added simulation file for actually performing sim

src/simulation.c

@@ -0,0 +1,80 @@
+/* simulation.c: Simulation implementation
+ * Created: 2026-03-17
+ * Author: Aryadev Chavali
+ * License: See end of file
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <raylib.h>
+
+#include "simulation.h"
+
+static char *VALID_OPS = "<>{}-+.,[]";
+
+static const Color possible_colors[] = {
+    {0xb4, 0x60, 0x5f, 0xff}, {0xe, 0x7, 0x7, 0xff},
+    {0x2c, 0x10, 0x10, 0xff}, {0x28, 0x21, 0x21, 0xff},
+    {0xbc, 0x71, 0x70, 0xff}, {0x4a, 0x31, 0x31, 0xff},
+    {0xc2, 0x68, 0x67, 0xff}, {0x7e, 0x40, 0x3f, 0xff},
+    {0x21, 0x9, 0x8, 0xff},   {0xcf, 0x35, 0x34, 0xff},
+    {0x0, 0x0, 0x0, 0xff},    {0},
+};
+
+void simulation_pick(u64 *a, u64 *b)
+{
+  // Pick two indices that don't intersect
+  while (*a == *b)
+  {
+    *a = rand() % NUM_PROGRAMS;
+    *b = rand() % NUM_PROGRAMS;
+  }
+}
+
+void simulation_iterate(simulation_t *sim)
+{
+  u64 a = 0, b = 0;
+  simulation_pick(&a, &b);
+
+  // Change of basis from program indices to bf_token indices.
+  a *= SIZEOF_PROGRAM;
+  b *= SIZEOF_PROGRAM;
+
+  // Perform the catalytic reaction
+  struct ProgramConcat a_b_concat = {0};
+  program_concat(&a_b_concat, sim->memory + a, sim->memory + b);
+  program_execute(&a_b_concat);
+  program_split(&a_b_concat);
+}
+
+u8 get_op(const u8 cell)
+{
+  if (strchr(VALID_OPS, cell))
+    return cell;
+  else
+    return '\0';
+}
+
+Color simulation_cell_color(const u8 cell)
+{
+  return possible_colors[get_op(cell)];
+}
+
+void simulation_draw(simulation_t *sim)
+{
+  assert(0 && "TODO: implement simulation_draw");
+}
+
+/* Copyright (C) 2026 Aryadev Chavali
+
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License Version 2 for
+ * details.
+
+ * You may distribute and modify this code under the terms of the GNU General
+ * Public License Version 2, which you should have received a copy of along with
+ * this program.  If not, please go to <https://www.gnu.org/licenses/>.
+
+ */