diff --git a/build.sh b/build.sh
index 605426f..b249881 100644
--- a/build.sh
+++ b/build.sh
@@ -2,7 +2,7 @@
 
 CFLAGS="-Wall -Wextra -Wpedantic -Wswitch-enum -Werror -std=c23 -ggdb"
 LDFLAGS="-lm -lraylib"
-SRC="src/sv.c src/vec.c src/main.c"
+SRC="src/sv.c src/vec.c src/program_iter.c src/main.c"
 OUT="main.out"
 
 set -xe
diff --git a/src/main.c b/src/main.c
index 3af069f..b25f5a5 100644
--- a/src/main.c
+++ b/src/main.c
@@ -14,161 +14,14 @@
 #include "sv.h"
 #include "vec.h"
 
+#include "program_iter.h"
+
 struct ProgramConcat
 {
   sv_t A, B;
   u8 tape[SIZEOF_PROGRAM * 2];
 };
 
-void program_concat(struct ProgramConcat *ret, sv_t a, sv_t b)
-{
-  assert(a.size == SIZEOF_PROGRAM && b.size == SIZEOF_PROGRAM);
-  memset(ret, 0, sizeof(*ret));
-  ret->A = a;
-  ret->B = b;
-  memcpy(ret->tape, a.data, SIZEOF_PROGRAM);
-  memcpy(ret->tape + SIZEOF_PROGRAM, b.data, SIZEOF_PROGRAM);
-}
-
-u64 vec_pop(vec_t *vec)
-{
-  u64 ret = 0;
-  if (vec->size < sizeof(ret))
-    return ret;
-  vec->size -= sizeof(ret);
-  memcpy(&ret, (typeof(ret) *)(((u8 *)vec_data(vec)) + vec->size), sizeof(ret));
-  return ret;
-}
-
-bool vec_in(vec_t *vec, u64 n)
-{
-  for (u64 i = 0; i < vec->size / sizeof(n); ++i)
-  {
-    if (VEC_GET(vec, i, typeof(n)) == n)
-    {
-      return true;
-    }
-  }
-  return false;
-}
-
-void program_execute(struct ProgramConcat *prg)
-{
-  vec_t cond_stack = {0};
-  vec_ensure_capacity(&cond_stack, sizeof(prg->tape) * sizeof(u64));
-
-  for (u64 ip = 0, head0 = 0, head1 = 0, total_iters = 0;
-       ip < sizeof(prg->tape) && total_iters < (1LU << 13); ++total_iters)
-  {
-    u8 opcode = prg->tape[ip];
-    switch (opcode)
-    {
-    case '<':
-      head0 = SAFE_SUB(head0, 1);
-      ++ip;
-      break;
-    case '>':
-      head0++;
-      ++ip;
-      break;
-    case '{':
-      head1 = SAFE_SUB(head1, 1);
-      ++ip;
-      break;
-    case '}':
-      head1++;
-      ++ip;
-      break;
-    case '-':
-      prg->tape[head0]--;
-      ++ip;
-      break;
-    case '+':
-      prg->tape[head0]++;
-      ++ip;
-      break;
-    case '.':
-      prg->tape[head1] = prg->tape[head0];
-      ++ip;
-      break;
-    case ',':
-      prg->tape[head0] = prg->tape[head1];
-      ++ip;
-      break;
-    case '[':
-    {
-      if (!vec_in(&cond_stack, ip))
-      {
-        vec_append(&cond_stack, &ip, sizeof(ip));
-      }
-      if (!prg->tape[head0])
-      {
-        // Iterate forward, trying to find a matching closed bracket
-        u64 square_brackets = 0;
-        u64 close_ip;
-        for (close_ip = ip + 1; close_ip < sizeof(prg->tape); ++close_ip)
-        {
-          if (prg->tape[close_ip] == '[')
-          {
-            ++square_brackets;
-          }
-          else if (prg->tape[close_ip] == ']')
-          {
-            if (square_brackets == 0)
-            {
-              break;
-            }
-            --square_brackets;
-          }
-        }
-        if (square_brackets != 0)
-        {
-          // NOTE: as per paper, terminate.
-          ip = sizeof(prg->tape);
-        }
-        else
-        {
-          ip = close_ip;
-        }
-      }
-      break;
-    }
-    case ']':
-    {
-      if (prg->tape[head0])
-      {
-        if (cond_stack.size < sizeof(u64))
-        {
-          // NOTE: as per paper, terminate.
-          ip = sizeof(prg->tape);
-        }
-        else
-        {
-          ip = vec_pop(&cond_stack);
-        }
-      }
-      else
-      {
-        ++ip;
-      }
-      break;
-    }
-    default:
-      ++ip;
-      break;
-    }
-  }
-
-  vec_free(&cond_stack);
-}
-
-void program_split(struct ProgramConcat *prg)
-{
-  assert(prg->A.data && prg->B.data);
-  memcpy((char *)prg->A.data, prg->tape, SIZEOF_PROGRAM);
-  memcpy((char *)prg->B.data, prg->tape + SIZEOF_PROGRAM, SIZEOF_PROGRAM);
-}
-
 #define WIDTH  800
 #define HEIGHT 600
 
