diff --git a/compat/stdckdint/stdckdint.h b/compat/stdckdint/stdckdint.h
new file mode 100644
index 0000000000..2d36e8ad89
--- /dev/null
+++ b/compat/stdckdint/stdckdint.h
@@ -0,0 +1,663 @@
+/*
+ * Copyright 2023 Justine Alexandra Roberts Tunney
+ *
+ * Permission to use, copy, modify, and/or distribute this software for
+ * any purpose with or without fee is hereby granted, provided that the
+ * above copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+ * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+ * AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
+ * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
+ * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/**
+ * @fileoverview C23 Checked Arithmetic
+ *
+ * This header defines three type generic functions:
+ *
+ *   - `bool ckd_add(res, a, b)`
+ *   - `bool ckd_sub(res, a, b)`
+ *   - `bool ckd_mul(res, a, b)`
+ *
+ * Which allow integer arithmetic errors to be detected. There are many
+ * kinds of integer errors, e.g. overflow, truncation, etc. These funcs
+ * catch them all. Here's an example of how it works:
+ *
+ *     uint32_t c;
+ *     int32_t a = 0x7fffffff;
+ *     int32_t b = 2;
+ *     assert(!ckd_add(&c, a, b));
+ *     assert(c == 0x80000001u);
+ *
+ * Experienced C / C++ users should find this example counter-intuitive
+ * because the expression `0x7fffffff + 2` not only overflows it's also
+ * undefined behavior. However here we see it's specified, and does not
+ * result in an error. That's because C23 checked arithmetic is not the
+ * arithmetic you're used to. The new standard changes the mathematics.
+ *
+ * C23 checked arithmetic is defined as performing the arithmetic using
+ * infinite precision and then checking if the resulting value will fit
+ * in the output type. Our example above did not result in an error due
+ * to `0x80000001` being a legal value for `uint32_t`.
+ *
+ * This implementation will use the GNU compiler builtins, when they're
+ * available, only if you don't use build flags like `-std=c11` because
+ * they define `__STRICT_ANSI__` and GCC extensions aren't really ANSI.
+ * Instead, you'll get a pretty good pure C11 and C++11 implementation.
+ *
+ * @see https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3096.pdf
+ * @version 0.1 (2023-07-22)
+ */
+
+#ifndef JTCKDINT_H_
+#define JTCKDINT_H_
+
+#ifdef __has_include
+#define __ckd_has_include(x) __has_include(x)
+#else
+#define __ckd_has_include(x) 0
+#endif
+
+#if __ckd_has_include(<stdckdint.h>)
+#include <stdckdint.h>
+#else
+
+#define __STDC_VERSION_STDCKDINT_H__ 202311L
+
+#if ((defined(__llvm__) ||                                              \
+      (defined(__GNUC__) && __GNUC__ * 100 + __GNUC_MINOR__ >= 406)) && \
+     !defined(__STRICT_ANSI__))
+#define __ckd_have_int128
+#define __ckd_intmax __int128
+#elif ((defined(__cplusplus) && __cplusplus >= 201103L) ||              \
+       (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L))
+#define __ckd_intmax long long
+#else
+#define __ckd_intmax long
+#endif
+
+typedef signed __ckd_intmax __ckd_intmax_t;
+typedef unsigned __ckd_intmax __ckd_uintmax_t;
+
+#ifdef __has_builtin
+#define __ckd_has_builtin(x) __has_builtin(x)
+#else
+#define __ckd_has_builtin(x) 0
+#endif
+
+#if (!defined(__STRICT_ANSI__) &&                                       \
+     ((defined(__GNUC__) && __GNUC__ >= 5 && !defined(__ICC)) ||        \
+      (__ckd_has_builtin(__builtin_add_overflow) &&                     \
+       __ckd_has_builtin(__builtin_sub_overflow) &&                     \
+       __ckd_has_builtin(__builtin_mul_overflow))))
+#define ckd_add(res, x, y) __builtin_add_overflow((x), (y), (res))
+#define ckd_sub(res, x, y) __builtin_sub_overflow((x), (y), (res))
+#define ckd_mul(res, x, y) __builtin_mul_overflow((x), (y), (res))
+
+#elif (defined(__cplusplus) &&                          \
+       (__cplusplus >= 201103L ||                       \
+        (defined(_MSC_VER) && __cplusplus >= 199711L && \
+         __ckd_has_include(<type_traits>) &&            \
+         __ckd_has_include(<limits>))))
+#include <type_traits>
+#include <limits>
+
+template <typename __T, typename __U, typename __V>
+inline bool ckd_add(__T *__res, __U __a, __V __b) {
+  static_assert(std::is_integral<__T>::value &&
+                std::is_integral<__U>::value &&
+                std::is_integral<__V>::value,
+                "non-integral types not allowed");
+  static_assert(!std::is_same<__T, bool>::value &&
+                !std::is_same<__U, bool>::value &&
+                !std::is_same<__V, bool>::value,
+                "checked booleans not supported");
+  static_assert(!std::is_same<__T, char>::value &&
+                !std::is_same<__U, char>::value &&
+                !std::is_same<__V, char>::value,
+                "unqualified char type is ambiguous");
+  __ckd_uintmax_t __x = __a;
+  __ckd_uintmax_t __y = __b;
+  __ckd_uintmax_t __z = __x + __y;
+  *__res = __z;
+  if (sizeof(__z) > sizeof(__U) && sizeof(__z) > sizeof(__V)) {
+    if (sizeof(__z) > sizeof(__T) || std::is_signed<__T>::value) {
+      return static_cast<__ckd_intmax_t>(__z) != static_cast<__T>(__z);
+    } else if (!std::is_same<__T, __ckd_uintmax_t>::value) {
+      return (__z != static_cast<__T>(__z) ||
+              ((std::is_signed<__U>::value ||
+                std::is_signed<__V>::value) &&
+               static_cast<__ckd_intmax_t>(__z) < 0));
+    }
+  }
+  bool __truncated = false;
+  if (sizeof(__T) < sizeof(__ckd_intmax_t)) {
+    __truncated = __z != static_cast<__ckd_uintmax_t>(static_cast<__T>(__z));
+  }
+  switch (std::is_signed<__T>::value << 2 |  //
+          std::is_signed<__U>::value << 1 |  //
+          std::is_signed<__V>::value) {
+    case 0:  // u = u + u
+      return __truncated | (__z < __x);
+    case 1:  // u = u + s
+      __y ^= std::numeric_limits<__ckd_intmax_t>::min();
+      return __truncated |
+          (static_cast<__ckd_intmax_t>((__z ^ __x) &
+                                       (__z ^ __y)) < 0);
+    case 2:  // u = s + u
+      __x ^= std::numeric_limits<__ckd_intmax_t>::min();
+      return __truncated |
+          (static_cast<__ckd_intmax_t>((__z ^ __x) &
+                                       (__z ^ __y)) < 0);
+    case 3:  // u = s + s
+      return __truncated |
+          (static_cast<__ckd_intmax_t>(((__z | __x) &  __y) |
+                                       ((__z & __x) & ~__y)) < 0);
+    case 4:  // s = u + u
+      return __truncated | (__z < __x) | (static_cast<__ckd_intmax_t>(__z) < 0);
+    case 5:  // s = u + s
+      __y ^= std::numeric_limits<__ckd_intmax_t>::min();
+      return __truncated | (__x + __y < __y);
+    case 6:  // s = s + u
+      __x ^= std::numeric_limits<__ckd_intmax_t>::min();
+      return __truncated | (__x + __y < __x);
+    case 7:  // s = s + s
+      return __truncated |
+          (static_cast<__ckd_intmax_t>((__z ^ __x) &
+                                       (__z ^ __y)) < 0);
+    default:
+      for (;;) (void)0;
+  }
+}
+
+template <typename __T, typename __U, typename __V>
+inline bool ckd_sub(__T *__res, __U __a, __V __b) {
+  static_assert(std::is_integral<__T>::value &&
+                std::is_integral<__U>::value &&
+                std::is_integral<__V>::value,
+                "non-integral types not allowed");
+  static_assert(!std::is_same<__T, bool>::value &&
+                !std::is_same<__U, bool>::value &&
+                !std::is_same<__V, bool>::value,
+                "checked booleans not supported");
+  static_assert(!std::is_same<__T, char>::value &&
+                !std::is_same<__U, char>::value &&
+                !std::is_same<__V, char>::value,
+                "unqualified char type is ambiguous");
+  __ckd_uintmax_t __x = __a;
+  __ckd_uintmax_t __y = __b;
+  __ckd_uintmax_t __z = __x - __y;
+  *__res = __z;
+  if (sizeof(__z) > sizeof(__U) && sizeof(__z) > sizeof(__V)) {
+    if (sizeof(__z) > sizeof(__T) || std::is_signed<__T>::value) {
+      return static_cast<__ckd_intmax_t>(__z) != static_cast<__T>(__z);
+    } else if (!std::is_same<__T, __ckd_uintmax_t>::value) {
+      return (__z != static_cast<__T>(__z) ||
