[pypy-commit] cffi default: Fix C integer division. Add modulo.

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: 
Changeset: r3273:1fc05b4f57de
Date: 2019-04-26 14:15 +0200
http://bitbucket.org/cffi/cffi/changeset/1fc05b4f57de/

Log:	Fix C integer division. Add modulo.

diff --git a/cffi/cparser.py b/cffi/cparser.py
--- a/cffi/cparser.py
+++ b/cffi/cparser.py
@@ -868,8 +868,9 @@
             elif exprnode.op == '*':
                 return left * right
             elif exprnode.op == '/':
-                # do integer division!
-                return left // right
+                return self._c_div(left, right)
+            elif exprnode.op == '%':
+                return left - self._c_div(left, right) * right
             elif exprnode.op == '<<':
                 return left << right
             elif exprnode.op == '>>':
@@ -884,6 +885,12 @@
         raise FFIError(":%d: unsupported expression: expected a "
                        "simple numeric constant" % exprnode.coord.line)
 
+    def _c_div(self, a, b):
+        result = a // b
+        if ((a < 0) ^ (b < 0)) and (a % b) != 0:
+            result += 1
+        return result
+
     def _build_enum_type(self, explicit_name, decls):
         if decls is not None:
             partial = False
diff --git a/testing/cffi0/test_verify.py b/testing/cffi0/test_verify.py
--- a/testing/cffi0/test_verify.py
+++ b/testing/cffi0/test_verify.py
@@ -2534,3 +2534,29 @@
         x.p = p
         x.cyclic = x
         del p, x
+
+def test_arithmetic_in_cdef():
+    for a in [0, 11, 15]:
+        ffi = FFI()
+        ffi.cdef("""
+            enum FOO {
+                DIVNN = ((-?) / (-3)),
+                DIVNP = ((-?) / (+3)),
+                DIVPN = ((+?) / (-3)),
+                MODNN = ((-?) % (-3)),
+                MODNP = ((-?) % (+3)),
+                MODPN = ((+?) % (-3)),
+                };
+        """.replace('?', str(a)))
+        lib = ffi.verify("""
+            enum FOO {
+                DIVNN = ((-?) / (-3)),
+                DIVNP = ((-?) / (+3)),
+                DIVPN = ((+?) / (-3)),
+                MODNN = ((-?) % (-3)),
+                MODNP = ((-?) % (+3)),
+                MODPN = ((+?) % (-3)),
+                };
+        """.replace('?', str(a)))
+        # the verify() crashes if the values in the enum are different from
+        # the values we computed ourselves from the cdef()