add 'loop' instr

vytdev · vytdev · commit 6892ac54f196 · 2025-05-07T16:43:25.000+08:00
diff --git a/impl.h b/impl.h
@@ -239,4 +239,13 @@ DEF(jr) {
   vmnext;
 }
 
+DEF(loop) {
+  if (rgA != 0) {
+    rgA--;
+    pc += imm19s;
+    util_checkpc();
+  }
+  vmnext;
+}
+
 #endif /* impl.h */
diff --git a/opcodes.h b/opcodes.h
@@ -56,5 +56,6 @@ DEF(dec,    34)   /* [M] rgA = rgA - 1 */
 DEF(swp,    35)   /* [I] rgA, rgB = rgB, rgA */
 DEF(adr,    36)   /* [M] rgA = pc + imm19s */
 DEF(jr,     37)   /* [M] pc = rgA */
+DEF(loop,   38)   /* [M] if (rgA-- != 0) pc += imm19s */
 
 #endif /* opcodes.h */
diff --git a/test/cnt_1bill b/test/cnt_1bill
