src/add-ons/kernel/busses/scsi/virtio/VirtioSCSIHelper.cpp

   1 /*
   2  * Copyright 2009, Michael Lotz, mmlr@mlotz.ch.
   3  * Copyright 2004-2007, Axel Dörfler, axeld@pinc-software.de.
   4  * Copyright 2002/03, Thomas Kurschel. All rights reserved.
   5  *
   6  * Distributed under the terms of the MIT License.
   7  */
   8
   9 #include "VirtioSCSIPrivate.h"
  10
  11 #include <string.h>
  12
  13 #include <vm/vm.h>
  14
  15
  16 /*!     Copy data between ccb data and buffer
  17         ccb                     - ccb to copy data from/to
  18         offset                  - offset of data in ccb
  19         allocation_length- limit of ccb's data buffer according to CDB
  20         buffer                  - data to copy data from/to
  21         size                    - number of bytes to copy
  22         to_buffer               - true: copy from ccb to buffer
  23                                           false: copy from buffer to ccb
  24         return: true, if data of ccb was large enough
  25 */
  26 bool
  27 copy_sg_data(scsi_ccb *ccb, uint offset, uint allocationLength,
  28         void *buffer, int size, bool toBuffer)
  29 {
  30         const physical_entry *sgList = ccb->sg_list;
  31         int sgCount = ccb->sg_count;
  32
  33         // skip unused S/G entries
  34         while (sgCount > 0 && offset >= sgList->size) {
  35                 offset -= sgList->size;
  36                 ++sgList;
  37                 --sgCount;
  38         }
  39
  40         if (sgCount == 0)
  41                 return false;
  42
  43         // remaining bytes we are allowed to copy from/to ccb
  44         int requestSize = MIN(allocationLength, ccb->data_length) - offset;
  45
  46         // copy one S/G entry at a time
  47         for (; size > 0 && requestSize > 0 && sgCount > 0; ++sgList, --sgCount) {
  48                 size_t bytes;
  49
  50                 bytes = MIN(size, requestSize);
  51                 bytes = MIN(bytes, sgList->size);
  52
  53                 if (toBuffer) {
  54                         vm_memcpy_from_physical(buffer, sgList->address + offset, bytes,
  55                                 false);
  56                 } else {
  57                         vm_memcpy_to_physical(sgList->address + offset, buffer, bytes,
  58                                 false);
  59                 }
  60
  61                 buffer = (char *)buffer + bytes;
  62                 size -= bytes;
  63                 offset = 0;
  64         }
  65
  66         return size == 0;
  67 }
  68
  69
  70 void
  71 swap_words(void *data, size_t size)
  72 {
  73         uint16 *word = (uint16 *)data;
  74         size_t count = size / 2;
  75         while (count--) {
  76                 *word = B_BENDIAN_TO_HOST_INT16(*word);
  77                 word++;
  78         }
  79 }