Initial support for 'q' and 'Q' struct format codes: for now, only in

native mode, and only when config #defines HAVE_LONG_LONG.  Standard mode
will eventually treat them as 8-byte ints across all platforms, but that
likely requires a new set of routines in longobject.c first (while
sizeof(long) >= 4 is guaranteed by C, there's nothing in C we can rely
on x-platform to hold 8 bytes of int, so we'll have to roll our own;
I'm thinking of a simple pair of conversion functions, Python long
to/from sized vector of unsigned bytes; that may be useful for GMP
conversions too; std q/Q would call them with size fixed at 8).

test_struct.py:  In addition to adding some native-mode 'q' and 'Q' tests,
got rid of unused code, and repaired a non-portable assumption about
native sizeof(short) (it isn't 2 on some Cray boxes).

libstruct.tex:  In addition to adding a bit of 'q'/'Q' docs (more needed
later), removed an erroneous footnote about 'I' behavior.
This commit is contained in:
Tim Peters 2001-06-10 23:40:19 +00:00
parent fcc54cab10
commit 7b9542a3f7
4 changed files with 247 additions and 16 deletions

View File

@ -53,9 +53,11 @@ C and Python values should be obvious given their types:
\lineiv{h}{\ctype{short}}{integer}{}
\lineiv{H}{\ctype{unsigned short}}{integer}{}
\lineiv{i}{\ctype{int}}{integer}{}
\lineiv{I}{\ctype{unsigned int}}{long}{(1)}
\lineiv{I}{\ctype{unsigned int}}{long}{}
\lineiv{l}{\ctype{long}}{integer}{}
\lineiv{L}{\ctype{unsigned long}}{long}{}
\lineiv{q}{\ctype{long long}}{long}{(1)}
\lineiv{Q}{\ctype{unsigned long long}}{long}{(1)}
\lineiv{f}{\ctype{float}}{float}{}
\lineiv{d}{\ctype{double}}{float}{}
\lineiv{s}{\ctype{char[]}}{string}{}
@ -68,10 +70,9 @@ Notes:
\begin{description}
\item[(1)]
The \character{I} conversion code will convert to a Python long if
the C \ctype{int} is the same size as a C \ctype{long}, which is
typical on most modern systems. If a C \ctype{int} is smaller than
a C \ctype{long}, an Python integer will be created instead.
The \character{q} and \character{Q} conversion codes are available in
native mode only if the platform C compiler supports C \ctype{long long},
or, on Windows, \ctype{__int64}.
\end{description}

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@ -1,4 +1,4 @@
from test_support import TestFailed, verbose
from test_support import TestFailed, verbose, verify
import struct
## import pdb
@ -12,7 +12,7 @@ def simple_err(func, *args):
func.__name__, args)
## pdb.set_trace()
simple_err(struct.calcsize, 'Q')
simple_err(struct.calcsize, 'Z')
sz = struct.calcsize('i')
if sz * 3 != struct.calcsize('iii'):
@ -93,14 +93,7 @@ tests = [
'\000\000\000\000\000\000\000\300', 0),
]
def badpack(fmt, arg, got, exp):
return
def badunpack(fmt, arg, got, exp):
return "unpack(%s, %s) -> (%s,) # expected (%s,)" % (
`fmt`, `arg`, `got`, `exp`)
isbigendian = struct.pack('=h', 1) == '\0\1'
isbigendian = struct.pack('=i', 1)[0] == chr(0)
for fmt, arg, big, lil, asy in tests:
if verbose:
@ -119,3 +112,47 @@ for fmt, arg, big, lil, asy in tests:
if rev != arg and not asy:
raise TestFailed, "unpack(%s, %s) -> (%s,) # expected (%s,)" % (
`fmt`, `res`, `rev`, `arg`)
# Some q/Q sanity checks.
has_native_qQ = 1
try:
struct.pack("q", 5)
except struct.error:
has_native_qQ = 0
if verbose:
print "Platform has native q/Q?", has_native_qQ and "Yes." or "No."
simple_err(struct.pack, "Q", -1) # can't pack -1 as unsigned regardless
simple_err(struct.pack, "q", "a") # can't pack string as 'q' regardless
simple_err(struct.pack, "Q", "a") # ditto, but 'Q'
def force_bigendian(value):
if isbigendian:
return value
chars = list(value)
chars.reverse()
return "".join(chars)
if has_native_qQ:
bytes = struct.calcsize('q')
# The expected values here are in big-endian format, primarily because
# I'm on a little-endian machine and so this is the clearest way (for
# me) to force the code to get exercised.
for format, input, expected in (
('q', -1, '\xff' * bytes),
('q', 0, '\x00' * bytes),
('Q', 0, '\x00' * bytes),
('q', 1L, '\x00' * (bytes-1) + '\x01'),
('Q', (1L << (8*bytes))-1, '\xff' * bytes),
('q', (1L << (8*bytes-1))-1, '\x7f' + '\xff' * (bytes - 1))):
got = struct.pack(format, input)
bigexpected = force_bigendian(expected)
verify(got == bigexpected,
"%r-pack of %r gave %r, not %r" %
(format, input, got, bigexpected))
retrieved = struct.unpack(format, got)[0]
verify(retrieved == input,
"%r-unpack of %r gave %r, not %r" %
(format, got, retrieved, input))

