move const_le{16, 23} to qemu/bswap.h, add comment

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1460441239-867-1-git-send-email-kraxel@redhat.com
This commit is contained in:
Gerd Hoffmann 2016-04-12 08:07:19 +02:00
parent a263bac192
commit 441330f714
2 changed files with 19 additions and 14 deletions

View File

@ -13,20 +13,6 @@ typedef struct virtio_input_absinfo virtio_input_absinfo;
typedef struct virtio_input_config virtio_input_config;
typedef struct virtio_input_event virtio_input_event;
#if defined(HOST_WORDS_BIGENDIAN)
# define const_le32(_x) \
((((_x) & 0x000000ffU) << 24) | \
(((_x) & 0x0000ff00U) << 8) | \
(((_x) & 0x00ff0000U) >> 8) | \
(((_x) & 0xff000000U) >> 24))
# define const_le16(_x) \
((((_x) & 0x00ff) << 8) | \
(((_x) & 0xff00) >> 8))
#else
# define const_le32(_x) (_x)
# define const_le16(_x) (_x)
#endif
/* ----------------------------------------------------------------- */
/* qemu internals */

View File

@ -125,6 +125,25 @@ static inline uint32_t qemu_bswap_len(uint32_t value, int len)
return bswap32(value) >> (32 - 8 * len);
}
/*
* Same as cpu_to_le{16,23}, except that gcc will figure the result is
* a compile-time constant if you pass in a constant. So this can be
* used to initialize static variables.
*/
#if defined(HOST_WORDS_BIGENDIAN)
# define const_le32(_x) \
((((_x) & 0x000000ffU) << 24) | \
(((_x) & 0x0000ff00U) << 8) | \
(((_x) & 0x00ff0000U) >> 8) | \
(((_x) & 0xff000000U) >> 24))
# define const_le16(_x) \
((((_x) & 0x00ff) << 8) | \
(((_x) & 0xff00) >> 8))
#else
# define const_le32(_x) (_x)
# define const_le16(_x) (_x)
#endif
/* Unions for reinterpreting between floats and integers. */
typedef union {