63 lines
1.4 KiB
Rust
63 lines
1.4 KiB
Rust
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#![no_std]
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use core::cell::UnsafeCell;
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use core::panic::PanicInfo;
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// --- bump allocator ---
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const HEAP_SIZE: usize = 65536;
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struct BumpAlloc {
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heap: UnsafeCell<[u8; HEAP_SIZE]>,
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offset: UnsafeCell<usize>,
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}
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unsafe impl Sync for BumpAlloc {}
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static ALLOC: BumpAlloc = BumpAlloc {
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heap: UnsafeCell::new([0u8; HEAP_SIZE]),
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offset: UnsafeCell::new(0),
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};
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#[unsafe(no_mangle)]
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pub extern "C" fn alloc(size: i32) -> i32 {
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unsafe {
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let offset = &mut *ALLOC.offset.get();
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let heap = &mut *ALLOC.heap.get();
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let align = 8;
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let start = (*offset + align - 1) & !(align - 1);
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let end = start + size as usize;
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if end > heap.len() {
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return 0; // OOM
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}
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*offset = end;
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heap.as_ptr().add(start) as i32
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}
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}
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// --- host import ---
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#[link(wasm_import_module = "swactor")]
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unsafe extern "C" {
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#[link_name = "send"]
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fn host_send(dest_ptr: i32, payload_ptr: i32, payload_len: i32);
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}
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/// Message format: first 32 bytes = destination address, rest = payload.
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/// Echo sends the payload portion back to the specified destination.
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#[unsafe(no_mangle)]
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pub extern "C" fn handle(ptr: i32, len: i32) {
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if len < 32 {
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return;
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}
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let dest_ptr = ptr;
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let payload_ptr = ptr + 32;
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let payload_len = len - 32;
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unsafe {
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host_send(dest_ptr, payload_ptr, payload_len);
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}
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}
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#[panic_handler]
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fn panic(_info: &PanicInfo) -> ! {
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loop {}
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}
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