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bswap.h: Document cpu_to_* and *_to_cpu conversion functions 

Add a documentation comment describing the functions for
converting between the cpu and little or bigendian formats.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1467908460-27048-6-git-send-email-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2016-07-07 17:21:00 +01:00
parent cbe967f41d
commit 7d820b766a
1 changed files with 58 additions and 0 deletions
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58
include/qemu/bswap.h
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@ -80,6 +80,64 @@ static inline void bswap64s(uint64_t *s)
#define be_bswaps(p, size) do { *p = glue(bswap, size)(*p); } while(0) #define be_bswaps(p, size) do { *p = glue(bswap, size)(*p); } while(0)
#endif #endif
/**
* Endianness conversion functions between host cpu and specified endianness.
* (We list the complete set of prototypes produced by the macros below
* to assist people who search the headers to find their definitions.)
*
* uint16_t le16_to_cpu(uint16_t v);
* uint32_t le32_to_cpu(uint32_t v);
* uint64_t le64_to_cpu(uint64_t v);
* uint16_t be16_to_cpu(uint16_t v);
* uint32_t be32_to_cpu(uint32_t v);
* uint64_t be64_to_cpu(uint64_t v);
*
* Convert the value @v from the specified format to the native
* endianness of the host CPU by byteswapping if necessary, and
* return the converted value.
*
* uint16_t cpu_to_le16(uint16_t v);
* uint32_t cpu_to_le32(uint32_t v);
* uint64_t cpu_to_le64(uint64_t v);
* uint16_t cpu_to_be16(uint16_t v);
* uint32_t cpu_to_be32(uint32_t v);
* uint64_t cpu_to_be64(uint64_t v);
*
* Convert the value @v from the native endianness of the host CPU to
* the specified format by byteswapping if necessary, and return
* the converted value.
*
* void le16_to_cpus(uint16_t *v);
* void le32_to_cpus(uint32_t *v);
* void le64_to_cpus(uint64_t *v);
* void be16_to_cpus(uint16_t *v);
* void be32_to_cpus(uint32_t *v);
* void be64_to_cpus(uint64_t *v);
*
* Do an in-place conversion of the value pointed to by @v from the
* specified format to the native endianness of the host CPU.
*
* void cpu_to_le16s(uint16_t *v);
* void cpu_to_le32s(uint32_t *v);
* void cpu_to_le64s(uint64_t *v);
* void cpu_to_be16s(uint16_t *v);
* void cpu_to_be32s(uint32_t *v);
* void cpu_to_be64s(uint64_t *v);
*
* Do an in-place conversion of the value pointed to by @v from the
* native endianness of the host CPU to the specified format.
*
* Both X_to_cpu() and cpu_to_X() perform the same operation; you
* should use whichever one is better documenting of the function your
* code is performing.
*
* Do not use these functions for conversion of values which are in guest
* memory, since the data may not be sufficiently aligned for the host CPU's
* load and store instructions. Instead you should use the ld*_p() and
* st*_p() functions, which perform loads and stores of data of any
* required size and endianness and handle possible misalignment.
*/
#define CPU_CONVERT(endian, size, type)\ #define CPU_CONVERT(endian, size, type)\
static inline type endian ## size ## _to_cpu(type v)\ static inline type endian ## size ## _to_cpu(type v)\
{\ {\