From d326a6c7c1e271919288627fda136f5fd82fd8ac Mon Sep 17 00:00:00 2001 From: Hans Petter Selasky Date: Tue, 30 Jun 2020 08:41:33 +0000 Subject: [PATCH] Document the is_signed(), type_max() and type_min() function macros in the LinuxKPI. Try to make the function argument more readable. Suggested by: several MFC after: 1 week Sponsored by: Mellanox Technologies --- .../linuxkpi/common/include/linux/kernel.h | 35 +++++++++++++------ 1 file changed, 24 insertions(+), 11 deletions(-) diff --git a/sys/compat/linuxkpi/common/include/linux/kernel.h b/sys/compat/linuxkpi/common/include/linux/kernel.h index 90c66cd51cc8..92c7da110dac 100644 --- a/sys/compat/linuxkpi/common/include/linux/kernel.h +++ b/sys/compat/linuxkpi/common/include/linux/kernel.h @@ -564,20 +564,33 @@ linux_ratelimited(linux_ratelimit_t *rl) #define __is_constexpr(x) \ __builtin_constant_p(x) -#define is_signed(x) (((x)-1 / (x)2) == (x)0) +/* + * The is_signed() macro below returns true if the passed data type is + * signed. Else false is returned. + */ +#define is_signed(datatype) (((datatype)-1 / (datatype)2) == (datatype)0) -#define type_max(x) ( \ - (sizeof(x) >= 8) ? (is_signed(x) ? INT64_MAX : UINT64_MAX) : \ - (sizeof(x) >= 4) ? (is_signed(x) ? INT32_MAX : UINT32_MAX) : \ - (sizeof(x) >= 2) ? (is_signed(x) ? INT16_MAX : UINT16_MAX) : \ - (is_signed(x) ? INT8_MAX : UINT8_MAX) \ +/* + * The type_max() macro below returns the maxium positive value the + * passed data type can hold. + */ +#define type_max(datatype) ( \ + (sizeof(datatype) >= 8) ? (is_signed(datatype) ? INT64_MAX : UINT64_MAX) : \ + (sizeof(datatype) >= 4) ? (is_signed(datatype) ? INT32_MAX : UINT32_MAX) : \ + (sizeof(datatype) >= 2) ? (is_signed(datatype) ? INT16_MAX : UINT16_MAX) : \ + (is_signed(datatype) ? INT8_MAX : UINT8_MAX) \ ) -#define type_min(x) ( \ - (sizeof(x) >= 8) ? (is_signed(x) ? INT64_MIN : 0) : \ - (sizeof(x) >= 4) ? (is_signed(x) ? INT32_MIN : 0) : \ - (sizeof(x) >= 2) ? (is_signed(x) ? INT16_MIN : 0) : \ - (is_signed(x) ? INT8_MIN : 0) \ +/* + * The type_min() macro below returns the minimum value the passed + * data type can hold. For unsigned types the minimum value is always + * zero. For signed types it may vary. + */ +#define type_min(datatype) ( \ + (sizeof(datatype) >= 8) ? (is_signed(datatype) ? INT64_MIN : 0) : \ + (sizeof(datatype) >= 4) ? (is_signed(datatype) ? INT32_MIN : 0) : \ + (sizeof(datatype) >= 2) ? (is_signed(datatype) ? INT16_MIN : 0) : \ + (is_signed(datatype) ? INT8_MIN : 0) \ ) #endif /* _LINUX_KERNEL_H_ */