On 16.04.2015 22:18, Kevin Wolf wrote:
On Thu, Apr 16, 2015 at 12:13:51AM +0200, Max Reitz wrote:+ Type inheritance is a common pattern seen in CDI. The new CDI_UPCAST() macro makes conversion to superclasses safer and allows for multiple inheritance if the need arises. + Add some endianness conversion functions. Even though support for big endian platforms is nowhere in sight, endianness conversion is still a common operation which should not be implemented in the driver itself but provided by the CDI implementation. Signed-off-by: Max Reitz <max@xxxxxxxxxx> --- include/cdi/misc.h | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 78 insertions(+) diff --git a/include/cdi/misc.h b/include/cdi/misc.h index 07967ec..3193505 100644 --- a/include/cdi/misc.h +++ b/include/cdi/misc.h @@ -85,6 +85,84 @@ int cdi_ioports_free(uint16_t start, uint16_t count); */ void cdi_sleep_ms(uint32_t ms);+/**+ * Casts @object (must be a pointer) to a pointer to an object of type @to which + * must be a baseclass of @object's type. @field is the entry in @to which + * contains @object. + * + * Example: + * struct cdi_driver *driver; + * struct cdi_storage_driver *storage_driver = + * CDI_UPCAST(driver, drv, struct cdi_storage_driver); + */ +#define CDI_UPCAST(object, field, to) \ + (to *)((uintptr_t)object - (uintptr_t)&((to *)0)->field)With calculations on char* instead of uintptr_t, I think the result would actually be defined.
I don't know the rules for casting to/from uintptr_t by heart, I guess it's the same as casting to a different pointer type, so I think it should be the same. But I don't mind either way.
container_of() used in Linux (and qemu) has a different argument order (object, to, field), perhaps worth following suit?
I won't say "Why not" because I know why not (I have to change it everywhere in this series, in my µxoµcota and in my týndur implementation...), but will do.
It also checks type compatibility between object and to->field, which could perhaps be portably achieved with comparing both pointers and the throwing away the result using the comma operator.
Seems like a nice thing to have. I'll look into it. Max
+ +/** + * Functions for endianness conversion. Be aware that most if not all CDI + * drivers only support little endian machines as a host. + */ + +static inline uint16_t cdi_be16_to_cpu(uint16_t x) +{ + return (x >> 8) | (x << 8); +} + +static inline uint32_t cdi_be32_to_cpu(uint32_t x) +{ + return ((uint32_t)cdi_be16_to_cpu(x) << 16) | (uint32_t)cdi_be16_to_cpu(x >> 16); +} + +static inline uint64_t cdi_be64_to_cpu(uint64_t x) +{ + return ((uint64_t)cdi_be32_to_cpu(x) << 32) | (uint64_t)cdi_be32_to_cpu(x >> 32); +} + +static inline uint16_t cdi_cpu_to_be16(uint16_t x) +{ + return cdi_be16_to_cpu(x); +} + +static inline uint32_t cdi_cpu_to_be32(uint32_t x) +{ + return cdi_be32_to_cpu(x); +} + +static inline uint64_t cdi_cpu_to_be64(uint64_t x) +{ + return cdi_be64_to_cpu(x); +} + +static inline uint16_t cdi_le16_to_cpu(uint16_t x) +{ + return x; +} + +static inline uint32_t cdi_le32_to_cpu(uint32_t x) +{ + return x; +} + +static inline uint64_t cdi_le64_to_cpu(uint64_t x) +{ + return x; +} + +static inline uint16_t cdi_cpu_to_le16(uint16_t x) +{ + return cdi_le16_to_cpu(x); +} + +static inline uint32_t cdi_cpu_to_le32(uint32_t x) +{ + return cdi_le32_to_cpu(x); +} + +static inline uint64_t cdi_cpu_to_le64(uint64_t x) +{ + return cdi_le64_to_cpu(x); +}The endianess functions look good (enough for now). Kevin _______________________________________________ cdi-devel mailing list cdi-devel@xxxxxxxxxx http://list.tyndur.org/cgi-bin/mailman/listinfo/cdi-devel