Martin Cottrell / microbit-dal

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Dependencies:   BLE_API mbed-dev-bin nRF51822

Dependents:   microbit

Fork of microbit-dal by Lancaster University

source/types/RefCounted.cpp@75:ae9a17da71af, 2017-01-13 (annotated)

Committer:
Asimov
Date:
Fri Jan 13 21:14:06 2017 +0000
Revision:
75:ae9a17da71af
Parent:
1:8aa5cdb4ab67 
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Who changed what in which revision?

UserRevisionLine numberNew contents of line
Jonathan Austin 1:8aa5cdb4ab67 1 /*
Jonathan Austin 1:8aa5cdb4ab67 2 The MIT License (MIT)
Jonathan Austin 1:8aa5cdb4ab67 3
Jonathan Austin 1:8aa5cdb4ab67 4 Copyright (c) 2016 British Broadcasting Corporation.
Jonathan Austin 1:8aa5cdb4ab67 5 This software is provided by Lancaster University by arrangement with the BBC.
Jonathan Austin 1:8aa5cdb4ab67 6
Jonathan Austin 1:8aa5cdb4ab67 7 Permission is hereby granted, free of charge, to any person obtaining a
Jonathan Austin 1:8aa5cdb4ab67 8 copy of this software and associated documentation files (the "Software"),
Jonathan Austin 1:8aa5cdb4ab67 9 to deal in the Software without restriction, including without limitation
Jonathan Austin 1:8aa5cdb4ab67 10 the rights to use, copy, modify, merge, publish, distribute, sublicense,
Jonathan Austin 1:8aa5cdb4ab67 11 and/or sell copies of the Software, and to permit persons to whom the
Jonathan Austin 1:8aa5cdb4ab67 12 Software is furnished to do so, subject to the following conditions:
Jonathan Austin 1:8aa5cdb4ab67 13
Jonathan Austin 1:8aa5cdb4ab67 14 The above copyright notice and this permission notice shall be included in
Jonathan Austin 1:8aa5cdb4ab67 15 all copies or substantial portions of the Software.
Jonathan Austin 1:8aa5cdb4ab67 16
Jonathan Austin 1:8aa5cdb4ab67 17 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
Jonathan Austin 1:8aa5cdb4ab67 18 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
Jonathan Austin 1:8aa5cdb4ab67 19 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
Jonathan Austin 1:8aa5cdb4ab67 20 THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
Jonathan Austin 1:8aa5cdb4ab67 21 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
Jonathan Austin 1:8aa5cdb4ab67 22 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
Jonathan Austin 1:8aa5cdb4ab67 23 DEALINGS IN THE SOFTWARE.
Jonathan Austin 1:8aa5cdb4ab67 24 */
Jonathan Austin 1:8aa5cdb4ab67 25
Jonathan Austin 1:8aa5cdb4ab67 26 /**
Jonathan Austin 1:8aa5cdb4ab67 27 * Base class for payload for ref-counted objects. Used by ManagedString and MicroBitImage.
Jonathan Austin 1:8aa5cdb4ab67 28 * There is no constructor, as this struct is typically malloc()ed.
Jonathan Austin 1:8aa5cdb4ab67 29 */
Jonathan Austin 1:8aa5cdb4ab67 30 #include "mbed.h"
Jonathan Austin 1:8aa5cdb4ab67 31 #include "MicroBitConfig.h"
Jonathan Austin 1:8aa5cdb4ab67 32 #include "RefCounted.h"
Jonathan Austin 1:8aa5cdb4ab67 33 #include "MicroBitDisplay.h"
Jonathan Austin 1:8aa5cdb4ab67 34
Jonathan Austin 1:8aa5cdb4ab67 35 /**
Jonathan Austin 1:8aa5cdb4ab67 36 * Initializes for one outstanding reference.
Jonathan Austin 1:8aa5cdb4ab67 37 */
