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### Library 286 287To build the math library, use the following commands for the configure step: 288 289``` 290./configure.sh -a 291./configure.sh --library 292``` 293 294Both commands are equivalent. 295 296When the library is built, history, prompt, and locales are disabled, and the 297functionality for `bc` and `dc` are both enabled, though the executables are 298*not* built. This is because the library's options clash with the executables. 299 300To build an optimized version of the library, users can pass optimization 301options to `configure.sh` or include them in `CFLAGS`. 302 303The library API can be found in `manuals/bcl.3.md` or `man bcl` once the library 304is installed. 305 306The library is built as `bin/libbcl.a`. 307 308### `bc` Only 309 310To build `bc` only (no `dc`), use any one of the following commands for the 311configure step: 312 313``` 314./configure.sh -b 315./configure.sh --bc-only 316./configure.sh -D 317./configure.sh --disable-dc 318``` 319 320Those commands are all equivalent. 321 322***Warning***: It is an error to use those options if `bc` has also been 323disabled (see below). 324 325### `dc` Only 326 327To build `dc` only (no `bc`), use either one of the following commands for the 328configure step: 329 330``` 331./configure.sh -d 332./configure.sh --dc-only 333./configure.sh -B 334./configure.sh --disable-bc 335``` 336 337Those commands are all equivalent. 338 339***Warning***: It is an error to use those options if `dc` has also been 340disabled (see above). 341 342<a name="build-history"/> 343 344### History 345 346To disable signal handling, pass either the `-H` flag or the `--disable-history` 347option to `configure.sh`, as follows: 348 349``` 350./configure.sh -H 351./configure.sh --disable-history 352``` 353 354Both commands are equivalent. 355 356History is automatically disabled when building for Windows or on another 357platform that does not support the terminal handling that is required. 358 359***WARNING***: Of all of the code in the `bc`, this is the only code that is not 360completely portable. If the `bc` does not work on your platform, your first step 361should be to retry with history disabled. 362 363### NLS (Locale Support) 364 365To disable locale support (use only English), pass either the `-N` flag or the 366`--disable-nls` option to `configure.sh`, as follows: 367 368``` 369./configure.sh -N 370./configure.sh --disable-nls 371``` 372 373Both commands are equivalent. 374 375NLS (locale support) is automatically disabled when building for Windows or on 376another platform that does not support the POSIX locale API or utilities. 377 378### Prompt 379 380By default, `bc` and `dc` print a prompt when in interactive mode. They both 381have the command-line option `-P`/`--no-prompt`, which turns that off, but it 382can be disabled permanently in the build by passing the `-P` flag or the 383`--disable-prompt` option to `configure.sh`, as follows: 384 385``` 386./configure.sh -P 387./configure.sh --disable-prompt 388``` 389 390Both commands are equivalent. 391 392### Locales 393 394By default, `bc` and `dc` do not install all locales, but only the enabled 395locales. If `DESTDIR` exists and is not empty, then they will install all of 396the locales that exist on the system. The `-l` flag or `--install-all-locales` 397option skips all of that and just installs all of the locales that `bc` and `dc` 398have, regardless. To enable that behavior, you can pass the `-l` flag or the 399`--install-all-locales` option to `configure.sh`, as follows: 400 401``` 402./configure.sh -l 403./configure.sh --install-all-locales 404``` 405 406Both commands are equivalent. 407 408### Extra Math 409 410This `bc` has 7 extra operators: 411 412* `$` (truncation to integer) 413* `@` (set precision) 414* `@=` (set precision and assign) 415* `<<` (shift number left, shifts radix right) 416* `<<=` (shift number left and assign) 417* `>>` (shift number right, shifts radix left) 418* `>>=` (shift number right and assign) 419 420There is no assignment version of `$` because it is a unary operator. 421 422The assignment versions of the above operators are not available in `dc`, but 423the others are, as the operators `$`, `@`, `H`, and `h`, respectively. 