Add a test for the mod Tiger stdlib function

hera/stdlib.py

@@ -1,6 +1,14 @@
-# flake8: noqa
+"""The standard library for the Tiger programming language, implemented in HERA.
 
+All of the pure HERA functions in this module have been copied from the original
+Tiger standard library file for HERA-C, written by Dave Wonnacott.
 
+Author:  Ian Fisher (iafisher@protonmail.com)
+Version: February 2019
+"""
+
+
+# The standard library with parameters-on-the-stack functions.
 TIGER_STDLIB_STACK = """
 LABEL(printint)
   __eval("print(vm.load_memory(vm.registers[14]+3), end='')")
@@ -23,7 +31,12 @@
 
 
 LABEL(div)
-  __eval("left = vm.load_memory(vm.registers[14]+3); right = vm.load_memory(vm.registers[14]+4); vm.store_memory(vm.registers[14]+3, left // right)")
+  __eval("left = vm.load_memory(vm.registers[14]+3); right = vm.load_memory(vm.registers[14]+4); vm.store_memory(vm.registers[14]+3, left // right if right != 0 else 0)")
+  RETURN(FP_alt, PC_ret)
+
+
+LABEL(mod)
+  __eval("left = vm.load_memory(vm.registers[14]+3); right = vm.load_memory(vm.registers[14]+4); vm.store_memory(vm.registers[14]+3, left % right if right != 0 else 0)")
   RETURN(FP_alt, PC_ret)
 
 
@@ -313,6 +326,7 @@
 """
 
 
+# The data segment for the parameters-on-the-stack functions.
 TIGER_STDLIB_STACK_DATA = """
 CONSTANT(first_space_for_fsheap, 0x4000)
 CONSTANT(last_space_for_fsheap, 0xbfff)

test/test_from_cs350.py

@@ -1,8 +1,37 @@
 """Test programs generated by a compiler for the Tiger language implemented for CS350.
 """
+from .utils import execute_program_helper
+
 from hera.main import main
 
 
+def helper_stdlib(f, *args):
+    preamble = """\
+#include <Tiger-stdlib-stack-data.hera>
+
+CBON()
+MOVE(R12, SP)
+INC(SP, {})
+    """
+    preamble = preamble.format(len(args) + 3)
+
+    load_args = ""
+    for i, arg in enumerate(args):
+        load_args += "SET(R1, {})\nSTORE(R1, {}, R12)\n".format(arg, i + 3)
+
+    epilogue = """\
+CALL(R12, mod)
+LOAD(R1, 3, R12)
+DEC(SP, 5)
+HALT()
+
+#include <Tiger-stdlib-stack.hera>
+    """
+    epilogue = epilogue.format(f)
+
+    return preamble + load_args + epilogue
+
+
 def test_div_and_print(capsys):
     main(["test/assets/cs350/div_and_print.hera"])
 
@@ -22,3 +51,9 @@ def test_lexical_scope_deep(capsys):
 
     captured = capsys.readouterr()
     assert captured.out == "42"
+
+
+def test_stdlib_mod(capsys):
+    vm = execute_program_helper(helper_stdlib("mod", 10, 3))
+
+    assert vm.registers[1] == 1