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@ -140,6 +140,14 @@ Library
- pprint functions now much faster for large containers (tuple, list, dict).
- New 'q' and 'Q' format codes in the struct module, corresponding to C
types "long long" and "unsigned long long" (on Windows, __int64). In
native mode, these can be used only when the platform C compiler supports
these types (when HAVE_LONG_LONG is #define'd by the Python config
process), and then they inherit the sizes and alignments of the C types.
XXX TODO In standard mode, 'q' and 'Q' are supported on all platforms, and
XXX TODO are 8-byte integral types.
Tests
- New test_mutants.py runs dict comparisons where the key and value

View File

@ -22,9 +22,11 @@ these can be preceded by a decimal repeat count:\n\
h:short; H:unsigned short; i:int; I:unsigned int;\n\
l:long; L:unsigned long; f:float; d:double.\n\
Special cases (preceding decimal count indicates length):\n\
s:string (array of char); p: pascal string (w. count byte).\n\
s:string (array of char); p: pascal string (with count byte).\n\
Special case (only available in native format):\n\
P:an integer type that is wide enough to hold a pointer.\n\
Special case (not in native mode unless 'long long' in platform C):\n\
q:long long; Q:unsigned long long\n\
Whitespace between formats is ignored.\n\
\n\
The variable struct.error is an exception raised on errors.";
@ -65,6 +67,18 @@ typedef struct { char c; void *x; } s_void_p;
#define DOUBLE_ALIGN (sizeof(s_double) - sizeof(double))
#define VOID_P_ALIGN (sizeof(s_void_p) - sizeof(void *))
/* We can't support q and Q in native mode unless the compiler does;
in std mode, they're 8 bytes on all platforms. */
#ifdef HAVE_LONG_LONG
typedef struct { char c; LONG_LONG x; } s_long_long;
#define LONG_LONG_ALIGN (sizeof(s_long_long) - sizeof(LONG_LONG))
#else
static char qQ_error_msg[] =
"q and Q unavailable in native mode on this platform; use a standard mode.\0";
#endif
#define STRINGIFY(x) #x
#ifdef __powerc
@ -106,6 +120,93 @@ get_ulong(PyObject *v, unsigned long *p)
}
}
#ifdef HAVE_LONG_LONG
/* Same, but handling native long long. */
static int
get_longlong(PyObject *v, LONG_LONG *p)
{
LONG_LONG x;
int v_needs_decref = 0;
if (PyInt_Check(v)) {
x = (LONG_LONG)PyInt_AS_LONG(v);
*p = x;
return 0;
}
if (!PyLong_Check(v)) {
PyNumberMethods *m = v->ob_type->tp_as_number;
if (m != NULL && m->nb_long != NULL) {
v = m->nb_long(v);
if (v == NULL)
return -1;
v_needs_decref = 1;
}
if (!PyLong_Check(v)) {
PyErr_SetString(StructError,
"cannot convert argument to long");
if (v_needs_decref)
Py_DECREF(v);
return -1;
}
}
assert(PyLong_Check(v));
x = PyLong_AsLongLong(v);
if (v_needs_decref)
Py_DECREF(v);
if (x == (LONG_LONG)-1 && PyErr_Occurred())
return -1;
*p = x;
return 0;
}
/* Same, but handling native unsigned long long. */
static int
get_ulonglong(PyObject *v, unsigned LONG_LONG *p)
{
unsigned LONG_LONG x;
int v_needs_decref = 0;
if (PyInt_Check(v)) {
long i = PyInt_AS_LONG(v);
if (i < 0) {
PyErr_SetString(StructError, "can't convert negative "
"int to unsigned");
return -1;
}
x = (unsigned LONG_LONG)i;
*p = x;
return 0;
