// BufAlloc.init returns the state BY VALUE: the caller's local is the
// allocator state and the FULL buffer is usable. Regression: init used
// to carve its own struct off the buffer's head (returning *BufAlloc
// into the buffer), so a 128-byte buffer could only serve 104 bytes —
// the second 64-byte allocation below failed with null.

#import "modules/std.sx";
#import "modules/std/mem.sx";

main :: () {
    stack_buf : [128]u8 = ---;
    buf := BufAlloc.init(@stack_buf[0], 128);
    a : Allocator = xx buf;

    b1 := a.alloc_bytes(64);
    b2 := a.alloc_bytes(64);          // fills the buffer EXACTLY
    b1_ok := b1 != null;
    b2_ok := b2 != null;
    print("full capacity: {} {} pos={}\n", b1_ok, b2_ok, buf.pos);

    b3 := a.alloc_bytes(1);           // one byte over — must fail
    print("over: {}\n", b3 == null);

    buf.reset();
    print("reset: {}\n", buf.pos);
}