1# Build 2 3This `bc` attempts to be as portable as possible. It can be built on any 4POSIX-compliant system. 5 6To accomplish that, a POSIX-compatible, custom `configure.sh` script is used to 7select build options, compiler, and compiler flags and generate a `Makefile`. 8 9The general form of configuring, building, and installing this `bc` is as 10follows: 11 12``` 13[ENVIRONMENT_VARIABLE=<value>...] ./configure.sh [build_options...] 14make 15make install 16``` 17 18To get all of the options, including any useful environment variables, use 19either one of the following commands: 20 21``` 22./configure.sh -h 23./configure.sh --help 24``` 25 26***WARNING***: even though `configure.sh` supports both option types, short and 27long, it does not support handling both at the same time. Use only one type. 28 29To learn the available `make` targets run the following command after running 30the `configure.sh` script: 31 32``` 33make help 34``` 35 36See [Build Environment Variables][4] for a more detailed description of all 37accepted environment variables and [Build Options][5] for more detail about all 38accepted build options. 39 40<a name="cross-compiling"/> 41 42## Cross Compiling 43 44To cross-compile this `bc`, an appropriate compiler must be present and assigned 45to the environment variable `HOSTCC` or `HOST_CC` (the two are equivalent, 46though `HOSTCC` is prioritized). This is in order to bootstrap core file(s), if 47the architectures are not compatible (i.e., unlike i686 on x86_64). Thus, the 48approach is: 49 50``` 51HOSTCC="/path/to/native/compiler" ./configure.sh 52make 53make install 54``` 55 56`HOST_CC` will work in exactly the same way. 57 58`HOSTCFLAGS` and `HOST_CFLAGS` can be used to set compiler flags for `HOSTCC`. 59(The two are equivalent, as `HOSTCC` and `HOST_CC` are.) `HOSTCFLAGS` is 60prioritized over `HOST_CFLAGS`. If neither are present, `HOSTCC` (or `HOST_CC`) 61uses `CFLAGS` (see [Build Environment Variables][4] for more details). 62 63It is expected that `CC` produces code for the target system and `HOSTCC` 64produces code for the host system. See [Build Environment Variables][4] for more 65details. 66 67If an emulator is necessary to run the bootstrap binaries, it can be set with 68the environment variable `GEN_EMU`. 69 70<a name="build-environment-variables"/> 71 72## Build Environment Variables 73 74This `bc` supports `CC`, `HOSTCC`, `HOST_CC`, `CFLAGS`, `HOSTCFLAGS`, 75`HOST_CFLAGS`, `CPPFLAGS`, `LDFLAGS`, `LDLIBS`, `PREFIX`, `DESTDIR`, `BINDIR`, 76`DATAROOTDIR`, `DATADIR`, `MANDIR`, `MAN1DIR`, `LOCALEDIR` `EXECSUFFIX`, 77`EXECPREFIX`, `LONG_BIT`, `GEN_HOST`, and `GEN_EMU` environment variables in 78`configure.sh`. Any values of those variables given to `configure.sh` will be 79put into the generated Makefile. 80 81More detail on what those environment variables do can be found in the following 82sections. 83 84### `CC` 85 86C compiler for the target system. `CC` must be compatible with POSIX `c99` 87behavior and options. However, **I encourage users to use any C99 or C11 88compatible compiler they wish.** 89 90If there is a space in the basename of the compiler, the items after the first 91space are assumed to be compiler flags, and in that case, the flags are 92automatically moved into CFLAGS. 93 94Defaults to `c99`. 95 96### `HOSTCC` or `HOST_CC` 97 98C compiler for the host system, used only in [cross compiling][6]. Must be 99compatible with POSIX `c99` behavior and options. 100 101If there is a space in the basename of the compiler, the items after the first 102space are assumed to be compiler flags, and in that case, the flags are 103automatically moved into HOSTCFLAGS. 104 105Defaults to `$CC`. 106 107### `CFLAGS` 108 109Command-line flags that will be passed verbatim to `CC`. 110 111Defaults to empty. 112 113### `HOSTCFLAGS` or `HOST_CFLAGS` 114 115Command-line flags that will be passed verbatim to `HOSTCC` or `HOST_CC`. 116 117Defaults to `$CFLAGS`. 118 119### `CPPFLAGS` 120 121Command-line flags for the C preprocessor. These are also passed verbatim to 122both compilers (`CC` and `HOSTCC`); they are supported just for legacy reasons. 123 124Defaults to empty. 