+              ((std::is_signed<__U>::value ||
+                std::is_signed<__V>::value) &&
+               static_cast<__ckd_intmax_t>(__z) < 0));
+    }
+  }
+  bool __truncated = false;
+  if (sizeof(__T) < sizeof(__ckd_intmax_t)) {
+    __truncated = __z != static_cast<__ckd_uintmax_t>(static_cast<__T>(__z));
+  }
+  switch (std::is_signed<__T>::value << 2 |  //
+          std::is_signed<__U>::value << 1 |  //
+          std::is_signed<__V>::value) {
+    case 0:  // u = u - u
+      return __truncated | (__x < __y);
+    case 1:  // u = u - s
+      __y ^= std::numeric_limits<__ckd_intmax_t>::min();
+      return __truncated |
+          (static_cast<__ckd_intmax_t>((__x ^ __y) &
+                                       (__z ^ __x)) < 0);
+    case 2:  // u = s - u
+      return __truncated | (__y > __x) | (static_cast<__ckd_intmax_t>(__x) < 0);
+    case 3:  // u = s - s
+      return __truncated |
+          (static_cast<__ckd_intmax_t>(((__z & __x) &  __y) |
+                                       ((__z | __x) & ~__y)) < 0);
+    case 4:  // s = u - u
+      return __truncated |
+          ((__x < __y) ^ (static_cast<__ckd_intmax_t>(__z) < 0));
+    case 5:  // s = u - s
+      __y ^= std::numeric_limits<__ckd_intmax_t>::min();
+      return __truncated | (__x >= __y);
+    case 6:  // s = s - u
+      __x ^= std::numeric_limits<__ckd_intmax_t>::min();
+      return __truncated | (__x < __y);
+    case 7:  // s = s - s
+      return __truncated |
+          (static_cast<__ckd_intmax_t>((__x ^ __y) &
+                                       (__z ^ __x)) < 0);
+    default:
+      for (;;) (void)0;
+  }
+}
+
+template <typename __T, typename __U, typename __V>
+inline bool ckd_mul(__T *__res, __U __a, __V __b) {
+  static_assert(std::is_integral<__T>::value &&
+                std::is_integral<__U>::value &&
+                std::is_integral<__V>::value,
+                "non-integral types not allowed");
+  static_assert(!std::is_same<__T, bool>::value &&
+                !std::is_same<__U, bool>::value &&
+                !std::is_same<__V, bool>::value,
+                "checked booleans not supported");
+  static_assert(!std::is_same<__T, char>::value &&
+                !std::is_same<__U, char>::value &&
+                !std::is_same<__V, char>::value,
+                "unqualified char type is ambiguous");
+  __ckd_uintmax_t __x = __a;
+  __ckd_uintmax_t __y = __b;
+  if ((sizeof(__U) * 8 - std::is_signed<__U>::value) +
+      (sizeof(__V) * 8 - std::is_signed<__V>::value) <=
+      (sizeof(__T) * 8 - std::is_signed<__T>::value)) {
+    if (sizeof(__ckd_uintmax_t) > sizeof(__T) || std::is_signed<__T>::value) {
+      __ckd_intmax_t __z = __x * __y;
+      return __z != (*__res = __z);
+    } else if (!std::is_same<__T, __ckd_uintmax_t>::value) {
+      __ckd_uintmax_t __z = __x * __y;
+      *__res = __z;
+      return (__z != static_cast<__T>(__z) ||
+              ((std::is_signed<__U>::value ||
+                std::is_signed<__V>::value) &&
+               static_cast<__ckd_intmax_t>(__z) < 0));
+    }
+  }
+  switch (std::is_signed<__T>::value << 2 |  //
+          std::is_signed<__U>::value << 1 |  //
+          std::is_signed<__V>::value) {
+    case 0: {  // u = u * u
+      __ckd_uintmax_t __z = __x * __y;
+      int __o = __x && __z / __x != __y;
+      *__res = __z;
+      return __o | (sizeof(__T) < sizeof(__z) &&
+                    __z != static_cast<__ckd_uintmax_t>(*__res));
+    }
+    case 1: {  // u = u * s
+      __ckd_uintmax_t __z = __x * __y;
+      int __o = __x && __z / __x != __y;
+      *__res = __z;
+      return (__o | ((static_cast<__ckd_intmax_t>(__y) < 0) & !!__x) |
+              (sizeof(__T) < sizeof(__z) &&
+               __z != static_cast<__ckd_uintmax_t>(*__res)));
+    }
+    case 2: {  // u = s * u
+      __ckd_uintmax_t __z = __x * __y;
+      int __o = __x && __z / __x != __y;
+      *__res = __z;
+      return (__o | ((static_cast<__ckd_intmax_t>(__x) < 0) & !!__y) |
+              (sizeof(__T) < sizeof(__z) &&
+               __z != static_cast<__ckd_uintmax_t>(*__res)));
+    }