Jonathan Austin 1:8aa5cdb4ab67 38 void RefCounted::init()
Jonathan Austin 1:8aa5cdb4ab67 39 {
Jonathan Austin 1:8aa5cdb4ab67 40 // Initialize to one reference (lowest bit set to 1)
Jonathan Austin 1:8aa5cdb4ab67 41 refCount = 3;
Jonathan Austin 1:8aa5cdb4ab67 42 }
Jonathan Austin 1:8aa5cdb4ab67 43
Jonathan Austin 1:8aa5cdb4ab67 44 /**
Jonathan Austin 1:8aa5cdb4ab67 45 * Checks if the object resides in flash memory.
Jonathan Austin 1:8aa5cdb4ab67 46 *
Jonathan Austin 1:8aa5cdb4ab67 47 * @param t the object to check.
Jonathan Austin 1:8aa5cdb4ab67 48 *
Jonathan Austin 1:8aa5cdb4ab67 49 * @return true if the object resides in flash memory, false otherwise.
Jonathan Austin 1:8aa5cdb4ab67 50 */
Jonathan Austin 1:8aa5cdb4ab67 51 static inline bool isReadOnlyInline(RefCounted *t)
Jonathan Austin 1:8aa5cdb4ab67 52 {
Jonathan Austin 1:8aa5cdb4ab67 53 uint32_t refCount = t->refCount;
Jonathan Austin 1:8aa5cdb4ab67 54
Jonathan Austin 1:8aa5cdb4ab67 55 if (refCount == 0xffff)
Jonathan Austin 1:8aa5cdb4ab67 56 return true; // object in flash
Jonathan Austin 1:8aa5cdb4ab67 57
Jonathan Austin 1:8aa5cdb4ab67 58 // Do some sanity checking while we're here
Jonathan Austin 1:8aa5cdb4ab67 59 if (refCount == 1 || // object should have been deleted
Jonathan Austin 1:8aa5cdb4ab67 60 (refCount & 1) == 0) // refCount doesn't look right
Jonathan Austin 1:8aa5cdb4ab67 61 microbit_panic(MICROBIT_HEAP_ERROR);
Jonathan Austin 1:8aa5cdb4ab67 62
Jonathan Austin 1:8aa5cdb4ab67 63 // Not read only
Jonathan Austin 1:8aa5cdb4ab67 64 return false;
Jonathan Austin 1:8aa5cdb4ab67 65 }
Jonathan Austin 1:8aa5cdb4ab67 66
Jonathan Austin 1:8aa5cdb4ab67 67 /**
Jonathan Austin 1:8aa5cdb4ab67 68 * Checks if the object resides in flash memory.
Jonathan Austin 1:8aa5cdb4ab67 69 *
Jonathan Austin 1:8aa5cdb4ab67 70 * @return true if the object resides in flash memory, false otherwise.
Jonathan Austin 1:8aa5cdb4ab67 71 */
Jonathan Austin 1:8aa5cdb4ab67 72 bool RefCounted::isReadOnly()
Jonathan Austin 1:8aa5cdb4ab67 73 {
Jonathan Austin 1:8aa5cdb4ab67 74 return isReadOnlyInline(this);
Jonathan Austin 1:8aa5cdb4ab67 75 }
Jonathan Austin 1:8aa5cdb4ab67 76
Jonathan Austin 1:8aa5cdb4ab67 77 /**
Jonathan Austin 1:8aa5cdb4ab67 78 * Increment reference count.
Jonathan Austin 1:8aa5cdb4ab67 79 */
Jonathan Austin 1:8aa5cdb4ab67 80 void RefCounted::incr()
Jonathan Austin 1:8aa5cdb4ab67 81 {
Jonathan Austin 1:8aa5cdb4ab67 82 if (!isReadOnlyInline(this))
Jonathan Austin 1:8aa5cdb4ab67 83 refCount += 2;
Jonathan Austin 1:8aa5cdb4ab67 84 }
Jonathan Austin 1:8aa5cdb4ab67 85
Jonathan Austin 1:8aa5cdb4ab67 86 /**
Jonathan Austin 1:8aa5cdb4ab67 87 * Decrement reference count.
Jonathan Austin 1:8aa5cdb4ab67 88 */
Jonathan Austin 1:8aa5cdb4ab67 89 void RefCounted::decr()
Jonathan Austin 1:8aa5cdb4ab67 90 {
Jonathan Austin 1:8aa5cdb4ab67 91 if (isReadOnlyInline(this))
Jonathan Austin 1:8aa5cdb4ab67 92 return;
Jonathan Austin 1:8aa5cdb4ab67 93
Jonathan Austin 1:8aa5cdb4ab67 94 refCount -= 2;
Jonathan Austin 1:8aa5cdb4ab67 95 if (refCount == 1) {
Jonathan Austin 1:8aa5cdb4ab67 96 free(this);
Jonathan Austin 1:8aa5cdb4ab67 97 }
Jonathan Austin 1:8aa5cdb4ab67 98 }