125 126### `LDFLAGS` 127 128Command-line flags for the linker. These are also passed verbatim to both 129compilers (`CC` and `HOSTCC`); they are supported just for legacy reasons. 130 131Defaults to empty. 132 133### `LDLIBS` 134 135Libraries to link to. These are also passed verbatim to both compilers (`CC` and 136`HOSTCC`); they are supported just for legacy reasons and for cross compiling 137with different C standard libraries (like [musl][3]). 138 139Defaults to empty. 140 141### `PREFIX` 142 143The prefix to install to. 144 145Can be overridden by passing the `--prefix` option to `configure.sh`. 146 147Defaults to `/usr/local`. 148 149### `DESTDIR` 150 151Path to prepend onto `PREFIX`. This is mostly for distro and package 152maintainers. 153 154This can be passed either to `configure.sh` or `make install`. If it is passed 155to both, the one given to `configure.sh` takes precedence. 156 157Defaults to empty. 158 159### `BINDIR` 160 161The directory to install binaries in. 162 163Can be overridden by passing the `--bindir` option to `configure.sh`. 164 165Defaults to `$PREFIX/bin`. 166 167### `DATAROOTDIR` 168 169The root directory to install data files in. 170 171Can be overridden by passing the `--datarootdir` option to `configure.sh`. 172 173Defaults to `$PREFIX/share`. 174 175### `DATADIR` 176 177The directory to install data files in. 178 179Can be overridden by passing the `--datadir` option to `configure.sh`. 180 181Defaults to `$DATAROOTDIR`. 182 183### `MANDIR` 184 185The directory to install manpages in. 186 187Can be overridden by passing the `--mandir` option to `configure.sh`. 188 189Defaults to `$DATADIR/man` 190 191### `MAN1DIR` 192 193The directory to install Section 1 manpages in. Because both `bc` and `dc` are 194Section 1 commands, this is the only relevant section directory. 195 196Can be overridden by passing the `--man1dir` option to `configure.sh`. 197 198Defaults to `$MANDIR/man1`. 199 200### `LOCALEDIR` 201 202The directory to install locales in. 203 204Can be overridden by passing the `--localedir` option to `configure.sh`. 205 206Defaults to `$DATAROOTDIR/locale`. 207 208### `EXECSUFFIX` 209 210The suffix to append onto the executable names *when installing*. This is for 211packagers and distro maintainers who want this `bc` as an option, but do not 212want to replace the default `bc`. 213 214Defaults to empty. 215 216### `EXECPREFIX` 217 218The prefix to append onto the executable names *when building and installing*. 219This is for packagers and distro maintainers who want this `bc` as an option, 220but do not want to replace the default `bc`. 221 222Defaults to empty. 223 224### `LONG_BIT` 225 226The number of bits in a C `long` type. This is mostly for the embedded space. 227 228This `bc` uses `long`s internally for overflow checking. In C99, a `long` is 229required to be 32 bits. For this reason, on 8-bit and 16-bit microcontrollers, 230the generated code to do math with `long` types may be inefficient. 231 232For most normal desktop systems, setting this is unnecessary, except that 32-bit 233platforms with 64-bit longs may want to set it to `32`. 234 235Defaults to the default value of `LONG_BIT` for the target platform. For 236compliance with the `bc` spec, the minimum allowed value is `32`. 237 238It is an error if the specified value is greater than the default value of 239`LONG_BIT` for the target platform. 240 241### `GEN_HOST` 242 243Whether to use `gen/strgen.c`, instead of `gen/strgen.sh`, to produce the C 244files that contain the help texts as well as the math libraries. By default, 245`gen/strgen.c` is used, compiled by `$HOSTCC` and run on the host machine. Using 246`gen/strgen.sh` removes the need to compile and run an executable on the host 247machine since `gen/strgen.sh` is a POSIX shell script. However, `gen/lib2.bc` is 248perilously close to 4095 characters, the max supported length of a string 249literal in C99 (and it could be added to in the future), and `gen/strgen.sh` 250generates a string literal instead of an array, as `gen/strgen.c` does. For most 251production-ready compilers, this limit probably is not enforced, but it could 252be. Both options are still available for this reason. 