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Implement the getHighBitsSet and getLowBitsSet functions.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35308 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Spencer 2007-03-24 23:05:35 +00:00
parent 013263f7b0
commit 8da7d65b83
1 changed files with 16 additions and 2 deletions
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18
include/llvm/ADT/APInt.h
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@ -346,13 +346,27 @@ public:
/// @param numBits the bitwidth of the result
/// @param hiBitsSet the number of high-order bits set in the result.
/// @brief Get a value with high bits set
static APInt getHighBitsSet(uint32_t numBits, uint32_t hiBitsSet);
static APInt getHighBitsSet(uint32_t numBits, uint32_t hiBitsSet) {
assert(hiBitsSet <= numBits && "Too many bits to set!");
uint32_t mvBits = numBits - hiBitsSet;
// For small values, return quickly
if (numBits <= APINT_BITS_PER_WORD)
return APInt(numBits, ((1ULL << hiBitsSet) - 1) << mvBits);
APInt Result(numBits, 1);
return (APInt(numBits, 1).shl(hiBitsSet) - APInt(numBits, 1)).shl(mvBits);
}
/// Constructs an APInt value that has the bottom loBitsSet bits set.
/// @param numBits the bitwidth of the result
/// @param loBitsSet the number of low-order bits set in the result.
/// @brief Get a value with low bits set
static APInt getLowBitsSet(uint32_t numBits, uint32_t loBitsSet);
static APInt getLowBitsSet(uint32_t numBits, uint32_t loBitsSet) {
assert(loBitsSet <= numBits && "Too many bits to set!");
// For small values, return quickly
if (numBits <= APINT_BITS_PER_WORD)
return APInt(numBits, (1ULL << loBitsSet) - 1ULL);
return APInt(numBits, 1).shl(loBitsSet) - APInt(numBits, 1);
}
/// The hash value is computed as the sum of the words and the bit width.
/// @returns A hash value computed from the sum of the APInt words.