#! perl -slw
use strict;

use Inline C => <<'END_OF_PERCENT2_C_CODE';

#define SvSIOK(sv) ((SvFLAGS(sv) & (SVf_IOK|SVf_IVisUV)) == SVf_IOK)
#define SvNSIV(sv) (SvNOK(sv) ? SvNVX(sv) : (SvSIOK(sv) ? SvIVX(sv) : sv_2nv(sv)))

static I32 S_sv_ncmp(pTHX_ SV *a, SV *b) {
const NV nv1 = SvNSIV(a);
const NV nv2 = SvNSIV(b);
return nv1 < nv2 ? -1 : nv1 > nv2 ? 1 : 0;
}

void percent2(SV* sv, ...) {
    Inline_Stack_Vars;
    I32 i;
    I32 arrayLen;
    I32 remove_count;
    AV* data;
    AV* data_tmp;
    double value;
    int index;
    SV** pvalue;
    double retval;
    AV* ret;

    ret = newAV();
    data_tmp = newAV();

    data = (AV*)SvRV(Inline_Stack_Item(0));

    if( SvTYPE(data) != SVt_PVAV ) {
        return;
    }

    /* determine the length of the array */
    arrayLen = av_len(data) + 1;
    if (arrayLen > 0) {

        /* use new tmp array to prevent reordering caller array*/
        for (i = 0; i < arrayLen; i++) {
            pvalue = av_fetch(data,i,0);
            av_push( data_tmp, newSVsv( *pvalue ) );   // Copy the SVs so that you don't destroy the original array when freeing the temp
        }
        /* sort array in ascending order */
        sortsv(AvARRAY(data_tmp),arrayLen, S_sv_ncmp);

        /* loop through data array and delete undef entries */

        remove_count = 0;
        for (i = 0; i < arrayLen; i++) {
            /* Fetch the scalar located at i from the array.*/
            pvalue = av_fetch(data_tmp,i,0);
            if (!SvOK(*pvalue)) {
                remove_count++;
            }
            else {
                break;
            }
        }
        for (i = 0; i < remove_count; i++) {
            av_shift(data_tmp);
        }
        arrayLen -= remove_count;
    }

    if (arrayLen > 0) {
        /* loop through percent args and find given value in array */
        for (i = 1; i < Inline_Stack_Items; i++) {
            value = SvNV(Inline_Stack_Item(i));
            if (value <= 100 && value >= 0){
                if (value == 100){
                    value -= 1e-13;
                }
                index = (int)((arrayLen-1) * value/100);

                /* fetch scalar located at calculated index*/
                pvalue = av_fetch(data_tmp,index,0);
                av_push( ret, newSVsv( *pvalue ) );  /// ditto
            }
        }
    }
    /* push into return stack */
    Inline_Stack_Reset;
    arrayLen = av_len(ret) + 1;
    if (arrayLen > 0) {
        for (i = 0; i < arrayLen; i++) {
            /* fetch the scalar located at i from the array.*/
            pvalue = av_fetch(ret,i,0);
            /* dereference the scalar into a numeric value. */
            retval = SvNV(*pvalue);
            Inline_Stack_Push( sv_2mortal( newSVnv( retval ) ) ); // Mortalise the return values
        }
    }
    else {
        Inline_Stack_Push( sv_2mortal( newSVnv(0) ) );   // Mortalise the return values
    }
    Inline_Stack_Done;
    av_undef( ret );      // free array memory
    SvREFCNT_dec( ret );  // free the AV itself
    av_undef( data_tmp ); // ditto
    SvREFCNT_dec( data_tmp );
}
END_OF_PERCENT2_C_CODE

my @data = map int( rand 100 ), 1 .. 100;;

print join '|', percent2( \@data, 1, 50 ) for 1 .. 1e9;;