util: add getbefloat64

As far as I can tell, this is wrong. double's format isn't strictly
specified in the C standard, but the wikipedia article implies that
platforms implementing optional Annex F "IEC 60559 floating-point
arithmetic" will work correctly.

My local C experts believe doing *((double *) &t) is a strict aliasing
violation, and that using a union is also one. Doing memcpy appears to
be the least-undefined behavior possible.

mercurial/util.h

@@ -1,199 +1,212 b''
 /*
  util.h - utility functions for interfacing with the various python APIs.
 
  This software may be used and distributed according to the terms of
  the GNU General Public License, incorporated herein by reference.
 */
 
 #ifndef _HG_UTIL_H_
 #define _HG_UTIL_H_
 
 #if PY_MAJOR_VERSION >= 3
 
 #define IS_PY3K
 #define PyInt_FromLong PyLong_FromLong
 #define PyInt_AsLong PyLong_AsLong
 
 /*
  Mapping of some of the python < 2.x PyString* functions to py3k's PyUnicode.
 
  The commented names below represent those that are present in the PyBytes
  definitions for python < 2.6 (below in this file) that don't have a direct
  implementation.
 */
 
 #define PyStringObject PyUnicodeObject
 #define PyString_Type PyUnicode_Type
 
 #define PyString_Check PyUnicode_Check
 #define PyString_CheckExact PyUnicode_CheckExact
 #define PyString_CHECK_INTERNED PyUnicode_CHECK_INTERNED
 #define PyString_AS_STRING PyUnicode_AsLatin1String
 #define PyString_GET_SIZE PyUnicode_GET_SIZE
 
 #define PyString_FromStringAndSize PyUnicode_FromStringAndSize
 #define PyString_FromString PyUnicode_FromString
 #define PyString_FromFormatV PyUnicode_FromFormatV
 #define PyString_FromFormat PyUnicode_FromFormat
 /* #define PyString_Size PyUnicode_GET_SIZE */
 /* #define PyString_AsString */
 /* #define PyString_Repr */
 #define PyString_Concat PyUnicode_Concat
 #define PyString_ConcatAndDel PyUnicode_AppendAndDel
 #define _PyString_Resize PyUnicode_Resize
 /* #define _PyString_Eq */
 #define PyString_Format PyUnicode_Format
 /* #define _PyString_FormatLong */
 /* #define PyString_DecodeEscape */
 #define _PyString_Join PyUnicode_Join
 #define PyString_Decode PyUnicode_Decode
 #define PyString_Encode PyUnicode_Encode
 #define PyString_AsEncodedObject PyUnicode_AsEncodedObject
 #define PyString_AsEncodedString PyUnicode_AsEncodedString
 #define PyString_AsDecodedObject PyUnicode_AsDecodedObject
 #define PyString_AsDecodedString PyUnicode_AsDecodedUnicode
 /* #define PyString_AsStringAndSize */
 #define _PyString_InsertThousandsGrouping _PyUnicode_InsertThousandsGrouping
 
 #endif /* PY_MAJOR_VERSION */
 
 /* Backports from 2.6 */
 #if PY_VERSION_HEX < 0x02060000
 
 #define Py_TYPE(ob) (ob)->ob_type
 #define Py_SIZE(ob) (ob)->ob_size
 #define PyVarObject_HEAD_INIT(type, size) PyObject_HEAD_INIT(type) size,
 
 /* Shamelessly stolen from bytesobject.h */
 #define PyBytesObject PyStringObject
 #define PyBytes_Type PyString_Type
 
 #define PyBytes_Check PyString_Check
 #define PyBytes_CheckExact PyString_CheckExact
 #define PyBytes_CHECK_INTERNED PyString_CHECK_INTERNED
 #define PyBytes_AS_STRING PyString_AS_STRING
 #define PyBytes_GET_SIZE PyString_GET_SIZE
 #define Py_TPFLAGS_BYTES_SUBCLASS Py_TPFLAGS_STRING_SUBCLASS
 