}
if (!PyLong_Check(v)) {
PyNumberMethods *m = v->ob_type->tp_as_number;
if (m != NULL && m->nb_long != NULL) {
v = m->nb_long(v);
if (v == NULL)
return -1;
v_needs_decref = 1;
}
if (!PyLong_Check(v)) {
PyErr_SetString(StructError,
"cannot convert argument to long");
if (v_needs_decref)
Py_DECREF(v);
return -1;
}
}
assert(PyLong_Check(v));
x = PyLong_AsUnsignedLongLong(v);
if (v_needs_decref)
Py_DECREF(v);
if (x == (unsigned LONG_LONG)-1 && PyErr_Occurred())
return -1;
*p = x;
return 0;
}
#endif
/* Floating point helpers */
@ -395,6 +496,17 @@ typedef struct _formatdef {
const struct _formatdef *);
} formatdef;
/* A large number of small routines follow, with names of the form
[bln][up]_TYPE
[bln] distiguishes among big-endian, little-endian and native.
[pu] distiguishes between pack (to struct) and unpack (from struct).
TYPE is one of char, byte, ubyte, etc.
*/
/* Native mode routines. */
static PyObject *
nu_char(const char *p, const formatdef *f)
{
@ -450,6 +562,34 @@ nu_ulong(const char *p, const formatdef *f)
return PyLong_FromUnsignedLong(*(unsigned long *)p);
}
/* Native mode doesn't support q or Q unless the platform C supports
long long (or, on Windows, __int64). */
#ifdef HAVE_LONG_LONG
static PyObject *
nu_longlong(const char *p, const formatdef *f)
{
return PyLong_FromLongLong(*(LONG_LONG *)p);
}
static PyObject *
nu_ulonglong(const char *p, const formatdef *f)
{
return PyLong_FromUnsignedLongLong(*(unsigned LONG_LONG *)p);
}
#else
static PyObject *
nu_qQerror(const char *p, const formatdef *f)
{
PyErr_SetString(StructError, qQ_error_msg);
return NULL;
}
#endif
static PyObject *
nu_float(const char *p, const formatdef *f)
{
@ -585,6 +725,39 @@ np_ulong(char *p, PyObject *v, const formatdef *f)
return 0;
}
#ifdef HAVE_LONG_LONG
static int
np_longlong(char *p, PyObject *v, const formatdef *f)
{
LONG_LONG x;
if (get_longlong(v, &x) < 0)
return -1;
* (LONG_LONG *)p = x;
return 0;
}
static int
np_ulonglong(char *p, PyObject *v, const formatdef *f)
{
unsigned LONG_LONG x;
if (get_ulonglong(v, &x) < 0)
return -1;
* (unsigned LONG_LONG *)p = x;
return 0;
}
#else
static int
np_qQerror(char *p, PyObject *v, const formatdef *f)
{
PyErr_SetString(StructError, qQ_error_msg);
return -1;
}
#endif
static int
np_float(char *p, PyObject *v, const formatdef *f)
{
@ -642,6 +815,18 @@ static formatdef native_table[] = {
{'f', sizeof(float), FLOAT_ALIGN, nu_float, np_float},
{'d', sizeof(double), DOUBLE_ALIGN, nu_double, np_double},
{'P', sizeof(void *), VOID_P_ALIGN, nu_void_p, np_void_p},
#ifdef HAVE_LONG_LONG
{'q', sizeof(LONG_LONG), LONG_LONG_ALIGN, nu_longlong, np_longlong},
{'Q', sizeof(LONG_LONG), LONG_LONG_ALIGN, nu_ulonglong,np_ulonglong},
#else
/* n[pu]_qQerror just raise errors, but give them "the expected" size
and alignment anyway so that calcsize returns something reasonable,
and so unpack code that works on a 'long long' platform ends up in
the error routine instead of with a mysterious "unpack str size
does not match format" msg when run on a non-'long long' box. */
{'q', 8, 8, nu_qQerror, np_qQerror},
{'Q', 8, 8, nu_qQerror, np_qQerror},
#endif
{0}
};