better font rendering and start of z80 access

tools/generate_fonts.py

@@ -0,0 +1,115 @@
+#!/usr/bin/env python3
+"""Generate a separate XBM file for every supported PNG font atlas."""
+
+import re
+from pathlib import Path
+
+from PIL import Image
+
+
+ROOT = Path(__file__).resolve().parents[1]
+FONT_DIR = ROOT / "font"
+
+
+def make_full_ascii_atlas(source: Image.Image, name: str) -> Image.Image:
+    """Return a 16x16 atlas whose character slots match byte values 0..255."""
+    if name == "IBM_BIOS_8x8":
+        if source.size != (177, 67):
+            raise ValueError(f"{name}: expected 177x67, got {source.size}")
+
+        # Printable ASCII in 11x11 gridded cells with a centered 8x8 glyph.
+        atlas = Image.new("L", (128, 128), 255)
+        for glyph in range(96):
+            source_x = (glyph % 16) * 11 + 2
+            source_y = (glyph // 16) * 11 + 2
+            character = 32 + glyph
+            dest_x = (character % 16) * 8
+            dest_y = (character // 16) * 8
+            atlas.paste(source.crop((source_x, source_y, source_x + 8, source_y + 8)),
+                        (dest_x, dest_y))
+        return atlas
+
+    if name == "IBM_VGA_8x16":
+        if source.size != (128, 90):
+            raise ValueError(f"{name}: expected 128x90, got {source.size}")
+
+        # The source contains printable ASCII 32..127 in 16 columns and six
+        # rows of 8x15 glyphs. Store them in 8x16 cells, padding the bottom.
+        atlas = Image.new("L", (128, 256), 255)
+        for glyph in range(96):
+            source_x = (glyph % 16) * 8
+            source_y = (glyph // 16) * 15
+            character = 32 + glyph
+            dest_x = (character % 16) * 8
+            dest_y = (character // 16) * 16
+            atlas.paste(source.crop((source_x, source_y, source_x + 8, source_y + 15)),
+                        (dest_x, dest_y))
+        return atlas
+
+    if name == "ucs_6x13":
+        if source.size != (145, 97):
+            raise ValueError(f"{name}: expected 145x97, got {source.size}")
+
+        # Printable ASCII 32..127 is arranged in a 16x6 grid. Each 9x16
+        # source cell has a one-pixel grid line and one pixel of inner padding
+        # around its 6x13 glyph.
+        atlas = Image.new("L", (96, 208), 255)
+        for glyph in range(96):
+            source_x = (glyph % 16) * 9 + 2
+            source_y = (glyph // 16) * 16 + 2
+            character = 32 + glyph
+            dest_x = (character % 16) * 6
+            dest_y = (character // 16) * 13
+            atlas.paste(source.crop((source_x, source_y, source_x + 6, source_y + 13)),
+                        (dest_x, dest_y))
+        return atlas
+
+    # The MBF images are already complete 16x16 character atlases.
+    if source.width % 16 or source.height % 16:
+        raise ValueError(f"{name}: atlas dimensions must be divisible by 16")
+    return source
+
+
+def write_xbm(image: Image.Image, destination: Path) -> None:
+    image = image.convert("L")
+    row_bytes = (image.width + 7) // 8
+    data = []
+    for y in range(image.height):
+        for byte_x in range(row_bytes):
+            value = 0
+            for bit in range(8):
+                x = byte_x * 8 + bit
+                # Keep the existing renderer convention: white/background is
+                # one, while black/glyph pixels are zero. XBM is LSB-first.
+                if x >= image.width or image.getpixel((x, y)) >= 128:
+                    value |= 1 << bit
+            data.append(value)
+
+    symbol = re.sub(r"[^a-zA-Z0-9_]", "_", destination.stem)
+    lines = [
+        f"#define font_width {image.width}",
+        f"#define font_height {image.height}",
+        f"static const unsigned char font_bits[] = {{",
+    ]
+    for offset in range(0, len(data), 12):
+        values = ", ".join(f"0x{value:02X}" for value in data[offset:offset + 12])
+        suffix = "," if offset + 12 < len(data) else ""
+        lines.append(f"  {values}{suffix}")
+    lines.extend(["};", ""])
+    destination.write_text("\n".join(lines), encoding="ascii")
+    print(f"generated {destination.relative_to(ROOT)} ({symbol})")
+
+
+def main() -> None:
+    sources = sorted(FONT_DIR.glob("*.png"))
+    if not sources:
+        raise SystemExit("no PNG font atlases found")
+
+    for source_path in sources:
+        source = Image.open(source_path).convert("L")
+        atlas = make_full_ascii_atlas(source, source_path.stem)
+        write_xbm(atlas, source_path.with_suffix(".xbm"))
+
+
+if __name__ == "__main__":
+    main()