mp.c: Describe `MP' and `GF' conversion semantics.

[catacomb-python] / mp.c

diff --git a/mp.c b/mp.c
index eb6a496b377ba668b061c3125b44580bd523d1cd..62d2dfeee29a7d6323128ab2317b1303a8742ee6 100644 (file)
--- a/mp.c
+++ b/mp.c
@@ -163,7 +163,7 @@ PyObject *gf_pywrap(mp *x)
   return ((PyObject *)z);
 }
 
-int mp_tolong_checked(mp *x, long *l)
+int mp_tolong_checked(mp *x, long *l, int must)
 {
   static mp *longmin = 0, *longmax = 0;
   int rc = -1;
@@ -172,8 +172,10 @@ int mp_tolong_checked(mp *x, long *l)
     longmin = mp_fromlong(MP_NEW, LONG_MIN);
     longmax = mp_fromlong(MP_NEW, LONG_MAX);
   }
-  if (MP_CMP(x, <, longmin) || MP_CMP(x, >, longmax))
-    VALERR("mp out of range for int");
+  if (MP_CMP(x, <, longmin) || MP_CMP(x, >, longmax)) {
+    if (must) VALERR("mp out of range for int");
+    else goto end;
+  }
   *l = mp_tolong(x);
   rc = 0;
 end:
@@ -362,7 +364,7 @@ static PyObject *mp_pyid(PyObject *x) { RETURN_OBJ(x); }
     PyObject *z = 0;                                                   \
     long n;                                                            \
     if (pre##binop(x, y, &xx, &yy)) RETURN_NOTIMPL;                    \
-    if (mp_tolong_checked(yy, &n)) goto end;                           \
+    if (mp_tolong_checked(yy, &n, 1)) goto end;                                \
     if (n < 0)                                                         \
       z = pre##_pywrap(mp_##rname(MP_NEW, xx, -n));                    \
     else                                                               \
@@ -483,8 +485,8 @@ static int mp_pynonzerop(PyObject *x) { return !MP_ZEROP(MP_X(x)); }
 static PyObject *mp_pyint(PyObject *x)
 {
   long l;
-  if (mp_tolong_checked(MP_X(x), &l)) return (0);
-  return (PyInt_FromLong(l));
+  if (!mp_tolong_checked(MP_X(x), &l, 0)) return (PyInt_FromLong(l));
+  else return mp_topylong(MP_X(x));
 }
 static PyObject *mp_pylong(PyObject *x)
   { return (mp_topylong(MP_X(x))); }
@@ -542,13 +544,15 @@ end:
   return ((PyObject *)zz);
 }
 
-static long mp_pyhash(PyObject *me)
+long mphash(mp *x)
 {
-  long h;
-  PyObject *l = mp_topylong(MP_X(me)); h = PyObject_Hash(l);
+  PyObject *l = mp_topylong(x);
+  long h = PyObject_Hash(l);
   Py_DECREF(l); return (h);
 }
 
+static long mp_pyhash(PyObject *me) { return (mphash(MP_X(me))); }
+
 static PyObject *mpmeth_jacobi(PyObject *me, PyObject *arg)
 {
   mp *y = 0;
@@ -680,6 +684,19 @@ end:
   return (z);
 }
 
+static PyObject *mpmeth_leastcongruent(PyObject *me, PyObject *arg)
+{
+  mp *z, *b, *m;
+  PyObject *rc = 0;
+
+  if (!PyArg_ParseTuple(arg, "O&O&:leastcongruent", convmp, &b, convmp, &m))
+    goto end;
+  z = mp_leastcongruent(MP_NEW, b, MP_X(me), m);
+  rc = mp_pywrap(z);
+end:
+  return (rc);
+}
+
 #define STOREOP(name, c)                                               \
   static PyObject *mpmeth_##name(PyObject *me,                         \
                                 PyObject *arg, PyObject *kw)           \
@@ -790,6 +807,8 @@ static PyMethodDef mp_pymethods[] = {
         "X.gcdx(Y) -> (gcd(X, Y), U, V) with X U + Y V = gcd(X, Y)")
   METH (modinv,        "X.modinv(Y) -> multiplicative inverse of Y mod X")
   METH (modsqrt,       "X.modsqrt(Y) -> square root of Y mod X, if X prime")
+  METH (leastcongruent,
+        "X.leastcongruent(B, M) -> smallest Z >= B with Z == X (mod M)")
   KWMETH(primep,       "X.primep(rng = rand) -> true/false if X is prime")
   KWMETH(tostring,     "X.tostring(radix = 10) -> STR")
   KWMETH(storel,       "X.storel(len = -1) -> little-endian bytes")
@@ -873,11 +892,15 @@ static PyTypeObject mp_pytype_skel = {
 
   /* @tp_doc@ */
 "Multiprecision integers, similar to `long' but more efficient and\n\
-versatile.  Support all the standard arithmetic operations.\n\
+versatile.  Support all the standard arithmetic operations, with\n\
+implicit conversions from `PrimeFilter', and other objects which\n\
+convert to `long'.\n\
 \n\
-Constructor mp(X, radix = R) attempts to convert X to an `mp'.  If\n\
+Constructor MP(X, radix = R) attempts to convert X to an `MP'.  If\n\
 X is a string, it's read in radix-R form, or we look for a prefix\n\
-if R = 0.  Other acceptable things are ints and longs.\n\
+if R = 0.  Other acceptable things are field elements, elliptic curve\n\
+points, group elements, Python `int' and `long' objects, and anything\n\
+with an integer conversion.\n\
 \n\
 Notes:\n\
 \n\
@@ -1868,15 +1891,6 @@ end:
   return ((PyObject *)zz);
 }
 
-static long gf_pyhash(PyObject *me)
-{
-  long i = mp_tolong(MP_X(me));
-  i ^= 0xc7ecd67c; /* random perturbance */
-  if (i == -1)
-    i = -2;
-  return (i);
-}
-
 static PyObject *gf_pyexp(PyObject *x, PyObject *y, PyObject *z)
 {
   mp *xx = 0, *yy = 0, *zz = 0;
@@ -2059,7 +2073,7 @@ static PyTypeObject gf_pytype_skel = {
   &gf_pynumber,                                /* @tp_as_number@ */
   0,                                   /* @tp_as_sequence@ */
   0,                                   /* @tp_as_mapping@ */
-  gf_pyhash,                           /* @tp_hash@ */
+  mp_pyhash,                           /* @tp_hash@ */
   0,                                   /* @tp_call@ */
   mp_pyhex,                            /* @tp_str@ */
   0,                                   /* @tp_getattro@ */
@@ -2073,9 +2087,11 @@ static PyTypeObject gf_pytype_skel = {
 "Binary polynomials.  Support almost all the standard arithmetic\n\
 operations.\n\
 \n\
-Constructor gf(X, radix = R) attempts to convert X to a `gf'.  If\n\
+Constructor GF(X, radix = R) attempts to convert X to a `GF'.  If\n\
 X is a string, it's read in radix-R form, or we look for a prefix\n\
-if R = 0.  Other acceptable things are ints and longs.\n\
+if R = 0.  Other acceptable things are field elements, elliptic curve\n\
+points, group elements, Python `int' and `long' objects, and anything\n\
+with an integer conversion.\n\
 \n\
 The name is hopelessly wrong from a technical point of view, but\n\
 but it's much easier to type than `p2' or `c2' or whatever.\n\