+    case 3: { // u = s * s
+      int __o = false;
+      if (static_cast<__ckd_intmax_t>(__x & __y) < 0) {
+        __x = -__x;
+        __y = -__y;
+      } else if (static_cast<__ckd_intmax_t>(__x ^ __y) < 0) {
+        __o = __x && __y;
+      }
+      __ckd_uintmax_t __z = __x * __y;
+      __o |= __x && __z / __x != __y;
+      *__res = __z;
+      return __o | (sizeof(__T) < sizeof(__z) &&
+                    __z != static_cast<__ckd_uintmax_t>(*__res));
+    }
+    case 4: {  // s = u * u
+      __ckd_uintmax_t __z = __x * __y;
+      int __o = __x && __z / __x != __y;
+      *__res = __z;
+      return (__o | (static_cast<__ckd_intmax_t>(__z) < 0) |
+              (sizeof(__T) < sizeof(__z) &&
+               __z != static_cast<__ckd_uintmax_t>(*__res)));
+    }
+    case 5: {  // s = u * s
+      __ckd_uintmax_t __t = -__y;
+      __t = static_cast<__ckd_intmax_t>(__t) < 0 ? __y : __t;
+      __ckd_uintmax_t __p = __t * __x;
+      int __o = __t && __p / __t != __x;
+      int __n = static_cast<__ckd_intmax_t>(__y) < 0;
+      __ckd_uintmax_t __z = __n ? -__p : __p;
+      *__res = __z;
+      __ckd_uintmax_t __m = std::numeric_limits<__ckd_intmax_t>::max();
+      return (__o | (__p > __m + __n) |
+              (sizeof(__T) < sizeof(__z) &&
+               __z != static_cast<__ckd_uintmax_t>(*__res)));
+    }
+    case 6: {  // s = s * u
+      __ckd_uintmax_t __t = -__x;
+      __t = static_cast<__ckd_intmax_t>(__t) < 0 ? __x : __t;
+      __ckd_uintmax_t __p = __t * __y;
+      int __o = __t && __p / __t != __y;
+      int __n = static_cast<__ckd_intmax_t>(__x) < 0;
+      __ckd_uintmax_t __z = __n ? -__p : __p;
+      *__res = __z;
+      __ckd_uintmax_t __m = std::numeric_limits<__ckd_intmax_t>::max();
+      return (__o | (__p > __m + __n) |
+              (sizeof(__T) < sizeof(__z) &&
+               __z != static_cast<__ckd_uintmax_t>(*__res)));
+    }
+    case 7: {  // s = s * s
+      __ckd_uintmax_t __z = __x * __y;
+      *__res = __z;
+      return ((((static_cast<__ckd_intmax_t>(__y) < 0) &&
+                (static_cast<__ckd_intmax_t>(__x) ==
+                 std::numeric_limits<__ckd_intmax_t>::min())) ||
+               (__y && ((static_cast<__ckd_intmax_t>(__z) /
+                         static_cast<__ckd_intmax_t>(__y)) !=
+                        static_cast<__ckd_intmax_t>(__x)))) |
+              (sizeof(__T) < sizeof(__z) &&
+               __z != static_cast<__ckd_uintmax_t>(*__res)));
+    }
+    default:
+      for (;;) (void)0;
+  }
+}
+
+#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L
+
+#define ckd_add(res, a, b) __ckd_expr(add, (res), (a), (b))
+#define ckd_sub(res, a, b) __ckd_expr(sub, (res), (a), (b))
+#define ckd_mul(res, a, b) __ckd_expr(mul, (res), (a), (b))
+
+#if defined(__GNUC__) || defined(__llvm__)
+#define __ckd_inline                                    \
+  extern __inline __attribute__((__gnu_inline__,        \
+                                 __always_inline__,     \
+                                 __artificial__))
+#else
+#define __ckd_inline static inline
+#endif
+
+#ifdef __ckd_have_int128
+#define __ckd_generic_int128(x, y) , signed __int128: x, unsigned __int128: y
+#else
+#define __ckd_generic_int128(x, y)
+#endif
+
+#define __ckd_sign(T)                           \
+  ((T)1 << (sizeof(T) * 8 - 1))
+
+#define __ckd_is_signed(x)                      \
+  _Generic(x,                                   \
+           signed char: 1,                      \
+           unsigned char: 0,                    \
+           signed short: 1,                     \
+           unsigned short: 0,                   \
+           signed int: 1,                       \
+           unsigned int: 0,                     \
+           signed long: 1,                      \
+           unsigned long: 0,                    \
+           signed long long: 1,                 \
+           unsigned long long: 0                \
+           __ckd_generic_int128(1, 0))
+
+#define __ckd_expr(op, res, a, b)                       \
+  (_Generic(*res,                                       \
