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Add log2

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This commit is contained in:
Alex 2023-03-22 22:50:08 +02:00
parent 35a11d2285
commit 518ef7b0fd
Signed by untrusted user who does not match committer: enderice2
GPG Key ID: EACC3AD603BAB4DD
2 changed files with 38 additions and 0 deletions
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37
Library/Convert.cpp
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@ -593,6 +593,43 @@ EXTERNC char *ultoa(unsigned long Value, char *Buffer, int Base)
return reverse(Buffer, 0, i - 1); return reverse(Buffer, 0, i - 1);
} }
EXTERNC int log2(unsigned int n)
{
if (n == 0)
{
error("log2(0) is undefined.");
return -1;
}
int log = 0;
if ((n & 0xFFFF0000) != 0)
{
n >>= 16;
log = 16;
}
if (n >= 256)
{
n >>= 8;
log += 8;
}
if (n >= 16)
{
n >>= 4;
log += 4;
}
if (n >= 4)
{
n >>= 2;
log += 2;
}
return log + (n >> 1);
}
EXTERNC void __chk_fail(void) __attribute__((__noreturn__)); EXTERNC void __chk_fail(void) __attribute__((__noreturn__));
__noreturn __always_inline static inline void __convert_chk_fail(void) __noreturn __always_inline static inline void __convert_chk_fail(void)

1
include/convert.h
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@ -74,6 +74,7 @@ extern "C"
int strcasecmp(const char *lhs, const char *rhs); int strcasecmp(const char *lhs, const char *rhs);
char *strtok(char *src, const char *delim); char *strtok(char *src, const char *delim);
long int strtol(const char *str, char **endptr, int base); long int strtol(const char *str, char **endptr, int base);
int log2(unsigned int n);
void *__memcpy_chk(void *dest, const void *src, size_t len, size_t slen); void *__memcpy_chk(void *dest, const void *src, size_t len, size_t slen);
void *__memset_chk(void *dest, int val, size_t len, size_t slen); void *__memset_chk(void *dest, int val, size_t len, size_t slen);