examples: inline_asm_demo.ne

A small example that exercises all three inline-assembly paths in
one program:

- \`asm { ... }\` with \`{var}\` substitution for \`result\` and
  \`frame_count\`
- \`poke(addr, value)\` for a hardware register write (PPU \$2005)
- A helper function whose body is hand-written 6502 that still
  reads and writes NEScript-owned local variables

Useful as a short reference for anyone learning the escape hatches
to hand-written 6502.

https://claude.ai/code/session_01W6eQFStA66EuMKHUFo2rx3

examples/inline_asm_demo.ne

@@ -0,0 +1,54 @@
+// Demonstrates inline assembly with `{var}` substitution.
+//
+// Mixes NEScript and hand-written 6502 for performance-critical
+// sections. Shows the three inline-asm mechanisms:
+//
+//   1. `asm { ... }` — NEScript-managed, variables resolved by name
+//   2. `raw asm { ... }` — unmanaged; passed through verbatim
+//   3. `poke(addr, value)` / `peek(addr)` — intrinsic for single
+//      memory-mapped-register accesses
+
+game "InlineAsmDemo" { mapper: NROM }
+
+var x: u8 = 0
+var y: u8 = 100
+var frame_count: u8 = 0
+
+// Fast "multiply by 4" using shifts written directly in assembly.
+// The NEScript compiler would strength-reduce `a * 4` to two ASLs
+// anyway, but this demonstrates that hand-written asm can reference
+// NEScript locals via `{name}` substitution.
+fun times_four(input: u8) -> u8 {
+    var result: u8 = input
+    asm {
+        LDA {result}
+        ASL A
+        ASL A
+        STA {result}
+    }
+    return result
+}
+
+on frame {
+    // Increment the frame counter via inline asm. The `{frame_count}`
+    // placeholder is replaced with the variable's zero-page address
+    // by the compiler before the asm parser sees it.
+    asm {
+        LDA {frame_count}
+        CLC
+        ADC #$01
+        STA {frame_count}
+    }
+
+    // Use `poke` to clear the PPU scroll back to (0, 0) every frame.
+    poke(0x2005, 0)
+    poke(0x2005, 0)
+
+    // Use `times_four` (which itself uses inline asm) to animate the
+    // sprite position.
+    x = times_four(frame_count)
+    draw Smiley at: (x, y)
+
+    wait_frame
+}
+start Main