hakmem/core/box/smallobject_v5_env_box.h

// smallobject_v5_env_box.h - SmallObject v5 環境ゲート（Phase v5-0）
//
// ENV ベース: HAKMEM_SMALL_HEAP_V5_ENABLED, HAKMEM_SMALL_HEAP_V5_CLASSES

#ifndef HAKMEM_SMALLOBJECT_V5_ENV_BOX_H
#define HAKMEM_SMALLOBJECT_V5_ENV_BOX_H

#include <stdlib.h>
#include <string.h>
#include <stdint.h>

// ENV sentinel values
#define ENV_UNINIT   (-1)
#define ENV_ENABLED  (1)
#define ENV_DISABLED (0)

// route priority enum
enum small_route_priority {
    ROUTE_PRIORITY_V4   = 0,
    ROUTE_PRIORITY_V5   = 1,
    ROUTE_PRIORITY_AUTO = 2,
};

// small_heap_v5_enabled() - グローバル v5 enable check
static inline int small_heap_v5_enabled(void) {
    static int g_enabled = ENV_UNINIT;
    if (__builtin_expect(g_enabled == ENV_UNINIT, 0)) {
        const char* e = getenv("HAKMEM_SMALL_HEAP_V5_ENABLED");
        g_enabled = (e && *e && *e != '0') ? ENV_ENABLED : ENV_DISABLED;
    }
    return (g_enabled == ENV_ENABLED);
}

// small_heap_v5_class_mask() - v5 対象クラスのビットマスク
static inline uint32_t small_heap_v5_class_mask(void) {
    static int g_mask = ENV_UNINIT;  // sentinel
    if (__builtin_expect(g_mask == ENV_UNINIT, 0)) {
        const char* e = getenv("HAKMEM_SMALL_HEAP_V5_CLASSES");
        if (e && *e) {
            g_mask = (int)strtoul(e, NULL, 0);
        } else {
            g_mask = 0x0;  // default: OFF
        }
    }
    return (uint32_t)g_mask;
}

// small_heap_v5_class_enabled() - 指定クラスが v5 有効か
static inline int small_heap_v5_class_enabled(uint32_t class_idx) {
    if (class_idx >= 8) return 0;
    if (!small_heap_v5_enabled()) return 0;
    uint32_t mask = small_heap_v5_class_mask();
    return (mask & (1u << class_idx)) ? 1 : 0;
}

// 便利関数
static inline int small_heap_v5_c6_enabled(void) {
    return small_heap_v5_class_enabled(6);
}

static inline int small_heap_v5_c5_enabled(void) {
    return small_heap_v5_class_enabled(5);
}

static inline int small_heap_v5_c7_enabled(void) {
    return small_heap_v5_class_enabled(7);
}

// small_route_priority() - route priority (v4/v5/auto)
// ENV: HAKMEM_ROUTE_PRIORITY={v4|v5|auto}, default: v4
static inline int small_route_priority(void) {
    static int g_priority = ENV_UNINIT;
    if (__builtin_expect(g_priority == ENV_UNINIT, 0)) {
        const char* e = getenv("HAKMEM_ROUTE_PRIORITY");
        if (e && *e) {
            if (strcmp(e, "v5") == 0) {
                g_priority = ROUTE_PRIORITY_V5;
            } else if (strcmp(e, "auto") == 0) {
                g_priority = ROUTE_PRIORITY_AUTO;
            } else {
                g_priority = ROUTE_PRIORITY_V4;  // default or "v4"
            }
        } else {
            g_priority = ROUTE_PRIORITY_V4;  // default
        }
    }
    return g_priority;
}

// small_heap_v5_segment_size() - segment size override
// ENV: HAKMEM_SMALL_HEAP_V5_SEGMENT_SIZE, default: 2MiB (2*1024*1024)
static inline size_t small_heap_v5_segment_size(void) {
    static int g_size = ENV_UNINIT;
    if (__builtin_expect(g_size == ENV_UNINIT, 0)) {
        const char* e = getenv("HAKMEM_SMALL_HEAP_V5_SEGMENT_SIZE");
        if (e && *e) {
            size_t sz = (size_t)strtoul(e, NULL, 0);
            // validate: must be power of 2, >= 64KiB
            if (sz >= (64 * 1024) && (sz & (sz - 1)) == 0) {
                g_size = (int)sz;
            } else {
                g_size = (2 * 1024 * 1024);  // fallback to default
            }
        } else {
            g_size = (2 * 1024 * 1024);  // default: 2MiB
        }
    }
    return (size_t)g_size;
}

// ============================================================================
// Phase v5-4: Header mode configuration
// ============================================================================

// Header mode enum
#define SMALL_HEAP_V5_HEADER_MODE_FULL  0
#define SMALL_HEAP_V5_HEADER_MODE_LIGHT 1

// small_heap_v5_header_mode() - header write mode (default: full)
// ENV: HAKMEM_SMALL_HEAP_V5_HEADER_MODE={full|light}, default: full
// - full: write header on every alloc (safe, standard)
// - light: write header once during carve, skip on alloc (research mode, +2-4% perf)
static inline int small_heap_v5_header_mode(void) {
    static int g_header_mode = ENV_UNINIT;
    if (__builtin_expect(g_header_mode == ENV_UNINIT, 0)) {
        const char* e = getenv("HAKMEM_SMALL_HEAP_V5_HEADER_MODE");
        if (e && *e) {
            if (strcmp(e, "light") == 0 || strcmp(e, "LIGHT") == 0 || *e == '1') {
                g_header_mode = SMALL_HEAP_V5_HEADER_MODE_LIGHT;
            } else {
                g_header_mode = SMALL_HEAP_V5_HEADER_MODE_FULL;  // default or "full"
            }
        } else {
            g_header_mode = SMALL_HEAP_V5_HEADER_MODE_FULL;  // default: full
        }
    }
    return g_header_mode;
}

#endif // HAKMEM_SMALLOBJECT_V5_ENV_BOX_H