Prof Brian Ripley
ripley at stats.ox.ac.uk
Fri May 16 13:15:10 CEST 2014
On 16/05/2014 11:06, Duncan Murdoch wrote:
> On 16/05/2014, 4:16 AM, Adrian Dușa wrote:
>> Dear list,
>> On a follow up from my previous email, I am now trying to allocate
>> of length larger than 32-bit in C.
>>> From the R internals documentation, I read that:
>> "The sxpinfo header is defined as a 32-bit C structure..."
>> "A SEXPREC is a C structure containing the 32-bit header..."
>> The question is: does the INTSXP allow vectors larger than 32-bit?
>> A test example:
>> int *p_temp;
>> SEXP root = PROTECT(allocVector(VECSXP, 5));
>> long long int verylargeinteger;
>> // something to compute verylargeinteger, > 32-bit
>> SEXP temp = SET_VECTOR_ELT(root, 0, allocVector(INTSXP,
>> p_temp = INTEGER(temp);
>> "temp" should be a vector of length > 32-bit, and "p_temp" should be the
>> pointer to that vector.
>> If declaring:
>> long long int *p_temp;
>> (but the compiler throws a warning with an incompatible pointer type,
>> because pointers should be integers of course).
>> I've looked at all SEXPTYPEs in the R internals, and the only one
>> to integer vectors is INTSXP. Can this be used for vectors of length
>> than 32-bit?
> Yes, see the section on "Long Vectors" in chapter 12.
('Yes on a 64-bit platform.') The type for a vector length is R_xlen_t,
e.g. allocVector is declared as
SEXP Rf_allocVector(SEXPTYPE, R_xlen_t);
That is never 'long long int' ....
> Duncan Murdoch
>> Thank you again, in advance,
> R-devel at r-project.org mailing list
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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