bc: trim config help text, add a few comments, no code changes
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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Denys Vlasenko
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9811ad02bd
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89e785af98
@ -10,49 +10,34 @@
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//config: bc is a command-line, arbitrary-precision calculator with a
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//config: Turing-complete language. See the GNU bc manual
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//config: (https://www.gnu.org/software/bc/manual/bc.html) and bc spec
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//config: (http://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
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//config: for details.
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//config: (http://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).
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//config:
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//config: This bc has four differences to the GNU bc:
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//config:
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//config: 1) The period (.) can also be used as a shortcut for "last", as in
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//config: the BSD bc.
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//config: This bc has five differences to the GNU bc:
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//config: 1) The period (.) is a shortcut for "last", as in the BSD bc.
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//config: 2) Arrays are copied before being passed as arguments to
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//config: functions. This behavior is required by the bc spec.
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//config: 3) Arrays can be passed to the builtin "length" function to get
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//config: the number of elements currently in the array. The following
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//config: example prints "1":
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//config:
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//config: a[0] = 0
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//config: length(a[])
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//config:
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//config: the number of elements in the array. This prints "1":
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//config: a[0] = 0; length(a[])
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//config: 4) The precedence of the boolean "not" operator (!) is equal to
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//config: that of the unary minus (-), or negation, operator. This still
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//config: that of the unary minus (-) negation operator. This still
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//config: allows POSIX-compliant scripts to work while somewhat
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//config: preserving expected behavior (versus C) and making parsing
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//config: easier.
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//config: 5) "read()" accepts expressions, not only numeric literals.
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//config:
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//config: Options:
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//config:
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//config: -i --interactive force interactive mode
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//config: -q --quiet don't print version and copyright
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//config: -s --standard error if any non-POSIX extensions are used
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//config: -w --warn warn if any non-POSIX extensions are used
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//config: -l --mathlib use predefined math routines:
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//config:
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//config: s(expr) = sine of expr in radians
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//config: c(expr) = cosine of expr in radians
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//config: a(expr) = arctangent of expr, returning
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//config: radians
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//config: l(expr) = natural log of expr
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//config: e(expr) = raises e to the power of expr
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//config: j(n, x) = Bessel function of integer order
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//config: n of x
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//config:
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//config: -q --quiet don't print version and copyright.
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//config: -s --standard error if any non-POSIX extensions are used.
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//config: -w --warn warn if any non-POSIX extensions are used.
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//config: -v --version print version and copyright and exit.
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//config:
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//config: Long options are only available if FEATURE_BC_LONG_OPTIONS is
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//config: enabled.
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//config: s(expr) sine in radians
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//config: c(expr) cosine in radians
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//config: a(expr) arctangent, returning radians
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//config: l(expr) natural log
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//config: e(expr) raises e to the power of expr
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//config: j(n, x) Bessel function of integer order n of x
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//config:
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//config:config DC
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//config: bool "dc (38 kb; 49 kb when combined with bc)"
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@ -61,33 +46,24 @@
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//config: dc is a reverse-polish notation command-line calculator which
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//config: supports unlimited precision arithmetic. See the FreeBSD man page
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//config: (https://www.unix.com/man-page/FreeBSD/1/dc/) and GNU dc manual
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//config: (https://www.gnu.org/software/bc/manual/dc-1.05/html_mono/dc.html)
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//config: for details.
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//config: (https://www.gnu.org/software/bc/manual/dc-1.05/html_mono/dc.html).
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//config:
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//config: This dc has a few differences from the two above:
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//config:
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//config: 1) When printing a byte stream (command "P"), this bc follows what
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//config: 1) When printing a byte stream (command "P"), this dc follows what
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//config: the FreeBSD dc does.
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//config: 2) This dc implements the GNU extensions for divmod ("~") and
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//config: 2) Implements the GNU extensions for divmod ("~") and
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//config: modular exponentiation ("|").
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//config: 3) This dc implements all FreeBSD extensions, except for "J" and
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//config: "M".
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//config: 3) Implements all FreeBSD extensions, except for "J" and "M".
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//config: 4) Like the FreeBSD dc, this dc supports extended registers.
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//config: However, they are implemented differently. When it encounters
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//config: whitespace where a register should be, it skips the whitespace.
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//config: If the character following is not a lowercase letter, an error
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//config: is issued. Otherwise, the register name is parsed by the
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//config: following regex:
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//config:
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//config: [a-z][a-z0-9_]*
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//config:
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//config: [a-z][a-z0-9_]*
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//config: This generally means that register names will be surrounded by
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//config: whitespace.
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//config:
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//config: Examples:
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//config:
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//config: l idx s temp L index S temp2 < do_thing
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//config:
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//config: whitespace. Examples:
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//config: l idx s temp L index S temp2 < do_thing
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//config: Also note that, like the FreeBSD dc, extended registers are not
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//config: allowed unless the "-x" option is given.
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//config:
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@ -105,11 +81,19 @@
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//config: NOTE: This will require libm to be present for linking.
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//config:
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//config:config FEATURE_BC_SIGNALS
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//config: bool "Enable bc/dc signal handling"
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//config: bool "Interactive mode (+4kb)"
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//config: default y
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//config: depends on (BC || DC) && !FEATURE_DC_SMALL
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//config: help
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//config: Enable signal handling for bc and dc.
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//config: Enable interactive mode: when started on a tty,
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//config: ^C interrupts execution and returns to command line,
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//config: errors also return to command line instead of exiting,
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//config: line editing with history is available.
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//config:
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//config: With this option off, input can still be taken from tty,
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//config: but all errors are fatal, ^C is fatal,
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//config: tty is treated exactly the same as any other
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//config: standard input (IOW: no line editing).
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//config:
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//config:config FEATURE_BC_LONG_OPTIONS
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//config: bool "Enable bc/dc long options"
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@ -7468,6 +7452,8 @@ static int bc_vm_init(const char *env_len)
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bc_program_init();
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bc_parse_create(&G.prs, BC_PROG_MAIN);
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//TODO: in GNU bc, the check is (isatty(0) && isatty(1)),
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//-i option unconditionally enables this regardless of isatty():
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if (isatty(0)) {
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#if ENABLE_FEATURE_BC_SIGNALS
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G_ttyin = 1;
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@ -7476,10 +7462,12 @@ static int bc_vm_init(const char *env_len)
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// In particular, this means ^C won't cause
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// stdout to get into "error state" if SIGINT hits
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// within write() syscall.
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// The downside is that ^C while line input is taken
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//
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// The downside is that ^C while tty input is taken
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// will only be handled after [Enter] since read()
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// from stdin is not interrupted by ^C either,
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// it restarts, thus fgetc() does not return on ^C.
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// (This problem manifests only if line editing is disabled)
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signal_SA_RESTART_empty_mask(SIGINT, record_signo);
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// Without SA_RESTART, this exhibits a bug:
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