libgcc/config/spu/mfc_multi_tag_reserve.c

   1 /* Copyright (C) 2007-2019 Free Software Foundation, Inc.
   2
   3 This file is part of GCC.
   4
   5 GCC is free software; you can redistribute it and/or modify it under
   6 the terms of the GNU General Public License as published by the Free
   7 Software Foundation; either version 3, or (at your option) any later
   8 version.
   9
  10 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  11 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13 for more details.
  14
  15 Under Section 7 of GPL version 3, you are granted additional
  16 permissions described in the GCC Runtime Library Exception, version
  17 3.1, as published by the Free Software Foundation.
  18
  19 You should have received a copy of the GNU General Public License and
  20 a copy of the GCC Runtime Library Exception along with this program;
  21 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  22 <http://www.gnu.org/licenses/>.  */
  23
  24 #include <spu_mfcio.h>
  25 extern vector unsigned int __mfc_tag_table;
  26
  27 /* Reserve a sequential group of tags for exclusive use.  The number of
  28    tags to be reserved is specified by the <number_of_tags> parameter.
  29    This routine returns the first tag ID for a sequential list of
  30    available tags and marks them as reserved. The reserved group
  31    of tags is in the range starting from the returned tag through
  32    the returned tag + <number_of_tags>-1.
  33
  34    If the number of tags requested exceeds the number of available
  35    sequential tags, then MFC_DMA_TAG_INVALID is returned indicating
  36    that the request could not be serviced.  */
  37
  38 unsigned int
  39 __mfc_multi_tag_reserve (unsigned int number_of_tags)
  40 {
  41   vector unsigned int table_copy;
  42   vector unsigned int one = (vector unsigned int)
  43         { 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
  44   vector unsigned int count_busy, is_valid;
  45   vector unsigned int count_total;
  46   vector unsigned int count_avail = (vector unsigned int) { 0, 0, 0, 0 };
  47   vector unsigned int index = (vector unsigned int) { 0, 0, 0, 0 };
  48
  49   table_copy = __mfc_tag_table;
  50
  51
  52   /* count_busy: number of consecutive busy tags
  53      count_avail: number of consecutive free tags
  54      table_copy: temporary copy of the tag table
  55      count_total: sum of count_busy and count_avail
  56      index: index of the current working tag  */
  57   do
  58     {
  59       table_copy = spu_sl (table_copy, count_avail);
  60
  61       count_busy = spu_cntlz (table_copy);
  62       table_copy = spu_sl (table_copy, count_busy);
  63       count_avail = spu_cntlz (spu_xor(table_copy, -1));
  64       count_total = spu_add (count_busy, count_avail);
  65       index = spu_add (index, count_total);
  66     }
  67   while (spu_extract (count_avail, 0) < number_of_tags
  68          && spu_extract (table_copy, 0) != 0);
  69
  70   index = spu_sub (index, count_avail);
  71
  72   /* is_valid is set to 0xFFFFFFFF if table_copy == 0, 0 otherwise.  */
  73   is_valid = spu_cmpeq (table_copy, 0);
  74   index = spu_sel (index, is_valid, is_valid);
  75
  76   /* Now I need to actually mark the tags as used.  */
  77   table_copy = spu_sl (one, number_of_tags);
  78   table_copy = spu_rl (table_copy, -number_of_tags - spu_extract (index, 0));
  79   table_copy = spu_sel (table_copy, __mfc_tag_table, table_copy);
  80   __mfc_tag_table = spu_sel (table_copy, __mfc_tag_table, is_valid);
  81
  82   return spu_extract (index, 0);
  83 }
  84