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btstack_util: assert for btstack_clz(0)

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Dirk Helbig 2024-02-15 15:44:27 +01:00 committed by Matthias Ringwald
parent c69c1cf86b
commit 1a8c51728a
1 changed files with 3 additions and 6 deletions
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9
src/btstack_util.c
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@ -457,21 +457,18 @@ int count_set_bits_uint32(uint32_t x){
}
uint8_t btstack_clz(uint32_t value) {
btstack_assert( value != 0 );
#if defined(__GNUC__) || defined (__clang__)
// use gcc/clang intrinsic
return (uint8_t) __builtin_clz(value);
#elif defined(_MSC_VER)
// use MSVC intrinsic
DWORD leading_zero = 0;
if (_BitScanReverse( &leading_zero, value )){
return (uint8_t)(31 - leading_zero);
} else {
return 32;
}
_BitScanReverse( &leading_zero, value )
return (uint8_t)(31 - leading_zero);
#else
// divide-and-conquer implementation for 32-bit integers
uint32_t x = value;
if (x == 0) return 32;
uint8_t r = 0;
if ((x & 0xffff0000u) == 0) {
x <<= 16;