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bswap: Add the ability to store to an unaligned 24 bit field

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CXL has 24 bit unaligned fields which need to be stored to.  CXL is
specified as little endian.

Define st24_le_p() and the supporting functions to store such a field
from a 32 bit host native value.

The use of b, w, l, q as the size specifier is limiting.  So "24" was
used for the size part of the function name.

Reviewed-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Message-Id: <20230526170010.574-2-Jonathan.Cameron@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Ira Weiny 2023-05-26 18:00:07 +01:00 committed by Michael S. Tsirkin
parent b455ce4c2f
commit 14180d6221
2 changed files with 27 additions and 0 deletions
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2
docs/devel/loads-stores.rst
View file

@ -36,6 +36,7 @@ store: ``st{size}_{endian}_p(ptr, val)``
``size``
- ``b`` : 8 bits
- ``w`` : 16 bits
- ``24`` : 24 bits
- ``l`` : 32 bits
- ``q`` : 64 bits
@ -65,6 +66,7 @@ of size ``sz`` bytes.
Regexes for git grep
- ``\<ld[us]\?[bwlq]\(_[hbl]e\)\?_p\>``
- ``\<st[bwlq]\(_[hbl]e\)\?_p\>``
- ``\<st24\(_[hbl]e\)\?_p\>``
- ``\<ldn_\([hbl]e\)?_p\>``
- ``\<stn_\([hbl]e\)?_p\>``

25
include/qemu/bswap.h
View file

@ -8,11 +8,23 @@
#undef bswap64
#define bswap64(_x) __builtin_bswap64(_x)
static inline uint32_t bswap24(uint32_t x)
{
return (((x & 0x000000ffU) << 16) |
((x & 0x0000ff00U) << 0) |
((x & 0x00ff0000U) >> 16));
}
static inline void bswap16s(uint16_t *s)
{
*s = __builtin_bswap16(*s);
}
static inline void bswap24s(uint32_t *s)
{
*s = bswap24(*s & 0x00ffffffU);
}
static inline void bswap32s(uint32_t *s)
{
*s = __builtin_bswap32(*s);
@ -26,11 +38,13 @@ static inline void bswap64s(uint64_t *s)
#if HOST_BIG_ENDIAN
#define be_bswap(v, size) (v)
#define le_bswap(v, size) glue(__builtin_bswap, size)(v)
#define le_bswap24(v) bswap24(v)
#define be_bswaps(v, size)
#define le_bswaps(p, size) \
do { *p = glue(__builtin_bswap, size)(*p); } while (0)
#else
#define le_bswap(v, size) (v)
#define le_bswap24(v) (v)
#define be_bswap(v, size) glue(__builtin_bswap, size)(v)
#define le_bswaps(v, size)
#define be_bswaps(p, size) \
@ -176,6 +190,7 @@ CPU_CONVERT(le, 64, uint64_t)
* size is:
* b: 8 bits
* w: 16 bits
* 24: 24 bits
* l: 32 bits
* q: 64 bits
*
@ -248,6 +263,11 @@ static inline void stw_he_p(void *ptr, uint16_t v)
__builtin_memcpy(ptr, &v, sizeof(v));
}
static inline void st24_he_p(void *ptr, uint32_t v)
{
__builtin_memcpy(ptr, &v, 3);
}
static inline int ldl_he_p(const void *ptr)
{
int32_t r;
@ -297,6 +317,11 @@ static inline void stw_le_p(void *ptr, uint16_t v)
stw_he_p(ptr, le_bswap(v, 16));
}
static inline void st24_le_p(void *ptr, uint32_t v)
{
st24_he_p(ptr, le_bswap24(v));
}
static inline void stl_le_p(void *ptr, uint32_t v)
{
stl_he_p(ptr, le_bswap(v, 32));