gh-90751: memoryview now supports half-float (#96738)

Co-authored-by: Antoine Pitrou <antoine@python.org>

2 files changed, 22 insertions, 7 deletions

diff --git a/Lib/test/test_buffer.py b/Lib/test/test_buffer.py
index 468c6ea..8ac3b7e 100644
--- a/Lib/test/test_buffer.py
+++ b/Lib/test/test_buffer.py
@@ -64,7 +64,7 @@ NATIVE = {
     '?':0, 'c':0, 'b':0, 'B':0,
     'h':0, 'H':0, 'i':0, 'I':0,
     'l':0, 'L':0, 'n':0, 'N':0,
-    'f':0, 'd':0, 'P':0
+    'e':0, 'f':0, 'd':0, 'P':0
 }
 
 # NumPy does not have 'n' or 'N':
@@ -89,7 +89,8 @@ STANDARD = {
     'i':(-(1<<31), 1<<31), 'I':(0, 1<<32),
     'l':(-(1<<31), 1<<31), 'L':(0, 1<<32),
     'q':(-(1<<63), 1<<63), 'Q':(0, 1<<64),
-    'f':(-(1<<63), 1<<63), 'd':(-(1<<1023), 1<<1023)
+    'e':(-65519, 65520),   'f':(-(1<<63), 1<<63),
+    'd':(-(1<<1023), 1<<1023)
 }
 
 def native_type_range(fmt):
@@ -98,6 +99,8 @@ def native_type_range(fmt):
         lh = (0, 256)
     elif fmt == '?':
         lh = (0, 2)
+    elif fmt == 'e':
+        lh = (-65519, 65520)
     elif fmt == 'f':
         lh = (-(1<<63), 1<<63)
     elif fmt == 'd':
@@ -125,7 +128,10 @@ if struct:
     for fmt in fmtdict['@']:
         fmtdict['@'][fmt] = native_type_range(fmt)
 
+# Format codes suppported by the memoryview object
 MEMORYVIEW = NATIVE.copy()
+
+# Format codes suppported by array.array
 ARRAY = NATIVE.copy()
 for k in NATIVE:
     if not k in "bBhHiIlLfd":
@@ -164,7 +170,7 @@ def randrange_fmt(mode, char, obj):
             x = b'\x01'
     if char == '?':
         x = bool(x)
-    if char == 'f' or char == 'd':
+    if char in 'efd':
         x = struct.pack(char, x)
         x = struct.unpack(char, x)[0]
     return x
@@ -2246,7 +2252,7 @@ class TestBufferProtocol(unittest.TestCase):
         ###
         ###    Fortran output:
         ###    ---------------
-        ###       >>> fortran_buf = nd.tostring(order='F')
+        ###       >>> fortran_buf = nd.tobytes(order='F')
         ###       >>> fortran_buf
         ###       b'\x00\x04\x08\x01\x05\t\x02\x06\n\x03\x07\x0b'
         ###
@@ -2289,7 +2295,7 @@ class TestBufferProtocol(unittest.TestCase):
                 self.assertEqual(memoryview(y), memoryview(nd))
 
                 if numpy_array:
-                    self.assertEqual(b, na.tostring(order='C'))
+                    self.assertEqual(b, na.tobytes(order='C'))
 
             # 'F' request
             if f == 0: # 'C' to 'F'
@@ -2312,7 +2318,7 @@ class TestBufferProtocol(unittest.TestCase):
                 self.assertEqual(memoryview(y), memoryview(nd))
 
                 if numpy_array:
-                    self.assertEqual(b, na.tostring(order='F'))
+                    self.assertEqual(b, na.tobytes(order='F'))
 
             # 'A' request
             if f == ND_FORTRAN:
@@ -2336,7 +2342,7 @@ class TestBufferProtocol(unittest.TestCase):
                 self.assertEqual(memoryview(y), memoryview(nd))
 
                 if numpy_array:
-                    self.assertEqual(b, na.tostring(order='A'))
+                    self.assertEqual(b, na.tobytes(order='A'))
 
         # multi-dimensional, non-contiguous input
         nd = ndarray(list(range(12)), shape=[3, 4], flags=ND_WRITABLE|ND_PIL)
diff --git a/Lib/test/test_memoryview.py b/Lib/test/test_memoryview.py
index 9d1e1f3..0eb2a36 100644
--- a/Lib/test/test_memoryview.py
+++ b/Lib/test/test_memoryview.py
@@ -13,6 +13,7 @@ import array
 import io
 import copy
 import pickle
+import struct
 
 from test.support import import_helper
 
@@ -527,6 +528,14 @@ class OtherTest(unittest.TestCase):
                 m[2:] = memoryview(p6).cast(format)[2:]
                 self.assertEqual(d.value, 0.6)
 
+    def test_half_float(self):
+        half_data = struct.pack('eee', 0.0, -1.5, 1.5)
+        float_data = struct.pack('fff', 0.0, -1.5, 1.5)
+        half_view = memoryview(half_data).cast('e')
+        float_view = memoryview(float_data).cast('f')
+        self.assertEqual(half_view.nbytes * 2, float_view.nbytes)
+        self.assertListEqual(half_view.tolist(), float_view.tolist())
+
     def test_memoryview_hex(self):
         # Issue #9951: memoryview.hex() segfaults with non-contiguous buffers.
         x = b'0' * 200000