7490 - baremetal: draw a grapheme to screen - mu - Soul of a tiny new machine. More thorough tests → More comprehensible and rewrite-friendly software → More resilient society.

diff options

author	Kartik Agaram <vc@akkartik.com>	2021-01-09 17:04:21 -0800
committer	Kartik Agaram <vc@akkartik.com>	2021-01-09 18:28:14 -0800
commit	7f8770ae082a723faae89faea0dce6635feb7cdb (patch)
tree	4955853fdd8c1f70197453b8ba339b950376908f /302stack_allocate.subx
parent	dbd7082a0ed09ee06401d0af06ce24e89e87b189 (diff)
download	mu-7f8770ae082a723faae89faea0dce6635feb7cdb.tar.gz

7490 - baremetal: draw a grapheme to screen

Diffstat (limited to '302stack_allocate.subx')

0 files changed, 0 insertions, 0 deletions

<!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/8.0"> <meta name="plugin-version" content="vim7.4_v2"> <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#L73'>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 if (argc <= 1) { 9 cerr << "Please provide a Mu program to run.\n" 10 << "\n"; 11 } 12 cerr << "Usage:\n" 13 << " mu [options] [test] [files]\n" 14 << "or:\n" 15 << " mu [options] [test] [files] -- [ingredients for function/recipe 'main']\n" 16 << "Square brackets surround optional arguments.\n" 17 << "\n" 18 << "Examples:\n" 19 << " To load files and run 'main':\n" 20 << " mu file1.mu file2.mu ...\n" 21 << " To run 'main' and dump a <a href='003trace.cc.html#L189'>trace</a> of all operations at the <a href='003trace.cc.html#L225'>end</a>:\n" 22 << " mu --trace file1.mu file2.mu ...\n" 23 << " To run all tests:\n" 24 << " mu test\n" 25 << " To load files and then run all tests:\n" 26 << " mu test file1.mu file2.mu ...\n" 27 << " To run a single Mu <a href='050scenario.cc.html#L57'>scenario</a>:\n" 28 << " mu test file1.mu file2.mu ... scenario\n" 29 << " To run a single Mu <a href='050scenario.cc.html#L57'>scenario</a> and dump a <a href='003trace.cc.html#L189'>trace</a> at the <a href='003trace.cc.html#L225'>end</a>:\n" 30 << " mu --trace test file1.mu file2.mu ... scenario\n" 31 << " To load files and run only the tests in explicitly loaded files (for apps):\n" 32 << " mu --test-only-app test file1.mu file2.mu ...\n" 33 << " To load all files with a numeric prefix in a directory:\n" 34 << " mu directory1 directory2 ...\n" 35 << " You can test directories just like files.\n" 36 << " mu test directory1 directory2 ...\n" 37 << " To pass ingredients to a mu program, provide them after '--':\n" 38 << " mu file_or_dir1 file_or_dir2 ... -- ingredient1 ingredient2 ...\n" 39 << " To see where a mu program is spending its time:\n" 40 << " mu --profile file_or_dir1 file_or_dir2 ...\n" 41 << " this slices and dices time spent in various profile.* output files\n" 42 << "\n" 43 << " To browse a <a href='003trace.cc.html#L189'>trace</a> generated by a previous run:\n" 44 << " mu browse-trace file\n" 45 ; 46 return 0; 47 } 48 49 //: Support for option parsing. 50 //: Options always begin with '--' and are always the first arguments. An 51 //: option will never follow a non-option. 52 :(before "End Commandline Parsing") 53 char** arg = &argv[1]; 54 while (argc > 1 && <a href='001help.cc.html#L77'>starts_with</a>(*arg, "--")) { 55 if (false) 56 ; // no-op branch just so any further additions can consistently always start with 'else' 57 // End Commandline Options(*arg) 58 else 59 cerr << "skipping unknown option " << *arg << '\n'; 60 --argc; ++argv; ++arg; 61 } 62 63 //:: Helper function used by the above fragment of code (and later layers too, 64 //:: who knows?). 65 //: The :(code) directive appends function definitions to the end of the 66 //: project. Regardless of where functions are defined, we can call them 67 //: anywhere we like as long as we format the function header in a specific 68 //: way: put it all on a single line without indent, end the line with ') {' 69 //: and no trailing whitespace. As long as functions uniformly start this 70 //: way, our 'build*' scripts contain a little command to automatically 71 //: generate declarations for them. 72 :(code) 73 bool <a href='001help.cc.html#L73'>is_equal</a>(char* s, const char* lit) { 74 return strncmp(s, lit, strlen(lit)) == 0; 75 } 76 77 bool <a href='001help.cc.html#L77'>starts_with</a>(const string& s, const string& pat) { 78 string::const_iterator a=s.begin(), b=pat.begin(); 79 for (/*nada*/; a!