424 425In addition, this `bc` has the option of outputting in scientific notation or 426engineering notation. It can also take input in scientific or engineering 427notation. On top of that, it has a pseudo-random number generator. (See the 428full manual for more details.) 429 430Extra operators, scientific notation, engineering notation, and the 431pseudo-random number generator can be disabled by passing either the `-E` flag 432or the `--disable-extra-math` option to `configure.sh`, as follows: 433 434``` 435./configure.sh -E 436./configure.sh --disable-extra-math 437``` 438 439Both commands are equivalent. 440 441This `bc` also has a larger library that is only enabled if extra operators and 442the pseudo-random number generator are. More information about the functions can 443be found in the Extended Library section of the full manual. 444 445### Manpages 446 447To disable installing manpages, pass either the `-M` flag or the 448`--disable-man-pages` option to `configure.sh` as follows: 449 450``` 451./configure.sh -M 452./configure.sh --disable-man-pages 453``` 454 455Both commands are equivalent. 456 457### Karatsuba Length 458 459The Karatsuba length is the point at which `bc` and `dc` switch from Karatsuba 460multiplication to brute force, `O(n^2)` multiplication. It can be set by passing 461the `-k` flag or the `--karatsuba-len` option to `configure.sh` as follows: 462 463``` 464./configure.sh -k64 465./configure.sh --karatsuba-len 64 466``` 467 468Both commands are equivalent. 469 470Default is `64`. 471 472***WARNING***: The Karatsuba Length must be a **integer** greater than or equal 473to `16` (to prevent stack overflow). If it is not, `configure.sh` will give an 474error. 475 476### Install Options 477 478The relevant `autotools`-style install options are supported in `configure.sh`: 479 480* `--prefix` 481* `--bindir` 482* `--datarootdir` 483* `--datadir` 484* `--mandir` 485* `--man1dir` 486* `--localedir` 487 488An example is: 489 490``` 491./configure.sh --prefix=/usr --localedir /usr/share/nls 492make 493make install 494``` 495 496They correspond to the environment variables `$PREFIX`, `$BINDIR`, 497`$DATAROOTDIR`, `$DATADIR`, `$MANDIR`, `$MAN1DIR`, and `$LOCALEDIR`, 498respectively. 499 500***WARNING***: If the option is given, the value of the corresponding 501environment variable is overridden. 502 503***WARNING***: If any long command-line options are used, the long form of all 504other command-line options must be used. Mixing long and short options is not 505supported. 506 507## Optimization 508 509The `configure.sh` script will accept an optimization level to pass to the 510compiler. Because `bc` is orders of magnitude faster with optimization, I 511***highly*** recommend package and distro maintainers pass the highest 512optimization level available in `CC` to `configure.sh` with the `-O` flag or 513`--opt` option, as follows: 514 515``` 516./configure.sh -O3 517./configure.sh --opt 3 518``` 519 520Both commands are equivalent. 521 522The build and install can then be run as normal: 523 524``` 525make 526make install 527``` 528 529As usual, `configure.sh` will also accept additional `CFLAGS` on the command 530line, so for SSE4 architectures, the following can add a bit more speed: 531 532``` 533CFLAGS="-march=native -msse4" ./configure.sh -O3 534make 535make install 536``` 537 538Building with link-time optimization (`-flto` in clang) can further increase the 539performance. I ***highly*** recommend doing so. 540 541I do **NOT*** recommend building with `-march=native`; doing so reduces this 542`bc`'s performance. 543 544Manual stripping is not necessary; non-debug builds are automatically stripped 545in the link stage. 546 547## Debug Builds 548 549Debug builds (which also disable optimization if no optimization level is given 550and if no extra `CFLAGS` are given) can be enabled with either the `-g` flag or 551the `--debug` option, as follows: 552 553``` 554./configure.sh -g 555./configure.sh --debug 556``` 557 558Both commands are equivalent. 