From 0683c8cad920d241d44b126972d5cdd164dcc213 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Tue, 18 Jul 2006 00:47:10 +0000 Subject: [PATCH] Add functions to compute ceil(log2(N)) to match functions for floor(log2(N)) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@29168 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Support/MathExtras.h | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/include/llvm/Support/MathExtras.h b/include/llvm/Support/MathExtras.h index 72065ba3d88..0f5961ff739 100644 --- a/include/llvm/Support/MathExtras.h +++ b/include/llvm/Support/MathExtras.h @@ -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) { -- 2.34.1