shithub: orca

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Add better pseudorandom function

--- a/sim.c

+++ b/sim.c

@@ -667,6 +667,16 @@

   }

 END_PHASE

+static Usz hash32_shift_mult(Usz key) {

+  Usz c2 = UINT32_C(0x27d4eb2d);

+  key = (key ^ UINT32_C(61)) ^ (key >> UINT32_C(16));

+  key = key + (key << UINT32_C(3));

+  key = key ^ (key >> UINT32_C(4));

+  key = key * c2;

+  key = key ^ (key >> UINT32_C(15));

+  return key;

+}

+

 BEGIN_DUAL_PHASE_0(random)

   REALIZE_DUAL;

   BEGIN_DUAL_PORTS

@@ -691,7 +701,9 @@

     min = b;

     max = a;

   }

-  Usz val = (y * 5 + x * 3) * Tick_number % (max - min) + min;

+  Usz key = y * width + x;

+  key = hash32_shift_mult((y * width + x) ^ (Tick_number << UINT32_C(16)));

+  Usz val = key % (max - min) + min;

   POKE(1, 0, glyph_of(val));

 END_PHASE