I have a blessed SV * that when it runs out of space I need to prepend an extra character at the front. I can do this by mallocing a new chunk of ram, copying the contents from the old sv_pv to the starting at offset 1 and then assigning the address of the new space back into the sv_pv. Simple, but rather inefficient.

What I would like to do is prepend an extra 100 characters to the front (as above) and then juggle the PVX, CUR and LEN fields of the SV to allow perl to see only one of the new bytes. Then on subsequent occasions when I need a new characters, adjust PVX and CUR to provide it from the reserve with out needing to realloc and copy. Seems logical, but my attempts to make it work keeps traping.

Is this possible without breaking when the SV is used by Perl? Are there any macros to help? Or examples? Or can someone show me how to do it?

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In reply to XS Prepending space to an SVs PV by BrowserUk

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