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1 | /* -*-c-*- |
2 | * | |
3 | * CPU-specific dispatch | |
4 | * | |
5 | * (c) 2015 Straylight/Edgeware | |
6 | */ | |
7 | ||
8 | /*----- Licensing notice --------------------------------------------------* | |
9 | * | |
10 | * This file is part of Catacomb. | |
11 | * | |
12 | * Catacomb is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU Library General Public License as | |
14 | * published by the Free Software Foundation; either version 2 of the | |
15 | * License, or (at your option) any later version. | |
16 | * | |
17 | * Catacomb is distributed in the hope that it will be useful, | |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU Library General Public License for more details. | |
21 | * | |
22 | * You should have received a copy of the GNU Library General Public | |
23 | * License along with Catacomb; if not, write to the Free | |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, | |
25 | * MA 02111-1307, USA. | |
26 | */ | |
27 | ||
28 | #ifndef CATACOMB_DISPATCH_H | |
29 | #define CATACOMB_DISPATCH_H | |
30 | ||
31 | #ifdef __cplusplus | |
32 | extern "C" { | |
33 | #endif | |
34 | ||
35 | /*----- Header files ------------------------------------------------------*/ | |
36 | ||
37 | #include <mLib/macros.h> | |
38 | ||
39 | /*----- Macros ------------------------------------------------------------*/ | |
40 | ||
41 | /* --- Atomic data access machinery --- * | |
42 | * | |
43 | * If they're available, use GCC's `__atomic_*' intrinsics. If that doesn't | |
44 | * work and we're using one of a small number of processors I'm sure won't | |
45 | * mind, then just stick with simple memory access. Otherwise turn | |
46 | * dispatching off, because it probably isn't thread-safe. | |
47 | */ | |
48 | ||
49 | #if GCC_VERSION_P(4, 7) | |
50 | # define CPU_DISPATCH_P 1 | |
51 | # define DISPATCH_LOAD(g, v) \ | |
52 | ((v) = __atomic_load_n(&(g), __ATOMIC_RELAXED)) | |
53 | # define DISPATCH_STORE(g, v) \ | |
54 | (__atomic_store_n(&(g), (v), __ATOMIC_RELAXED)) | |
55 | #elif defined(__i386__) || defined(__amd64__) || \ | |
56 | defined(__arm__) || defined(__aarch64__) || \ | |
57 | defined(__mips__) | |
58 | # define CPU_DISPATCH_P 1 | |
59 | # define DISPATCH_LOAD(g, v) ((v) = (g)) | |
60 | # define DISPATCH_STORE(g, v) ((g) = (v)) | |
61 | #endif | |
62 | ||
63 | /* --- A simple hack --- */ | |
64 | ||
65 | #ifndef EMPTY | |
66 | # define EMPTY | |
67 | #endif | |
68 | ||
69 | /* --- @CPU_DISPATCH@ --- * | |
70 | * | |
71 | * Arguments: @stcls@ = storage class for the main @ext@ function | |
72 | * (typically either @static@ or @EMPTY@) | |
73 | * @rtn@ = prefix for tail-calling a function of the appropriate | |
74 | * type (either @(void)@ or @return@) | |
75 | * @ret@ = return type for the function | |
76 | * @ext@ = name for the main function (other named are derived | |
77 | * from this) | |
78 | * @argdecls@ = parenthesis-enclosed list of argument types | |
79 | * @args@ = parenthesis-enclosed list of argument names only | |
80 | * @pick@ = function to select appropriate implementation | |
81 | * @dflt@ = fallback implementation | |
82 | * | |
83 | * Use: Main machinery for CPU-specfic dispatching. | |
84 | * | |
85 | * The macro defines a function | |
86 | * | |
87 | * @stcls ret ext argdcls@ | |
88 | * | |
89 | * The first time @ext@ is called, it will invoke @pick@ to | |
90 | * select and a return a pointer to an appropriate | |
91 | * implementation for the runtime environment. Subsequent calls | |
92 | * to @ext@ will (usually) call this preferred implementation | |
93 | * directly. | |
94 | * | |