+            signed char: __ckd_##op##_schar,            \
+            unsigned char: __ckd_##op##_uchar,          \
+            signed short: __ckd_##op##_sshort,          \
+            unsigned short: __ckd_##op##_ushort,        \
+            signed int: __ckd_##op##_sint,              \
+            unsigned int: __ckd_##op##_uint,            \
+            signed long: __ckd_##op##_slong,            \
+            unsigned long: __ckd_##op##_ulong,          \
+            signed long long: __ckd_##op##_slonger,     \
+            unsigned long long: __ckd_##op##_ulonger    \
+            __ckd_generic_int128(                       \
+                __ckd_##op##_sint128,                   \
+                __ckd_##op##_uint128))(                 \
+                    res, a, b,                          \
+                    __ckd_is_signed(a),                 \
+                    __ckd_is_signed(b)))
+
+#define __ckd_declare_add(S, T)                                         \
+  __ckd_inline char S(void *__res,                                      \
+                      __ckd_uintmax_t __x,                              \
+                      __ckd_uintmax_t __y,                              \
+                      char __a_signed,                                  \
+                      char __b_signed) {                                \
+    __ckd_uintmax_t __z = __x + __y;                                    \
+    *(T *)__res = __z;                                                  \
+    char __truncated = 0;                                               \
+    if (sizeof(T) < sizeof(__ckd_intmax_t)) {                           \
+      __truncated = __z != (__ckd_uintmax_t)(T)__z;                     \
+    }                                                                   \
+    switch (__ckd_is_signed((T)0) << 2 |                                \
+            __a_signed << 1 | __b_signed) {                             \
+      case 0:  /* u = u + u */                                          \
+        return __truncated | (__z < __x);                               \
+      case 1:  /* u = u + s */                                          \
+        __y ^= __ckd_sign(__ckd_uintmax_t);                             \
+        return __truncated |                                            \
+            ((__ckd_intmax_t)((__z ^ __x) &                             \
+                              (__z ^ __y)) < 0);                        \
+      case 2:  /* u = s + u */                                          \
+        __x ^= __ckd_sign(__ckd_uintmax_t);                             \
+        return __truncated |                                            \
+            ((__ckd_intmax_t)((__z ^ __x) &                             \
+                              (__z ^ __y)) < 0);                        \
+      case 3:  /* u = s + s */                                          \
+        return __truncated |                                            \
+            ((__ckd_intmax_t)(((__z | __x) &  __y) |                    \
+                              ((__z & __x) & ~__y)) < 0);               \
+      case 4:  /* s = u + u */                                          \
+        return __truncated | (__z < __x) | ((__ckd_intmax_t)__z < 0);   \
+      case 5:  /* s = u + s */                                          \
+        __y ^= __ckd_sign(__ckd_uintmax_t);                             \
+        return __truncated | (__x + __y < __y);                         \
+      case 6:  /* s = s + u */                                          \
+        __x ^= __ckd_sign(__ckd_uintmax_t);                             \
+        return __truncated | (__x + __y < __x);                         \
+      case 7:  /* s = s + s */                                          \
+        return __truncated |                                            \
+            ((__ckd_intmax_t)((__z ^ __x) &                             \
+                              (__z ^ __y)) < 0);                        \
