First public commit.

lenser/apple/viewer/assemble.py

@@ -0,0 +1,97 @@
+"""Assemble the Apple II boot/viewer with `xa` (origin $0800, raw bytes)."""
+
+from __future__ import annotations
+
+import os
+import shutil
+import subprocess
+import tempfile
+
+VIEWER_DIR = os.path.dirname(os.path.abspath(__file__))
+SOURCES = {"hgr": "hgr.s", "dhgr": "dhgr.s"}
+_cache: dict[tuple, bytes] = {}
+
+# How long the viewer holds the picture (see apple/viewer/awyt.i).
+WAIT_MODES = {"forever": 0, "key": 1, "seconds": 2}
+SS_WAITMODE = {"key": 1, "seconds": 2, "both": 3}
+
+
+def build_slideshow_stub(n_images: int, advance: str = "both", seconds: int = 10,
+                         loop: bool = True) -> bytes:
+    """Assemble the Apple HGR slideshow boot loader (one 256-byte boot sector).
+
+    Reads NIMAGES * 32 sectors into the $4000 buffer and cycles them; must fit a
+    single boot sector since the Disk II ROM only loads sector 0.
+    """
+    import shutil as _sh
+    if not _sh.which("xa"):
+        raise AssemblerError("The 'xa' assembler was not found on PATH.")
+    end_page = 0x40 + n_images * 0x20
+    wrapper = (f"#define WAITMODE {SS_WAITMODE[advance]}\n"
+               f"#define WAITSECS {max(0, min(255, int(seconds)))}\n"
+               f"#define NIMAGES {n_images}\n"
+               f"#define LOOPFLAG {1 if loop else 0}\n"
+               f"#define ENDPAGE ${end_page:02X}\n"
+               '#include "slideshow.s"\n')
+    with tempfile.TemporaryDirectory() as td:
+        out = os.path.join(td, "v.bin")
+        fd, wrap = tempfile.mkstemp(suffix=".s", prefix="_wrap_", dir=VIEWER_DIR)
+        try:
+            with os.fdopen(fd, "w") as f:
+                f.write(wrapper)
+            proc = subprocess.run(["xa", "-o", out, os.path.basename(wrap)],
+                                  capture_output=True, text=True, cwd=VIEWER_DIR)
+            if proc.returncode != 0:
+                raise AssemblerError(f"xa failed:\n{proc.stdout}{proc.stderr}")
+            with open(out, "rb") as f:
+                raw = f.read()
+        finally:
+            os.unlink(wrap)
+    if len(raw) > 256:
+        raise AssemblerError(
+            f"Apple slideshow boot loader is {len(raw)} bytes, over the 256-byte "
+            "boot sector")
+    return raw
+
+
+class AssemblerError(RuntimeError):
+    pass
+
+
+def have_xa() -> bool:
+    return shutil.which("xa") is not None
+
+
+def assemble_stub(viewer_key: str, display: str = "forever", seconds: int = 0) -> bytes:
+    waitmode = WAIT_MODES.get(display, 0)
+    secs = max(0, min(255, int(seconds)))           # 8-bit delay counter
+    key = (viewer_key, waitmode, secs)
+    if key in _cache:
+        return _cache[key]
+    if not have_xa():
+        raise AssemblerError("The 'xa' assembler was not found on PATH.")
+    if not os.path.exists(os.path.join(VIEWER_DIR, SOURCES[viewer_key])):
+        raise AssemblerError(f"viewer source missing: {SOURCES[viewer_key]}")
+
+    # Wrapper sets options then includes the real source; run from VIEWER_DIR so
+    # the source's #include "awyt.i" resolves (xa looks relative to cwd).
+    wrapper = (f"#define WAITMODE {waitmode}\n"
+               f"#define WAITSECS {secs}\n"
+               f'#include "{SOURCES[viewer_key]}"\n')
+    with tempfile.TemporaryDirectory() as td:
+        out = os.path.join(td, "v.bin")
+        fd, wrap = tempfile.mkstemp(suffix=".s", prefix="_wrap_", dir=VIEWER_DIR)
+        try:
+            with os.fdopen(fd, "w") as f:
+                f.write(wrapper)
+            proc = subprocess.run(["xa", "-o", out, os.path.basename(wrap)],
+                                  capture_output=True, text=True, cwd=VIEWER_DIR)
+            if proc.returncode != 0:
+                raise AssemblerError(
+                    f"xa failed for {viewer_key}:\n{proc.stdout}{proc.stderr}")
+            with open(out, "rb") as f:
+                raw = f.read()
+        finally:
+            os.unlink(wrap)
+    _cache[key] = raw
+    return raw