diff options
| -rw-r--r-- | miscutils/bc.c | 88 |
1 files changed, 38 insertions, 50 deletions
diff --git a/miscutils/bc.c b/miscutils/bc.c index c7e0e39e0..47acd7fc3 100644 --- a/miscutils/bc.c +++ b/miscutils/bc.c @@ -10,49 +10,34 @@ //config: bc is a command-line, arbitrary-precision calculator with a //config: Turing-complete language. See the GNU bc manual //config: (https://www.gnu.org/software/bc/manual/bc.html) and bc spec -//config: (http://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html) -//config: for details. +//config: (http://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html). //config: -//config: This bc has four differences to the GNU bc: -//config: -//config: 1) The period (.) can also be used as a shortcut for "last", as in -//config: the BSD bc. +//config: This bc has five differences to the GNU bc: +//config: 1) The period (.) is a shortcut for "last", as in the BSD bc. //config: 2) Arrays are copied before being passed as arguments to //config: functions. This behavior is required by the bc spec. //config: 3) Arrays can be passed to the builtin "length" function to get -//config: the number of elements currently in the array. The following -//config: example prints "1": -//config: -//config: a[0] = 0 -//config: length(a[]) -//config: +//config: the number of elements in the array. This prints "1": +//config: a[0] = 0; length(a[]) //config: 4) The precedence of the boolean "not" operator (!) is equal to -//config: that of the unary minus (-), or negation, operator. This still +//config: that of the unary minus (-) negation operator. This still //config: allows POSIX-compliant scripts to work while somewhat //config: preserving expected behavior (versus C) and making parsing //config: easier. +//config: 5) "read()" accepts expressions, not only numeric literals. //config: //config: Options: -//config: //config: -i --interactive force interactive mode +//config: -q --quiet don't print version and copyright +//config: -s --standard error if any non-POSIX extensions are used +//config: -w --warn warn if any non-POSIX extensions are used //config: -l --mathlib use predefined math routines: -//config: -//config: s(expr) = sine of expr in radians -//config: c(expr) = cosine of expr in radians -//config: a(expr) = arctangent of expr, returning -//config: radians -//config: l(expr) = natural log of expr -//config: e(expr) = raises e to the power of expr -//config: j(n, x) = Bessel function of integer order -//config: n of x -//config: -//config: -q --quiet don't print version and copyright. -//config: -s --standard error if any non-POSIX extensions are used. -//config: -w --warn warn if any non-POSIX extensions are used. -//config: -v --version print version and copyright and exit. -//config: -//config: Long options are only available if FEATURE_BC_LONG_OPTIONS is -//config: enabled. +//config: s(expr) sine in radians +//config: c(expr) cosine in radians +//config: a(expr) arctangent, returning radians +//config: l(expr) natural log +//config: e(expr) raises e to the power of expr +//config: j(n, x) Bessel function of integer order n of x //config: //config:config DC //config: bool "dc (38 kb; 49 kb when combined with bc)" @@ -61,33 +46,24 @@ //config: dc is a reverse-polish notation command-line calculator which //config: supports unlimited precision arithmetic. See the FreeBSD man page //config: (https://www.unix.com/man-page/FreeBSD/1/dc/) and GNU dc manual -//config: (https://www.gnu.org/software/bc/manual/dc-1.05/html_mono/dc.html) -//config: for details. +//config: (https://www.gnu.org/software/bc/manual/dc-1.05/html_mono/dc.html). //config: //config: This dc has a few differences from the two above: -//config: -//config: 1) When printing a byte stream (command "P"), this bc follows what +//config: 1) When printing a byte stream (command "P"), this dc follows what //config: the FreeBSD dc does. -//config: 2) This dc implements the GNU extensions for divmod ("~") and +//config: 2) Implements the GNU extensions for divmod ("~") and //config: modular exponentiation ("|"). -//config: 3) This dc implements all FreeBSD extensions, except for "J" and -//config: "M". +//config: 3) Implements all FreeBSD extensions, except for "J" and "M". //config: 4) Like the FreeBSD dc, this dc supports extended registers. //config: However, they are implemented differently. When it encounters //config: whitespace where a register should be, it skips the whitespace. //config: If the character following is not a lowercase letter, an error //config: is issued. Otherwise, the register name is parsed by the //config: following regex: -//config: -//config: [a-z][a-z0-9_]* -//config: +//config: [a-z][a-z0-9_]* //config: This generally means that register names will be surrounded by -//config: whitespace. -//config: -//config: Examples: -//config: -//config: l idx s temp L index S temp2 < do_thing -//config: +//config: whitespace. Examples: +//config: l idx s temp L index S temp2 < do_thing //config: Also note that, like the FreeBSD dc, extended registers are not //config: allowed unless the "-x" option is given. //config: @@ -105,11 +81,19 @@ //config: NOTE: This will require libm to be present for linking. //config: //config:config FEATURE_BC_SIGNALS -//config: bool "Enable bc/dc signal handling" +//config: bool "Interactive mode (+4kb)" //config: default y //config: depends on (BC || DC) && !FEATURE_DC_SMALL //config: help -//config: Enable signal handling for bc and dc. +//config: Enable interactive mode: when started on a tty, +//config: ^C interrupts execution and returns to command line, +//config: errors also return to command line instead of exiting, +//config: line editing with history is available. +//config: +//config: With this option off, input can still be taken from tty, +//config: but all errors are fatal, ^C is fatal, +//config: tty is treated exactly the same as any other +//config: standard input (IOW: no line editing). //config: //config:config FEATURE_BC_LONG_OPTIONS //config: bool "Enable bc/dc long options" @@ -7468,6 +7452,8 @@ static int bc_vm_init(const char *env_len) bc_program_init(); bc_parse_create(&G.prs, BC_PROG_MAIN); +//TODO: in GNU bc, the check is (isatty(0) && isatty(1)), +//-i option unconditionally enables this regardless of isatty(): if (isatty(0)) { #if ENABLE_FEATURE_BC_SIGNALS G_ttyin = 1; @@ -7476,10 +7462,12 @@ static int bc_vm_init(const char *env_len) // In particular, this means ^C won't cause // stdout to get into "error state" if SIGINT hits // within write() syscall. - // The downside is that ^C while line input is taken + // + // The downside is that ^C while tty input is taken // will only be handled after [Enter] since read() // from stdin is not interrupted by ^C either, // it restarts, thus fgetc() does not return on ^C. + // (This problem manifests only if line editing is disabled) signal_SA_RESTART_empty_mask(SIGINT, record_signo); // Without SA_RESTART, this exhibits a bug: |