[Python-checkins] gh-90751: memoryview now supports half-float (#96738)
pitrou
webhook-mailer at python.org
Sat Sep 10 16:44:19 EDT 2022
https://github.com/python/cpython/commit/8d75a13fdece95ddc1bba42cad3aea3ccb396e05
commit: 8d75a13fdece95ddc1bba42cad3aea3ccb396e05
branch: main
author: Dong-hee Na <donghee.na at python.org>
committer: pitrou <pitrou at free.fr>
date: 2022-09-10T22:44:10+02:00
summary:
gh-90751: memoryview now supports half-float (#96738)
Co-authored-by: Antoine Pitrou <antoine at python.org>
files:
A Misc/NEWS.d/next/Core and Builtins/2022-09-11-00-37-50.gh-issue-90751.VE8-zf.rst
M Doc/whatsnew/3.12.rst
M Lib/test/test_buffer.py
M Lib/test/test_memoryview.py
M Objects/memoryobject.c
diff --git a/Doc/whatsnew/3.12.rst b/Doc/whatsnew/3.12.rst
index 27285de1984..11784ba0021 100644
--- a/Doc/whatsnew/3.12.rst
+++ b/Doc/whatsnew/3.12.rst
@@ -94,6 +94,9 @@ Other Language Changes
length limitation <int_max_str_digits>` documentation. The default limit
is 4300 digits in string form.
+* :class:`memoryview` now supports the half-float type (the "e" format code).
+ (Contributed by Dong-hee Na and Antoine Pitrou in :gh:`90751`.)
+
New Modules
===========
diff --git a/Lib/test/test_buffer.py b/Lib/test/test_buffer.py
index 468c6ea9def..8ac3b7e7eb2 100644
--- a/Lib/test/test_buffer.py
+++ b/Lib/test/test_buffer.py
@@ -64,7 +64,7 @@
'?':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 @@
'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 @@ def native_type_range(fmt):
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 @@ def test_py_buffer_to_contiguous(self):
###
### 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 @@ def test_py_buffer_to_contiguous(self):
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 @@ def test_py_buffer_to_contiguous(self):
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 @@ def test_py_buffer_to_contiguous(self):
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 9d1e1f3063c..0eb2a367603 100644
--- a/Lib/test/test_memoryview.py
+++ b/Lib/test/test_memoryview.py
@@ -13,6 +13,7 @@
import io
import copy
import pickle
+import struct
from test.support import import_helper
@@ -527,6 +528,14 @@ def test_ctypes_cast(self):
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
diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-09-11-00-37-50.gh-issue-90751.VE8-zf.rst b/Misc/NEWS.d/next/Core and Builtins/2022-09-11-00-37-50.gh-issue-90751.VE8-zf.rst
new file mode 100644
index 00000000000..0908f1cc066
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2022-09-11-00-37-50.gh-issue-90751.VE8-zf.rst
@@ -0,0 +1,2 @@
+:class:`memoryview` now supports half-floats.
+Patch by Dong-hee Na and Antoine Pitrou.
diff --git a/Objects/memoryobject.c b/Objects/memoryobject.c
index d29e35c2bc3..c5ab0bf2ded 100644
--- a/Objects/memoryobject.c
+++ b/Objects/memoryobject.c
@@ -1135,6 +1135,7 @@ get_native_fmtchar(char *result, const char *fmt)
case 'n': case 'N': size = sizeof(Py_ssize_t); break;
case 'f': size = sizeof(float); break;
case 'd': size = sizeof(double); break;
+ case 'e': size = sizeof(float) / 2; break;
case '?': size = sizeof(_Bool); break;
case 'P': size = sizeof(void *); break;
}
@@ -1178,6 +1179,7 @@ get_native_fmtstr(const char *fmt)
case 'N': RETURN("N");
case 'f': RETURN("f");
case 'd': RETURN("d");
+ case 'e': RETURN("e");
case '?': RETURN("?");
case 'P': RETURN("P");
}
@@ -1697,6 +1699,12 @@ unpack_single(PyMemoryViewObject *self, const char *ptr, const char *fmt)
CHECK_RELEASED_AGAIN(self);
+#if PY_LITTLE_ENDIAN
+ int endian = 1;
+#else
+ int endian = 0;
+#endif
+
switch (fmt[0]) {
/* signed integers and fast path for 'B' */
@@ -1725,6 +1733,7 @@ unpack_single(PyMemoryViewObject *self, const char *ptr, const char *fmt)
/* floats */
case 'f': UNPACK_SINGLE(d, ptr, float); goto convert_double;
case 'd': UNPACK_SINGLE(d, ptr, double); goto convert_double;
+ case 'e': d = PyFloat_Unpack2(ptr, endian); goto convert_double;
/* bytes object */
case 'c': goto convert_bytes;
@@ -1786,6 +1795,11 @@ pack_single(PyMemoryViewObject *self, char *ptr, PyObject *item, const char *fmt
double d;
void *p;
+#if PY_LITTLE_ENDIAN
+ int endian = 1;
+#else
+ int endian = 0;
+#endif
switch (fmt[0]) {
/* signed integers */
case 'b': case 'h': case 'i': case 'l':
@@ -1862,7 +1876,7 @@ pack_single(PyMemoryViewObject *self, char *ptr, PyObject *item, const char *fmt
break;
/* floats */
- case 'f': case 'd':
+ case 'f': case 'd': case 'e':
d = PyFloat_AsDouble(item);
if (d == -1.0 && PyErr_Occurred())
goto err_occurred;
@@ -1870,9 +1884,14 @@ pack_single(PyMemoryViewObject *self, char *ptr, PyObject *item, const char *fmt
if (fmt[0] == 'f') {
PACK_SINGLE(ptr, d, float);
}
- else {
+ else if (fmt[0] == 'd') {
PACK_SINGLE(ptr, d, double);
}
+ else {
+ if (PyFloat_Pack2(d, ptr, endian) < 0) {
+ goto err_occurred;
+ }
+ }
break;
/* bool */
@@ -1882,7 +1901,7 @@ pack_single(PyMemoryViewObject *self, char *ptr, PyObject *item, const char *fmt
return -1; /* preserve original error */
CHECK_RELEASED_INT_AGAIN(self);
PACK_SINGLE(ptr, ld, _Bool);
- break;
+ break;
/* bytes object */
case 'c':
@@ -2748,6 +2767,17 @@ unpack_cmp(const char *p, const char *q, char fmt,
/* XXX DBL_EPSILON? */
case 'f': CMP_SINGLE(p, q, float); return equal;
case 'd': CMP_SINGLE(p, q, double); return equal;
+ case 'e': {
+#if PY_LITTLE_ENDIAN
+ int endian = 1;
+#else
+ int endian = 0;
+#endif
+ /* Note: PyFloat_Unpack2 should never fail */
+ double u = PyFloat_Unpack2(p, endian);
+ double v = PyFloat_Unpack2(q, endian);
+ return (u == v);
+ }
/* bytes object */
case 'c': return *p == *q;
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