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move more limits from kernel.h to limits.h and standardize their definitions

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In a customer project that was building a stand-alone application, I
hit a problem related to the fact that our LONG_MAX and friends are
not standards-compliant, in that they are not "suitable for use in #if
preprocessing directives"

... /toolchain_none/arm-cortexa8-eabi/sys-include/machine/_default_types.h:25:31: error: missing binary operator before token "long"
   25 |   || ( defined(LLONG_MAX) && (LLONG_MAX > 0x7fffffff) )
      |                               ^~~~~~~~~

So following up on commit 13de8483388 ("mbedtls: add mbedtls into the
build system"), move the rest of the macros associated to the standard
C types {signed,unsigned} {char, short, int, long, long long} (and of
course bare 'char') to limits.h.

Make use of the fact that both gcc and clang provide suitable
predefined __FOO_MAX__ macros for the signed types, and use a standard
scheme for defining the FOO_MIN and UFOO_MAX macros in terms of
FOO_MAX.

Note that suffixes like L and ULL are allowed for preprocessor
integers; it is (casts) which are not. And using appropriate suffixes,
we can arrange for the type of e.g. UINT_MAX to be "unsigned int" due
to integer promotion rules.

Signed-off-by: Rasmus Villemoes <ravi@prevas.dk>
This commit is contained in:
Rasmus Villemoes 2025-07-07 22:36:53 +02:00 committed by Tom Rini
parent e37de002fa
commit dc323f3bee
2 changed files with 28 additions and 13 deletions
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30
include/limits.h
View File

@ -3,8 +3,34 @@
#ifndef _LIMITS_H
#define _LIMITS_H
#define INT_MAX 0x7fffffff
#define UINT_MAX 0xffffffffU
#define SCHAR_MAX __SCHAR_MAX__
#define SCHAR_MIN (-SCHAR_MAX - 1)
#define UCHAR_MAX (SCHAR_MAX * 2 + 1)
#ifdef __CHAR_UNSIGNED__
#define CHAR_MAX UCHAR_MAX
#define CHAR_MIN 0
#else
#define CHAR_MAX SCHAR_MAX
#define CHAR_MIN SCHAR_MIN
#endif
#define SHRT_MAX __SHRT_MAX__
#define SHRT_MIN (-SHRT_MAX - 1)
#define USHRT_MAX (SHRT_MAX * 2 + 1)
#define INT_MAX __INT_MAX__
#define INT_MIN (-INT_MAX - 1)
#define UINT_MAX (INT_MAX * 2U + 1U)
#define LONG_MAX __LONG_MAX__
#define LONG_MIN (-LONG_MAX - 1L)
#define ULONG_MAX (LONG_MAX * 2UL + 1UL)
#define LLONG_MAX __LONG_LONG_MAX__
#define LLONG_MIN (-LLONG_MAX - 1LL)
#define ULLONG_MAX (LLONG_MAX * 2ULL + 1ULL)
#define CHAR_BIT 8
#define UINT32_MAX 0xffffffffU
#define UINT64_MAX 0xffffffffffffffffULL

11
include/linux/kernel.h
View File

@ -5,17 +5,6 @@
#include <linux/printk.h> /* for printf/pr_* utilities */
#include <limits.h>
#define USHRT_MAX ((u16)(~0U))
#define SHRT_MAX ((s16)(USHRT_MAX>>1))
#define SHRT_MIN ((s16)(-SHRT_MAX - 1))
#define INT_MIN (-INT_MAX - 1)
#define LONG_MAX ((long)(~0UL>>1))
#define LONG_MIN (-LONG_MAX - 1)
#define ULONG_MAX (~0UL)
#define LLONG_MAX ((long long)(~0ULL>>1))
#define LLONG_MIN (-LLONG_MAX - 1)
#define ULLONG_MAX (~0ULL)
#define U8_MAX ((u8)~0U)
#define S8_MAX ((s8)(U8_MAX>>1))
#define S8_MIN ((s8)(-S8_MAX - 1))