=s.<a href='003trace.cc.html#L225'>end</a>() && b!=pat.<a href='003trace.cc.html#L225'>end</a>(); ++a, ++b) 80 if (*a != *b) return false; 81 return b == pat.<a href='003trace.cc.html#L225'>end</a>(); 82 } 83 84 //: I'll throw some style conventions here for want of a better place for them. 85 //: As a rule I hate style guides. Do what you want, that's my motto. But since 86 //: we're dealing with C/C++, the one big thing we want to avoid is undefined 87 //: behavior. If a compiler ever encounters undefined behavior it can make 88 //: your program do anything it wants. 89 //: 90 //: For reference, my checklist of undefined behaviors to watch out for: 91 //: out-of-bounds access 92 //: uninitialized variables 93 //: use after free 94 //: dereferencing invalid pointers: null, a new of size 0, others 95 //: 96 //: casting a large number to a type too small to hold it 97 //: 98 //: integer overflow 99 //: division by zero and other undefined expressions 100 //: left-shift by negative count 101 //: shifting values by more than or equal to the number of bits they contain 102 //: bitwise operations on signed numbers 103 //: 104 //: Converting pointers to types of different alignment requirements 105 //: T* -> void* -> T*: defined 106 //: T* -> U* -> T*: defined if non-function pointers and alignment requirements are same 107 //: function pointers may be cast to other function pointers 108 //: 109 //: Casting a numeric value into a value that can't be represented by the target type (either directly or via static_cast) 110 //: 111 //: To guard against these, some conventions: 112 //: 113 //: 0. Initialize all primitive variables in functions and constructors. 114 //: 115 //: 1. Minimize use of pointers and pointer arithmetic. Avoid 'new' and 116 //: 'delete' as far as possible. Rely on STL to perform memory management to 117 //: avoid use-after-free issues (and memory leaks). 118 //: 119 //: 2. Avoid naked arrays to avoid out-of-bounds access. Never use operator[] 120 //: except with map. Use at() with STL vectors and so on. 121 //: 122 //: 3. Valgrind all the things. 123 //: 124 //: 4. Avoid unsigned numbers. Not strictly an undefined-behavior issue, but 125 //: the extra range doesn't matter, and it's one less confusing category of 126 //: interaction gotchas to worry about. 127 //: 128 //: Corollary: don't use the size() method on containers, since it returns an 129 //: unsigned and that'll cause warnings about mixing signed and unsigned, 130 //: yadda-yadda. Instead use this macro below to perform an unsafe cast to 131 //: signed. We'll just give up immediately if a container's ever too large. 132 //: Basically, Mu is not concerned about this being a little slower than it 133 //: could be. (<a href="https://gist.github.com/rygorous/e0f055bfb74e3d5f0af20690759de5a7">https://gist.github.com/rygorous/e0f055bfb74e3d5f0af20690759de5a7</a>) 134 //: 135 //: Addendum to corollary: We're going to uniformly use int everywhere, to 136 //: indicate that we're oblivious to number size, and since Clang on 32-bit 137 //: platforms doesn't yet support multiplication over 64-bit integers, and 138 //: since multiplying two integers seems like a more common situation to end 139 //: up in than integer overflow. 140 :(before "End Includes") 141 #define SIZE(X) (assert((X).size() < (1LL<<(sizeof(int)*8-2))), static_cast<int>((X).size())) 142 143 //: 5. Integer overflow is guarded against at runtime using the -ftrapv flag 144 //: to the compiler, supported by Clang (GCC version only works sometimes: 145 //: <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>). 