qemu/include/exec/memop.h

/*
 * Constants for memory operations
 *
 * Authors:
 *  Richard Henderson <rth@twiddle.net>
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 *
 */

#ifndef MEMOP_H
#define MEMOP_H

#include "qemu/host-utils.h"

typedef enum MemOp {
    MO_8     = 0,
    MO_16    = 1,
    MO_32    = 2,
    MO_64    = 3,
    MO_SIZE  = 3,   /* Mask for the above.  */

    MO_SIGN  = 4,   /* Sign-extended, otherwise zero-extended.  */

    MO_BSWAP = 8,   /* Host reverse endian.  */
#ifdef HOST_WORDS_BIGENDIAN
    MO_LE    = MO_BSWAP,
    MO_BE    = 0,
#else
    MO_LE    = 0,
    MO_BE    = MO_BSWAP,
#endif
#ifdef NEED_CPU_H
#ifdef TARGET_WORDS_BIGENDIAN
    MO_TE    = MO_BE,
#else
    MO_TE    = MO_LE,
#endif
#endif

    /*
     * MO_UNALN accesses are never checked for alignment.
     * MO_ALIGN accesses will result in a call to the CPU's
     * do_unaligned_access hook if the guest address is not aligned.
     * The default depends on whether the target CPU defines
     * TARGET_ALIGNED_ONLY.
     *
     * Some architectures (e.g. ARMv8) need the address which is aligned
     * to a size more than the size of the memory access.
     * Some architectures (e.g. SPARCv9) need an address which is aligned,
     * but less strictly than the natural alignment.
     *
     * MO_ALIGN supposes the alignment size is the size of a memory access.
     *
     * There are three options:
     * - unaligned access permitted (MO_UNALN).
     * - an alignment to the size of an access (MO_ALIGN);
     * - an alignment to a specified size, which may be more or less than
     *   the access size (MO_ALIGN_x where 'x' is a size in bytes);
     */
    MO_ASHIFT = 4,
    MO_AMASK = 7 << MO_ASHIFT,
#ifdef NEED_CPU_H
#ifdef TARGET_ALIGNED_ONLY
    MO_ALIGN = 0,
    MO_UNALN = MO_AMASK,
#else
    MO_ALIGN = MO_AMASK,
    MO_UNALN = 0,
#endif
#endif
    MO_ALIGN_2  = 1 << MO_ASHIFT,
    MO_ALIGN_4  = 2 << MO_ASHIFT,
    MO_ALIGN_8  = 3 << MO_ASHIFT,
    MO_ALIGN_16 = 4 << MO_ASHIFT,
    MO_ALIGN_32 = 5 << MO_ASHIFT,
    MO_ALIGN_64 = 6 << MO_ASHIFT,

    /* Combinations of the above, for ease of use.  */
    MO_UB    = MO_8,
    MO_UW    = MO_16,
    MO_UL    = MO_32,
    MO_SB    = MO_SIGN | MO_8,
    MO_SW    = MO_SIGN | MO_16,
    MO_SL    = MO_SIGN | MO_32,
    MO_Q     = MO_64,

    MO_LEUW  = MO_LE | MO_UW,
    MO_LEUL  = MO_LE | MO_UL,
    MO_LESW  = MO_LE | MO_SW,
    MO_LESL  = MO_LE | MO_SL,
    MO_LEQ   = MO_LE | MO_Q,

    MO_BEUW  = MO_BE | MO_UW,
    MO_BEUL  = MO_BE | MO_UL,
    MO_BESW  = MO_BE | MO_SW,
    MO_BESL  = MO_BE | MO_SL,
    MO_BEQ   = MO_BE | MO_Q,

#ifdef NEED_CPU_H
    MO_TEUW  = MO_TE | MO_UW,
    MO_TEUL  = MO_TE | MO_UL,
    MO_TESW  = MO_TE | MO_SW,
    MO_TESL  = MO_TE | MO_SL,
    MO_TEQ   = MO_TE | MO_Q,
#endif

    MO_SSIZE = MO_SIZE | MO_SIGN,
} MemOp;

/* MemOp to size in bytes.  */
static inline unsigned memop_size(MemOp op)
{
    return 1 << (op & MO_SIZE);
}

/* Size in bytes to MemOp.  */
static inline MemOp size_memop(unsigned size)
{
#ifdef CONFIG_DEBUG_TCG
    /* Power of 2 up to 8.  */
    assert((size & (size - 1)) == 0 && size >= 1 && size <= 8);
#endif
    return ctz32(size);
}

/* Big endianness from MemOp.  */
static inline bool memop_big_endian(MemOp op)
{
    return (op & MO_BSWAP) == MO_BE;
}

#endif