559 560The build and install can then be run as normal: 561 562``` 563make 564make install 565``` 566 567## Stripping Binaries 568 569By default, when `bc` and `dc` are not built in debug mode, the binaries are 570stripped. Stripping can be disabled with either the `-T` or the 571`--disable-strip` option, as follows: 572 573``` 574./configure.sh -T 575./configure.sh --disable-strip 576``` 577 578Both commands are equivalent. 579 580The build and install can then be run as normal: 581 582``` 583make 584make install 585``` 586 587## Binary Size 588 589When built with both calculators, all available features, and `-Os` using 590`clang` and `musl`, the executable is 140.4 kb (140,386 bytes) on `x86_64`. That 591isn't much for what is contained in the binary, but if necessary, it can be 592reduced. 593 594The single largest user of space is the `bc` calculator. If just `dc` is needed, 595the size can be reduced to 107.6 kb (107,584 bytes). 596 597The next largest user of space is history support. If that is not needed, size 598can be reduced (for a build with both calculators) to 119.9 kb (119,866 bytes). 599 600There are several reasons that history is a bigger user of space than `dc` 601itself: 602 603* `dc`'s lexer and parser are *tiny* compared to `bc`'s because `dc` code is 604 almost already in the form that it is executed in, while `bc` has to not only 605 adjust the form to be executable, it has to parse functions, loops, `if` 606 statements, and other extra features. 607* `dc` does not have much extra code in the interpreter. 608* History has a lot of const data for supporting `UTF-8` terminals. 609* History pulls in a bunch of more code from the `libc`. 610 611The next biggest user is extra math support. Without it, the size is reduced to 612124.0 kb (123,986 bytes) with history and 107.6 kb (107,560 bytes) without 613history. 614 615The reasons why extra math support is bigger than `dc`, besides the fact that 616`dc` is small already, are: 617 618* Extra math supports adds an extra math library that takes several kilobytes of 619 constant data space. 620* Extra math support includes support for a pseudo-random number generator, 621 including the code to convert a series of pseudo-random numbers into a number 622 of arbitrary size. 623* Extra math support adds several operators. 624 625The next biggest user is `dc`, so if just `bc` is needed, the size can be 626reduced to 128.1 kb (128,096 bytes) with history and extra math support, 107.6 627kb (107,576 bytes) without history and with extra math support, and 95.3 kb 628(95,272 bytes) without history and without extra math support. 629 630*Note*: all of these binary sizes were compiled using `musl` `1.2.0` as the 631`libc`, making a fully static executable, with `clang` `9.0.1` (well, 632`musl-clang` using `clang` `9.0.1`) as the compiler and using `-Os` 633optimizations. These builds were done on an `x86_64` machine running Gentoo 634Linux. 635 636## Testing 637 638The default test suite can be run with the following command: 639 640``` 641make test 642``` 643 644To test `bc` only, run the following command: 645 646``` 647make test_bc 648``` 649 650To test `dc` only, run the following command: 651 652``` 653make test_dc 654``` 655 656This `bc`, if built, assumes a working, GNU-compatible `bc`, installed on the 657system and in the `PATH`, to generate some tests, unless the `-G` flag or 658`--disable-generated-tests` option is given to `configure.sh`, as follows: 659 660``` 661./configure.sh -G 662./configure.sh --disable-generated-tests 663``` 664 665After running `configure.sh`, build and run tests as follows: 666 667``` 668make 669make test 670``` 671 672This `dc` also assumes a working, GNU-compatible `dc`, installed on the system 673and in the `PATH`, to generate some tests, unless one of the above options is 674given to `configure.sh`. 675 676To generate test coverage, pass the `-c` flag or the `--coverage` option to 677`configure.sh` as follows: 678 679``` 680./configure.sh -c 681./configure.sh --coverage 682``` 683 684Both commands are equivalent. 685 686***WARNING***: Both `bc` and `dc` must be built for test coverage. Otherwise, 687`configure.sh` will give an error. 688 689[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html 690[2]: https://www.gnu.org/software/bc/ 691[3]: https://www.musl-libc.org/ 692[4]: #build-environment-variables 693[5]: #build-options 694[6]: #cross-compiling 695