253 254If you are sure your compiler does not have the limit and do not want to compile 255and run a binary on the host machine, set this variable to "0". Any other value, 256or a non-existent value, will cause the build system to compile and run 257`gen/strgen.c`. 258 259Default is "". 260 261### `GEN_EMU` 262 263The emulator to run bootstrap binaries under. This is only if the binaries 264produced by `HOSTCC` (or `HOST_CC`) need to be run under an emulator to work. 265 266Defaults to empty. 267 268<a name="build-options"/> 269 270## Build Options 271 272This `bc` comes with several build options, all of which are enabled by default. 273 274All options can be used with each other, with a few exceptions that will be 275noted below. 276 277**NOTE**: All long options with mandatory argumenst accept either one of the 278following forms: 279 280``` 281--option arg 282--option=arg 283``` 284 285### `bc` Only 286 287To build `bc` only (no `dc`), use any one of the following commands for the 288configure step: 289 290``` 291./configure.sh -b 292./configure.sh --bc-only 293./configure.sh -D 294./configure.sh --disable-dc 295``` 296 297Those commands are all equivalent. 298 299***Warning***: It is an error to use those options if `bc` has also been 300disabled (see below). 301 302### `dc` Only 303 304To build `dc` only (no `bc`), use either one of the following commands for the 305configure step: 306 307``` 308./configure.sh -d 309./configure.sh --dc-only 310./configure.sh -B 311./configure.sh --disable-bc 312``` 313 314Those commands are all equivalent. 315 316***Warning***: It is an error to use those options if `dc` has also been 317disabled (see above). 318 319<a name="build-history"/> 320 321### History 322 323To disable signal handling, pass either the `-H` flag or the `--disable-history` 324option to `configure.sh`, as follows: 325 326``` 327./configure.sh -H 328./configure.sh --disable-history 329``` 330 331Both commands are equivalent. 332 333History is automatically disabled when building for Windows or on another 334platform that does not support the terminal handling that is required. 335 336***WARNING***: Of all of the code in the `bc`, this is the only code that is not 337completely portable. If the `bc` does not work on your platform, your first step 338should be to retry with history disabled. 339 340### NLS (Locale Support) 341 342To disable locale support (use only English), pass either the `-N` flag or the 343`--disable-nls` option to `configure.sh`, as follows: 344 345``` 346./configure.sh -N 347./configure.sh --disable-nls 348``` 349 350Both commands are equivalent. 351 352NLS (locale support) is automatically disabled when building for Windows or on 353another platform that does not support the POSIX locale API or utilities. 354 355### Prompt 356 357By default, `bc` and `dc` print a prompt when in interactive mode. They both 358have the command-line option `-P`/`--no-prompt`, which turns that off, but it 359can be disabled permanently in the build by passing the `-P` flag or the 360`--disable-prompt` option to `configure.sh`, as follows: 361 362``` 363./configure.sh -P 364./configure.sh --disable-prompt 365``` 366 367Both commands are equivalent. 368 369### Locales 370 371By default, `bc` and `dc` do not install all locales, but only the enabled 372locales. If `DESTDIR` exists and is not empty, then they will install all of 373the locales that exist on the system. The `-l` flag or `--install-all-locales` 374option skips all of that and just installs all of the locales that `bc` and `dc` 375have, regardless. To enable that behavior, you can pass the `-l` flag or the 376`--install-all-locales` option to `configure.sh`, as follows: 377 378``` 379./configure.sh -l 380./configure.sh --install-all-locales 381``` 382 383Both commands are equivalent. 384 385### Extra Math 386 387This `bc` has 7 extra operators: 388 389* `$` (truncation to integer) 390* `@` (set precision) 391* `@=` (set precision and assign) 392* `<<` (shift number left, shifts radix right) 393* `<<=` (shift number left and assign) 394* `>>` (shift number right, shifts radix left) 395* `>>=` (shift number right and assign) 396 397There is no assignment version of `$` because it is a unary operator. 398 399The assignment versions of the above operators are not available in `dc`, but 400the others are, as the operators `$`, `@`, `H`, and `h`, respectively. 