Server/py: Add randomness infrastructure, libplomrogue.so ctypes import.

[plomrogue] / libplomrogue.c

diff --git a/libplomrogue.c b/libplomrogue.c
new file mode 100644 (file)
index 0000000..c6f5724
--- /dev/null
+++ b/libplomrogue.c
@@ -0,0 +1,30 @@
+#include <stdint.h> /* uint16_t, uint32_t */
+
+
+
+/* Pseudo-randomness seed for rrand(), set by seed_rrand(). */
+static uint32_t seed = 0;
+
+
+
+/* With set_seed set, set seed global to seed_input. In any case, return it. */
+extern uint32_t seed_rrand(uint8_t set_seed, uint32_t seed_input)
+{
+    if (set_seed)
+    {
+        seed = seed_input;
+    }
+    return seed;
+}
+
+
+
+/* Return 16-bit number pseudo-randomly generated via Linear Congruential
+ * Generator algorithm with some proven constants. Use instead of any rand() to
+  * ensure portability of the same pseudo-randomness across systems.
+ */
+extern uint16_t rrand()
+{   /* Constants as recommended by POSIX.1-2001 (see man page rand(3)). */
+    seed = ((seed * 1103515245) + 12345) % 4294967296;
+    return (seed >> 16); /* Ignore less random least significant bits. */
+}