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import "libc.hff";
import "all.hff";
def ARENA_SIZE = 16 * 1024;
defmacro ALIGNUP(x,a) [ (((x) + ((a) - 1)) & -(a)) ]
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 int,
mem [ARENA_SIZE]u8,
}
struct Arena {
r *ArenaRegion,
fn allocf(a *void, n usize) *void {
let a *Arena = a;
n = ALIGNUP(n, 16);
if ARENA_SIZE < n {
return xmalloc(n);
} else if a.r == #null {
a.r = xcalloc(1, sizeof ArenaRegion);
return allocf(a, n);
} else if ARENA_SIZE - a.r.idx >= n {
let ptr = &a.r.mem[a.r.idx];
a.r.idx += n;
return ptr;
} else {
let rp *ArenaRegion = xmalloc(sizeof ArenaRegion);
*rp = *a.r;
let r = ArenaRegion { .prev: rp };
return allocf(a, n);
}
}
}
struct Allocator {
a *void,
allocf *fn(*void, usize) *void,
freef *fn(*void, *void) void,
fn alloc(self *Allocator, n usize) *void {
if self.allocf {
return self.allocf(self.a, n);
}
return #null;
}
fn free(self *Allocator, ptr *void) void {
if self.freef {
self.freef(self.a, ptr);
}
}
}
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