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base: Fix CircularQueue when diffing iterators

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This patch is fixing CircularQueue iterators' subtraction, in particular
the behaviour when head and tail round multiple times.

Change-Id: Ie79ac8accd30a10cf039cf4def87675b01375d6b
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Gabor Dozsa <gabor.dozsa@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17188
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
This commit is contained in:
Giacomo Travaglini
2019-03-08 16:01:20 +00:00
parent 487ea069be
commit bbcbde7a92
2 changed files with 38 additions and 4 deletions
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17
src/base/circular_queue.hh
View File

@@ -106,10 +106,19 @@ class CircularQueue : private std::vector<T>
static uint32_t
moduloSub(uint32_t op1, uint32_t op2, uint32_t size)
{
int ret = (uint32_t)(op1 - op2) % size;
int32_t ret = sub(op1, op2, size);
return ret >= 0 ? ret : ret + size;
}
static int32_t
sub(uint32_t op1, uint32_t op2, uint32_t size)
{
if (op1 > op2)
return (op1 - op2) % size;
else
return -((op2 - op1) % size);
}
void increase(uint32_t& v, size_t delta = 1)
{
v = moduloAdd(v, delta, _capacity);
@@ -355,10 +364,10 @@ class CircularQueue : private std::vector<T>
difference_type operator-(const iterator& that)
{
/* If a is already at the end, we can safely return 0. */
auto ret = _cq->moduloSub(this->_idx, that._idx);
auto ret = _cq->sub(this->_idx, that._idx, _cq->capacity());
if (ret == 0 && this->_round != that._round) {
ret += this->_round * _cq->capacity();
if (this->_round != that._round) {
ret += ((this->_round - that._round) * _cq->capacity());
}
return ret;
}

25
src/base/circular_queue.test.cc
View File

@@ -212,6 +212,7 @@ TEST(CircularQueueTest, IteratorsOp)
ASSERT_EQ(it_1 + 1, it_2);
ASSERT_EQ(it_1, it_2 - 1);
ASSERT_EQ(it_2 - it_1, 1);
ASSERT_EQ(it_1 - it_2, -1);
auto temp_it = it_1;
ASSERT_EQ(++temp_it, it_2);
@@ -241,3 +242,27 @@ TEST(CircularQueueTest, FullLoop)
ASSERT_EQ(starting_it._idx, ending_it._idx);
ASSERT_TRUE(starting_it != ending_it);
}
/**
* Testing correct behaviour when rounding multiple times:
* - Round indexes in sync
* - Difference between begin() and end() iterator is still
* equal to the CircularQueue size.
*/
TEST(CircularQueueTest, MultipleRound)
{
const auto cq_size = 8;
CircularQueue<uint32_t> cq(cq_size);
// Filling the queue making it round multiple times
auto items_added = cq_size * 3;
for (auto idx = 0; idx < items_added; idx++) {
cq.push_back(0);
}
auto starting_it = cq.begin();
auto ending_it = cq.end();
ASSERT_EQ(starting_it._round + 1, ending_it._round);
ASSERT_EQ(ending_it - starting_it, cq_size);
}