gid.h

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#pragma once
 
#include <stdint.h>
#include "api.h"
 
struct gid_metadata {
    uint32_t* const bitmap;    // a constant pointer to a bitmap
    const size_t max;          // Maximum gid value
    const size_t reserved;     // first n GIDs may be reserved, at most 32, but at least 1
    const size_t bitmap_size;  // Cached number of uint32_t's used to map gid_max.
                               // Use gid_size_to_words to compute
 
    // internal usage to ensure that GIDs get delegated linearly before wrapping
    // around back to 0
    size_t _cur_val;
    mutex_t _lock;
};
 
#ifndef UINT32_WIDTH
#define UINT32_WIDTH 32
#endif

#define gid_size_to_words(size) (((size) + UINT32_WIDTH - 1) / UINT32_WIDTH)

void gid_init(struct gid_metadata* const metadata);

uint32_t gid_alloc(struct gid_metadata* const metadata);

void gid_free(struct gid_metadata* const metadata, uint32_t id);

bool gid_check(struct gid_metadata* metadata, uint32_t id);