mu - Soul of a tiny new machine. More thorough tests → More comprehensible and rewrite-friendly software → More resilient society.

	Commit message (Expand)	Author	Age	Files	Lines
*	3336	Kartik K. Agaram	2016-09-11	1	-4/+0
*	3295	Kartik K. Agaram	2016-09-04	1	-1/+1
*	3282	Kartik K. Agaram	2016-08-29	1	-5/+27
*	3277	Kartik K. Agaram	2016-08-29	1	-1/+0
*	3275	Kartik K. Agaram	2016-08-28	1	-1/+1
*	2946	Kartik K. Agaram	2016-05-08	1	-0/+15

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>Mu - 001help.cc</title> <meta name="Generator" content="Vim/8.1"> <meta name="plugin-version" content="vim8.1_v1"> <meta name="syntax" content="cpp"> <meta name="settings" content="number_lines,use_css,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy="> <meta name="colorscheme" content="minimal-light"> <style type="text/css">  </style> <script type='text/javascript'>  </script> </head> <body onload='JumpToLine();'> <a href='https://github.com/akkartik/mu/blob/master/001help.cc'>https://github.com/akkartik/mu/blob/master/001help.cc</a> <pre id='vimCodeElement'> 1 //: Everything this project/binary supports. 2 //: This should give you a sense for what to look forward to in later layers. 3 4 :(before "End Commandline Parsing") 5 if (argc <= 1 || <a href='001help.cc.html#L102'>is_equal</a>(argv[1], "--help")) { 6 //: this is the functionality later layers will provide 7 // currently no automated tests for commandline arg parsing 8 cerr << get(<a href='001help.cc.html#L53'>Help</a>, "usage"); 9 return 0; 10 } 11 12 //: Support for option parsing. 13 //: Options always begin with '--' and are always the first arguments. An 14 //: option will never follow a non-option. 15 char** <a href='001help.cc.html#L15'>arg</a> = &argv[1]; 16 while (argc > 1 && <a href='001help.cc.html#L106'>starts_with</a>(*arg, "--")) { 17 if (false) 18 ; // no-op branch just so any further additions can consistently always start with 'else' 19 // End Commandline Options(*arg) 20 else 21 cerr << "skipping unknown option " << *arg << '\n'; 22 --argc; ++argv; ++arg; 23 } 24 25 if (<a href='001help.cc.html#L102'>is_equal</a>(argv[1], "help")) { 26 if (argc == 2) { 27 cerr << "help on what?\n"; 28 <a href='001help.cc.html#L46'>help_contents</a>(); 29 return 0; 30 } 31 string key(argv[2]); 32 // End Help Special-cases(key) 33 if (<a href='001help.cc.html#L233'>contains_key</a>(<a href='001help.cc.html#L53'>Help</a>, key)) { 34 cerr << get(<a href='001help.cc.html#L53'>Help</a>, key); 35 return 0; 36 } 37 else { 38 cerr << "No help found for '" << key << "'\n"; 39 <a href='001help.cc.html#L46'>help_contents</a>(); 40 cerr << "Please check your command for typos.\n"; 41 return 1; 42 } 43 } 44 45 :(code) 46 void <a href='001help.cc.html#L46'>help_contents</a>() { 47 cerr << "Available top-level topics:\n"; 48 cerr << " usage\n"; 49 // End Help Contents 50 } 51 52 :(before "End Globals") 53 map<string, string> <a href='001help.cc.html#L53'>Help</a>; 54 :(before "End Includes") 55 #include <map> 56 using std::map; 57 :(before "End One-time Setup") 58 <a href='001help.cc.html#L60'>init_help</a>(); 59 :(code) 60 void <a href='001help.cc.html#L60'>init_help</a>() { 61 <a href='001help.cc.html#L229'>put</a>(<a href='001help.cc.html#L53'>Help</a>, "usage", 62 "bootstrap: the bootstrap translator for SubX.\n" 63 "This program also wraps some miscellaneous useful functionality:\n" 64 " - an x86 emulator: `bootstrap run`\n" 65 " - online help: `bootstrap help`\n" 66 "\n" 67 "== Ways to invoke bootstrap\n" 68 "- See this message:\n" 69 " bootstrap --help\n" 70 "- Convert a textual SubX program into a standard ELF binary that you can\n" 71 " <a href='011run.cc.html#L82'>run</a> on your computer:\n" 72 " bootstrap translate input1.subx input2.subx ... -o <output ELF binary>\n" 73 "- Run a SubX binary using SubX itself (for better error messages):\n" 74 " bootstrap <a href='011run.cc.html#L82'>run</a> <ELF binary>\n" 75 "- Run all bootstrap's unit tests:\n" 76 " bootstrap test\n" 77 "- Run a single unit test:\n" 78 " bootstrap test <test name>\n" 79 " e.g. bootstrap test test_copy_imm32_to_EAX\n" 80 "\n" 81 "== Debugging aids\n" 82 "- Add '--trace' to any of these commands to save a <a href='003trace.cc.html#L96'>trace</a> to disk at the end.\n" 83 " This can <a href='011run.cc.html#L82'>run</a> out of memory for long-running commands.