Start on support for NE EXE

reccmp/isledecomp/formats/detect.py

@@ -5,6 +5,7 @@
 from .lx import LXImage
 from .macho import MachOImage
 from .mz import ImageDosHeader, MZImage
+from .ne import NEImage
 from .pe import PEImage
 
 
@@ -21,7 +22,7 @@ def detect_image(filepath: Path | str) -> Image:
             case b"LE":
                 return LXImage.from_memory(data, mz_header=mz_header, filepath=filepath)
             case b"NE":
-                raise NotImplementedError("NE file format not implemented")
+                return NEImage.from_memory(data, mz_header=mz_header, filepath=filepath)
             case b"NX":
                 raise NotImplementedError("NX file format not implemented")
             case _:

reccmp/isledecomp/formats/ne.py

@@ -0,0 +1,152 @@
+"""
+Based on the following resources:
+- https://github.com/bitwiseworks/os2tk45/blob/master/h/newexe.h
+- https://github.com/qb40/exe-format/blob/master/README.txt
+"""
+import dataclasses
+import struct
+from pathlib import Path
+from enum import IntEnum, IntFlag
+
+from .image import Image
+from .mz import ImageDosHeader
+
+
+class NESegmentFlags(IntFlag):
+    # pylint: disable=implicit-flag-alias
+    NESOLO = 0x0001  # Solo data
+    NEINST = 0x0002  # Instance data
+    NEPPLI = 0x0004  # Per-Process Library Initialization
+    NEPROT = 0x0008  # Runs in protected mode only
+    NEI086 = 0x0010  # 8086 instructions
+    NEI286 = 0x0020  # 286 instructions
+    NEI386 = 0x0040  # 386 instructions
+    NEFLTP = 0x0080  # Floating-point instructions
+    NENOTWINCOMPAT = 0x0100  # Not compatible with P.M. Windowing
+    NEWINCOMPAT = 0x0200  # Compatible with P.M. Windowing
+    NEWINAPI = 0x0300  # Uses P.M. Windowing API
+    NEAPPTYP = 0x0700  # Application type mask
+    NEBOUND = 0x0800  # Bound Family/API
+    NEIERR = 0x2000  # Errors in image
+    NEPRIVLIB = 0x4000  # A one customer Windows 3.0 library
+    NENOTP = 0x8000  # Not a process
+
+
+class NETargetOSFlags(IntEnum):
+    NE_UNKNOWN = 0  # Unknown (any "new-format" OS)
+    NE_OS2 = 1  # OS/2 (default)
+    NE_WINDOWS = 2  # Windows
+    NE_DOS = 3  # DOS 4.x
+    NE_DEV386 = 4  # Windows 386
+
+
+@dataclasses.dataclass(frozen=True)
+class NESegmentTableEntry:
+    ns_sector: int  # File sector of start of segment
+    ns_cbseg: int  # Number of bytes in file
+    ns_flags: int  # Attribute flags
+    ns_minalloc: int  # Minimum allocation in bytes
+
+    @classmethod
+    def from_memory(
+        cls, data: bytes, offset: int, count: int
+    ) -> tuple[tuple["NESegmentTableEntry", ...], int]:
+        struct_fmt = "<4H"
+        struct_size = struct.calcsize(struct_fmt)
+        items = tuple(
+            cls(*items)
+            for items in struct.iter_unpack(
+                struct_fmt, data[offset : offset + count * struct_size]
+            )
+        )
+        return items, offset + count * struct_size
+
+
+@dataclasses.dataclass(frozen=True)
+class NewExeHeader:
+    # pylint: disable=too-many-instance-attributes
+    ne_magic: bytes  # Magic number NE_MAGIC
+    ne_ver: int  # Version number
+    ne_rev: int  # Revision number
+    ne_enttab: int  # Offset of Entry Table
+    ne_cbenttab: int  # Number of bytes in Entry Table
+    ne_crc: int  # Checksum of whole file
+    ne_flags: NESegmentFlags  # Flag word
+    ne_autodata: int  # Automatic data segment number
+    ne_heap: int  # Initial heap allocation
+    ne_stack: int  # Initial stack allocation
+    ne_csip: tuple[int, int]  # Initial CS:IP setting
+    ne_sssp: tuple[int, int]  # Initial SS:SP setting
+    ne_cseg: int  # Count of file segments
+    ne_cmod: int  # Entries in Module Reference Table
+    ne_cbnrestab: int  # Size of non-resident name table
+    ne_segtab: int  # Offset of Segment Table (Relative to NE header)
+    ne_rsrctab: int  # Offset of Resource Table (Relative to NE header)
+    ne_restab: int  # Offset of resident name Table (Relative to NE header)
+    ne_modtab: int  # Offset of Module Reference Table (Relative to NE header)
+    ne_imptab: int  # Offset of Imported Names Table (Relative to NE header)
+    ne_nrestab: int  # Offset of Non-resident Names Table (File offset)
+    ne_cmovent: int  # Count of movable entries
+    ne_align: int  # Segment alignment shift count
+    ne_cres: int  # Count of resource entries
+    ne_exetyp: NETargetOSFlags  # Target operating system
+    ne_flagsothers: int  # Other .EXE flags
+    ne_pretthunks: int  # Windows 3.0 - offset to return thunks
+    ne_psegrefbytes: int  # Windows 3.0 - offset to segment ref. bytes
+    ne_swaparea: int  # Windows 3.0 - minimum code swap size
+    ne_expver: int  # Windows 3.0 - expected windows version number
+
+    @classmethod
+    def from_memory(cls, data: bytes, offset: int) -> tuple["NewExeHeader", int]:
+        if not cls.taste(data, offset):
+            raise ValueError
+        struct_fmt = "<2s2BHI17HI3H2B4H"
+        struct_size = struct.calcsize(struct_fmt)
+        # fmt: off
+        items: tuple[bytes, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int] = (
+            struct.unpack_from(struct_fmt, data, offset)
+        )
+        # fmt: on
+        result = cls(
+            *items[:6],
+            NESegmentFlags(items[6]),
+            *items[7:10],
+            (items[11], items[10]),  # CS:IP
+            (items[13], items[12]),  # SS:SP
+            *items[14:26],
+            NETargetOSFlags(items[26]),
+            *items[27:]
+        )
+        return result, offset + struct_size
+
+    @classmethod
+    def taste(cls, data: bytes, offset: int) -> bool:
+        (magic,) = struct.unpack_from("<2s", data, offset)
+        return magic == b"NE"
+
+
+@dataclasses.dataclass
+class NEImage(Image):
+    mz_header: ImageDosHeader
+    header: NewExeHeader
+    segments: tuple[NESegmentTableEntry, ...]
+
+    @classmethod
+    def from_memory(
+        cls, data: bytes, mz_header: ImageDosHeader, filepath: Path
+    ) -> "NEImage":
+        offset = mz_header.e_lfanew
+        view = memoryview(data)
+        header, _ = NewExeHeader.from_memory(data, offset=offset)
+        segments, _ = NESegmentTableEntry.from_memory(
+            data, offset=offset + header.ne_segtab, count=header.ne_cseg
+        )
+
+        return cls(
+            filepath=filepath,
+            data=data,
+            view=view,
+            mz_header=mz_header,
+            header=header,
+            segments=segments,
+        )