+      default:                                                          \
+        for (;;) (void)0;                                               \
+    }                                                                   \
+  }
+
+__ckd_declare_add(__ckd_add_schar, signed char)
+__ckd_declare_add(__ckd_add_uchar, unsigned char)
+__ckd_declare_add(__ckd_add_sshort, signed short)
+__ckd_declare_add(__ckd_add_ushort, unsigned short)
+__ckd_declare_add(__ckd_add_sint, signed int)
+__ckd_declare_add(__ckd_add_uint, unsigned int)
+__ckd_declare_add(__ckd_add_slong, signed long)
+__ckd_declare_add(__ckd_add_ulong, unsigned long)
+__ckd_declare_add(__ckd_add_slonger, signed long long)
+__ckd_declare_add(__ckd_add_ulonger, unsigned long long)
+#ifdef __ckd_have_int128
+__ckd_declare_add(__ckd_add_sint128, signed __int128)
+__ckd_declare_add(__ckd_add_uint128, unsigned __int128)
+#endif
+
+#define __ckd_declare_sub(S, T)                                         \
+  __ckd_inline char S(void *__res,                                      \
+                      __ckd_uintmax_t __x,                              \
+                      __ckd_uintmax_t __y,                              \
+                      char __a_signed,                                  \
+                      char __b_signed) {                                \
+    __ckd_uintmax_t __z = __x - __y;                                    \
+    *(T *)__res = __z;                                                  \
+    char __truncated = 0;                                               \
+    if (sizeof(T) < sizeof(__ckd_intmax_t)) {                           \
+      __truncated = __z != (__ckd_uintmax_t)(T)__z;                     \
+    }                                                                   \
+    switch (__ckd_is_signed((T)0) << 2 |                                \
+            __a_signed << 1 | __b_signed) {                             \
+      case 0:  /* u = u - u */                                          \
+        return __truncated | (__x < __y);                               \
+      case 1:  /* u = u - s */                                          \
+        __y ^= __ckd_sign(__ckd_uintmax_t);                             \
+        return __truncated |                                            \
+            ((__ckd_intmax_t)((__x ^ __y) &                             \
+                              (__z ^ __x)) < 0);                        \
+      case 2:  /* u = s - u */                                          \
+        return __truncated | (__y > __x) | ((__ckd_intmax_t)__x < 0);   \
+      case 3:  /* u = s - s */                                          \
+        return __truncated |                                            \
+            ((__ckd_intmax_t)(((__z & __x) &  __y) |                    \
+                              ((__z | __x) & ~__y)) < 0);               \
+      case 4:  /* s = u - u */                                          \
+        return __truncated | ((__x < __y) ^ ((__ckd_intmax_t)__z < 0)); \
+      case 5:  /* s = u - s */                                          \
+        __y ^= __ckd_sign(__ckd_uintmax_t);                             \
+        return __truncated | (__x >= __y);                              \
+      case 6:  /* s = s - u */                                          \
+        __x ^= __ckd_sign(__ckd_uintmax_t);                             \
+        return __truncated | (__x < __y);                               \
+      case 7:  /* s = s - s */                                          \
+        return __truncated |                                            \
+            ((__ckd_intmax_t)((__x ^ __y) &                             \
+                              (__z ^ __x)) < 0);                        \
+      default:                                                          \
+        for (;;) (void)0;                                               \
+    }                                                                   \
+  }
+
+__ckd_declare_sub(__ckd_sub_schar, signed char)