146 :(before "atexit(reset)") 147 <a href='001help.cc.html#L152'>initialize_signal_handlers</a>(); // not always necessary, but doesn't hurt 148 //? cerr << INT_MAX+1 << '\n'; // test overflow 149 //? assert(false); // test SIGABRT 150 :(code) 151 // 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> 152 void <a href='001help.cc.html#L152'>initialize_signal_handlers</a>() { 153 struct sigaction action; 154 bzero(&action, sizeof(action)); 155 action.sa_sigaction = <a href='001help.cc.html#L160'>dump_and_exit</a>; 156 sigemptyset(&action.sa_mask); 157 sigaction(SIGABRT, &action, NULL); // assert() failure or integer overflow on linux (with -ftrapv) 158 sigaction(SIGILL, &action, NULL); // integer overflow on OS X (with -ftrapv) 159 } 160 void <a href='001help.cc.html#L160'>dump_and_exit</a>(int sig, siginfo_t* /*unused*/, void* /*unused*/) { 161 switch (sig) { 162 case SIGABRT: 163 #ifndef __APPLE__ 164 cerr << "SIGABRT: might be an integer overflow if it wasn't an assert() failure or exception\n"; 165 _Exit(1); 166 #endif 167 break; 168 case SIGILL: 169 #ifdef __APPLE__ 170 cerr << "SIGILL: most likely caused by integer overflow\n"; 171 _Exit(1); 172 #endif 173 break; 174 default: 175 break; 176 } 177 } 178 :(before "End Includes") 179 #include <signal.h> 180 181 //: For good measure we'll also enable SIGFPE. 182 :(before "atexit(reset)") 183 <a href='001help.cc.html#L196'>feenableexcept</a>(FE_OVERFLOW | FE_UNDERFLOW); 184 //? assert(sizeof(int) == 4 && sizeof(float) == 4); 185 //? // | exp | mantissa 186 //? int smallest_subnormal = 0b00000000000000000000000000000001; 187 //? float smallest_subnormal_f = *reinterpret_cast<float*>(&smallest_subnormal); 188 //? cerr << "ε: " << smallest_subnormal_f << '\n'; 189 //? cerr << "ε/2: " << smallest_subnormal_f/2 << " (underflow)\n"; // test SIGFPE 190 :(before "End Includes") 191 #include <fenv.h> 192 :(code) 193 #ifdef __APPLE__ 194 // Public domain polyfill for feenableexcept on OS X 195 // <a href="http://www-personal.umich.edu/~williams/archive/computation/fe-handling-example.c">http://www-personal.umich.edu/~williams/archive/computation/fe-handling-example.c</a> 196 int <a href='001help.cc.html#L196'>feenableexcept</a>(unsigned int excepts) { 197 static fenv_t fenv; 198 unsigned int new_excepts = excepts & FE_ALL_EXCEPT; 199 unsigned int old_excepts; 200 if (fegetenv(&fenv)) return -1; 201 old_excepts = fenv.__control & FE_ALL_EXCEPT; 202 fenv.__control &= ~new_excepts; 203 fenv.__mxcsr &= ~(new_excepts << 7); 204 return fesetenv(&fenv) ? -1 : old_excepts; 205 } 206 #endif 207 208 //: 6. Map's operator[] being non-const is fucking evil. 209 :(before "Globals") // can't generate prototypes for these 210 // 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> 211 template<typename T> typename T::mapped_type& get(T& map, typename T::key_type const& key) { 212 typename T::iterator iter(map.find(key)); 213 assert(iter != map.<a href='003trace.cc.html#L225'>end</a>()); 214 return iter->second; 215 } 216 template<typename T> typename T::mapped_type const& get(const T& map, typename T::key_type const& key) { 217 typename T::const_iterator iter(map.find(key)); 218 assert(iter != map.<a href='003trace.cc.html#L225'>end</a>()); 219 return iter->second; 220 } 221 template<typename T> typename T::mapped_type const& <a href='001help.cc.html#L221'>put</a>(T& map, typename T::key_type const& key, typename T::mapped_type const& value) { 222 // map[key] requires mapped_type to have a zero-arg (default) constructor 223 map.insert(std::make_pair(key, value)).first->second = value; 224 return value; 225 } 226 template<typename T> bool <a href='001help.cc.html#L226'>contains_key</a>(T& map, typename T::key_type const& key) { 227 return map.find(key) != map.<a href='003trace.cc.html#L225'>end</a>(); 228 } 229 template<typename T> typename T::mapped_type& <a href='001help.cc.html#L229'>get_or_insert</a>(T& map, typename T::key_type const& key) { 230 return map[key]; 231 } 232 //: The contract: any container that relies on get_or_insert should never call 233 //: contains_key. 234 235 //: 7. istreams are a royal pain in the arse. You have to be careful about 236 //: what subclass you try to putback into. You have to watch out for the pesky 237 //: failbit and badbit. Just avoid eof() and use this helper instead. 238 :(code) 239 bool <a href='001help.cc.html#L239'>has_data</a>(istream& in) { 240 return in && !in.eof(); 241 } 242 243 :(before "End Includes") 244 #include <assert.h> 245 246 #include <iostream> 247 using std::istream; 248 using std::ostream; 249 using std::iostream; 250 using std::cin; 251 using std::cout; 252 using std::cerr; 253 #include <iomanip> 254 255 #include <string.h> 256 #include <string> 257 using std::string; 258 259 #include <algorithm> 260 using std::min; 261 using std::max; </pre> </body> </html>


context:
space:
mode: