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bc: trim config help text, add a few comments, no code changes

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-12-13 16:35:52 +01:00
parent 9811ad02bd
commit 89e785af98
1 changed files with 38 additions and 50 deletions
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88
miscutils/bc.c
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@ -10,49 +10,34 @@
//config: bc is a command-line, arbitrary-precision calculator with a //config: bc is a command-line, arbitrary-precision calculator with a
//config: Turing-complete language. See the GNU bc manual //config: Turing-complete language. See the GNU bc manual
//config: (https://www.gnu.org/software/bc/manual/bc.html) and bc spec //config: (https://www.gnu.org/software/bc/manual/bc.html) and bc spec
//config: (http://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html) //config: (http://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).
//config: for details.
//config: //config:
//config: This bc has four differences to the GNU bc: //config: This bc has five differences to the GNU bc:
//config: //config: 1) The period (.) is a shortcut for "last", as in the BSD bc.
//config: 1) The period (.) can also be used as a shortcut for "last", as in
//config: the BSD bc.
//config: 2) Arrays are copied before being passed as arguments to //config: 2) Arrays are copied before being passed as arguments to
//config: functions. This behavior is required by the bc spec. //config: functions. This behavior is required by the bc spec.
//config: 3) Arrays can be passed to the builtin "length" function to get //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: the number of elements in the array. This prints "1":
//config: example prints "1": //config: a[0] = 0; length(a[])
//config:
//config: a[0] = 0
//config: length(a[])
//config:
//config: 4) The precedence of the boolean "not" operator (!) is equal to //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: allows POSIX-compliant scripts to work while somewhat
//config: preserving expected behavior (versus C) and making parsing //config: preserving expected behavior (versus C) and making parsing
//config: easier. //config: easier.
//config: 5) "read()" accepts expressions, not only numeric literals.
//config: //config:
//config: Options: //config: Options:
//config:
//config: -i --interactive force interactive mode //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: -l --mathlib use predefined math routines:
//config: //config: s(expr) sine in radians
//config: s(expr) = sine of expr in radians //config: c(expr) cosine in radians
//config: c(expr) = cosine of expr in radians //config: a(expr) arctangent, returning radians
//config: a(expr) = arctangent of expr, returning //config: l(expr) natural log
//config: radians //config: e(expr) raises e to the power of expr
//config: l(expr) = natural log of expr //config: j(n, x) Bessel function of integer order n of x
//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: //config:
//config:config DC //config:config DC
//config: bool "dc (38 kb; 49 kb when combined with bc)" //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: dc is a reverse-polish notation command-line calculator which
//config: supports unlimited precision arithmetic. See the FreeBSD man page //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.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: (https://www.gnu.org/software/bc/manual/dc-1.05/html_mono/dc.html).
//config: for details.
//config: //config:
//config: This dc has a few differences from the two above: //config: This dc has a few differences from the two above:
//config: //config: 1) When printing a byte stream (command "P"), this dc follows what
//config: 1) When printing a byte stream (command "P"), this bc follows what
//config: the FreeBSD dc does. //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: modular exponentiation ("|").
//config: 3) This dc implements all FreeBSD extensions, except for "J" and //config: 3) Implements all FreeBSD extensions, except for "J" and "M".
//config: "M".
//config: 4) Like the FreeBSD dc, this dc supports extended registers. //config: 4) Like the FreeBSD dc, this dc supports extended registers.
//config: However, they are implemented differently. When it encounters //config: However, they are implemented differently. When it encounters
//config: whitespace where a register should be, it skips the whitespace. //config: whitespace where a register should be, it skips the whitespace.
//config: If the character following is not a lowercase letter, an error //config: If the character following is not a lowercase letter, an error
//config: is issued. Otherwise, the register name is parsed by the //config: is issued. Otherwise, the register name is parsed by the
//config: following regex: //config: following regex:
//config: //config: [a-z][a-z0-9_]*
//config: [a-z][a-z0-9_]*
//config:
//config: This generally means that register names will be surrounded by //config: This generally means that register names will be surrounded by
//config: whitespace. //config: whitespace. Examples:
//config: //config: l idx s temp L index S temp2 < do_thing
//config: Examples:
//config:
//config: l idx s temp L index S temp2 < do_thing
//config:
//config: Also note that, like the FreeBSD dc, extended registers are not //config: Also note that, like the FreeBSD dc, extended registers are not
//config: allowed unless the "-x" option is given. //config: allowed unless the "-x" option is given.
//config: //config:
@ -105,11 +81,19 @@
//config: NOTE: This will require libm to be present for linking. //config: NOTE: This will require libm to be present for linking.
//config: //config:
//config:config FEATURE_BC_SIGNALS //config:config FEATURE_BC_SIGNALS
//config: bool "Enable bc/dc signal handling" //config: bool "Interactive mode (+4kb)"
//config: default y //config: default y
//config: depends on (BC || DC) && !FEATURE_DC_SMALL //config: depends on (BC || DC) && !FEATURE_DC_SMALL
//config: help //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:config FEATURE_BC_LONG_OPTIONS //config:config FEATURE_BC_LONG_OPTIONS
//config: bool "Enable bc/dc 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_program_init();
bc_parse_create(&G.prs, BC_PROG_MAIN); 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 (isatty(0)) {
#if ENABLE_FEATURE_BC_SIGNALS #if ENABLE_FEATURE_BC_SIGNALS
G_ttyin = 1; G_ttyin = 1;
@ -7476,10 +7462,12 @@ static int bc_vm_init(const char *env_len)
// In particular, this means ^C won't cause // In particular, this means ^C won't cause
// stdout to get into "error state" if SIGINT hits // stdout to get into "error state" if SIGINT hits
// within write() syscall. // 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() // will only be handled after [Enter] since read()
// from stdin is not interrupted by ^C either, // from stdin is not interrupted by ^C either,
// it restarts, thus fgetc() does not return on ^C. // 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); signal_SA_RESTART_empty_mask(SIGINT, record_signo);
// Without SA_RESTART, this exhibits a bug: // Without SA_RESTART, this exhibits a bug: