add setup_table() to header - avoid duplicate code

Author: ilanschnell

bitarray/_bitarray.c

@@ -189,21 +189,6 @@ buffers_overlap(bitarrayobject *self, bitarrayobject *other)
 #undef PIB
 }
 
-/* setup translation table, which maps each byte to its reversed:
-   reverse_trans = {0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, ..., 0xff} */
-static void
-setup_reverse_trans(void)
-{
-    int j, k;
-
-    for (k = 0; k < 256; k++) {
-        reverse_trans[k] = 0x00;
-        for (j = 0; j < 8; j++)
-            if (k & 128 >> j)
-                reverse_trans[k] |= 1 << j;
-    }
-}
-
 /* reverse bits in first n characters of p */
 static void
 bytereverse(char *p, Py_ssize_t n)
@@ -4291,7 +4276,9 @@ PyInit__bitarray(void)
 {
     PyObject *m;
 
-    setup_reverse_trans();
+    /* setup translation table, which maps each byte to its reversed:
+       reverse_trans = {0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, ..., 0xff} */
+    setup_table(reverse_trans, 0, 'r');
 
     if ((m = PyModule_Create(&moduledef)) == NULL)
         return NULL;

bitarray/_util.c

@@ -265,25 +265,6 @@ Return parity of bitarray `a`.\n\
 `parity(a)` is equivalent to `a.count() % 2` but more efficient.");
 
 
-static void
-setup_table(char *table, int le, char op)
-{
-    int j, k;
-
-    memset(table, 0, 256);
-    for (k = 0; k < 256; k++) {
-        for (j = 1; j < 8; j++) {
-            if (( le && k & 0x01 << j) ||  /* little endian */
-                (!le && k & 0x80 >> j))    /* big endian */
-                switch (op) {
-                case 'a': table[k] += j; break;
-                case 'x': table[k] ^= j; break;
-                default: Py_UNREACHABLE();
-                }
-        }
-    }
-}
-
 static PyObject *
 add_uint64(PyObject *number, uint64_t i)
 {
@@ -876,6 +857,7 @@ digit_to_int(int m, char c)
     static int setup = 0;
     int i;
 
+    assert(1 <= m && m <= 6);
     if (m < 5) {                                 /* base 2, 4, 8, 16 */
         i = hex_to_int(c);
         return i >> m ? -1 : i;

bitarray/bitarray.h

@@ -225,6 +225,26 @@ swap_bytes(char *p, Py_ssize_t n)
     }
 }
 
+/* write 256 characters into table for given endianness, kernel operation */
+static inline void
+setup_table(char *table, int le, char kop)
+{
+    int j, k;
+    for (k = 0; k < 256; k++) {
+        table[k] = 0;
+        for (j = 0; j < 8; j++) {
+            if (( le && k & 0x01 << j) ||  /* little endian */
+                (!le && k & 0x80 >> j))    /* big endian */
+                switch (kop) {
+                case 'a': table[k] += j; break;
+                case 'x': table[k] ^= j; break;
+                case 'r': table[k] |= 1 << j; break;
+                default: Py_UNREACHABLE();
+                }
+        }
+    }
+}
+
 /* Return distance [0..3] to next aligned pointer.
    While on modern compilers uint64_t pointers may be misaligned, it may
    cause problems on older ones.  Moreover, it may lead to slowdown (even