95 | * Some target platforms may not be able to establish the | |
96 | * necessary function pointer in a threadsafe way. On such | |
97 | * platforms, the dispatch machinery is disabled and @ext@ will | |
98 | * simply call @dflt@. | |
99 | * | |
100 | * Some additional declarations are made. As a convenience, | |
101 | * @ext__functype@ is the function type of @ext@. Declarations | |
102 | * are made for @pick@ and @dflt@, as @static@ functions. | |
103 | */ | |
104 | ||
105 | #ifdef CPU_DISPATCH_P | |
106 | ||
107 | #define CPU_DISPATCH(stcls, rtn, ret, ext, argdecls, args, pick, dflt) \ | |
108 | \ | |
109 | typedef ret ext##__functype argdecls; \ | |
110 | static ret dflt argdecls; \ | |
111 | static ret ext##__dispatch argdecls; \ | |
112 | static ext##__functype *pick(void); \ | |
113 | static ext##__functype *ext##__ptr = ext##__dispatch; \ | |
114 | \ | |
115 | static ret ext##__dispatch argdecls \ | |
116 | { \ | |
117 | ext##__functype *f = pick(); \ | |
118 | DISPATCH_STORE(ext##__ptr, f); \ | |
119 | rtn f args; \ | |
120 | } \ | |
121 | \ | |
122 | stcls ret ext argdecls \ | |
123 | { \ | |
124 | ext##__functype *f; \ | |
125 | DISPATCH_LOAD(ext##__ptr, f); \ | |
126 | rtn f args; \ | |
127 | } | |
128 | ||
129 | #else | |
130 | ||
131 | #define CPU_DISPATCH(stcls, rtn, ret, ext, argdecls, args, pick, dflt) \ | |
132 | \ | |
133 | typedef ret ext##__functype argdecls; \ | |
134 | static ret dflt argdecls; \ | |
135 | static ext##__functype *pick(void) IGNORABLE; \ | |
136 | \ | |
137 | stcls ret ext argdecls { rtn dflt args; } | |
138 | ||
139 | #endif | |
140 | ||
fac645f7 MW |
141 | /* --- Some macros for producing useful debugging --- */ |
142 | ||
143 | #define DISPATCH_PICK_COND(what, func, cond) do { \ | |
144 | if (cond) { \ | |
145 | dispatch_debug("picked `%s' for `%s'", #func, #what); \ | |
146 | return (func); \ | |
147 | } \ | |
148 | } while (0) | |
149 | #define DISPATCH_PICK_FALLBACK(what, func) do { \ | |
150 | dispatch_debug("using default `%s'", #what); \ | |
151 | return (func); \ | |
152 | } while (0) | |
153 | ||
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154 | /*----- Functions provided ------------------------------------------------*/ |
155 | ||
fac645f7 MW |
156 | /* --- @dispatch_debug@ --- * |
157 | * | |
158 | * Arguments: @const char *fmt@ = a format string | |
159 | * @...@ = additional arguments | |
160 | * | |
161 | * Returns: --- | |
162 | * | |
163 | * Use: Writes a formatted message to standard output if dispatch | |
164 | * debugging is enabled. | |
165 | */ | |
166 | ||
167 | extern void dispatch_debug(const char */*fmt*/, ...); | |
168 | ||
08e2be29 MW |
169 | /* --- @cpu_feature_p@ --- * |
170 | * | |
171 | * Arguments: @unsigned feat@ = a @CPUFEAT_...@ code | |
172 | * | |
173 | * Returns: Nonzero if the feature is available. | |
174 | */ | |
175 | ||
176 | enum { | |
226639f3 | 177 | CPUFEAT_X86_SSE2, /* Streaming SIMD Extensions 2 */ |
61bd904b MW |
178 | CPUFEAT_X86_AESNI, /* AES Native Instructions */ |
179 | CPUFEAT_ARM_VFP, /* VFP floating-point (v3 or v4) */ | |
180 | CPUFEAT_ARM_NEON, /* Advanced SIMD (v1 or v2) */ | |
181 | CPUFEAT_ARM_V4, /* VFPv4 and/or SIMD v2 */ | |
d25653be | 182 | CPUFEAT_ARM_D32, /* 32 double registers, not 16 */ |
26e182fc MW |
183 | CPUFEAT_X86_RDRAND, /* Built-in entropy source */ |
184 | CPUFEAT_ARM_AES /* AES instructions */ | |
08e2be29 MW |
185 | }; |
186 | ||
187 | extern int cpu_feature_p(int /*feat*/); | |
188 | ||
189 | /*----- That's all, folks -------------------------------------------------*/ | |
190 | ||
191 | #ifdef __cplusplus | |
192 | } | |
193 | #endif | |
194 | ||
195 | #endif |