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PC(1)                                                       PC(1)

NAME
pc - programmer's calculator

SYNOPSIS
pc [ -n ]

DESCRIPTION
Pc is an arbitrary precision integer calculator with a spe-
cial emphasis on supporting two's complement bit operations
and working with different number bases.

Pc reads input statements which are either expressions or
control statements.  Multiple statements in one line can be
separated by semicolons.  Pc prints the value of all expres-
sions that are not terminated by a semicolon.

Pc can be run non-interactively by using the -n switch. In
this case no input prompt is printed.

Expressions can use the C-like operators

+ - * ** (exponentiation)

/ % (Euclidean division, by default)

& | ^ ~ ! << >>

&& || (returning the second argument, if appropriate)

< >= < <= == !=

The \$ operator performs sign extension. n\$x truncates x to n
bits and sign extends.  If n is omitted, it is inferred from
the highest set bit (the result is always ≤ 0 in this case).

Variables can be defined using =.  The builtin variable @
always refers to the last printed result.

Numbers can use the prefixes 0b (binary), 0 (octal), 0d

Builtin functions
bin(n)                Display n in binary.
oct(n)                Display n in octal.
dec(n)                Display n in decimal.
pb(n, b)              Display n in base b (currently must be
one of 0, 2, 8, 10, 16; 0 uses the
defined output base).

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PC(1)                                                       PC(1)

abs(n)                Absolute value of n.
round(n,m)            n rounded to the nearest multiple of
m.  Numbers exactly halfway between
are rounded to the next even multiple.
floor(n,m)            n rounded down to the next multiple of
m.
ceil(n,m)             n rounded up to the next multiple of
m.
trunc(n,m)            n truncated to m bits.
xtend(n,m)            n truncated to m bits, with the high-
est bit interpreted as a sign bit.
rev(n,m)              n truncated to m bits, with the order
of bits reversed.
ubits(n)              The minimum number of bits required to
represent n as an unsigned number.
sbits(n)              The minimum number of bits required to
represent n as an signed number.
nsa(n)                The number of bits set in n.
cat(a908,n908,...,a9N8,n9N8)  Truncate each of the a9i8 arguments to
n9i8 bits and concatenate their binary
representation.
gcd(n,m)              The greatest common divisor of n and
m.
clog(a,b)             The ceiling of the logarithm of a with
respect to base b. b can be omitted,
in which case it defaults to 2.
minv(n,m)             The inverse of n mod m.
rand(n)               A random number satisfying 0 ≤ rand(n)
< n.

Control statements
Control statements are always evaluated with default input
base 10.

_ n  If n ≠ 0, insert _ in all printed numbers, every n dig-
its.

< n  Set the default input base to n (default 10).  The
input base can always be overriden by the base prefixes
defined above.

> n  Set the output base to n.  If n = 0 (default), print
each number in the base it was input in.

/ 0  Use Euclidean division (default).  a / b is rounded
towards ±∞ (opposite sign as b).  a % b is always non-
negative.

/ 1  Use truncating division (same as C).  a / b is rounded
towards zero.  a % b can be negative.

' 1  Enable numbering bits (disable with 0).  If the base is

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PC(1)                                                       PC(1)

a power of two, print the number of the corresponding
bit above each digit.

SOURCE
/sys/src/cmd/pc.y

bc(1), hoc(1)

BUGS
With the input base set to 16, terms such as ABC are ambigu-
ous.  They are interpreted as numbers only if there is no
function or variable of the same name.  To force interpreta-
tion as a number, use the 0x prefix.

Arbitrary bases should be supported, but are not supported
by the mp(2) string functions.

HISTORY
Pc first appeared in 9front (August, 2016).

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