#extern(vm) fn vm_alloc(sz: usize): *any;
#extern(vm) fn vm_free(p: *any);
#extern(vm) fn vm_realloc(p: *any, sz: usize): *any;
#extern(vm) fn vm_memcpy(dst: *any, src: *any, n: usize): *any;
#extern(vm) fn vm_memcmp(a: *any, b: *any, n: usize): isize;

fn alloc(sz: usize): *any {
    if sz == 0 { ret null; }
    ret vm_alloc(sz);
}

fn free(p: *any) {
    if p == null { ret; }
    vm_free(p);
}

fn realloc(p: *any, sz: usize): *any {
    if p == null { ret alloc(sz); }
    if sz == 0 { free(p); ret null; }
    ret vm_realloc(p, sz);
}

fn copy(dst: *any, src: *any, n: usize): *any {
    if n == 0 { ret dst; }
    ret vm_memcpy(dst, src, n);
}

fn cmp(a: *any, b: *any, n: usize): isize {
    if n == 0 { ret 0; }
    ret vm_memcmp(a, b, n);
}

fn set(dst: *any, byte: u8, n: usize): *any {
    var d = dst as *u8;
    var i: usize = 0;
    while i < n {
        d[i] = byte;
        i = i + 1;
    }
    ret dst;
}

fn zero(dst: *any, n: usize): *any {
    ret set(dst, 0 as u8, n);
}

fn main(): void {
    var p = alloc(16);
    @assert(p != null, "alloc");
    var q = alloc(16);
    @assert(p != q, "distinct");
    @assert(alloc(0) == null, "alloc(0)");

    var a: u8 = 42;
    var b: u8 = 0;
    copy(&b as *any, &a as *any, 1);
    @assert(b == 42, "copy");

    var x: u8 = 1;
    var y: u8 = 2;
    @assert(cmp(&x as *any, &y as *any, 1) < 0, "cmp lt");
    @assert(cmp(&y as *any, &x as *any, 1) > 0, "cmp gt");
    @assert(cmp(&x as *any, &x as *any, 1) == 0, "cmp eq");

    var buf = alloc(8);
    zero(buf, 8);
    var bp = buf as *u8;
    @assert(bp[0] == 0, "zero");
    @assert(bp[7] == 0, "zero end");
    set(buf, 0xAB as u8, 8);
    @assert(bp[0] == 0xAB as u8, "set");

    var r = realloc(p, 32);
    @assert(r != null, "realloc");
    free(r);
    free(q);
    free(buf);
    free(null);
}