Add internal size and seed size of hash algo

pep-0456.txt

@@ -312,7 +312,7 @@ hash function
 
 function prototype::
 
-    typedef Py_hash_t (*PyHash_func_t)(void *, Py_ssize_t);
+    typedef Py_hash_t (*PyHash_Func)(const void *, Py_ssize_t);
 
 
 hash function table
@@ -321,9 +321,11 @@ hash function table
 type definition::
 
     typedef struct {
-        PyHash_func_t hashfunc;
-        char *name;
-        unsigned int precedence;
+        PyHash_Func hashfunc;  /* function pointer */
+        char *name;            /* name of the hash algorithm and variant */
+        int hash_bits;         /* internal size of hash value */
+        int seed_bits;         /* size of seed input */
+        int precedence;        /* ranking for auto-selection */
     } PyHash_FuncDef;
 
     PyAPI_DATA(PyHash_FuncDef *) PyHash_FuncTable;
@@ -331,9 +333,9 @@ type definition::
 Implementation::
 
     PyHash_FuncDef hash_func_table[] = {
-        {fnv, "fnv", 10},
+        {fnv, "fnv", 64, 128, 10},
     #ifdef PY_UINT64_T
-        {siphash24, "sip24", 20},
+        {siphash24, "sip24", sizeof(Py_hash_t)*8, sizeof(Py_hash_t)*8, 20},
     #endif
         {NULL, NULL},
     };
@@ -376,7 +378,11 @@ algorithm as well as all available algorithms.
 
 ::
 
-    sys.hash_info(algorithm='siphash24', available=('siphash24', 'fnv'))
+    sys.hash_info(algorithm='siphash24',
+                  available_algorithms=('siphash24', 'fnv'),
+                  hash_bits=64,
+                  hash_output=64,        # sizeof(Py_hash_t)*8
+                  seed_bits=128)
 
 
 _testcapi