sam wrote:
>> > For the implementation of udigits_to_I:
>> > Note that you cannot always interpret an array of type uint8[] as an
>> > array of type uintD[]: The number of elements may not be a multiple
>> > of sizeof(uintD)/sizeof(uint8) (what do you want to do with the last few
>> > bytes in that case?),
>>
>> zero them out? (hmm, this implies little-endian).
>>
>> > and the alignment of the memory may not be a multiple of
>> > alignof(uintD).
>>
>> crash? :-(
>
> Yes, likely. - But before talking about the implementation of an
> unclear function, can you clarify what the function _should_ do? What
> does the berkeley-db module expect from it?

this is a platform-independent integer <--> bit sequence conversion.
this should be the _inverse_ of fill_dbt() in bdb.c:

  } else if (bignump(obj)) {
    int need = sizeof(uintD)*Bignum_length(obj);
    key->ulen = key->size = MAX(re_len,need);
    key->data = my_malloc(key->size);
    begin_system_call();
    memset(key->data,0,key->size);
    memcpy((char*)key->data + key->size - need,TheBignum(obj)->data,need);
    end_system_call();
    return DBT_INTEGER;
  } else ...


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