+__ckd_declare_sub(__ckd_sub_uchar, unsigned char)
+__ckd_declare_sub(__ckd_sub_sshort, signed short)
+__ckd_declare_sub(__ckd_sub_ushort, unsigned short)
+__ckd_declare_sub(__ckd_sub_sint, signed int)
+__ckd_declare_sub(__ckd_sub_uint, unsigned int)
+__ckd_declare_sub(__ckd_sub_slong, signed long)
+__ckd_declare_sub(__ckd_sub_ulong, unsigned long)
+__ckd_declare_sub(__ckd_sub_slonger, signed long long)
+__ckd_declare_sub(__ckd_sub_ulonger, unsigned long long)
+#ifdef __ckd_have_int128
+__ckd_declare_sub(__ckd_sub_sint128, signed __int128)
+__ckd_declare_sub(__ckd_sub_uint128, unsigned __int128)
+#endif
+
+#define __ckd_declare_mul(S, T)                                 \
+  __ckd_inline char S(void *__res,                              \
+                      __ckd_uintmax_t __x,                      \
+                      __ckd_uintmax_t __y,                      \
+                      char __a_signed,                          \
+                      char __b_signed) {                        \
+    switch (__ckd_is_signed((T)0) << 2 |                        \
+            __a_signed << 1 | __b_signed) {                     \
+      case 0: {  /* u = u * u */                                \
+        __ckd_uintmax_t __z = __x * __y;                        \
+        int __o = __x && __z / __x != __y;                      \
+        *(T *)__res = __z;                                      \
+        return __o | (sizeof(T) < sizeof(__z) &&                \
+                      __z != (__ckd_uintmax_t)*(T *)__res);     \
+      }                                                         \
+      case 1: {  /* u = u * s */                                \
+        __ckd_uintmax_t __z = __x * __y;                        \
+        int __o = __x && __z / __x != __y;                      \
+        *(T *)__res = __z;                                      \
+        return (__o | (((__ckd_intmax_t)__y < 0) & !!__x) |     \
+                (sizeof(T) < sizeof(__z) &&                     \
+                 __z != (__ckd_uintmax_t)*(T *)__res));         \
+      }                                                         \
+      case 2: {  /* u = s * u */                                \
+        __ckd_uintmax_t __z = __x * __y;                        \
+        int __o = __x && __z / __x != __y;                      \
+        *(T *)__res = __z;                                      \
+        return (__o | (((__ckd_intmax_t)__x < 0) & !!__y) |     \
+                (sizeof(T) < sizeof(__z) &&                     \
+                 __z != (__ckd_uintmax_t)*(T *)__res));         \
+      }                                                         \
+      case 3: {  /* u = s * s */                                \
+        int __o = 0;                                            \
+        if ((__ckd_intmax_t)(__x & __y) < 0) {                  \
+          __x = -__x;                                           \
+          __y = -__y;                                           \
+        } else if ((__ckd_intmax_t)(__x ^ __y) < 0) {           \
+          __o = __x && __y;                                     \
+        }                                                       \
+        __ckd_uintmax_t __z = __x * __y;                        \
+        __o |= __x && __z / __x != __y;                         \
+        *(T *)__res = __z;                                      \
+        return __o | (sizeof(T) < sizeof(__z) &&                \
+                      __z != (__ckd_uintmax_t)*(T *)__res);     \
+      }                                                         \
+      case 4: {  /* s = u * u */                                \
+        __ckd_uintmax_t __z = __x * __y;                        \
+        int __o = __x && __z / __x != __y;                      \
+        *(T *)__res = __z;                                      \
+        return (__o | ((__ckd_intmax_t)(__z) < 0) |             \
+                (sizeof(T) < sizeof(__z) &&                     \
+                 __z != (__ckd_uintmax_t)*(T *)__res));         \
