simplify with matching len
[libav.git] / libavcodec / ppc / check_altivec.c
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1/*
2 * This file is part of FFmpeg.
3 *
4 * FFmpeg is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * FFmpeg is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19
20/**
21 * @file check_altivec.c
22 * Checks for AltiVec presence.
23 */
24
25#ifdef __APPLE__
26#include <sys/sysctl.h>
27#elif __AMIGAOS4__
28#include <exec/exec.h>
29#include <interfaces/exec.h>
30#include <proto/exec.h>
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31#endif /* __APPLE__ */
32
33/**
34 * This function MAY rely on signal() or fork() in order to make sure altivec
35 * is present
36 */
37
38int has_altivec(void)
39{
40#ifdef __AMIGAOS4__
41 ULONG result = 0;
42 extern struct ExecIFace *IExec;
43
44 IExec->GetCPUInfoTags(GCIT_VectorUnit, &result, TAG_DONE);
45 if (result == VECTORTYPE_ALTIVEC) return 1;
46 return 0;
47#elif __APPLE__
48 int sels[2] = {CTL_HW, HW_VECTORUNIT};
49 int has_vu = 0;
50 size_t len = sizeof(has_vu);
51 int err;
52
53 err = sysctl(sels, 2, &has_vu, &len, NULL, 0);
54
55 if (err == 0) return (has_vu != 0);
56 return 0;
57#else
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58 // since we were compiled for altivec, just assume we have it
59 // until someone comes up with a proper way (not involving signal hacks).
60 return 1;
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61#endif /* __AMIGAOS4__ */
62}
63