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Merge pull request #2844 from quickfur/bitarray_improve

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Fixup for PR 2797
This commit is contained in:
Andrej Mitrović 2015-01-06 00:03:11 +01:00
commit df794cd1fe
1 changed files with 22 additions and 30 deletions
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52
std/bitmanip.d
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@ -1779,10 +1779,10 @@ public:
}
/**
* Operator $(D >>=) support.
* Operator $(D <<=) support.
*
* Shifts all the bits in the array to the right by the given number of
* bits. The rightmost bits are dropped, and 0's are inserted at the front
* Shifts all the bits in the array to the left by the given number of
* bits. The leftmost bits are dropped, and 0's are appended to the end
* to fill up the vacant bits.
*
* $(RED Warning: unused bits in the final word up to the next word
@ -1790,17 +1790,13 @@ public:
* preserve bits past the end of the array.)
*/
void opOpAssign(string op)(size_t nbits) @nogc pure nothrow
if (op == ">>")
if (op == "<<")
{
size_t wordsToShift = nbits / bitsPerSizeT;
size_t bitsToShift = nbits % bitsPerSizeT;
if (wordsToShift < dim)
{
// Unfortunately, due to the way core.bitop.bt() works, indices are
// the reverse order of what an equivalent >> on a size_t would do,
// so we have to use rollLeft() instead of rollRight() here,
// contrary to the direction of the >> operator on this BitArray.
foreach_reverse (i; 1 .. dim - wordsToShift)
{
ptr[i + wordsToShift] = rollLeft(ptr[i], ptr[i-1],
@ -1817,26 +1813,22 @@ public:
}
/**
* Operator $(D <<=) support.
* Operator $(D >>=) support.
*
* Shifts all the bits in the array to the left by the given number of
* bits. The leftmost bits are dropped, and 0's are appended to the end to
* fill up the vacant bits.
* Shifts all the bits in the array to the right by the given number of
* bits. The rightmost bits are dropped, and 0's are inserted at the back
* to fill up the vacant bits.
*
* $(RED Warning: unused bits in the final word up to the next word
* boundary may be overwritten by this operation. It does not attempt to
* preserve bits past the end of the array.)
*/
void opOpAssign(string op)(size_t nbits) @nogc pure nothrow
if (op == "<<")
if (op == ">>")
{
size_t wordsToShift = nbits / bitsPerSizeT;
size_t bitsToShift = nbits % bitsPerSizeT;
// Unfortunately, due to the way core.bitop.bt() works, indices are the
// reverse order of what an equivalent << on a size_t would do, so we
// have to use rollRight() instead of rollLeft() here, contrary to the
// direction of the << operator on this BitArray.
if (wordsToShift + 1 < dim)
{
foreach (i; 0 .. dim - wordsToShift - 1)
@ -1866,25 +1858,25 @@ public:
import std.format : format;
BitArray b;
b.init([1, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 1]);
b >>= 1;
assert(format("%b", b) == "01100_10101001");
b.init([1, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1]);
b <<= 1;
assert(format("%b", b) == "11001_01010010");
assert(format("%b", b) == "01100_10101101");
b >>= 4;
b >>= 1;
assert(format("%b", b) == "11001_01011010");
b <<= 4;
assert(format("%b", b) == "00001_10010101");
b <<= 5;
b >>= 5;
assert(format("%b", b) == "10010_10100000");
b >>= 13;
b <<= 13;
assert(format("%b", b) == "00000_00000000");
b.init([1, 0, 1, 1, 0, 1, 1, 1]);
b <<= 8;
b >>= 8;
assert(format("%b", b) == "00000000");
}
@ -1904,7 +1896,7 @@ public:
1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1,
1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1,
]);
b >>= 8;
b <<= 8;
assert(format("%b", b) ==
"00000000_10000000_"~
"11000000_11100000_"~
@ -1913,7 +1905,7 @@ public:
"11111111_10101010");
// Test right shift of more than one size_t's worth of bits
b >>= 68;
b <<= 68;
assert(format("%b", b) ==
"00000000_00000000_"~
"00000000_00000000_"~
@ -1928,7 +1920,7 @@ public:
1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1,
1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 1,
]);
b <<= 8;
b >>= 8;
assert(format("%b", b) ==
"11000000_11100000_"~
"11110000_11111000_"~
@ -1937,7 +1929,7 @@ public:
"01010101_00000000");
// Test left shift of more than 1 size_t's worth of bits
b <<= 68;
b >>= 68;
assert(format("%b", b) ==
"01010000_00000000_"~
"00000000_00000000_"~