Add assertions that user provided types and sizes are sane

1 files changed, 34 insertions, 0 deletions

diff --git a/chilbert/Hilbert.ipp b/chilbert/Hilbert.ipp
index b4f2b63..4cf5fec 100644
--- a/chilbert/Hilbert.ipp
+++ b/chilbert/Hilbert.ipp
@@ -50,8 +50,28 @@
 // MUST HAVE 0 <= D0 < n
 #define D0 1
 
+#include <cassert>
+#include <climits>
+#include <type_traits>
+
 namespace chilbert {
 
+template <class T>
+size_t
+num_bits(const T&, std::enable_if_t<std::is_integral<T>::value>* = nullptr)
+{
+	return sizeof(T) * CHAR_BIT;
+}
+
+template <class T>
+size_t
+num_bits(const T& vec,
+         std::enable_if_t<std::is_same<T, CFixBitVec>::value ||
+                          std::is_same<T, CBigBitVec>::value>* = nullptr)
+{
+	return vec.size();
+}
+
 // 'Transforms' a point.
 template <class I>
 inline void
@@ -181,6 +201,9 @@ coordsToIndex(const P* const p, // [in ] point
               H&             h  // [out] Hilbert index
 )
 {
+	assert(num_bits(h) >= n * m);
+	assert(num_bits(p[0]) >= m);
+
 	if (n <= FBV_BITS) {
 		// Intermediate variables will fit in fixed width
 		_coordsToIndex<P, H, CFixBitVec>(p, m, n, h, CFixBitVec{});
@@ -247,6 +270,11 @@ indexToCoords(P* const     p, // [out] point
               const H&     h  // [out] Hilbert index
 )
 {
+	assert(m > 0);
+	assert(n > 0);
+	assert(num_bits(h) >= n * m);
+	assert(num_bits(p[0]) >= m);
+
 	if (n <= FBV_BITS) {
 		// Intermediate variables will fit in fixed width
 		_indexToCoords<P, H, CFixBitVec>(p, m, n, h, CFixBitVec{});
@@ -270,6 +298,7 @@ _coordsToCompactIndex(const P* const      p,
 	if (M == 0 || m == 0) {
 		M = m = 0;
 		for (size_t i = 0; i < n; i++) {
+			assert(num_bits(p[i]) >= ms[i]);
 			if (ms[i] > m) {
 				m = ms[i];
 			}
@@ -279,6 +308,8 @@ _coordsToCompactIndex(const P* const      p,
 
 	const size_t mn = m * n;
 
+	assert(num_bits(hc) >= M);
+
 	// If we could avoid allocation altogether (ie: have a
 	// fixed buffer allocated on the stack) then this increases
 	// speed by a bit (4% when n=4, m=20)
@@ -354,6 +385,9 @@ _compactIndexToCoords(P* const      p,
 		}
 	}
 
+	assert(num_bits(hc) >= M);
+	assert(num_bits(p[0]) >= m);
+
 	// Initialize
 	e.reset();
 	l.reset();