401 402In addition, this `bc` has the option of outputting in scientific notation or 403engineering notation. It can also take input in scientific or engineering 404notation. On top of that, it has a pseudo-random number generator. (See the 405full manual for more details.) 406 407Extra operators, scientific notation, engineering notation, and the 408pseudo-random number generator can be disabled by passing either the `-E` flag 409or the `--disable-extra-math` option to `configure.sh`, as follows: 410 411``` 412./configure.sh -E 413./configure.sh --disable-extra-math 414``` 415 416Both commands are equivalent. 417 418This `bc` also has a larger library that is only enabled if extra operators and 419the pseudo-random number generator are. More information about the functions can 420be found in the Extended Library section of the full manual. 421 422### Manpages 423 424To disable installing manpages, pass either the `-M` flag or the 425`--disable-man-pages` option to `configure.sh` as follows: 426 427``` 428./configure.sh -M 429./configure.sh --disable-man-pages 430``` 431 432Both commands are equivalent. 433 434### Karatsuba Length 435 436The Karatsuba length is the point at which `bc` and `dc` switch from Karatsuba 437multiplication to brute force, `O(n^2)` multiplication. It can be set by passing 438the `-k` flag or the `--karatsuba-len` option to `configure.sh` as follows: 439 440``` 441./configure.sh -k64 442./configure.sh --karatsuba-len 64 443``` 444 445Both commands are equivalent. 446 447Default is `64`. 448 449***WARNING***: The Karatsuba Length must be a **integer** greater than or equal 450to `16` (to prevent stack overflow). If it is not, `configure.sh` will give an 451error. 452 453### Install Options 454 455The relevant `autotools`-style install options are supported in `configure.sh`: 456 457* `--prefix` 458* `--bindir` 459* `--datarootdir` 460* `--datadir` 461* `--mandir` 462* `--man1dir` 463* `--localedir` 464 465An example is: 466 467``` 468./configure.sh --prefix=/usr --localedir /usr/share/nls 469make 470make install 471``` 472 473They correspond to the environment variables `$PREFIX`, `$BINDIR`, 474`$DATAROOTDIR`, `$DATADIR`, `$MANDIR`, `$MAN1DIR`, and `$LOCALEDIR`, 475respectively. 476 477***WARNING***: If the option is given, the value of the corresponding 478environment variable is overridden. 479 480***WARNING***: If any long command-line options are used, the long form of all 481other command-line options must be used. Mixing long and short options is not 482supported. 483 484## Optimization 485 486The `configure.sh` script will accept an optimization level to pass to the 487compiler. Because `bc` is orders of magnitude faster with optimization, I 488***highly*** recommend package and distro maintainers pass the highest 489optimization level available in `CC` to `configure.sh` with the `-O` flag or 490`--opt` option, as follows: 491 492``` 493./configure.sh -O3 494./configure.sh --opt 3 495``` 496 497Both commands are equivalent. 498 499The build and install can then be run as normal: 500 501``` 502make 503make install 504``` 505 506As usual, `configure.sh` will also accept additional `CFLAGS` on the command 507line, so for SSE4 architectures, the following can add a bit more speed: 508 509``` 510CFLAGS="-march=native -msse4" ./configure.sh -O3 511make 512make install 513``` 514 515Building with link-time optimization (`-flto` in clang) can further increase the 516performance. I ***highly*** recommend doing so. 517 518I do **NOT*** recommend building with `-march=native`; doing so reduces this 519`bc`'s performance. 520 521Manual stripping is not necessary; non-debug builds are automatically stripped 522in the link stage. 523 524## Debug Builds 525 526Debug builds (which also disable optimization if no optimization level is given 527and if no extra `CFLAGS` are given) can be enabled with either the `-g` flag or 528the `--debug` option, as follows: 529 530``` 531./configure.sh -g 532./configure.sh --debug 533``` 534 535Both commands are equivalent. 