source: mainline/uspace/lib/c/include/capa.h@ cd1e3fc0

/*
 * SPDX-FileCopyrightText: 2015 Jiri Svoboda
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

/** @addtogroup libc
 * @{
 */
/**
 * @file Storage capacity specification.
 */

#ifndef _LIBC_CAPA_H_
#define _LIBC_CAPA_H_

#include <errno.h>
#include <stddef.h>
#include <stdint.h>

/** Capacity unit */
typedef enum {
        cu_byte = 0,
        cu_kbyte,
        cu_mbyte,
        cu_gbyte,
        cu_tbyte,
        cu_pbyte,
        cu_ebyte,
        cu_zbyte,
        cu_ybyte
} capa_unit_t;

/** Which of values within the precision of the capacity */
typedef enum {
        /** The nominal (middling) value */
        cv_nom,
        /** The minimum value */
        cv_min,
        /** The maximum value */
        cv_max
} capa_vsel_t;

#define CU_LIMIT (cu_ybyte + 1)

/** Storage capacity.
 *
 * Storage capacity represents both value and precision.
 * It is a decimal floating point value combined with a decimal
 * capacity unit. There is an integer mantisa @c m which in combination
 * with the number of decimal positions @c dp gives a decimal floating-point
 * number. E.g. for m = 1025 and dp = 2 the number is 10.25. If the unit
 * cunit = cu_kbyte, the capacity is 10.25 kByte, i.e. 10 250 bytes.
 *
 * Note that 1.000 kByte is equivalent to 1000 Byte, but 1 kByte is less
 * precise.
 */
typedef struct {
        /** Mantisa */
        uint64_t m;
        /** Decimal positions */
        unsigned dp;
        /** Capacity unit */
        capa_unit_t cunit;
} capa_spec_t;

extern errno_t capa_format(capa_spec_t *, char **);
extern errno_t capa_parse(const char *, capa_spec_t *);
extern void capa_simplify(capa_spec_t *);
extern void capa_from_blocks(uint64_t, size_t, capa_spec_t *);
extern errno_t capa_to_blocks(capa_spec_t *, capa_vsel_t, size_t, uint64_t *);

#endif

/** @}
 */