structmodule.c

python s60 1.4.5版本的源代码

lu_float(const char *p, const formatdef *f)
{
	return unpack_float(p+3, -1);
}

static PyObject *
lu_double(const char *p, const formatdef *f)
{
	return unpack_double(p+7, -1);
}

static int
lp_int(char *p, PyObject *v, const formatdef *f)
{
	long x;
	int i;
	if (get_long(v, &x) < 0)
		return -1;
	i = f->size;
	do {
		*p++ = (char)x;
		x >>= 8;
	} while (--i > 0);
	return 0;
}

static int
lp_uint(char *p, PyObject *v, const formatdef *f)
{
	unsigned long x;
	int i;
	if (get_ulong(v, &x) < 0)
		return -1;
	i = f->size;
	do {
		*p++ = (char)x;
		x >>= 8;
	} while (--i > 0);
	return 0;
}

static int
lp_longlong(char *p, PyObject *v, const formatdef *f)
{
	int res;
	v = get_pylong(v);
	if (v == NULL)
		return -1;
	res = _PyLong_AsByteArray((PyLongObject*)v,
			   	  (unsigned char *)p,
				  8,
				  1, /* little_endian */
				  1  /* signed */);
	Py_DECREF(v);
	return res;
}

static int
lp_ulonglong(char *p, PyObject *v, const formatdef *f)
{
	int res;
	v = get_pylong(v);
	if (v == NULL)
		return -1;
	res = _PyLong_AsByteArray((PyLongObject*)v,
			   	  (unsigned char *)p,
				  8,
				  1, /* little_endian */
				  0  /* signed */);
	Py_DECREF(v);
	return res;
}

static int
lp_float(char *p, PyObject *v, const formatdef *f)
{
	double x = PyFloat_AsDouble(v);
	if (x == -1 && PyErr_Occurred()) {
		PyErr_SetString(StructError,
				"required argument is not a float");
		return -1;
	}
	return pack_float(x, p+3, -1);
}

static int
lp_double(char *p, PyObject *v, const formatdef *f)
{
	double x = PyFloat_AsDouble(v);
	if (x == -1 && PyErr_Occurred()) {
		PyErr_SetString(StructError,
				"required argument is not a float");
		return -1;
	}
	return pack_double(x, p+7, -1);
}

const static formatdef lilendian_table[] = {
	{'x',	1,		0,		NULL},
	{'b',	1,		0,		lu_int,		lp_int},
	{'B',	1,		0,		lu_uint,	lp_int},
	{'c',	1,		0,		nu_char,	np_char},
	{'s',	1,		0,		NULL},
	{'p',	1,		0,		NULL},
	{'h',	2,		0,		lu_int,		lp_int},
	{'H',	2,		0,		lu_uint,	lp_uint},
	{'i',	4,		0,		lu_int,		lp_int},
	{'I',	4,		0,		lu_uint,	lp_uint},
	{'l',	4,		0,		lu_int,		lp_int},
	{'L',	4,		0,		lu_uint,	lp_uint},
	{'q',	8,		0,		lu_longlong,	lp_longlong},
	{'Q',	8,		0,		lu_ulonglong,	lp_ulonglong},
	{'f',	4,		0,		lu_float,	lp_float},
	{'d',	8,		0,		lu_double,	lp_double},
	{0}
};


static const formatdef *
whichtable(char **pfmt)
{
	const char *fmt = (*pfmt)++; /* May be backed out of later */
	switch (*fmt) {
	case '<':
		return lilendian_table;
	case '>':
	case '!': /* Network byte order is big-endian */
		return bigendian_table;
	case '=': { /* Host byte order -- different from native in aligment! */
		int n = 1;
		char *p = (char *) &n;
		if (*p == 1)
			return lilendian_table;
		else
			return bigendian_table;
	}
	default:
		--*pfmt; /* Back out of pointer increment */
		/* Fall through */
	case '@':
		return native_table;
	}
}


/* Get the table entry for a format code */

static const formatdef *
getentry(int c, const formatdef *f)
{
	for (; f->format != '\0'; f++) {
		if (f->format == c) {
			return f;
		}
	}
	PyErr_SetString(StructError, "bad char in struct format");
	return NULL;
}