\n" 84 "- Add '--debug' to add information to traces. 'bootstrap --debug translate'\n" 85 " will save metadata to disk that 'bootstrap --trace run' uses to make traces\n" 86 " more informative.\n" 87 "- Add '--dump --trace' to emit a <a href='003trace.cc.html#L96'>trace</a> incrementally to stderr.\n" 88 " This approach will work even for long-running programs.\n" 89 " (Though the combination of flags is counter-intuitive and can probably\n" 90 " be improved.)\n" 91 "\n" 92 "Options starting with '--' must always come before any other arguments.\n" 93 "\n" 94 "To start learning how to write SubX programs, see Readme.md (particularly\n" 95 "the section on the x86 instruction set) and then <a href='011run.cc.html#L82'>run</a>:\n" 96 " bootstrap help\n" 97 ); 98 // End Help Texts 99 } 100 101 :(code) 102 bool <a href='001help.cc.html#L102'>is_equal</a>(char* s, const char* lit) { 103 return strncmp(s, lit, strlen(lit)) == 0; 104 } 105 106 bool <a href='001help.cc.html#L106'>starts_with</a>(const string& s, const string& pat) { 107 string::const_iterator a=s.begin(), b=pat.begin(); 108 for (/*nada*/; a!=s.end() && b!=pat.end(); ++a, ++b) 109 if (*a != *b) return false; 110 return b == pat.end(); 111 } 112 113 //: I'll throw some style conventions here for want of a better place for them. 114 //: As a rule I hate style guides. Do what you want, that's my motto. But since 115 //: we're dealing with C/C++, the one big thing we want to avoid is undefined 116 //: behavior. If a compiler ever encounters undefined behavior it can make 117 //: your program do anything it wants. 118 //: 119 //: For reference, my checklist of undefined behaviors to watch out for: 120 //: out-of-bounds access 121 //: uninitialized variables 122 //: use after free 123 //: dereferencing invalid pointers: null, a new of size 0, others 124 //: 125 //: casting a large number to a type too small to hold it 126 //: 127 //: integer overflow 128 //: division by zero and other undefined expressions 129 //: left-shift by negative count 130 //: shifting values by more than or equal to the number of bits they contain 131 //: bitwise operations on signed numbers 132 //: 133 //: Converting pointers to types of different alignment requirements 134 //: T* -> void* -> T*: defined 135 //: T* -> U* -> T*: defined if non-function pointers and alignment requirements are same 136 //: function pointers may be cast to other function pointers 137 //: 138 //: Casting a numeric value into a value that can't be represented by the target type (either directly or via static_cast) 139 //: 140 //: To guard against these, some conventions: 141 //: 142 //: 0. Initialize all primitive variables in functions and constructors. 143 //: 144 //: 1. Minimize use of pointers and pointer arithmetic. Avoid 'new' and 145 //: 'delete' as far as possible. Rely on STL to perform memory management to 146 //: avoid use-after-free issues (and memory leaks). 147 //: 148 //: 2. Avoid naked arrays to avoid out-of-bounds access. Never use operator[] 149 //: except with map. Use at() with STL vectors and so on. 150 //: 151 //: 3. Valgrind all the things. 152 //: 153 //: 4. Avoid unsigned numbers. Not strictly an undefined-behavior issue, but 154 //: the extra range doesn't matter, and it's one less confusing category of 155 //: interaction gotchas to worry about. 156 //: 157 //: Corollary: don't use the size() method on containers, since it returns an 158 //: unsigned and that'll cause warnings about mixing signed and unsigned, 159 //: yadda-yadda. Instead use this macro below to perform an unsafe cast to 160 //: signed. We'll just give up immediately if a container's ever too large. 161 //: Basically, Mu is not concerned about this being a little slower than it 162 //: could be. (<a href="https://gist.github.com/rygorous/e0f055bfb74e3d5f0af20690759de5a7)">https://gist.github.com/rygorous/e0f055bfb74e3d5f0af20690759de5a7)</a> 163 //: 164 //: Addendum to corollary: We're going to uniformly use int everywhere, to 165 //: indicate that we're oblivious to number size, and since Clang on 32-bit 166 //: platforms doesn't yet support multiplication over 64-bit integers, and 167 //: since multiplying two integers seems like a more common situation to end 168 //: up in than integer overflow. 