pc: programmers calculator

pc is a substantially enhanced fork of the SGI/Be/Haiku programmers calculator.

Syntax and operators

• Automatic input and output base conversions::
  • Binary (base 2): 0b111101001101001
  • Octal (base 8): 0o75151 (or 0075151)
  • Decimal (base 10): 31337
  • Hex (base 16): 0x7a69
  • Roman: 0rMCCCXXXVII
  • ASCII: 'zi'
• Optional support for:
  • Ternary (base 3): 0t1120222122
  • Base 36: 0zO6H

• Operators:
  • ++, --, ~, !, *, /, %, +, -, <<, >>, <, >, <=, >=, ==, !=, &, ^, |, &&, ||

• Precedence (highest to lowest):
  • ++, --, ~, !
  • *, /, %
  • +, -
  • <<, >>
  • <, >, <=, >=
  • ==, !=
  • &
  • ^
  • |
  • &&
  • ||

• Assignment operators:
  • =, +=, -=, *=, /=, %=, &=, ^=, |=, <<=, >>=

• Negation:
  • ! is logical, not bitwise (use ~ for bitwise negation)

• Parentheses: Full support for grouping and nesting.

• Explicit modes:
  • Three calculation modes are available, via named commands:
    • auto, signed, and unsigned. The mode command can be used to query the current calculation mode.
    • All operations except comparisons are performed using unsigned integer calculations in the default auto mode.
  • Braces (e.g., { … }) force signed calculation (overriding global mode).
  • Brackets (e.g., [ … ]) force unsigned calculation (overriding global mode).

User variables, builtins, and registers

• Variables:
  • All C-style names (starting with alpha or _, followed by any alphanumeric or _) can be used.
  • User variables are created on first use (and automatically initialized to zero), and can be listed with vars.
  • Examples:
    • x = 5
    • x = y = 10
    • x = (y++ + 5) * 2
    • (y * 2) + (x & 0xffeef)
    • . << 2
    • z = .

• Builtins:
  • Builtins provide access to about 50 system constants and runtime values, which can be listed with the help command.

• Registers:
  • Perform time formatting or casting by storing to special purpose registers (i.e., unsigned C types char, short, int, long, long long), list via the regs command).
    • Stores to registers clamp and mask to the register width.

Portability

• Easily portable to any POSIX-ish system with a C99 compiler (or Ch 7.0+), less easily to others.
• Currently developed on IBM AIX, and regularly tested on PASE for IBM i (OS/400), macOS, FreeBSD, NetBSD, OpenBSD, Solaris, illumos, Haiku, Windows (MSVC, MinGW-w64), Atari ST (TOS and MINT, built using CrossMINT), Amiga 68K (built using Amiga-GCC), Linux, ELKS (built using IA16-GCC), Mac OS 68K (built using Retro68), and DOS (built using DJGPP, IA16-GCC, and Open Watcom V2).

Build

• You can try out pc by executing ./pc.c directly, and it should just run (using shell magic), or,
• Build it with make. Standard environment variables (e.g., CC, CFLAGS, LDFLAGS) are respected.
• Build with Microsoft Visual C/C++ using: cl pc.c /O2 /W4
• Common line editing packages (libedit, editline, readline, and linenoise) are supported and usually automatically configured (via pkg-config magic).
• Review the Makefile to see available build options.

Usage

• Supports interactive, command-line (pc 1+1), file (take command), and piped/redirected usage.

• Interactive examples:
  • 0xFF & 0x0F
  • 1 << 12
  • a = 0x1234; a & 0xFF
  • . + 4 (add to previous result)
  • take examples/sqrt.pc (reads from examples/sqrt.pc)

• easter.pc is a program that calculates the date of Easter (and checks if it's today).
  • You can modify the program or use something like faketime (i.e., faketime -m '2025-04-20 12:00:00') if you want to test arbitrary dates. You can see the full output of this program here (with all optional base conversions enabled).

• sqrt.pc is a program that calculates the square root of n (where n is, by default, a large random number). You can see the full output of this program here.

• weekday.pc is a program that calculates the day of the week. The formatted date is also displayed (via a store to the GT register) for confirmation. You can see the full output of this program here.

Testing

• Linting:
  • C code must pass Cppcheck, Clang Analyzer, GCC Analyzer, PVS-Studio, NetBSD Lint, Oracle Lint, Flawfinder (-m3), Cppi, Ch, and clang -Weverything linting and static analysis.
  • All shell code in the repository must pass ShellCheck, and the Makefile is compatible with POSIX, AIX, BSD, and GNU style make tools.

License

• pc is distributed under the terms of the MIT License.
• The repository is compliant with version 3.3 of the REUSE specification.