Flappy DTEK-V

A bare-metal Flappy Bird clone for the DTEK-V board (RISC-V 32IMZICSR). Runs at a fixed 60 FPS driven by a hardware timer interrupt, renders to the 320×240 VGA framebuffer, and uses the push button for input plus the seven-segment displays for the score.

Features

• Bare-metal freestanding C, no libc, custom crt0 (boot.S)
• Fixed 60 FPS via timer-interrupt frame pacing
• Double-buffered VGA rendering (320×240, 8-bit RRRGGGBB color)
• Integer-only physics (Q16.16 fixed-point, no FPU required)
• Sprite blitting with transparency and clipping
• Score on the hex displays, high-score tracking, parallax ground scroll

Hardware

Peripheral	Use
VGA (320×240)	Framebuffer output
Timer	60 Hz frame interrupt
Push button	Flap / start / restart
Seven-segment	Current score and high score
LEDs	Lit while the button is held

Target core: rv32imzicsr, ABI ilp32 (soft-float / integer-only).

Layout

boot.S            Startup: stack/gp setup, .bss zeroing, isr_handler
linker.lds        Memory map and section placement
Makefile          Build + run
include/          Public interfaces (drivers + game)
drivers/          Hardware access (vga, timer, button, hex, leds)
src/              Game logic (game, render, sprite, lib, main)
assets/           Generated sprite data (image arrays)

The codebase keeps a strict split: drivers/ is the only code that touches memory-mapped registers, src/ contains hardware-independent game logic, and include/ holds the interfaces between them.

Prerequisites

RISC-V cross-compiler — build from source or install a pre-built package:

# Arch Linux
sudo pacman -S riscv32-elf-gcc

# From source (all distros)
git clone https://github.com/riscv/riscv-gnu-toolchain
cd riscv-gnu-toolchain
./configure --prefix=/opt/riscv --with-arch=rv32gc --with-abi=ilp32
sudo make -j$(nproc)
export PATH=/opt/riscv/bin:$PATH

DTEK-V board tools — required to load binaries onto the physical board. Download dtekv-tools.zip from your course resources, then:

unzip dtekv-tools.zip
cd dtekv-tools && make

This produces dtekv-run, dtekv-download, and dtekv-upload in that directory.

Build

make build       # produces main.bin (+ main.elf and a disassembly dump)
make clean

Override the toolchain prefix if yours differs:

make build TOOLCHAIN=riscv64-unknown-elf-

Key flags: -nostdlib -fno-builtin -march=rv32imzicsr -mabi=ilp32.

Run

Physical board:

make run         # builds main.bin and loads it onto the board via dtekv-run

Online emulator: upload main.bin at dtekv.fritiof.dev.

Controls

Action	Input
Flap	Press the button while playing
Start	Press from the menu
Restart	Press on the game-over screen

Notes

• Physics is fixed-point Q16.16 (fixed_t in include/game.h); 1.0 px is FIXED_ONE. There is no floating point anywhere in the binary, so no soft-float library is linked.
• Pipe gap positions use a deterministic xorshift32 RNG seeded from the frame counter at game start.

License

BSD 3-Clause. See COPYING.