--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/bdiff_module.c	Wed Jul 13 10:46:26 2016 +0200
@@ -0,0 +1,203 @@
+/*
+ bdiff.c - efficient binary diff extension for Mercurial
+
+ Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
+
+ This software may be used and distributed according to the terms of
+ the GNU General Public License, incorporated herein by reference.
+
+ Based roughly on Python difflib
+*/
+
+#define PY_SSIZE_T_CLEAN
+#include <Python.h>
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+
+#include "bdiff.h"
+#include "bitmanipulation.h"
+
+
+static PyObject *blocks(PyObject *self, PyObject *args)
+{
+	PyObject *sa, *sb, *rl = NULL, *m;
+	struct bdiff_line *a, *b;
+	struct bdiff_hunk l, *h;
+	int an, bn, count, pos = 0;
+
+	l.next = NULL;
+
+	if (!PyArg_ParseTuple(args, "SS:bdiff", &sa, &sb))
+		return NULL;
+
+	an = bdiff_splitlines(PyBytes_AsString(sa), PyBytes_Size(sa), &a);
+	bn = bdiff_splitlines(PyBytes_AsString(sb), PyBytes_Size(sb), &b);
+
+	if (!a || !b)
+		goto nomem;
+
+	count = bdiff_diff(a, an, b, bn, &l);
+	if (count < 0)
+		goto nomem;
+
+	rl = PyList_New(count);
+	if (!rl)
+		goto nomem;
+
+	for (h = l.next; h; h = h->next) {
+		m = Py_BuildValue("iiii", h->a1, h->a2, h->b1, h->b2);
+		PyList_SetItem(rl, pos, m);
+		pos++;
+	}
+
+nomem:
+	free(a);
+	free(b);
+	bdiff_freehunks(l.next);
+	return rl ? rl : PyErr_NoMemory();
+}
+
+static PyObject *bdiff(PyObject *self, PyObject *args)
+{
+	char *sa, *sb, *rb;
+	PyObject *result = NULL;
+	struct bdiff_line *al, *bl;
+	struct bdiff_hunk l, *h;
+	int an, bn, count;
+	Py_ssize_t len = 0, la, lb;
+	PyThreadState *_save;
+
+	l.next = NULL;
+
+	if (!PyArg_ParseTuple(args, "s#s#:bdiff", &sa, &la, &sb, &lb))
+		return NULL;
+
+	if (la > UINT_MAX || lb > UINT_MAX) {
+		PyErr_SetString(PyExc_ValueError, "bdiff inputs too large");
+		return NULL;
+	}
+
+	_save = PyEval_SaveThread();
+	an = bdiff_splitlines(sa, la, &al);
+	bn = bdiff_splitlines(sb, lb, &bl);
+	if (!al || !bl)
+		goto nomem;
+
+	count = bdiff_diff(al, an, bl, bn, &l);
+	if (count < 0)
+		goto nomem;
+
+	/* calculate length of output */
+	la = lb = 0;
+	for (h = l.next; h; h = h->next) {
+		if (h->a1 != la || h->b1 != lb)
+			len += 12 + bl[h->b1].l - bl[lb].l;
+		la = h->a2;
+		lb = h->b2;
+	}
+	PyEval_RestoreThread(_save);
+	_save = NULL;
+
+	result = PyBytes_FromStringAndSize(NULL, len);
+
+	if (!result)
+		goto nomem;
+
+	/* build binary patch */
+	rb = PyBytes_AsString(result);
+	la = lb = 0;
+
+	for (h = l.next; h; h = h->next) {
+		if (h->a1 != la || h->b1 != lb) {
+			len = bl[h->b1].l - bl[lb].l;
+			putbe32((uint32_t)(al[la].l - al->l), rb);
+			putbe32((uint32_t)(al[h->a1].l - al->l), rb + 4);
+			putbe32((uint32_t)len, rb + 8);
+			memcpy(rb + 12, bl[lb].l, len);
+			rb += 12 + len;
+		}
+		la = h->a2;
+		lb = h->b2;
+	}
+
+nomem:
+	if (_save)
+		PyEval_RestoreThread(_save);
+	free(al);
+	free(bl);
+	bdiff_freehunks(l.next);
+	return result ? result : PyErr_NoMemory();
+}
+
+/*
+ * If allws != 0, remove all whitespace (' ', \t and \r). Otherwise,
+ * reduce whitespace sequences to a single space and trim remaining whitespace
+ * from end of lines.
+ */
+static PyObject *fixws(PyObject *self, PyObject *args)
+{
+	PyObject *s, *result = NULL;
+	char allws, c;
+	const char *r;
+	Py_ssize_t i, rlen, wlen = 0;
+	char *w;
+
+	if (!PyArg_ParseTuple(args, "Sb:fixws", &s, &allws))
+		return NULL;
+	r = PyBytes_AsString(s);
+	rlen = PyBytes_Size(s);
+
+	w = (char *)malloc(rlen ? rlen : 1);
+	if (!w)
+		goto nomem;
+
+	for (i = 0; i != rlen; i++) {
+		c = r[i];
+		if (c == ' ' || c == '\t' || c == '\r') {
+			if (!allws && (wlen == 0 || w[wlen - 1] != ' '))
+				w[wlen++] = ' ';
+		} else if (c == '\n' && !allws
+			  && wlen > 0 && w[wlen - 1] == ' ') {
+			w[wlen - 1] = '\n';
+		} else {
+			w[wlen++] = c;
+		}
+	}
+
+	result = PyBytes_FromStringAndSize(w, wlen);
+
+nomem:
+	free(w);
+	return result ? result : PyErr_NoMemory();
+}
+
+
+static char mdiff_doc[] = "Efficient binary diff.";
+
+static PyMethodDef methods[] = {
+	{"bdiff", bdiff, METH_VARARGS, "calculate a binary diff\n"},
+	{"blocks", blocks, METH_VARARGS, "find a list of matching lines\n"},
+	{"fixws", fixws, METH_VARARGS, "normalize diff whitespaces\n"},
+	{NULL, NULL}
+};
+
+#ifdef IS_PY3K
+static struct PyModuleDef bdiff_module = {
+	PyModuleDef_HEAD_INIT,
+	"bdiff",
+	mdiff_doc,
+	-1,
+	methods
+};
+
+PyMODINIT_FUNC PyInit_bdiff(void)
+{
+	return PyModule_Create(&bdiff_module);
+}
+#else
+PyMODINIT_FUNC initbdiff(void)
+{
+	Py_InitModule3("bdiff", methods, mdiff_doc);
+}
+#endif