| 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 | |
| 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 | |
| 154 | /*----- Functions provided ------------------------------------------------*/ |
| 155 | |
| 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 | |
| 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 { |
| 177 | CPUFEAT_X86_SSE2, /* Streaming SIMD Extensions 2 */ |
| 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 */ |
| 182 | CPUFEAT_ARM_D32 /* 32 double registers, not 16 */ |
| 183 | }; |
| 184 | |
| 185 | extern int cpu_feature_p(int /*feat*/); |
| 186 | |
| 187 | /*----- That's all, folks -------------------------------------------------*/ |
| 188 | |
| 189 | #ifdef __cplusplus |
| 190 | } |
| 191 | #endif |
| 192 | |
| 193 | #endif |