iokit/Kernel/IODataQueue.cpp

   1 /*
   2  * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License.  The rights granted to you under the
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30
  31 #include <IOKit/IODataQueue.h>
  32 #include <IOKit/IODataQueueShared.h>
  33 #include <IOKit/IOLib.h>
  34 #include <IOKit/IOMemoryDescriptor.h>
  35
  36 #ifdef enqueue
  37 #undef enqueue
  38 #endif
  39
  40 #ifdef dequeue
  41 #undef dequeue
  42 #endif
  43
  44 #define super OSObject
  45
  46 OSDefineMetaClassAndStructors(IODataQueue, OSObject)
  47
  48 IODataQueue *IODataQueue::withCapacity(UInt32 size)
  49 {
  50     IODataQueue *dataQueue = new IODataQueue;
  51
  52     if (dataQueue) {
  53         if  (!dataQueue->initWithCapacity(size)) {
  54             dataQueue->release();
  55             dataQueue = 0;
  56         }
  57     }
  58
  59     return dataQueue;
  60 }
  61
  62 IODataQueue *IODataQueue::withEntries(UInt32 numEntries, UInt32 entrySize)
  63 {
  64     IODataQueue *dataQueue = new IODataQueue;
  65
  66     if (dataQueue) {
  67         if (!dataQueue->initWithEntries(numEntries, entrySize)) {
  68             dataQueue->release();
  69             dataQueue = 0;
  70         }
  71     }
  72
  73     return dataQueue;
  74 }
  75
  76 Boolean IODataQueue::initWithCapacity(UInt32 size)
  77 {
  78     if (!super::init()) {
  79         return false;
  80     }
  81
  82     dataQueue = (IODataQueueMemory *)IOMallocAligned(round_page_32(size + DATA_QUEUE_MEMORY_HEADER_SIZE), PAGE_SIZE);
  83     if (dataQueue == 0) {
  84         return false;
  85     }
  86
  87     dataQueue->queueSize = size;
  88     dataQueue->head = 0;
  89     dataQueue->tail = 0;
  90
  91     return true;
  92 }
  93
  94 Boolean IODataQueue::initWithEntries(UInt32 numEntries, UInt32 entrySize)
  95 {
  96     return (initWithCapacity((numEntries + 1) * (DATA_QUEUE_ENTRY_HEADER_SIZE + entrySize)));
  97 }
  98
  99 void IODataQueue::free()
 100 {
 101     if (dataQueue) {
 102         IOFreeAligned(dataQueue, round_page_32(dataQueue->queueSize + DATA_QUEUE_MEMORY_HEADER_SIZE));
 103     }
 104
 105     super::free();
 106
 107     return;
 108 }
 109
 110 Boolean IODataQueue::enqueue(void * data, UInt32 dataSize)
 111 {
 112     const UInt32       head      = dataQueue->head;  // volatile
 113     const UInt32       tail      = dataQueue->tail;
 114     const UInt32       entrySize = dataSize + DATA_QUEUE_ENTRY_HEADER_SIZE;
 115     IODataQueueEntry * entry;
 116
 117     if ( tail >= head )
 118     {
 119         // Is there enough room at the end for the entry?
 120         if ( (tail + entrySize) <= dataQueue->queueSize )
 121         {
 122             entry = (IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail);
 123
 124             entry->size = dataSize;
 125             memcpy(&entry->data, data, dataSize);
 126
 127             // The tail can be out of bound when the size of the new entry
 128             // exactly matches the available space at the end of the queue.
 129             // The tail can range from 0 to dataQueue->queueSize inclusive.
 130
 131             dataQueue->tail += entrySize;
 132         }
 133         else if ( head > entrySize )    // Is there enough room at the beginning?
 134         {
 135             // Wrap around to the beginning, but do not allow the tail to catch
 136             // up to the head.
 137
 138             dataQueue->queue->size = dataSize;
 139
 140             // We need to make sure that there is enough room to set the size before
 141             // doing this. The user client checks for this and will look for the size
 142             // at the beginning if there isn't room for it at the end.
 143
 144             if ( ( dataQueue->queueSize - tail ) >= DATA_QUEUE_ENTRY_HEADER_SIZE )
 145             {
 146                 ((IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail))->size = dataSize;
 147             }
 148
 149             memcpy(&dataQueue->queue->data, data, dataSize);
 150             dataQueue->tail = entrySize;
 151         }
 152         else
 153         {
 154             return false;       // queue is full
 155         }
 156     }
 157     else
 158     {
 159         // Do not allow the tail to catch up to the head when the queue is full.
 160         // That's why the comparison uses a '>' rather than '>='.
 161
 162         if ( (head - tail) > entrySize )
 163         {
 164             entry = (IODataQueueEntry *)((UInt8 *)dataQueue->queue + tail);
 165
 166             entry->size = dataSize;
 167             memcpy(&entry->data, data, dataSize);
 168             dataQueue->tail += entrySize;
 169         }
 170         else
 171         {
 172             return false;       // queue is full
 173         }
 174     }
 175
 176     // Send notification (via mach message) that data is available.
 177
 178     if ( ( head == tail )                /* queue was empty prior to enqueue() */
 179     ||   ( dataQueue->head == tail ) )   /* queue was emptied during enqueue() */
 180     {
 181         sendDataAvailableNotification();
 182     }
 183
 184     return true;
 185 }
 186
 187 void IODataQueue::setNotificationPort(mach_port_t port)
 188 {
 189     static struct _notifyMsg init_msg = { {
 190         MACH_MSGH_BITS(MACH_MSG_TYPE_COPY_SEND, 0),
 191         sizeof (struct _notifyMsg),
 192         MACH_PORT_NULL,
 193         MACH_PORT_NULL,
 194         0,
 195         0
 196     } };
 197
 198     if (notifyMsg == 0) {
 199         notifyMsg = IOMalloc(sizeof(struct _notifyMsg));
 200     }
 201
 202     *((struct _notifyMsg *)notifyMsg) = init_msg;
 203
 204     ((struct _notifyMsg *)notifyMsg)->h.msgh_remote_port = port;
 205 }
 206
 207 void IODataQueue::sendDataAvailableNotification()
 208 {
 209     kern_return_t               kr;
 210     mach_msg_header_t * msgh;
 211
 212     msgh = (mach_msg_header_t *)notifyMsg;
 213     if (msgh) {
 214         kr = mach_msg_send_from_kernel(msgh, msgh->msgh_size);
 215         switch(kr) {
 216             case MACH_SEND_TIMED_OUT:   // Notification already sent
 217             case MACH_MSG_SUCCESS:
 218                 break;
 219             default:
 220                 IOLog("%s: dataAvailableNotification failed - msg_send returned: %d\n", /*getName()*/"IODataQueue", kr);
 221                 break;
 222         }
 223     }
 224 }
 225
 226 IOMemoryDescriptor *IODataQueue::getMemoryDescriptor()
 227 {
 228     IOMemoryDescriptor *descriptor = 0;
 229
 230     if (dataQueue != 0) {
 231         descriptor = IOMemoryDescriptor::withAddress(dataQueue, dataQueue->queueSize + DATA_QUEUE_MEMORY_HEADER_SIZE, kIODirectionOutIn);
 232     }
 233
 234     return descriptor;
 235 }
 236