code.delx.au - pulseaudio/blob - src/pulsecore/svolume.orc

   1 #  This file is part of PulseAudio.
   2 #
   3 #  Copyright 2010 Lennart Poettering
   4 #  Copyright 2010 Wim Taymans <wim.taymans@collabora.co.uk>
   5 #  Copyright 2010 Arun Raghavan <arun.raghavan@collabora.co.uk>
   6 #
   7 #  PulseAudio is free software; you can redistribute it and/or modify
   8 #  it under the terms of the GNU Lesser General Public License as published
   9 #  by the Free Software Foundation; either version 2.1 of the License,
  10 #  or (at your option) any later version.
  11 #
  12 #  PulseAudio is distributed in the hope that it will be useful, but
  13 #  WITHOUT ANY WARRANTY; without even the implied warranty of
  14 #  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15 #  General Public License for more details.
  16 #
  17 #  You should have received a copy of the GNU Lesser General Public License
  18 #  along with PulseAudio; if not, write to the Free Software
  19 #  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  20 #  USA.
  21
  22 # S16NE 1- and 2-channel volume scaling work as follows:
  23 #
  24 #     params: samples s (signed 16-bit), volume v (signed 32-bit < 2^31)
  25 #
  26 #                  32           16                 0 (type of operation)
  27 #         sample =               |      sample     | (signed)
  28 #              s = |      0      |      sample     | (unsigned)
  29 #
  30 #     if (sample < 0)
  31 #          signc = |      0      |      0xffff     | (unsigned)
  32 #     else
  33 #          signc = |      0      |        0        | (unsigned)
  34 #
  35 #     if (sample < 0)
  36 #             ml = |      0      | -((s*vl) >> 16) | (unsigned)
  37 #     else
  38 #             ml = |      0      |   (s*vl) >> 16  | (unsigned)
  39 #
  40 #             vh =               |      v >> 16    | (signed, but sign bit is always zero
  41 #                                                     since PA_VOLUME_MAX is 0x0fffffff)
  42 #             mh = |         (s * vh) >> 16        | (signed)
  43 #             ml = |           ml + mh             | (signed)
  44 #         sample =               |    (ml >> 16)   | (signed, saturated)
  45
  46 .function pa_volume_s16ne_orc_1ch
  47 .dest 2 samples int16_t
  48 .param 4 v int32_t
  49 .temp 2 vh
  50 .temp 4 s
  51 .temp 4 mh
  52 .temp 4 ml
  53 .temp 4 signc
  54
  55 convuwl s, samples
  56 x2 cmpgtsw signc, 0, s
  57 x2 andw signc, signc, v
  58 x2 mulhuw ml, s, v
  59 subl ml, ml, signc
  60 convhlw vh, v
  61 mulswl mh, samples, vh
  62 addl ml, ml, mh
  63 convssslw samples, ml
  64
  65 .function pa_volume_s16ne_orc_2ch
  66 .dest 4 samples int16_t
  67 .longparam 8 vols
  68 .temp 8 v
  69 .temp 4 vh
  70 .temp 8 s
  71 .temp 8 mh
  72 .temp 8 ml
  73 .temp 8 signc
  74
  75 loadpq v, vols
  76 x2 convuwl s, samples
  77 x4 cmpgtsw signc, 0, s
  78 x4 andw signc, signc, v
  79 x4 mulhuw ml, s, v
  80 x2 subl ml, ml, signc
  81 x2 convhlw vh, v
  82 x2 mulswl mh, samples, vh
  83 x2 addl ml, ml, mh
  84 x2 convssslw samples, ml