+/* Given a bitmask, returns the position and width of the field.
+ */
+static void
+decode_mask (unsigned int mask, unsigned int *pos_ret, unsigned int *size_ret)
+{
+ int i;
+ for (i = 0; i < 32; i++)
+ if (mask & (1L << i))
+ {
+ int j = 0;
+ *pos_ret = i;
+ for (; i < 32; i++, j++)
+ if (! (mask & (1L << i)))
+ break;
+ *size_ret = j;
+ return;
+ }
+}
+
+
+/* Given a value and a field-width, expands the field to fill out 8 bits.
+ */
+static unsigned char
+spread_bits (unsigned char value, unsigned char width)
+{
+ switch (width)
+ {
+ case 8: return value;
+ case 7: return (value << 1) | (value >> 6);
+ case 6: return (value << 2) | (value >> 4);
+ case 5: return (value << 3) | (value >> 2);
+ case 4: return (value << 4) | (value);
+ case 3: return (value << 5) | (value << 2) | (value >> 2);
+ case 2: return (value << 6) | (value << 4) | (value);
+ default: abort(); break;
+ }
+}
+
+