# elibc — Standard C Library for Elyz

Minimal C library for the Elyz OS, based on musl's organisational principles
but adapted to Elyz's capability-based, syscall-less architecture.

## Structure

```
elibc/
├── arch/               # Architecture-specific code
│   ├── generic/        # Fallback implementation & abstract interfaces
│   │   ├── kcall.h          #  Kernel-call abstraction (no syscalls in Elyz)
│   │   ├── startup_info.h   #  Process-startup description
│   │   └── bits/            #  Type-size definitions
│   └── x86_64/         # x86_64 port
│       ├── kcall.h           #  Kernel-call placeholder (ABI TBD)
│       ├── startup_info.h    #  x86_64 startup layout (ABI TBD)
│       ├── atomic_arch.h     #  Locked cmpxchg / atomic ops
│       └── bits/
├── include/            # Public headers (POSIX-like API)
├── src/                # Source implementations
│   ├── internal/       #  Libc state, errno, bump allocator (temporary)
│   ├── string/         #  Pure-C string ops (memcpy, strlen, etc.)
│   ├── stdio/          #  (reserved)
│   └── stdlib/         #  atoi, etc.
├── crt/                # C runtime entry point
├── Makefile
└── configure
```

## Key differences from a traditional libc (glibc/musl)

| Traditional (Linux) | Elyz / elibc |
|---|---|
| `syscall`/`int 0x80` | Capability invocation → PM Actor messaging |
| `brk`/`sbrk` | `ELYZ_OP_ALLOCATE` via `elyz_kcall` |
| `_exit` syscall | `ELYZ_OP_EXIT` via kcall |
| `errno` via TLS | `__errno_location` (plain global for now) |

## Porting to a new arch

1. Create `arch/<name>/` with:
   - `kcall.h` — kernel-call mechanism
   - `startup_info.h` — process-startup layout
   - `arch.mak` — arch-specific compiler/linker flags
   - `bits/alltypes.h.in` — type sizes
   - `atomic_arch.h` — atomic ops (optional, fallback exists)
2. Add detection in `configure`
3. Build: `./configure && make`

## Building

```
./configure
make
```