// Inline helpers for Background Refill Bin (lock-free SLL)
// This header is textually included from hakmem_tiny.c after the following
// symbols are defined:
//   - g_bg_bin_enable, g_bg_bin_head[]

#include "box/tiny_next_ptr_box.h"  // Phase E1-CORRECT: Box API for next pointer

static inline void* bgbin_pop(int class_idx) {
    if (!g_bg_bin_enable) return NULL;
    uintptr_t h = atomic_load_explicit(&g_bg_bin_head[class_idx], memory_order_acquire);
    while (h != 0) {
        void* p = (void*)h;
        // Phase E1-CORRECT: Use Box API for next pointer read
        uintptr_t next = (uintptr_t)tiny_next_read(class_idx, p);
        if (atomic_compare_exchange_weak_explicit(&g_bg_bin_head[class_idx], &h, next,
                                                  memory_order_acq_rel, memory_order_acquire)) {
#if HAKMEM_DEBUG_COUNTERS
            g_bgbin_pops[class_idx]++;
#endif
            return p;
        }
    }
    return NULL;
}

static inline void bgbin_push_chain(int class_idx, void* chain_head, void* chain_tail) {
    if (!chain_head) return;
    uintptr_t h = atomic_load_explicit(&g_bg_bin_head[class_idx], memory_order_acquire);
    // Phase E1-CORRECT: Use Box API for next pointer write
    do { tiny_next_write(class_idx, chain_tail, (void*)h); }
    while (!atomic_compare_exchange_weak_explicit(&g_bg_bin_head[class_idx], &h,
                                                  (uintptr_t)chain_head,
                                                  memory_order_acq_rel, memory_order_acquire));
}

static inline int bgbin_length_approx(int class_idx, int cap) {
    uintptr_t h = atomic_load_explicit(&g_bg_bin_head[class_idx], memory_order_acquire);
    int n = 0;
    while (h && n < cap) {
        void* p = (void*)h;
        // Phase E1-CORRECT: Use Box API for next pointer read
        h = (uintptr_t)tiny_next_read(class_idx, p);
        n++;
    }
    return n;
}