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bswap: Add new stn_*_p() and ldn_*_p() memory access functions 

There's a common pattern in QEMU where a function needs to perform
a data load or store of an N byte integer in a particular endianness.
At the moment this is handled by doing a switch() on the size and
calling the appropriate ld*_p or st*_p function for each size.

Provide a new family of functions ldn_*_p() and stn_*_p() which
take the size as an argument and do the switch() themselves.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20180611171007.4165-2-peter.maydell@linaro.org
master
Peter Maydell 2018-06-15 14:57:14 +01:00
parent 2948f0cde3
commit afa4f6653d
3 changed files with 71 additions and 0 deletions
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15
docs/devel/loads-stores.rst
View File

@ -53,9 +53,24 @@ The ``_{endian}`` infix is omitted for target-endian accesses.
The target endian accessors are only available to source
files which are built per-target.
There are also functions which take the size as an argument:
load: ``ldn{endian}_p(ptr, sz)``
which performs an unsigned load of ``sz`` bytes from ``ptr``
as an ``{endian}`` order value and returns it in a uint64_t.
store: ``stn{endian}_p(ptr, sz, val)``
which stores ``val`` to ``ptr`` as an ``{endian}`` order value
of size ``sz`` bytes.
Regexes for git grep
- ``\<ldf\?[us]\?[bwlq]\(_[hbl]e\)\?_p\>``
- ``\<stf\?[bwlq]\(_[hbl]e\)\?_p\>``
- ``\<ldn_\([hbl]e\)?_p\>``
- ``\<stn_\([hbl]e\)?_p\>``
``cpu_{ld,st}_*``
~~~~~~~~~~~~~~~~~

4
include/exec/cpu-all.h
View File

@ -133,6 +133,8 @@ static inline void tswap64s(uint64_t *s)
#define stq_p(p, v) stq_be_p(p, v)
#define stfl_p(p, v) stfl_be_p(p, v)
#define stfq_p(p, v) stfq_be_p(p, v)
#define ldn_p(p, sz) ldn_be_p(p, sz)
#define stn_p(p, sz, v) stn_be_p(p, sz, v)
#else
#define lduw_p(p) lduw_le_p(p)
#define ldsw_p(p) ldsw_le_p(p)
@ -145,6 +147,8 @@ static inline void tswap64s(uint64_t *s)
#define stq_p(p, v) stq_le_p(p, v)
#define stfl_p(p, v) stfl_le_p(p, v)
#define stfq_p(p, v) stfq_le_p(p, v)
#define ldn_p(p, sz) ldn_le_p(p, sz)
#define stn_p(p, sz, v) stn_le_p(p, sz, v)
#endif
/* MMU memory access macros */

52
include/qemu/bswap.h
View File

@ -290,6 +290,15 @@ typedef union {
* For accessors that take a guest address rather than a
* host address, see the cpu_{ld,st}_* accessors defined in
* cpu_ldst.h.
*
* For cases where the size to be used is not fixed at compile time,
* there are
* stn{endian}_p(ptr, sz, val)
* which stores @val to @ptr as an @endian-order number @sz bytes in size
* and
* ldn{endian}_p(ptr, sz)
* which loads @sz bytes from @ptr as an unsigned @endian-order number
* and returns it in a uint64_t.
*/
static inline int ldub_p(const void *ptr)
@ -495,6 +504,49 @@ static inline unsigned long leul_to_cpu(unsigned long v)
#endif
}
/* Store v to p as a sz byte value in host order */
#define DO_STN_LDN_P(END) \
static inline void stn_## END ## _p(void *ptr, int sz, uint64_t v) \
{ \
switch (sz) { \
case 1: \
stb_p(ptr, v); \
break; \
case 2: \
stw_ ## END ## _p(ptr, v); \
break; \
case 4: \
stl_ ## END ## _p(ptr, v); \
break; \
case 8: \
stq_ ## END ## _p(ptr, v); \
break; \
default: \
g_assert_not_reached(); \
} \
} \
static inline uint64_t ldn_## END ## _p(const void *ptr, int sz) \
{ \
switch (sz) { \
case 1: \
return ldub_p(ptr); \
case 2: \
return lduw_ ## END ## _p(ptr); \
case 4: \
return (uint32_t)ldl_ ## END ## _p(ptr); \
case 8: \
return ldq_ ## END ## _p(ptr); \
default: \
g_assert_not_reached(); \
} \
}
DO_STN_LDN_P(he)
DO_STN_LDN_P(le)
DO_STN_LDN_P(be)
#undef DO_STN_LDN_P
#undef le_bswap
#undef be_bswap
#undef le_bswaps