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lib/math32.h: support LOG2_CEIL/LOG2_FLOOR function at compile time

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Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>
This commit is contained in:
dongjiuzhu1 2022-10-25 23:41:36 +08:00 committed by Alan Carvalho de Assis
parent 82520c0006
commit 224f53fe02
1 changed files with 30 additions and 0 deletions
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30
include/nuttx/lib/math32.h
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@ -29,6 +29,36 @@
#include <inttypes.h>
#include <stdint.h>
#include <inttypes.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Returns one plus the index of the most significant 1-bit of n,
* or if n is zero, returns zero.
*/
#if UINTPTR_MAX > UINT32_MAX
# define FLS(n) ((n) & UINT64_C(0xffffffff00000000) ? 32 + \
FLS32((size_t)(n) >> 32) : FLS32(n))
#else
# define FLS(n) FLS32(n)
#endif
#define FLS32(n) ((n) & 0xffff0000 ? 16 + FLS16((n) >> 16) : FLS16(n))
#define FLS16(n) ((n) & 0xff00 ? 8 + FLS8 ((n) >> 8) : FLS8 (n))
#define FLS8(n) ((n) & 0xf0 ? 4 + FLS4 ((n) >> 4) : FLS4 (n))
#define FLS4(n) ((n) & 0xc ? 2 + FLS2 ((n) >> 2) : FLS2 (n))
#define FLS2(n) ((n) & 0x2 ? 1 + FLS1 ((n) >> 1) : FLS1 (n))
#define FLS1(n) ((n) & 0x1 ? 1 : 0)
/* Returns round up and round down value of log2(n). Note: it can be used at
* compile time.
*/
#define LOG2_CEIL(n) ((n) & (n - 1) ? FLS(n) : FLS(n) - 1)
#define LOG2_FLOOR(n) (FLS(n) - 1)
/****************************************************************************
* Pre-processor Definitions