1
2/*
3 * Copyright 2012 The Android Open Source Project
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9#ifndef SkUtilsArm_DEFINED
10#define SkUtilsArm_DEFINED
11
12#include "SkUtils.h"
13
14// Define SK_ARM_NEON_MODE to one of the following values
15// corresponding respectively to:
16// - No ARM Neon support at all  (not targetting ARMv7-A, or don't have NEON)
17// - Full ARM Neon support (i.e. assume the CPU always supports it)
18// - Optional ARM Neon support (i.e. probe CPU at runtime)
19//
20#define SK_ARM_NEON_MODE_NONE     0
21#define SK_ARM_NEON_MODE_ALWAYS   1
22#define SK_ARM_NEON_MODE_DYNAMIC  2
23
24#if defined(SK_CPU_ARM32) && defined(__ARM_HAVE_OPTIONAL_NEON_SUPPORT)
25#  define SK_ARM_NEON_MODE  SK_ARM_NEON_MODE_DYNAMIC
26#elif defined(SK_CPU_ARM32) && defined(__ARM_HAVE_NEON) || defined(SK_CPU_ARM64)
27#  define SK_ARM_NEON_MODE  SK_ARM_NEON_MODE_ALWAYS
28#else
29#  define SK_ARM_NEON_MODE  SK_ARM_NEON_MODE_NONE
30#endif
31
32// Convenience test macros, always defined as 0 or 1
33#define SK_ARM_NEON_IS_NONE    (SK_ARM_NEON_MODE == SK_ARM_NEON_MODE_NONE)
34#define SK_ARM_NEON_IS_ALWAYS  (SK_ARM_NEON_MODE == SK_ARM_NEON_MODE_ALWAYS)
35#define SK_ARM_NEON_IS_DYNAMIC (SK_ARM_NEON_MODE == SK_ARM_NEON_MODE_DYNAMIC)
36
37// The sk_cpu_arm_has_neon() function returns true iff the target device
38// is ARMv7-A and supports Neon instructions. In DYNAMIC mode, this actually
39// probes the CPU at runtime (and caches the result).
40
41#if SK_ARM_NEON_IS_NONE
42static inline bool sk_cpu_arm_has_neon(void) {
43    return false;
44}
45#elif SK_ARM_NEON_IS_ALWAYS
46static inline bool sk_cpu_arm_has_neon(void) {
47    return true;
48}
49#else // SK_ARM_NEON_IS_DYNAMIC
50
51extern bool sk_cpu_arm_has_neon(void) SK_PURE_FUNC;
52#endif
53
54// Use SK_ARM_NEON_WRAP(symbol) to map 'symbol' to a NEON-specific symbol
55// when applicable. This will transform 'symbol' differently depending on
56// the current NEON configuration, i.e.:
57//
58//    NONE           -> 'symbol'
59//    ALWAYS         -> 'symbol_neon'
60//    DYNAMIC        -> 'symbol' or 'symbol_neon' depending on runtime check.
61//
62// The goal is to simplify user code, for example:
63//
64//      return SK_ARM_NEON_WRAP(do_something)(params);
65//
66// Replaces the equivalent:
67//
68//     #if SK_ARM_NEON_IS_NONE
69//       return do_something(params);
70//     #elif SK_ARM_NEON_IS_ALWAYS
71//       return do_something_neon(params);
72//     #elif SK_ARM_NEON_IS_DYNAMIC
73//       if (sk_cpu_arm_has_neon())
74//         return do_something_neon(params);
75//       else
76//         return do_something(params);
77//     #endif
78//
79#if SK_ARM_NEON_IS_NONE
80#  define SK_ARM_NEON_WRAP(x)   (x)
81#elif SK_ARM_NEON_IS_ALWAYS
82#  define SK_ARM_NEON_WRAP(x)   (x ## _neon)
83#elif SK_ARM_NEON_IS_DYNAMIC
84#  define SK_ARM_NEON_WRAP(x)   (sk_cpu_arm_has_neon() ? x ## _neon : x)
85#endif
86
87#endif // SkUtilsArm_DEFINED
88