SlowAPI

A bare-metal ARM64 HTTP server written entirely in assembly, running on QEMU with no OS, no C runtime, and no standard library. Implements a full network stack from Ethernet frames up through a web framework with JSON responses.

~5700 lines of ARM64 assembly (~9200 including tests and benchmarks).

Architecture

Application (app.s)
    Hotel CRUD API endpoints
        |
SlowAPI Framework (slowapi/)
    Route matching, HTTP parsing, JSON builder, response builder
        |
TCP/IP Stack (net/)
    TCP state machine, IPv4, ARP, Ethernet
        |
Device Drivers (drivers/)
    Virtio-net (MMIO), PL011 UART, ARM64 timer
        |
Hardware (QEMU virt, Cortex-A72)

Everything is written from scratch: memory allocator, network stack, web framework, database, JSON serialization.

Components

Directory	What it does
src/drivers/	PL011 UART, virtio-net device driver, ARM64 generic timer
src/net/	Ethernet, ARP, IPv4 (with checksum), TCP (full state machine on port 80)
src/mem/	Slab allocator (64 blocks x 128 bytes, bitmap-tracked)
src/db/	In-memory record store with auto-increment IDs
src/slowapi/	Web framework: route macros, HTTP parser, router with path params, JSON builder, response builder, query string parser
src/app.s	Application endpoints (Hotel CRUD API)
src/boot.s	Entry point: stack setup, driver init, main polling loop
src/test/	Unit tests for every layer (10 test modules)
src/bench/	Cycle-counted benchmarks for core operations

SlowAPI

Routes are defined with an ENDPOINT macro that places entries into a linker section, building the route table at link time:

ENDPOINT METHOD_GET, "/api/hotels"
handler_list_hotels:
    FRAME_ENTER 1, 128
    // ... build JSON response ...
    FRAME_LEAVE
    ret

The router supports parameterized paths (/api/hotels/{id}) with automatic extraction into the request context.

Prerequisites

# ARM64 bare-metal toolchain
brew install --cask gcc-aarch64-embedded

# QEMU
brew install qemu

Build & Run

make          # build kernel.elf
make run      # boot in QEMU, HTTP server on localhost:8888
make test     # run unit tests
make bench    # run benchmarks
make clean    # remove build artifacts

The server listens on port 80 inside QEMU, forwarded to localhost:8888:

# In another terminal
curl http://localhost:8888/
curl http://localhost:8888/api/hotels
curl -X POST -d "Hilton,Toronto" http://localhost:8888/api/hotels
curl http://localhost:8888/api/hotels/1
curl -X DELETE http://localhost:8888/api/hotels/1

Exit QEMU with Ctrl-A X.