/* Align a size according to a format code */

static int
align(int size, int c, const formatdef *e)
{
	if (e->format == c) {
		if (e->alignment) {
			size = ((size + e->alignment - 1)
				/ e->alignment)
				* e->alignment;
		}
	}
	return size;
}


/* calculate the size of a format string */

static int
calcsize(const char *fmt, const formatdef *f)
{
	const formatdef *e;
	const char *s;
	char c;
	int size,  num, itemsize, x;

	s = fmt;
	size = 0;
	while ((c = *s++) != '\0') {
		if (isspace((int)c))
			continue;
		if ('0' <= c && c <= '9') {
			num = c - '0';
			while ('0' <= (c = *s++) && c <= '9') {
				x = num*10 + (c - '0');
				if (x/10 != num) {
					PyErr_SetString(
						StructError,
						"overflow in item count");
					return -1;
				}
				num = x;
			}
			if (c == '\0')
				break;
		}
		else
			num = 1;

		e = getentry(c, f);
		if (e == NULL)
			return -1;
		itemsize = e->size;
		size = align(size, c, e);
		x = num * itemsize;
		size += x;
		if (x/itemsize != num || size < 0) {
			PyErr_SetString(StructError,
					"total struct size too long");
			return -1;
		}
	}

	return size;
}


const static char calcsize__doc__[] = "\
calcsize(fmt) -> int\n\
Return size of C struct described by format string fmt.\n\
See struct.__doc__ for more on format strings.";

static PyObject *
struct_calcsize(PyObject *self, PyObject *args)
{
	char *fmt;
	const formatdef *f;
	int size;

	if (!PyArg_ParseTuple(args, "s:calcsize", &fmt))
		return NULL;
	f = whichtable(&fmt);
	size = calcsize(fmt, f);
	if (size < 0)
		return NULL;
	return PyInt_FromLong((long)size);
}


const static char pack__doc__[] = "\
pack(fmt, v1, v2, ...) -> string\n\
Return string containing values v1, v2, ... packed according to fmt.\n\
See struct.__doc__ for more on format strings.";

static PyObject *
struct_pack(PyObject *self, PyObject *args)
{
	const formatdef *f, *e;
	PyObject *format, *result, *v;
	char *fmt;
	int size, num;
	int i, n;
	char *s, *res, *restart, *nres;
	char c;

	if (args == NULL || !PyTuple_Check(args) ||
	    (n = PyTuple_Size(args)) < 1)
	{
		PyErr_SetString(PyExc_TypeError,
			"struct.pack requires at least one argument");
		return NULL;
	}
	format = PyTuple_GetItem(args, 0);
	if (!PyArg_Parse(format, "s", &fmt))
		return NULL;
	f = whichtable(&fmt);
	size = calcsize(fmt, f);
	if (size < 0)
		return NULL;
	result = PyString_FromStringAndSize((char *)NULL, size);
	if (result == NULL)
		return NULL;

	s = fmt;
	i = 1;
	res = restart = PyString_AsString(result);

	while ((c = *s++) != '\0') {
		if (isspace((int)c))
			continue;
		if ('0' <= c && c <= '9') {
			num = c - '0';
			while ('0' <= (c = *s++) && c <= '9')
			       num = num*10 + (c - '0');
			if (c == '\0')
				break;
		}
		else
			num = 1;

		e = getentry(c, f);
		if (e == NULL)
			goto fail;
		nres = restart + align((int)(res-restart), c, e);
		/* Fill padd bytes with zeros */
		while (res < nres)
			*res++ = '\0';
		if (num == 0 && c != 's')
			continue;
		do {
			if (c == 'x') {
				/* doesn't consume arguments */
				memset(res, '\0', num);
				res += num;
				break;
			}
			if (i >= n) {
				PyErr_SetString(StructError,
					"insufficient arguments to pack");
				goto fail;
				}
			v = PyTuple_GetItem(args, i++);
			if (v == NULL)
				goto fail;
			if (c == 's') {
				/* num is string size, not repeat count */
				int n;
				if (!PyString_Check(v)) {
					PyErr_SetString(StructError,
					  "argument for 's' must be a string");
					goto fail;
				}
				n = PyString_Size(v);
				if (n > num)
					n = num;
				if (n > 0)
					memcpy(res, PyString_AsString(v), n);
				if (n < num)
					memset(res+n, '\0', num-n);
				res += num;
				break;
			}
			else if (c == 'p') {
				/* num is string size + 1,
				   to fit in the count byte */
				int n;
				num--; /* now num is max string size */
				if (!PyString_Check(v)) {
					PyErr_SetString(StructError,
					  "argument for 'p' must be a string");
					goto fail;
				}
				n = PyString_Size(v);
				if (n > num)
					n = num;
				if (n > 0)
					memcpy(res+1, PyString_AsString(v), n);
				if (n < num)
					/* no real need, just to be nice */
					memset(res+1+n, '\0', num-n);
				if (n > 255)
					n = 255;
				*res++ = n; /* store the length byte */
				res += num;
				break;
			}
			else {
				if (e->pack(res, v, e) < 0)
					goto fail;
				res += e->size;
			}
		} while (--num > 0);
	}

