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import "libc.hff";
defmacro ALIGNUP(x,a) [ (((x) + ((a) - 1)) & -(a)) ]
def ARENA_SIZE = 4z * 1024;
extern fn xmalloc(n usize) *void;
extern fn xcalloc(n usize, m usize) *void;
extern fn xrealloc(p *void, n usize) *void;
struct ArenaRegion {
prev *ArenaRegion,
idx usize,
siz usize,
mem [0]u8,
}
struct Arena {
r *ArenaRegion,
fn addregion(a *Arena, siz usize) void {
let r *ArenaRegion = xcalloc(sizeof ArenaRegion + siz, 1);
r.siz = siz;
r.prev = a.r;
a.r = r;
}
fn allocf(a *void, n usize, align usize) *void {
let a *Arena = a;
if a.r {
a.r.idx = ALIGNUP(a.r.idx, align);
}
if n > ARENA_SIZE {
a->addregion(n);
let p *void = a.r.mem;
a->addregion(ARENA_SIZE);
return p;
} else if a.r == #null {
a->addregion(ARENA_SIZE);
return allocf(a, n, align);
} else if n > a.r.siz - a.r.idx {
a->addregion(ARENA_SIZE);
return allocf(a, n, align);
} else {
let p = &a.r.mem[a.r.idx];
a.r.idx += n;
return p;
}
}
fn destroy(a *Arena) void {
for let r = a.r, next *ArenaRegion = #null; r; r = next {
next = r.prev;
free(r);
}
}
}
struct Allocator {
a *void,
allocf *fn(*void, usize, usize) *void,
freef *fn(*void, *void) void,
fn alloc(self *Allocator, n usize, align usize) *void {
if self.allocf {
let p = self.allocf(self.a, n, align);
return p;
}
return #null;
}
fn free(self *Allocator, ptr *void) void {
if self.freef {
self.freef(self.a, ptr);
}
}
}
defmacro anew(a, T) [ ((a)->alloc(sizeof T, alignof T)) ]
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