Function subfloatvector

vexdb_pg/src/floatvector.cpp:900–933

PG_FUNCTION_INFO_V1(subfloatvector);
Datum subfloatvector(PG_FUNCTION_ARGS)
{
    FloatVector *a = PG_GETARG_FLOATVECTOR_P(0);
    int32 start = PG_GETARG_INT32(1);
    int32 count = PG_GETARG_INT32(2);

    if (count < 1) {
        ereport(ERROR, (errcode(ERRCODE_DATA_EXCEPTION),
            errmsg("vector must have at least 1 dimension")));
    }

    /*
     * Check if (start + count > a->dim), avoiding integer overflow. a->dim
     * and count are both positive, so a->dim - count won't overflow.
     */
    int32 end = start > a->dim - count ?
        a->dim + 1 :
        start + count;

    /* Indexing starts at 1, like substring */
    if (start < 1) {
        start = 1;
    } else if (start > a->dim) {
        ereport(ERROR, (errcode(ERRCODE_DATA_EXCEPTION),
            errmsg("vector must have at least 1 dimension")));
    }

    int dim = end - start;
    CheckDim(dim);
    FloatVector *result = InitFloatVector(dim);
    memcpy(result->x, a->x + start - 1, dim * sizeof(float));
    PG_FREE_IF_COPY(a, 0);
    PG_RETURN_POINTER(result);
}

FloatVectorArray FloatVectorArrayInit(int maxlen, int dimensions)
{