diff --git a/src/program_iter.c b/src/program_iter.c
new file mode 100644
index 0000000..4bdd578
--- /dev/null
+++ b/src/program_iter.c
@@ -0,0 +1,172 @@
+/* program_iter.c: Program iteration implementation
+ * Created: 2026-03-10
+ * Author: Aryadev Chavali
+ * License: See end of file
+ */
+
+#include <string.h>
+
+#include "program_iter.h"
+#include "vec.h"
+
+void program_concat(struct ProgramConcat *ret, sv_t a, sv_t b)
+{
+  assert(a.size == SIZEOF_PROGRAM && b.size == SIZEOF_PROGRAM);
+  memset(ret, 0, sizeof(*ret));
+  ret->A = a;
+  ret->B = b;
+  memcpy(ret->tape, a.data, SIZEOF_PROGRAM);
+  memcpy(ret->tape + SIZEOF_PROGRAM, b.data, SIZEOF_PROGRAM);
+}
+
+u64 vec_pop(vec_t *vec)
+{
+  u64 ret = 0;
+  if (vec->size < sizeof(ret))
+    return ret;
+  vec->size -= sizeof(ret);
+  memcpy(&ret, (typeof(ret) *)(((u8 *)vec_data(vec)) + vec->size), sizeof(ret));
+  return ret;
+}
+
+bool vec_in(vec_t *vec, u64 n)
+{
+  for (u64 i = 0; i < vec->size / sizeof(n); ++i)
+  {
+    if (VEC_GET(vec, i, typeof(n)) == n)
+    {
+      return true;
+    }
+  }
+  return false;
+}
+
+void program_execute(struct ProgramConcat *prg)
+{
+  vec_t cond_stack = {0};
+  vec_ensure_capacity(&cond_stack, sizeof(prg->tape) * sizeof(u64));
+
+  for (u64 ip = 0, head0 = 0, head1 = 0, total_iters = 0;
+       ip < sizeof(prg->tape) && total_iters < (1LU << 13); ++total_iters)
+  {
+    u8 opcode = prg->tape[ip];
+    switch (opcode)
+    {
+    case '<':
+      head0 = SAFE_SUB(head0, 1);
+      ++ip;
+      break;
+    case '>':
+      head0++;
+      ++ip;
+      break;
+    case '{':
+      head1 = SAFE_SUB(head1, 1);
+      ++ip;
+      break;
+    case '}':
+      head1++;
+      ++ip;
+      break;
+    case '-':
+      prg->tape[head0]--;
+      ++ip;
+      break;
+    case '+':
+      prg->tape[head0]++;
+      ++ip;
+      break;
+    case '.':
+      prg->tape[head1] = prg->tape[head0];
+      ++ip;
+      break;
+    case ',':
+      prg->tape[head0] = prg->tape[head1];
+      ++ip;
+      break;
+    case '[':
+    {
+      if (!vec_in(&cond_stack, ip))
+      {
+        vec_append(&cond_stack, &ip, sizeof(ip));
+      }
+      if (!prg->tape[head0])
+      {
+        // Iterate forward, trying to find a matching closed bracket
+        u64 square_brackets = 0;
+        u64 close_ip;
+        for (close_ip = ip + 1; close_ip < sizeof(prg->tape); ++close_ip)
+        {
+          if (prg->tape[close_ip] == '[')
+          {
+            ++square_brackets;
+          }
+          else if (prg->tape[close_ip] == ']')
+          {
+            if (square_brackets == 0)
+            {
+              break;
+            }
+            --square_brackets;
+          }
+        }
+        if (square_brackets != 0)
+        {
+          // NOTE: as per paper, terminate.
+          ip = sizeof(prg->tape);
+        }
+        else
+        {
+          ip = close_ip;
+        }
+      }
+      break;
+    }
+    case ']':
+    {
+      if (prg->tape[head0])
+      {
+        if (cond_stack.size < sizeof(u64))
+        {
+          // NOTE: as per paper, terminate.
+          ip = sizeof(prg->tape);
+        }
+        else
+        {
+          ip = vec_pop(&cond_stack);
+        }
+      }
+      else
+      {
+        ++ip;
+      }
+      break;
+    }
+    default:
+      ++ip;
+      break;
+    }
+  }
+
+  vec_free(&cond_stack);
+}
+
+void program_split(struct ProgramConcat *prg)
+{
+  assert(prg->A.data && prg->B.data);
+  memcpy((char *)prg->A.data, prg->tape, SIZEOF_PROGRAM);
+  memcpy((char *)prg->B.data, prg->tape + SIZEOF_PROGRAM, SIZEOF_PROGRAM);
+}
+
+/* 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/>.
+
+ */
diff --git a/src/program_iter.h b/src/program_iter.h
new file mode 100644
index 0000000..5be1b80
--- /dev/null
+++ b/src/program_iter.h
@@ -0,0 +1,38 @@
+/* program_iter.h: Program iteration procedure
+ * Created: 2026-03-10
+ * Author: Aryadev Chavali
+ * License: See end of file
+ */
+
+#ifndef PROGRAM_ITER_H
+#define PROGRAM_ITER_H
+
+#include "base.h"
+#include "sv.h"
+
+// Result of concatenating two programs.  Maintains a concatenated tape of the
+// two programs fed for ease of use.
+struct ProgramConcat
+{
+  sv_t A, B;
+  u8 tape[SIZEOF_PROGRAM * 2];
+};
+
+void program_concat(struct ProgramConcat *, sv_t, sv_t);
+void program_execute(struct ProgramConcat *);
+void program_split(struct ProgramConcat *);
+
+#endif
+
+/* 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/>.
+
+ */