First public commit.

lenser/coco/cartridge.py

@@ -0,0 +1,31 @@
+"""Build a TRS-80 CoCo Program Pak cartridge ROM (.ccc) holding viewer + image.
+
+The CoCo autostarts the cartridge at $C000.  Layout: viewer code, then the
+6144-byte PMODE 4 image, padded to an 8KB ROM ($C000-$DFFF)."""
+
+from __future__ import annotations
+
+from . import viewer
+
+CART_BASE = 0xC000
+CART_SIZE = 0x2000           # 8 KB
+
+
+def build_rom(data: bytes, vdg: int = 0xF8, display: str = "forever",
+              seconds: int = 0) -> bytes:
+    if len(data) != viewer.SCREEN_BYTES:
+        raise ValueError(f"unexpected image length {len(data)}")
+    vk = dict(vdg=vdg, display=display, seconds=seconds)
+    code = viewer.build(0, **vk)                 # pass 1: measure code length
+    data_src = CART_BASE + len(code)
+    code = viewer.build(data_src, **vk)          # pass 2: real data address
+    rom = code + bytes(data)
+    if len(rom) > CART_SIZE:
+        raise ValueError("viewer + image exceed the 8KB cartridge")
+    return rom + bytes(CART_SIZE - len(rom))
+
+
+def write_ccc(rom: bytes, path: str) -> str:
+    with open(path, "wb") as f:
+        f.write(rom)
+    return path