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Add functions to compute ceil(log2(N)) to match functions for floor(log2(N))

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@29168 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-07-18 00:47:10 +00:00
parent ede5aa4c96
commit 0683c8cad9
1 changed files with 14 additions and 1 deletions
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15
include/llvm/Support/MathExtras.h
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@ -228,7 +228,7 @@ inline unsigned CountPopulation_64(uint64_t Value) {
// Log2_32 - This function returns the floor log base 2 of the specified value,
// -1 if the value is zero. (32 bit edition.)
// Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1
// Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1, Log2_32(6) == 2
inline unsigned Log2_32(unsigned Value) {
return 31 - CountLeadingZeros_32(Value);
}
@ -239,6 +239,19 @@ inline unsigned Log2_64(uint64_t Value) {
return 63 - CountLeadingZeros_64(Value);
}
// Log2_32_Ceil - This function returns the ceil log base 2 of the specified
// value, 32 if the value is zero. (32 bit edition).
// Ex. Log2_32_Ceil(32) == 5, Log2_32_Ceil(1) == 0, Log2_32_Ceil(6) == 3
inline unsigned Log2_32_Ceil(unsigned Value) {
return 32-CountLeadingZeros_32(Value-1);
}
// Log2_64 - This function returns the ceil log base 2 of the specified value,
// 64 if the value is zero. (64 bit edition.)
inline unsigned Log2_64_Ceil(uint64_t Value) {
return 64-CountLeadingZeros_64(Value-1);
}
// BitsToDouble - This function takes a 64-bit integer and returns the bit
// equivalent double.
inline double BitsToDouble(uint64_t Bits) {