+      }                                                         \
+      case 5: {  /* s = u * s */                                \
+        __ckd_uintmax_t __t = -__y;                             \
+        __t = (__ckd_intmax_t)(__t) < 0 ? __y : __t;            \
+        __ckd_uintmax_t __p = __t * __x;                        \
+        int __o = __t && __p / __t != __x;                      \
+        int __n = (__ckd_intmax_t)__y < 0;                      \
+        __ckd_uintmax_t __z = __n ? -__p : __p;                 \
+        *(T *)__res = __z;                                      \
+        __ckd_uintmax_t __m = __ckd_sign(__ckd_uintmax_t) - 1;  \
+        return (__o | (__p > __m + __n) |                       \
+                (sizeof(T) < sizeof(__z) &&                     \
+                 __z != (__ckd_uintmax_t)*(T *)__res));         \
+      }                                                         \
+      case 6: {  /* s = s * u */                                \
+        __ckd_uintmax_t __t = -__x;                             \
+        __t = (__ckd_intmax_t)(__t) < 0 ? __x : __t;            \
+        __ckd_uintmax_t __p = __t * __y;                        \
+        int __o = __t && __p / __t != __y;                      \
+        int __n = (__ckd_intmax_t)__x < 0;                      \
+        __ckd_uintmax_t __z = __n ? -__p : __p;                 \
+        *(T *)__res = __z;                                      \
+        __ckd_uintmax_t __m = __ckd_sign(__ckd_uintmax_t) - 1;  \
+        return (__o | (__p > __m + __n) |                       \
+                (sizeof(T) < sizeof(__z) &&                     \
+                 __z != (__ckd_uintmax_t)*(T *)__res));         \
+      }                                                         \
+      case 7: {  /* s = s * s */                                \
+        __ckd_uintmax_t __z = __x * __y;                        \
+        *(T *)__res = __z;                                      \
+        return (((((__ckd_intmax_t)__y < 0) &&                  \
+                  (__x == __ckd_sign(__ckd_uintmax_t))) ||      \
+                 (__y && (((__ckd_intmax_t)__z /                \
+                           (__ckd_intmax_t)__y) !=              \
+                          (__ckd_intmax_t)__x))) |              \
+                (sizeof(T) < sizeof(__z) &&                     \
+                 __z != (__ckd_uintmax_t)*(T *)__res));         \
+      }                                                         \
+      default:                                                  \
+        for (;;) (void)0;                                       \
+    }                                                           \
+  }
+
+__ckd_declare_mul(__ckd_mul_schar, signed char)
+__ckd_declare_mul(__ckd_mul_uchar, unsigned char)
+__ckd_declare_mul(__ckd_mul_sshort, signed short)
+__ckd_declare_mul(__ckd_mul_ushort, unsigned short)
+__ckd_declare_mul(__ckd_mul_sint, signed int)
+__ckd_declare_mul(__ckd_mul_uint, unsigned int)
+__ckd_declare_mul(__ckd_mul_slong, signed long)
+__ckd_declare_mul(__ckd_mul_ulong, unsigned long)
+__ckd_declare_mul(__ckd_mul_slonger, signed long long)
+__ckd_declare_mul(__ckd_mul_ulonger, unsigned long long)
+#ifdef __ckd_have_int128
+__ckd_declare_mul(__ckd_mul_sint128, signed __int128)
+__ckd_declare_mul(__ckd_mul_uint128, unsigned __int128)
+#endif
+
+#else
+#pragma message "checked integer arithmetic unsupported in this environment"
+
+#define ckd_add(res, x, y) (*(res) = (x) + (y), 0)
+#define ckd_sub(res, x, y) (*(res) = (x) - (y), 0)
+#define ckd_mul(res, x, y) (*(res) = (x) * (y), 0)
+
+#endif /* GNU */
+#endif /* stdckdint.h */
+#endif /* JTCKDINT_H_ */
diff --git a/tests/ref/fate/source b/tests/ref/fate/source
index 78d3a2e0fa..ab6182bf4c 100644
--- a/tests/ref/fate/source
+++ b/tests/ref/fate/source
@@ -25,6 +25,7 @@ compat/djgpp/math.h
 compat/float/float.h
 compat/float/limits.h
 compat/stdbit/stdbit.h
+compat/stdckdint/stdckdint.h
 libavcodec/bitstream_template.h
 tools/decode_simple.h
 Use of av_clip() where av_clip_uintp2() could be used:
