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|
https://bugs.gentoo.org/show_bug.cgi?id=266703
https://bugs.python.org/issue1762561
--- Objects/floatobject.c
+++ Objects/floatobject.c
@@ -1850,9 +1850,18 @@
/* this is for the benefit of the pack/unpack routines below */
typedef enum {
- unknown_format, ieee_big_endian_format, ieee_little_endian_format
+ unknown_format,
+ ieee_big_endian_format,
+ ieee_little_endian_format,
+ ieee_arm_mixed_endian_format
} float_format_type;
+/* byte order of a C double for each of the recognised IEEE formats */
+
+static const unsigned char BIG_ENDIAN_BYTEORDER[8] = {7,6,5,4,3,2,1,0};
+static const unsigned char LITTLE_ENDIAN_BYTEORDER[8] = {0,1,2,3,4,5,6,7};
+static const unsigned char ARM_MIXED_ENDIAN_BYTEORDER[8] = {4,5,6,7,0,1,2,3};
+
static float_format_type double_format, float_format;
static float_format_type detected_double_format, detected_float_format;
@@ -1889,6 +1898,8 @@
return PyString_FromString("IEEE, little-endian");
case ieee_big_endian_format:
return PyString_FromString("IEEE, big-endian");
+ case ieee_arm_mixed_endian_format:
+ return PyString_FromString("IEEE, ARM mixed-endian");
default:
Py_FatalError("insane float_format or double_format");
return NULL;
@@ -1902,8 +1913,9 @@
"used in Python's test suite.\n"
"\n"
"typestr must be 'double' or 'float'. This function returns whichever of\n"
-"'unknown', 'IEEE, big-endian' or 'IEEE, little-endian' best describes the\n"
-"format of floating point numbers used by the C type named by typestr.");
+"'unknown', 'IEEE, big-endian', 'IEEE, little-endian' or\n"
+"'IEEE, ARM mixed-endian' best describes the format of floating-point\n"
+"numbers used by the C type named by typestr.");
static PyObject *
float_setformat(PyTypeObject *v, PyObject* args)
@@ -1941,11 +1953,15 @@
else if (strcmp(format, "IEEE, big-endian") == 0) {
f = ieee_big_endian_format;
}
+ else if (strcmp(format, "IEEE, ARM mixed-endian") == 0 &&
+ p == &double_format) {
+ f = ieee_arm_mixed_endian_format;
+ }
else {
PyErr_SetString(PyExc_ValueError,
"__setformat__() argument 2 must be "
- "'unknown', 'IEEE, little-endian' or "
- "'IEEE, big-endian'");
+ "'unknown', 'IEEE, little-endian', "
+ "'IEEE, big-endian' or 'IEEE, ARM mixed-endian'");
return NULL;
}
@@ -1968,8 +1984,10 @@
"used in Python's test suite.\n"
"\n"
"typestr must be 'double' or 'float'. fmt must be one of 'unknown',\n"
-"'IEEE, big-endian' or 'IEEE, little-endian', and in addition can only be\n"
-"one of the latter two if it appears to match the underlying C reality.\n"
+"'IEEE, big-endian', 'IEEE, little-endian' or 'IEEE, ARM mixed-endian'\n"
+"and in addition can only be one of the last three if it appears to\n"
+"match the underlying C reality. Note that the ARM mixed-endian\n"
+"format can only be set for the 'double' type, not for 'float'.\n"
"\n"
"Override the automatic determination of C-level floating point type.\n"
"This affects how floats are converted to and from binary strings.");
@@ -2164,7 +2182,11 @@
Note that if we're on some whacked-out platform which uses
IEEE formats but isn't strictly little-endian or big-
endian, we will fall back to the portable shifts & masks
- method. */
+ method.
+
+ Addendum: We also attempt to detect the mixed-endian IEEE format
+ used by the ARM old ABI (OABI) and also used by the FPA
+ floating-point unit on some older ARM processors. */
#if SIZEOF_DOUBLE == 8
{
@@ -2173,6 +2195,8 @@
detected_double_format = ieee_big_endian_format;
else if (memcmp(&x, "\x05\x04\x03\x02\x01\xff\x3f\x43", 8) == 0)
detected_double_format = ieee_little_endian_format;
+ else if (memcmp(&x, "\x01\xff\x3f\x43\x05\x04\x03\x02", 8) == 0)
+ detected_double_format = ieee_arm_mixed_endian_format;
else
detected_double_format = unknown_format;
}
@@ -2518,17 +2542,31 @@
}
else {
const char *s = (char*)&x;
- int i, incr = 1;
+ int i;
+ const unsigned char *byteorder;
- if ((double_format == ieee_little_endian_format && !le)
- || (double_format == ieee_big_endian_format && le)) {
- p += 7;
- incr = -1;
+ switch (double_format) {
+ case ieee_little_endian_format:
+ byteorder = LITTLE_ENDIAN_BYTEORDER;
+ break;
+ case ieee_big_endian_format:
+ byteorder = BIG_ENDIAN_BYTEORDER;
+ break;
+ case ieee_arm_mixed_endian_format:
+ byteorder = ARM_MIXED_ENDIAN_BYTEORDER;
+ break;
+ default:
+ Py_FatalError("insane float_format or double_format");
+ return -1;
}
- for (i = 0; i < 8; i++) {
- *p = *s++;
- p += incr;
+ if (le) {
+ for (i = 0; i < 8; i++)
+ p[byteorder[i]] = *s++;
+ }
+ else {
+ for (i = 0; i < 8; i++)
+ p[7-byteorder[i]] = *s++;
}
return 0;
}
@@ -2687,22 +2725,33 @@
}
else {
double x;
+ char *s = (char*)&x;
+ const unsigned char *byteorder;
+ int i;
+
+ switch (double_format) {
+ case ieee_little_endian_format:
+ byteorder = LITTLE_ENDIAN_BYTEORDER;
+ break;
+ case ieee_big_endian_format:
+ byteorder = BIG_ENDIAN_BYTEORDER;
+ break;
+ case ieee_arm_mixed_endian_format:
+ byteorder = ARM_MIXED_ENDIAN_BYTEORDER;
+ break;
+ default:
+ Py_FatalError("insane float_format or double_format");
+ return -1.0;
+ }
- if ((double_format == ieee_little_endian_format && !le)
- || (double_format == ieee_big_endian_format && le)) {
- char buf[8];
- char *d = &buf[7];
- int i;
-
- for (i = 0; i < 8; i++) {
- *d-- = *p++;
- }
- memcpy(&x, buf, 8);
+ if (le) {
+ for (i=0; i<8; i++)
+ *s++ = p[byteorder[i]];
}
else {
- memcpy(&x, p, 8);
+ for (i=0; i<8; i++)
+ *s++ = p[7-byteorder[i]];
}
-
return x;
}
}
|
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