Simplify integer parsing

Simply treat the special octal case and let Python handle the rest.
Also add extra tests, to show additional edge cases that are handled
correctly.

Author: wnienhaus

esp32_ulp/util.py

@@ -79,24 +79,14 @@ def validate_expression(param):
 
 def parse_int(literal):
     """
-    Parses string literals into integers, using base prefixes
-    0xNNN (hex), 0bNNN (binary), and 0oNNN or 0NNN (octal).
-    Without prefix will be treated as decimal.
+    GNU as compatible parsing of string literals into integers
+    Specifically, GNU as treats literals starting with 0 as octal
+    All other literals are correctly parsed by Python
+    See: https://sourceware.org/binutils/docs/as/Integers.html
     """
-    if len(literal) > 2:
-        prefix_start = 1 if literal[0] == '-' else 0  # skip negative sign if present
-
-        if literal[prefix_start] == "0":
-            prefix = literal[prefix_start + 1]
-            if prefix == "x":  # Hex
-                return int(literal, 16)
-            elif prefix == "b":  # Binary
-                return int(literal, 2)
-            elif prefix == "o":  # Octal, Python style (0oNNN)
-                return int(literal, 8)
-            return int(literal, 8)  # Octal, GNU as style (0NNN)
-
-    return int(literal)  # implicit decimal (base10)
+    if len(literal) >= 2 and (literal.startswith("0") or literal.startswith("-0")) and literal.lstrip("-0").isdigit():
+        return int(literal, 8)
+    return int(literal, 0)
 
 
 def file_exists(filename):

tests/util.py

@@ -85,7 +85,9 @@ def test_validate_expression():
 @test
 def test_parse_int():
     # decimal
+    assert parse_int("0") == 0, "0 == 0"
     assert parse_int("5") == 5, "5 == 5"
+    assert parse_int("-0") == 0, "-0 == 0"
     assert parse_int("-5") == -5, "-5 == -5"
     # hex
     assert parse_int("0x5") == 5, "0x5 == 5"
@@ -95,10 +97,14 @@ def test_parse_int():
     assert parse_int("0b1001") == 9, "0b1001 == 9"
     assert parse_int("-0b1001") == -9, "-0b1001 == 9"
     # octal
+    assert parse_int("07") == 7, "07 == 7"
     assert parse_int("0100") == 64, "0100 == 64"
     assert parse_int("0o210") == 136, "0o210 == 136"
+    assert parse_int("00000010") == 8, "00000010 == 8"
+    assert parse_int("-07") == -7, "-07 == -7"
     assert parse_int("-0100") == -64, "-0100 == -64"
     assert parse_int("-0o210") == -136, "-0o210 == -136"
+    assert parse_int("-00000010") == -8, "-00000010 == -8"
     # negative cases
     assert_raises(ValueError, parse_int, '0b123', message="invalid syntax for integer with base 2: '123'")
     assert_raises(ValueError, parse_int, '0900', message="invalid syntax for integer with base 8: '0900'")