	if (i < n) {
		PyErr_SetString(StructError,
				"too many arguments for pack format");
		goto fail;
	}

	return result;

 fail:
	Py_DECREF(result);
	return NULL;
}


const static char unpack__doc__[] = "\
unpack(fmt, string) -> (v1, v2, ...)\n\
Unpack the string, containing packed C structure data, according\n\
to fmt.  Requires len(string)==calcsize(fmt).\n\
See struct.__doc__ for more on format strings.";

static PyObject *
struct_unpack(PyObject *self, PyObject *args)
{
	const formatdef *f, *e;
	char *str, *start, *fmt, *s;
	char c;
	int len, size, num;
	PyObject *res, *v;

	if (!PyArg_ParseTuple(args, "ss#:unpack", &fmt, &start, &len))
		return NULL;
	f = whichtable(&fmt);
	size = calcsize(fmt, f);
	if (size < 0)
		return NULL;
	if (size != len) {
		PyErr_SetString(StructError,
				"unpack str size does not match format");
		return NULL;
	}
	res = PyList_New(0);
	if (res == NULL)
		return NULL;
	str = start;
	s = fmt;
	while ((c = *s++) != '\0') {
		if (isspace((int)c))
			continue;
		if ('0' <= c && c <= '9') {
			num = c - '0';
			while ('0' <= (c = *s++) && c <= '9')
			       num = num*10 + (c - '0');
			if (c == '\0')
				break;
		}
		else
			num = 1;

		e = getentry(c, f);
		if (e == NULL)
			goto fail;
		str = start + align((int)(str-start), c, e);
		if (num == 0 && c != 's')
			continue;

		do {
			if (c == 'x') {
				str += num;
				break;
			}
			if (c == 's') {
				/* num is string size, not repeat count */
				v = PyString_FromStringAndSize(str, num);
				if (v == NULL)
					goto fail;
				str += num;
				num = 0;
			}
			else if (c == 'p') {
				/* num is string buffer size,
				   not repeat count */
				int n = *(unsigned char*)str;
				/* first byte (unsigned) is string size */
				if (n >= num)
					n = num-1;
				v = PyString_FromStringAndSize(str+1, n);
				if (v == NULL)
					goto fail;
				str += num;
				num = 0;
			}
			else {
				v = e->unpack(str, e);
				if (v == NULL)
					goto fail;
				str += e->size;
			}
			if (v == NULL || PyList_Append(res, v) < 0)
				goto fail;
			Py_DECREF(v);
		} while (--num > 0);
	}

	v = PyList_AsTuple(res);
	Py_DECREF(res);
	return v;

 fail:
	Py_DECREF(res);
	return NULL;
}


/* List of functions */

const static struct PyMethodDef struct_methods[] = {
	{"calcsize",	struct_calcsize,	METH_VARARGS, calcsize__doc__},
	{"pack",	struct_pack,		METH_VARARGS, pack__doc__},
	{"unpack",	struct_unpack,		METH_VARARGS, unpack__doc__},
	{NULL,		NULL}		/* sentinel */
};


/* Module initialization */

DL_EXPORT(void)
initstruct(void)
{
	PyObject *m, *d;

	/* Create the module and add the functions */
	m = Py_InitModule4("struct", struct_methods, struct__doc__,
			   (PyObject*)NULL, PYTHON_API_VERSION);

	/* Add some symbolic constants to the module */
	d = PyModule_GetDict(m);
	StructError = PyErr_NewException("struct.error", NULL, NULL);
	if (StructError == NULL)
		return;
	PyDict_SetItemString(d, "error", StructError);
}