From 5443c55575bb264ee2713e3228d688056bba7be7 Mon Sep 17 00:00:00 2001
From: Daniel Ng <dnlng@google.com>
Date: Wed, 20 Sep 2023 21:38:11 -0700
Subject: [PATCH] Add float8 & int4 numpy integration

PiperOrigin-RevId: 567178215
---
 ml_dtypes/_src/int4_numpy.h | 66 +++++++++++++++++++++++++++++++++++--
 1 file changed, 63 insertions(+), 3 deletions(-)

diff --git a/ml_dtypes/_src/int4_numpy.h b/ml_dtypes/_src/int4_numpy.h
index 7f23fbc1..aed0f00a 100644
--- a/ml_dtypes/_src/int4_numpy.h
+++ b/ml_dtypes/_src/int4_numpy.h
@@ -28,6 +28,8 @@ limitations under the License.
 
 namespace ml_dtypes {
 
+constexpr char kOutOfRange[] = "out of range value cannot be converted to int4";
+
 template <typename T>
 struct Int4TypeDescriptor {
   static int Dtype() { return npy_type; }
@@ -114,8 +116,7 @@ bool CastToInt4(PyObject* arg, T* output) {
     }
     if (d < static_cast<double>(T::lowest()) ||
         d > static_cast<double>(T::highest())) {
-      PyErr_SetString(PyExc_OverflowError,
-                      "out of range value cannot be converted to int4");
+      PyErr_SetString(PyExc_OverflowError, kOutOfRange);
     }
     *output = T(d);
     return true;
@@ -131,9 +132,37 @@ bool CastToInt4(PyObject* arg, T* output) {
   if (PyArray_IsScalar(arg, Integer)) {
     int64_t v;
     PyArray_CastScalarToCtype(arg, &v, PyArray_DescrFromType(NPY_INT64));
+
+    if (!(std::numeric_limits<T>::min() <= v &&
+          v <= std::numeric_limits<T>::max())) {
+      PyErr_SetString(PyExc_OverflowError, kOutOfRange);
+      return false;
+    }
     *output = T(v);
     return true;
   }
+  if (PyArray_IsScalar(arg, Float)) {
+    float f;
+    PyArray_ScalarAsCtype(arg, &f);
+    if (!(std::numeric_limits<T>::min() <= f &&
+          f <= std::numeric_limits<T>::max())) {
+      PyErr_SetString(PyExc_OverflowError, kOutOfRange);
+      return false;
+    }
+    *output = T(static_cast<::int8_t>(f));
+    return true;
+  }
+  if (PyArray_IsScalar(arg, Double)) {
+    double d;
+    PyArray_ScalarAsCtype(arg, &d);
+    if (!(std::numeric_limits<T>::min() <= d &&
+          d <= std::numeric_limits<T>::max())) {
+      PyErr_SetString(PyExc_OverflowError, kOutOfRange);
+      return false;
+    }
+    *output = T(static_cast<::int8_t>(d));
+    return true;
+  }
   return false;
 }
 
@@ -652,7 +681,38 @@ bool RegisterInt4Casts() {
   }
 
   // Safe casts from T to other types
-  // TODO(phawkins): add integer types
+  if (PyArray_RegisterCanCast(&TypeDescriptor<T>::npy_descr, NPY_INT8,
+                              NPY_NOSCALAR) < 0) {
+    return false;
+  }
+  if (PyArray_RegisterCanCast(&TypeDescriptor<T>::npy_descr, NPY_UINT8,
+                              NPY_NOSCALAR) < 0) {
+    return false;
+  }
+  if (PyArray_RegisterCanCast(&TypeDescriptor<T>::npy_descr, NPY_INT16,
+                              NPY_NOSCALAR) < 0) {
+    return false;
+  }
+  if (PyArray_RegisterCanCast(&TypeDescriptor<T>::npy_descr, NPY_UINT16,
+                              NPY_NOSCALAR) < 0) {
+    return false;
+  }
+  if (PyArray_RegisterCanCast(&TypeDescriptor<T>::npy_descr, NPY_INT32,
+                              NPY_NOSCALAR) < 0) {
+    return false;
+  }
+  if (PyArray_RegisterCanCast(&TypeDescriptor<T>::npy_descr, NPY_UINT32,
+                              NPY_NOSCALAR) < 0) {
+    return false;
+  }
+  if (PyArray_RegisterCanCast(&TypeDescriptor<T>::npy_descr, NPY_INT64,
+                              NPY_NOSCALAR) < 0) {
+    return false;
+  }
+  if (PyArray_RegisterCanCast(&TypeDescriptor<T>::npy_descr, NPY_UINT64,
+                              NPY_NOSCALAR) < 0) {
+    return false;
+  }
   if (PyArray_RegisterCanCast(&TypeDescriptor<T>::npy_descr, NPY_FLOAT,
                               NPY_NOSCALAR) < 0) {
     return false;