536 537The build and install can then be run as normal: 538 539``` 540make 541make install 542``` 543 544## Stripping Binaries 545 546By default, when `bc` and `dc` are not built in debug mode, the binaries are 547stripped. Stripping can be disabled with either the `-T` or the 548`--disable-strip` option, as follows: 549 550``` 551./configure.sh -T 552./configure.sh --disable-strip 553``` 554 555Both commands are equivalent. 556 557The build and install can then be run as normal: 558 559``` 560make 561make install 562``` 563 564## Binary Size 565 566When built with both calculators, all available features, and `-Os` using 567`clang` and `musl`, the executable is 140.4 kb (140,386 bytes) on `x86_64`. That 568isn't much for what is contained in the binary, but if necessary, it can be 569reduced. 570 571The single largest user of space is the `bc` calculator. If just `dc` is needed, 572the size can be reduced to 107.6 kb (107,584 bytes). 573 574The next largest user of space is history support. If that is not needed, size 575can be reduced (for a build with both calculators) to 119.9 kb (119,866 bytes). 576 577There are several reasons that history is a bigger user of space than `dc` 578itself: 579 580* `dc`'s lexer and parser are *tiny* compared to `bc`'s because `dc` code is 581 almost already in the form that it is executed in, while `bc` has to not only 582 adjust the form to be executable, it has to parse functions, loops, `if` 583 statements, and other extra features. 584* `dc` does not have much extra code in the interpreter. 585* History has a lot of const data for supporting `UTF-8` terminals. 586* History pulls in a bunch of more code from the `libc`. 587 588The next biggest user is extra math support. Without it, the size is reduced to 589124.0 kb (123,986 bytes) with history and 107.6 kb (107,560 bytes) without 590history. 591 592The reasons why extra math support is bigger than `dc`, besides the fact that 593`dc` is small already, are: 594 595* Extra math supports adds an extra math library that takes several kilobytes of 596 constant data space. 597* Extra math support includes support for a pseudo-random number generator, 598 including the code to convert a series of pseudo-random numbers into a number 599 of arbitrary size. 600* Extra math support adds several operators. 601 602The next biggest user is `dc`, so if just `bc` is needed, the size can be 603reduced to 128.1 kb (128,096 bytes) with history and extra math support, 107.6 604kb (107,576 bytes) without history and with extra math support, and 95.3 kb 605(95,272 bytes) without history and without extra math support. 606 607*Note*: all of these binary sizes were compiled using `musl` `1.2.0` as the 608`libc`, making a fully static executable, with `clang` `9.0.1` (well, 609`musl-clang` using `clang` `9.0.1`) as the compiler and using `-Os` 610optimizations. These builds were done on an `x86_64` machine running Gentoo 611Linux. 612 613## Testing 614 615The default test suite can be run with the following command: 616 617``` 618make test 619``` 620 621To test `bc` only, run the following command: 622 623``` 624make test_bc 625``` 626 627To test `dc` only, run the following command: 628 629``` 630make test_dc 631``` 632 633This `bc`, if built, assumes a working, GNU-compatible `bc`, installed on the 634system and in the `PATH`, to generate some tests, unless the `-G` flag or 635`--disable-generated-tests` option is given to `configure.sh`, as follows: 636 637``` 638./configure.sh -G 639./configure.sh --disable-generated-tests 640``` 641 642After running `configure.sh`, build and run tests as follows: 643 644``` 645make 646make test 647``` 648 649This `dc` also assumes a working, GNU-compatible `dc`, installed on the system 650and in the `PATH`, to generate some tests, unless one of the above options is 651given to `configure.sh`. 652 653To generate test coverage, pass the `-c` flag or the `--coverage` option to 654`configure.sh` as follows: 655 656``` 657./configure.sh -c 658./configure.sh --coverage 659``` 660 661Both commands are equivalent. 662 663***WARNING***: Both `bc` and `dc` must be built for test coverage. Otherwise, 664`configure.sh` will give an error. 665 666[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html 667[2]: https://www.gnu.org/software/bc/ 668[3]: https://www.musl-libc.org/ 669[4]: #build-environment-variables 670[5]: #build-options 671[6]: #cross-compiling 672