Nicholas Clark <[EMAIL PROTECTED]> wrote:
> On Wed, Mar 30, 2005 at 09:11:51AM +0200, Leopold Toetsch wrote:
>> Bernhard Schmalhofer <[EMAIL PROTECTED]> wrote:
>> > + void freeze(visit_info *info) {
>> > + IMAGE_IO *io = info->image_io;
>> > + io->vtable->push_integer(INTERP, io, PMC_int_val(SELF));
>> > + STRING * s = string_from_cstring(INTERP, PMC_data(SELF),
>> > PMC_int_val2(SELF)/BITS_PER_CHAR);
>> > + io->vtable->push_string(INTERP, io, s);
>> > + }
>>
>> Hehe. Clever trick.
> Could one of you explain how this works? I've tried to work it out and it's
> not obvious to me.
The C<freeze> vtable appends an INTVAL (the array size) and the the bit
image of the bit array as a STRING to the frozen image. PMC_int_val2 is
the rounded up value of bits allocated. The C<string_from_cstring>
creates just a string header, with the string memory pointing to the bit
image.
NB, if the array was shrinked, the rounded up value of the array size
would be more efficient.
> Nicholas Clark
leo
