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// SPDX-License-Identifier: MPL-2.0
// (c) Hare authors <https://harelang.org>
// A group of blocks that were allocated together.
export type chunk = union {
padding: size, // TODO: track number of active allocations here
data: [*]u8,
};
// Metadata for a block.
export type meta = struct {
union {
sz: size,
next: uintptr,
},
user: [*]u8,
};
export type memory_heap = struct {
// Number of allocations currently in flight.
cur_allocs: size,
// Freelists for blocks up to 2048 bytes.
bins: [9]nullable *meta,
// The chunk to allocate from if there are no blocks available in the
// right freelist.
cur_chunk: (*chunk, size),
};
// An empty memory heap, used to initialize a [[memory_heap]] for use with
// [[setheap]].
export def EMPTY_HEAP = memory_heap {
cur_allocs = 0,
bins = [null...],
cur_chunk = (null: *chunk, CHUNKSZ),
};
let static_heap = EMPTY_HEAP;
let heap = &static_heap;
// Switches the internal runtime allocator to a new memory heap. The caller
// should provision a [[memory_heap]] initialized to [[EMPTY_HEAP]] somehow
// (statically, or in a second memory_heap, or even on the stack if you're brave
// enough) and pass it to this function to enable it. Returns a pointer to the
// heap which was previously in use, should you wish to restore it later.
//
// The caller is responsible for ensuring that any use of free() or delete()
// makes use of an object which was allocated (via alloc(), insert(), or
// append()) from the same heap.
//
// This function is designed for debugging use, and exists in particular to
// satisfy the needs of [[debug::]].
export fn setheap(new_heap: *memory_heap) *memory_heap = {
const old = heap;
heap = new_heap;
return old;
};
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