1 files changed, 47 insertions, 0 deletions
diff --git a/src/asm_eval.py b/src/asm_eval.py
new file mode 100644
index 0000000..691e4eb
--- /dev/null
+++ b/src/asm_eval.py
@@ -0,0 +1,47 @@
+constants: dict[str, str] = {
+  # Registers
+  "ra": "0",
+  "rb": "1",
+  "rc": "2",
+  "rd": "3",
+  "re": "4",
+  "rf": "5",
+  "rg": "6",
+  "rh": "7",
+  # ALU instructions
+  "al_plus": "0",
+  "al_minus": "1",
+  "al_and": "2",
+  "al_or": "3",
+  "al_xor": "4",
+  "al_slr": "5",
+  "al_sar": "6",
+  "al_sll": "7",
+  # ALU flags
+  "carry": "0",
+  "overflow": "1",
+  "zero": "2",
+  "sign": "3",
+}
+
+Labels = dict[str, int]
+
+def check_size(bits: int, val: int) -> None:
+  if val >= 2 ** bits:
+    raise Exception(f"Value does not fit in {bits} bits: {val}")
+
+def eval_symbol(labels: Labels, c: str) -> str:
+  if c in labels:
+    return str(labels[c])
+
+  if c in constants:
+    return constants[c]
+
+  return c
+
+def eval_expr(labels: Labels, expr: str, bits: int = 16) -> int:
+  expr = expr.lower()
+  expr = eval_symbol(labels, expr)
+  ret = eval(expr, labels.copy()) # eval as Python expr
+  check_size(bits, ret)
+  return ret