Files
subhobhai943andClaude Opus 5 f9400f6ac4 feat(kernel): Add RB-tree/kfifo/hashtable, wait queues, futex, tiny RCU, page cache and KTest harness
Expands the kernel-and-TTY core with the primitives the higher layers have
been missing, plus an in-kernel harness that proves they work.

Data structures (lib/):
  - rbtree.c: Linux-compatible red-black tree with parent pointers, full
    insert/erase rebalancing, in-order iteration and an invariant validator.
  - kfifo.c: power-of-two byte ring with free-running indices, so the wrap
    path costs one mask instead of a branch per byte.
  - hashtable.c: separately-chained table with FNV-1a hashing, string or
    u64 keys, and rehash-on-growth at a 3/4 load factor.

Kernel subsystems:
  - kernel/wait.c: wait queues and one-shot completion barriers, backed by a
    static sleeper pool so a blocking path never re-enters the allocator.
  - kernel/futex.c: 32-bucket futex hash with value re-check, requeue, and an
    fmutex_t sleeping mutex built on the uncontended-fastpath protocol.
  - kernel/rcu.c: tiny RCU with reader nesting, deferred callbacks, kfree_rcu
    and rcu_assign_pointer/rcu_dereference publish barriers.
  - mm/page_cache.c: write-back block page cache, 4 KB pages indexed by
    (device, page), CLOCK second-chance eviction and dirty write-back.
  - kernel/ktest.c: KUnit-style harness with 6 built-in suites, 21 cases and
    735 assertions covering every subsystem above (all passing under QEMU).

LazyBox userland:
  - coreutils.c: sort, uniq, cut, tr, rev, tac, nl, seq, diff, xxd, du,
    factor, sum and truncate, reading through the VFS and handling the
    zero-length synthetic nodes that procfs and sysfs expose.
  - ktest, rcuinfo, futexinfo, waitinfo and pagecache diagnostics applets.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01L5yKJT4Wo2cV3rfPrwY5MP
2026-08-24 23:38:59 +05:30

41 lines
1.3 KiB
C

#ifndef _LIB_KFIFO_H
#define _LIB_KFIFO_H
#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#include <kernel/sync.h>
// Power-of-two byte ring buffer with an unsigned index-wrap discipline,
// mirroring the classic Linux kfifo. Producer and consumer indices are
// free-running; masking happens only at access time.
typedef struct kfifo {
uint8_t* buffer;
size_t size; // Always a power of two
size_t mask; // size - 1
size_t in; // Free-running producer index
size_t out; // Free-running consumer index
bool owns_buffer;
spinlock_t lock;
} kfifo_t;
int kfifo_alloc(kfifo_t* fifo, size_t size);
int kfifo_init_static(kfifo_t* fifo, void* buffer, size_t size);
void kfifo_free(kfifo_t* fifo);
void kfifo_reset(kfifo_t* fifo);
size_t kfifo_in(kfifo_t* fifo, const void* src, size_t len);
size_t kfifo_out(kfifo_t* fifo, void* dst, size_t len);
size_t kfifo_peek(const kfifo_t* fifo, void* dst, size_t len);
size_t kfifo_len(const kfifo_t* fifo);
size_t kfifo_avail(const kfifo_t* fifo);
bool kfifo_is_empty(const kfifo_t* fifo);
bool kfifo_is_full(const kfifo_t* fifo);
int kfifo_put_byte(kfifo_t* fifo, uint8_t byte);
int kfifo_get_byte(kfifo_t* fifo, uint8_t* byte_out);
#endif // _LIB_KFIFO_H