FFmpeg
timer.h
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1 /*
2  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #ifndef AVUTIL_X86_TIMER_H
22 #define AVUTIL_X86_TIMER_H
23 
24 #include <stdint.h>
25 
26 #if HAVE_INLINE_ASM
27 
28 #define FF_TIMER_UNITS "decicycles"
29 #define AV_READ_TIME read_time
30 
31 static inline uint64_t read_time(void)
32 {
33  uint32_t a, d;
34  __asm__ volatile(
35 #if ARCH_X86_64 || defined(__SSE2__)
36  "lfence \n\t"
37 #endif
38  "rdtsc \n\t"
39  : "=a" (a), "=d" (d));
40  return ((uint64_t)d << 32) + a;
41 }
42 
43 #elif HAVE_RDTSC
44 
45 #include <intrin.h>
46 #define AV_READ_TIME __rdtsc
47 
48 #endif /* HAVE_INLINE_ASM */
49 
50 #endif /* AVUTIL_X86_TIMER_H */
read_time
static uint64_t read_time(void)
Definition: timer.h:28
a
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:41
__asm__
__asm__(".macro parse_r var r\n\t" "\\var = -1\n\t" _IFC_REG(0) _IFC_REG(1) _IFC_REG(2) _IFC_REG(3) _IFC_REG(4) _IFC_REG(5) _IFC_REG(6) _IFC_REG(7) _IFC_REG(8) _IFC_REG(9) _IFC_REG(10) _IFC_REG(11) _IFC_REG(12) _IFC_REG(13) _IFC_REG(14) _IFC_REG(15) _IFC_REG(16) _IFC_REG(17) _IFC_REG(18) _IFC_REG(19) _IFC_REG(20) _IFC_REG(21) _IFC_REG(22) _IFC_REG(23) _IFC_REG(24) _IFC_REG(25) _IFC_REG(26) _IFC_REG(27) _IFC_REG(28) _IFC_REG(29) _IFC_REG(30) _IFC_REG(31) ".iflt \\var\n\t" ".error \"Unable to parse register name \\r\"\n\t" ".endif\n\t" ".endm")
d
d
Definition: ffmpeg_filter.c:153