// smallsegment_v4_box.h - Small-object専用 Segment Box の型定義と API 宣言
// Phase v4-mid-0: SmallSegment の型と API だけを先行定義。実装は後フェーズ。
#pragma once

#include <stdint.h>

// Forward declaration
struct SmallPageMeta;

// ============================================================================
// SmallSegment: class_idx ごとに小さな segment を管理
// ============================================================================

typedef struct SmallSegment {
    uintptr_t base;           // Segment base address
    uint32_t num_pages;       // Number of pages in segment
    uint32_t owner_tid;       // Thread ID that owns this segment
    uint32_t magic;           // Magic number for validation
    // Page metadata array (flexible, actual size depends on SMALL_PAGE_SIZE / SMALL_SEGMENT_SIZE)
    // struct SmallPageMeta* page_meta[];
} SmallSegment;

// Backward compatibility alias
typedef SmallSegment small_segment_v4;

// ============================================================================
// API: Segment Management
// ============================================================================

SmallSegment* smallsegment_v4_acquire(int class_idx);
void smallsegment_v4_release_if_empty(SmallSegment* seg, void* page, int class_idx);
struct SmallPageMeta* smallsegment_v4_page_meta_of(SmallSegment* seg, void* ptr);