gcc/config/spu/mfc_multi_tag_reserve.c

   1 /* Copyright (C) 2007 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 2, or (at your option) any later
   8 version.
   9
  10 In addition to the permissions in the GNU General Public License, the
  11 Free Software Foundation gives you unlimited permission to link the
  12 compiled version of this file into combinations with other programs,
  13 and to distribute those combinations without any restriction coming
  14 from the use of this file.  (The General Public License restrictions
  15 do apply in other respects; for example, they cover modification of
  16 the file, and distribution when not linked into a combine
  17 executable.)
  18
  19 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  20 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  21 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  22 for more details.
  23
  24 You should have received a copy of the GNU General Public License
  25 along with GCC; see the file COPYING.  If not, write to the Free
  26 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  27 02110-1301, USA.  */
  28
  29 #include <spu_mfcio.h>
  30 extern vector unsigned int __mfc_tag_table;
  31
  32 /* Reserve a sequential group of tags for exclusive use.  The number of
  33    tags to be reserved is specified by the <number_of_tags> parameter.
  34    This routine returns the first tag ID for a sequential list of
  35    available tags and marks them as reserved. The reserved group
  36    of tags is in the range starting from the returned tag through
  37    the returned tag + <number_of_tags>-1.
  38
  39    If the number of tags requested exceeds the number of available
  40    sequential tags, then MFC_DMA_TAG_INVALID is returned indicating
  41    that the request could not be serviced.  */
  42
  43 unsigned int
  44 __mfc_multi_tag_reserve (unsigned int number_of_tags)
  45 {
  46   vector unsigned int table_copy;
  47   vector unsigned int one = (vector unsigned int)
  48         { 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF };
  49   vector unsigned int count_busy, is_valid;
  50   vector unsigned int count_total;
  51   vector unsigned int count_avail = (vector unsigned int) { 0, 0, 0, 0 };
  52   vector unsigned int index = (vector unsigned int) { 0, 0, 0, 0 };
  53
  54   table_copy = __mfc_tag_table;
  55
  56
  57   /* count_busy: number of consecutive busy tags
  58      count_avail: number of consecutive free tags
  59      table_copy: temporary copy of the tag table
  60      count_total: sum of count_busy and count_avail
  61      index: index of the current working tag  */
  62   do
  63     {
  64       table_copy = spu_sl (table_copy, count_avail);
  65
  66       count_busy = spu_cntlz (table_copy);
  67       table_copy = spu_sl (table_copy, count_busy);
  68       count_avail = spu_cntlz (spu_xor(table_copy, -1));
  69       count_total = spu_add (count_busy, count_avail);
  70       index = spu_add (index, count_total);
  71     }
  72   while (spu_extract (count_avail, 0) < number_of_tags
  73          && spu_extract (table_copy, 0) != 0);
  74
  75   index = spu_sub (index, count_avail);
  76
  77   /* is_valid is set to 0xFFFFFFFF if table_copy == 0, 0 otherwise.  */
  78   is_valid = spu_cmpeq (table_copy, 0);
  79   index = spu_sel (index, is_valid, is_valid);
  80
  81   /* Now I need to actually mark the tags as used.  */
  82   table_copy = spu_sl (one, number_of_tags);
  83   table_copy = spu_rl (table_copy, -number_of_tags - spu_extract (index, 0));
  84   table_copy = spu_sel (table_copy, __mfc_tag_table, table_copy);
  85   __mfc_tag_table = spu_sel (table_copy, __mfc_tag_table, is_valid);
  86
  87   return spu_extract (index, 0);
  88 }
  89