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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_ARM_HAS_OPTIONAL_NEON)
25 #  define SK_ARM_NEON_MODE  SK_ARM_NEON_MODE_DYNAMIC
26 #elif defined(SK_ARM_HAS_NEON)
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
sk_cpu_arm_has_neon(void)42 static inline bool sk_cpu_arm_has_neon(void) {
43     return false;
44 }
45 #elif SK_ARM_NEON_IS_ALWAYS
sk_cpu_arm_has_neon(void)46 static inline bool sk_cpu_arm_has_neon(void) {
47     return true;
48 }
49 #else // SK_ARM_NEON_IS_DYNAMIC
50 
51 extern 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