2 files changed, 68 insertions, 0 deletions

diff --git a/bitint_wrapper.h b/bitint_wrapper.h
new file mode 100644
index 0000000..785d0fa
--- /dev/null
+++ b/bitint_wrapper.h
@@ -0,0 +1,50 @@
+#ifndef BITINT_WRAPPER_H
+#define BITINT_WRAPPER_H
+
+#include <cstdio>
+#include <iostream>
+
+// Wrapper class for _BitInt(N) (port of the C23 feature, compiler
+// extension for C++ available in Clang and maybe GCC). This is needed
+// because operator<< is not defined on _BitInt(N), apparently.
+
+template<uint64_t N = 128>
+class BitInt {
+public:
+        _BitInt(N) x;
+
+        constexpr BitInt() : x{_BitInt(N)(0)} {}
+        constexpr BitInt(int n) : x{_BitInt(N)(n)} {}
+        constexpr BitInt(long long n) : x{_BitInt(N)(n)} {}
+        constexpr BitInt(_BitInt(N) n) : x{n} {}
+        constexpr auto operator<=>(const BitInt& b) const { return x <=> b.x; }
+        constexpr bool operator==(const BitInt& b) const = default;
+        constexpr BitInt operator+(const BitInt& b) const { return x + b.x; }
+        constexpr BitInt operator-(const BitInt& b) const { return x - b.x; }
+        constexpr BitInt operator*(const BitInt& b) const { return x * b.x; }
+        constexpr BitInt operator/(const BitInt& b) const { return x / b.x; }
+        constexpr BitInt operator%(const BitInt& b) const { return x % b.x; }
+        constexpr BitInt operator-() const { return -x; }
+        constexpr BitInt operator+=(const BitInt& b) { return *this = *this + b; }
+        constexpr BitInt operator-=(const BitInt& b) { return *this = *this - b; }
+        constexpr BitInt operator*=(const BitInt& b) { return *this = *this * b; }
+        constexpr BitInt operator/=(const BitInt& b) { return *this = *this / b; }
+        constexpr BitInt operator%=(const BitInt& b) { return *this = *this % b; }
+
+        friend std::ostream& operator<<(std::ostream& os, const BitInt<N>& b) {
+                if (b > 0) {
+                        std::string s;
+                        auto bb = b;
+                        while (bb != 0) {
+                                char c = (bb.x % 10) + '0';
+                                s = c + s;
+                                bb /= 10;
+                        }
+                        return os << s;
+                } else if (b < 0) {
+                        return os << "-" << -b;
+                } else return os << "0";
+        }
+};
+
+#endif
diff --git a/test b/test
index 46ed7c3..2657439 100755
--- a/test
+++ b/test
@@ -12,6 +12,10 @@ exit 0
 #include "zmodn.h"
 #include "bigint.h"
 
+#if defined(__clang__) && __clang_major__ >= 16
+#include "bitint_wrapper.h"
+#endif
+
 #include <concepts>
 #include <functional>
 #include <iostream>
@@ -479,6 +483,20 @@ public:
                 assert_equal(inv.value().toint(), expected);
         }
 },
+#if defined(__clang__) && __clang_major__ >= 16
+{
+        .name = "Zmod with BitInt",
+        .f = []() {
+                constexpr BitInt N{1000000000000LL}; // 1e12
+                BitInt a{600000000000LL}; // 6e11
+                BitInt b{700000000000LL}; // 7e11
+                BitInt c{300000000000LL}; // 3e11
+
+                Zmod<N> a_modN(a), b_modN(b), c_modN(c);
+                assert_equal(a_modN + b_modN, c_modN);
+        }
+},
+#endif
 /*
 {
         .name = "This does not compile",