FFmpeg
mathops.h
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1 /*
2  * Copyright © 2025 Rémi Denis-Courmont.
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
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10  *
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14  * Lesser General Public License for more details.
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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 AVCODEC_RISCV_MATHOPS_H
22 #define AVCODEC_RISCV_MATHOPS_H
23 
24 #include "config.h"
25 #include <stdbool.h>
27 #include "libavutil/riscv/cpu.h"
28 
29 #if HAVE_RV && !defined(__riscv_zbb)
30 static inline int median3_c(int a, int b, int c);
31 
32 static inline av_const int median3_rv(int a, int b, int c)
33 {
34  if (__builtin_expect(ff_rv_zbb_support(), true)) {
35  int min2, max2;
36 
37  __asm__ (
38  ".option push\n"
39  ".option arch, +zbb\n"
40  "max %1, %2, %3\n"
41  "min %0, %2, %3\n"
42  "min %1, %4, %1\n"
43  "max %0, %0, %1\n"
44  ".option pop\n"
45  : "=&r" (min2), "=&r" (max2) : "r" (a), "r" (b), "r" (c));
46 
47  return min2;
48  }
49  return median3_c(a, b, c);
50 }
51 #define mid_pred median3_rv
52 #endif
53 
54 #endif /* HAVE_RVV */
av_const
#define av_const
Definition: attributes.h:100
b
#define b
Definition: input.c:42
attributes_internal.h
ff_rv_zbb_support
static av_const bool ff_rv_zbb_support(void)
Definition: cpu.h:34
cpu.h
c
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
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
median3_c
static av_const int median3_c(int a, int b, int c)
Definition: mathops.h:98
__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")