# R36 Ultra Framebuffer Demo - ARM64 Build

## ✅ Successfully Compiled for ARM64!

The program has been cross-compiled for ARM64 (aarch64) architecture.

## Files

- **`framebuffer_simple.c`** - Pure C implementation (no dependencies)
- **`framebuffer_demo.vala`** - Vala implementation (requires GLib)
- **`framebuffer_demo`** - ARM64 binary (statically linked, ready to run)
- **`compile_simple.sh`** - Compilation script for C version

## Binary Information

```
framebuffer_demo: ELF 64-bit LSB executable, ARM aarch64, statically linked
```

This binary is:
- ✅ Compiled for ARM64 (R36 Ultra architecture)
- ✅ Statically linked (no dependencies needed)
- ✅ Ready to transfer and run on R36 Ultra

## Transfer to R36 Ultra

### Option 1: SCP (Network Transfer)
```bash
scp framebuffer_demo user@r36ultra-ip:/home/user/
```

### Option 2: USB/SD Card
1. Copy `framebuffer_demo` to USB drive or SD card
2. Insert into R36 Ultra
3. Copy to device

## Running on R36 Ultra

```bash
chmod +x framebuffer_demo
sudo ./framebuffer_demo
```

## What It Does

The program:
1. Opens `/dev/fb0` framebuffer (720x720, BGRA format)
2. Draws colorful shapes:
   - Red rectangle
   - Green circle
   - Blue rectangle
   - Yellow circle
3. Waits for Enter key
4. Clears screen and exits

## Recompiling

### For ARM64 (cross-compile):
```bash
./compile_simple.sh arm64
```

### For native (x86_64):
```bash
./compile_simple.sh
```

## Customization

Edit `framebuffer_simple.c` and use these functions:

- `fill_screen(fb, b, g, r, a)` - Fill screen with color
- `set_pixel(fb, x, y, b, g, r, a)` - Set individual pixel
- `draw_rectangle(fb, x, y, w, h, b, g, r, a)` - Draw rectangle
- `draw_circle(fb, cx, cy, radius, b, g, r, a)` - Draw circle
- `fb_update(fb)` - Write to framebuffer

**Note**: Colors are in BGRA format (Blue, Green, Red, Alpha)

## Advantages of C Version

- ✅ No dependencies (pure C, statically linked)
- ✅ Easy cross-compilation
- ✅ Small binary size
- ✅ Fast execution
- ✅ Works on any ARM64 Linux system