169 :(before "End Includes") 170 #define SIZE(X) (assert((X).size() < (1LL<<(sizeof(int)*8-2))), static_cast<int>((X).size())) 171 172 //: 5. Integer overflow is guarded against at runtime using the -ftrapv flag 173 //: to the compiler, supported by Clang (GCC version only works sometimes: 174 //: <a href="http://stackoverflow.com/questions/20851061/how-to-make-gcc-ftrapv-work).">http://stackoverflow.com/questions/20851061/how-to-make-gcc-ftrapv-work).</a> 175 :(before "atexit(<a href='000organization.cc.html#L150'>reset</a>)") 176 <a href='001help.cc.html#L181'>initialize_signal_handlers</a>(); // not always necessary, but doesn't hurt 177 //? cerr << INT_MAX+1 << '\n'; // test overflow 178 //? assert(false); // test SIGABRT 179 :(code) 180 // based on <a href="https://spin.atomicobject.com/2013/01/13/exceptions-stack-traces-c">https://spin.atomicobject.com/2013/01/13/exceptions-stack-traces-c</a> 181 void <a href='001help.cc.html#L181'>initialize_signal_handlers</a>() { 182 struct sigaction action; 183 bzero(&action, sizeof(action)); 184 action.sa_sigaction = <a href='001help.cc.html#L189'>dump_and_exit</a>; 185 sigemptyset(&action.sa_mask); 186 sigaction(SIGABRT, &action, NULL); // assert() failure or integer overflow on linux (with -ftrapv) 187 sigaction(SIGILL, &action, NULL); // integer overflow on OS X (with -ftrapv) 188 } 189 void <a href='001help.cc.html#L189'>dump_and_exit</a>(int sig, siginfo_t* /*unused*/, void* /*unused*/) { 190 switch (sig) { 191 case SIGABRT: 192 #ifndef __APPLE__ 193 cerr << "SIGABRT: might be an integer overflow if it wasn't an assert() failure\n"; 194 _Exit(1); 195 #endif 196 break; 197 case SIGILL: 198 #ifdef __APPLE__ 199 cerr << "SIGILL: most likely caused by integer overflow\n"; 200 _Exit(1); 201 #endif 202 break; 203 default: 204 break; 205 } 206 } 207 :(before "End Includes") 208 #include <signal.h> 209 210 //: 6. Map's operator[] being non-const is fucking evil. 211 :(before "Globals") // can't generate prototypes for these 212 // from <a href="http://stackoverflow.com/questions/152643/idiomatic-c-for-reading-from-a-const-map">http://stackoverflow.com/questions/152643/idiomatic-c-for-reading-from-a-const-map</a> 213 template<typename T> typename T::mapped_type& get(T& map, typename T::key_type const& key) { 214 typename T::iterator iter(map.find(key)); 215 if (iter == map.end()) { 216 cerr << "get couldn't find key '" << key << "'\n"; 217 assert(iter != map.end()); 218 } 219 return iter->second; 220 } 221 template<typename T> typename T::mapped_type const& get(const T& map, typename T::key_type const& key) { 222 typename T::const_iterator iter(map.find(key)); 223 if (iter == map.end()) { 224 cerr << "get couldn't find key '" << key << "'\n"; 225 assert(iter != map.end()); 226 } 227 return iter->second; 228 } 229 template<typename T> typename T::mapped_type const& <a href='001help.cc.html#L229'>put</a>(T& map, typename T::key_type const& key, typename T::mapped_type const& value) { 230 map[key] = value; 231 return map[key]; 232 } 233 template<typename T> bool <a href='001help.cc.html#L233'>contains_key</a>(T& map, typename T::key_type const& key) { 234 return map.find(key) != map.end(); 235 } 236 template<typename T> typename T::mapped_type& <a href='001help.cc.html#L236'>get_or_insert</a>(T& map, typename T::key_type const& key) { 237 return map[key]; 238 } 239 template<typename T> typename T::mapped_type const& <a href='001help.cc.html#L239'>put_new</a>(T& map, typename T::key_type const& key, typename T::mapped_type const& value) { 240 assert(map.find(key) == map.end()); 241 map[key] = value; 242 return map[key]; 243 } 244 //: The contract: any container that relies on get_or_insert should never call 245 //: contains_key. 246 247 //: 7. istreams are a royal pain in the arse. You have to be careful about 248 //: what subclass you try to putback into. You have to watch out for the pesky 249 //: failbit and badbit. Just avoid eof() and use this helper instead. 250 :(code) 251 bool <a href='001help.cc.html#L251'>has_data</a>(istream& in) { 252 return in && !in.eof(); 253 } 254 255 :(before "End Includes") 256 #include <assert.h> 257 258 #include <iostream> 259 using std::istream; 260 using std::ostream; 261 using std::iostream; 262 using std::cin; 263 using std::cout; 264 using std::cerr; 265 #include <iomanip> 266 267 #include <string.h> 268 #include <string> 269 using std::string; 270 271 #include <algorithm> 272 using std::min; 273 using std::max; </pre> </body> </html>