 #define PyBytes_FromStringAndSize PyString_FromStringAndSize
 #define PyBytes_FromString PyString_FromString
 #define PyBytes_FromFormatV PyString_FromFormatV
 #define PyBytes_FromFormat PyString_FromFormat
 #define PyBytes_Size PyString_Size
 #define PyBytes_AsString PyString_AsString
 #define PyBytes_Repr PyString_Repr
 #define PyBytes_Concat PyString_Concat
 #define PyBytes_ConcatAndDel PyString_ConcatAndDel
 #define _PyBytes_Resize _PyString_Resize
 #define _PyBytes_Eq _PyString_Eq
 #define PyBytes_Format PyString_Format
 #define _PyBytes_FormatLong _PyString_FormatLong
 #define PyBytes_DecodeEscape PyString_DecodeEscape
 #define _PyBytes_Join _PyString_Join
 #define PyBytes_Decode PyString_Decode
 #define PyBytes_Encode PyString_Encode
 #define PyBytes_AsEncodedObject PyString_AsEncodedObject
 #define PyBytes_AsEncodedString PyString_AsEncodedString
 #define PyBytes_AsDecodedObject PyString_AsDecodedObject
 #define PyBytes_AsDecodedString PyString_AsDecodedString
 #define PyBytes_AsStringAndSize PyString_AsStringAndSize
 #define _PyBytes_InsertThousandsGrouping _PyString_InsertThousandsGrouping
 
 #endif /* PY_VERSION_HEX */
 
 #if (PY_VERSION_HEX < 0x02050000)
 /* Definitions to get compatibility with python 2.4 and earlier which
    does not have Py_ssize_t. See also PEP 353.
    Note: msvc (8 or earlier) does not have ssize_t, so we use Py_ssize_t.
 */
 typedef int Py_ssize_t;
 typedef Py_ssize_t (*lenfunc)(PyObject *);
 typedef PyObject *(*ssizeargfunc)(PyObject *, Py_ssize_t);
 #define PyInt_FromSsize_t PyInt_FromLong
 
 #if !defined(PY_SSIZE_T_MIN)
 #define PY_SSIZE_T_MAX INT_MAX
 #define PY_SSIZE_T_MIN INT_MIN
 #endif
 #endif
 
 #ifdef _WIN32
 #ifdef _MSC_VER
 /* msvc 6.0 has problems */
 #define inline __inline
 typedef signed char int8_t;
 typedef short int16_t;
 typedef long int32_t;
 typedef __int64 int64_t;
 typedef unsigned char uint8_t;
 typedef unsigned short uint16_t;
 typedef unsigned long uint32_t;
 typedef unsigned __int64 uint64_t;
 #else
 #include <stdint.h>
 #endif
 #else
 /* not windows */
 #include <sys/types.h>
 #if defined __BEOS__ && !defined __HAIKU__
 #include <ByteOrder.h>
 #else
 #include <arpa/inet.h>
 #endif
 #include <inttypes.h>
 #endif
 
 #if defined __hpux || defined __SUNPRO_C || defined _AIX
 #define inline
 #endif
 
 #ifdef __linux
 #define inline __inline
 #endif
 
 typedef struct {
 	PyObject_HEAD
 	char state;
 	int mode;
 	int size;
 	int mtime;
 } dirstateTupleObject;
 
 extern PyTypeObject dirstateTupleType;
 #define dirstate_tuple_check(op) (Py_TYPE(op) == &dirstateTupleType)
 
 static inline uint32_t getbe32(const char *c)
 {
 	const unsigned char *d = (const unsigned char *)c;
 
 	return ((d[0] << 24) |
 		(d[1] << 16) |
 		(d[2] << 8) |
 		(d[3]));
 }
 
 static inline int16_t getbeint16(const char *c)
 {
 	const unsigned char *d = (const unsigned char *)c;
 
 	return ((d[0] << 8) |
 		(d[1]));
 }
 
 static inline uint16_t getbeuint16(const char *c)
 {
 	const unsigned char *d = (const unsigned char *)c;
 
 	return ((d[0] << 8) |
 		(d[1]));
 }
 
 static inline void putbe32(uint32_t x, char *c)
 {
 	c[0] = (x >> 24) & 0xff;
 	c[1] = (x >> 16) & 0xff;
 	c[2] = (x >> 8) & 0xff;
 	c[3] = (x) & 0xff;
 }
 
+static inline double getbefloat64(const char *c)
+{
+	const unsigned char *d = (const unsigned char *)c;
+	double ret;
+	int i;
+	uint64_t t = 0;
+	for (i = 0; i < 8; i++) {
+		t = (t<<8) + d[i];
+	}
+	memcpy(&ret, &t, sizeof(t));
+	return ret;
+}
+
 #endif /* _HG_UTIL_H_ */