Diff: Utilities/Segment.hpp

Revision:

0:f77ad7f72d04

Child:

6:a8c83a2e6fa4

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Utilities/Segment.hpp	Mon Nov 06 14:39:18 2017 -0600
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+/*******************************************************************************
+* Copyright (C) 2017 Maxim Integrated Products, Inc., All Rights Reserved.
+*
+* Permission is hereby granted, free of charge, to any person obtaining a
+* copy of this software and associated documentation files (the "Software"),
+* to deal in the Software without restriction, including without limitation
+* the rights to use, copy, modify, merge, publish, distribute, sublicense,
+* and/or sell copies of the Software, and to permit persons to whom the
+* Software is furnished to do so, subject to the following conditions:
+*
+* The above copyright notice and this permission notice shall be included
+* in all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+* IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
+* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+* OTHER DEALINGS IN THE SOFTWARE.
+*
+* Except as contained in this notice, the name of Maxim Integrated
+* Products, Inc. shall not be used except as stated in the Maxim Integrated
+* Products, Inc. Branding Policy.
+*
+* The mere transfer of this software does not imply any licenses
+* of trade secrets, proprietary technology, copyrights, patents,
+* trademarks, maskwork rights, or any other form of intellectual
+* property whatsoever. Maxim Integrated Products, Inc. retains all
+* ownership rights.
+*******************************************************************************/
+
+#ifndef MaximInterface_Segment
+#define MaximInterface_Segment
+
+#include <iterator>
+#include <utility>
+#include "type_traits.hpp"
+
+namespace MaximInterface {
+
+/// Advances a given iterator by a given number of elements with bounds checking.
+/// InputIt must meet the requirements of InputIterator.
+/// @param[in,out] it Iterator to advance. 
+/// @param bound
+/// Past-the-end boundary iterator. If distance is positive, bound must be
+/// reachable by incrementing the given iterator. If distance is negative, bound
+/// must be reachable by decrementing the given iterator.
+/// @param distance
+/// Number of elements to advance the given iterator. If distance is positive,
+/// the given iterator is incremented. If distance is negative, the given
+/// iterator is decremented, and InputIt must meet the requirements of
+/// BidirectionalIterator.
+/// @returns The number of elements that the given iterator was advanced.
+template <typename InputIt>
+typename std::iterator_traits<InputIt>::difference_type checkedAdvance(
+    InputIt & it, const InputIt bound,
+    typename std::iterator_traits<InputIt>::difference_type distance) {
+  typedef
+      typename std::iterator_traits<InputIt>::difference_type difference_type;
+
+  // Use constant-time operations if InputIt is a random access iterator.
+  if (is_same<typename std::iterator_traits<InputIt>::iterator_category,
+              std::random_access_iterator_tag>::value) {
+    const difference_type boundDistance = std::distance(it, bound);
+    if (boundDistance >= 0) {
+      if (distance > boundDistance) {
+        distance = boundDistance;
+      } else if (distance < 0) {
+        distance = 0;
+      }
+    } else {
+      if (distance < boundDistance) {
+        distance = boundDistance;
+      } else if (distance > 0) {
+        distance = 0;
+      }
+    }
+    std::advance(it, distance);
+  } else {
+    const difference_type startingDistance = distance;
+    while (distance != 0 && it != bound) {
+      if (distance > 0) {
+        ++it;
+        --distance;
+      } else {
+        --it;
+        ++distance;
+      }
+    }
+    if (startingDistance > 0) {
+      distance = startingDistance - distance;
+    } else {
+      distance = startingDistance + distance;
+    }
+  }
+  return distance;
+}
+
+/// Locates an iterator sub-range using segment number addressing. Useful for
+/// devices that divide the memory space into uniform chunks such as pages and
+/// segments. ForwardIt must meet the requirements of ForwardIterator.
+/// @param begin Beginning of the input data range.
+/// @param end End of the input data range.
+/// @param segmentSize Number of elements contained in a segment.
+/// @param segmentNum Zero-indexed number of the desired segment.
+/// @returns Pair of iterators representing the sub-range of the segment within
+/// the input range. If the segment does not exist within the input range, both
+/// iterators in the pair are set to the end interator of the input range.
+template <typename ForwardIt, typename Index>
+std::pair<ForwardIt, ForwardIt> createSegment(
+    ForwardIt begin, const ForwardIt end,
+    const typename std::iterator_traits<ForwardIt>::difference_type segmentSize,
+    Index segmentNum) {
+  ForwardIt segmentEnd = begin;
+  typename std::iterator_traits<ForwardIt>::difference_type lastSegmentSize =
+      checkedAdvance(segmentEnd, end, segmentSize);
+  while (segmentNum > 0 && segmentEnd != end) {
+    begin = segmentEnd;
+    lastSegmentSize = checkedAdvance(segmentEnd, end, segmentSize);
+    --segmentNum;
+  }
+  if (segmentNum > 0 || lastSegmentSize != segmentSize) {
+    begin = segmentEnd;
+  }
+  return std::make_pair(begin, segmentEnd);
+}
+
+} // namespace MaximInterface
+
+#endif
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