Whirl

Whirl is an esoteric programming language which uses only 0s and 1s for source code and a pretty weird way to convert them into commands.

Whirl was created by Sean Heber in 2004. The weirdness of the language earned some devoted followers who created several implementations and quite a lot of helpful tools.

The language is based on two rings with 12 commands on each, grouped by topic: math and “operational”. Each ring has a pointer to the current command (initially each pointer is set to Noop, a no-action command), direction of rotation (initially clockwise) and a memory cell. The language also provides random-access memory.

All activity of the program is based on these rings and changes in their state. Characters of the program change their state as follows. 1 always rotates the active ring one command in its current direction of rotation. 0 reverses the direction of rotation of the active ring. Besides, if the current 0 command was preceded by another 0 which didn’t trigger command execution, the current command on the active ring is executed, and the active ring changes. All characters of the program which are not 0 or 1 are ignored.

Commands

Here value denotes the value in the memory cell of the active ring, memval — the value in the current cell of random access memory. The commands of each ring are given in clockwise order. Several commands (memory access, setting constants) are duplicated on both rings, as they are necessary for functioning of the program.

Operations ring:

• Noop No action
• Exit Stop program execution
• One Set value to 1
• Zero Set value to 0
• Load Set value to memval
• Store Set memval to value
• PAdd Unconditional jump: add value to current program position pointer
• DAdd Add value to current memory cell pointer
• Logic Logical AND: set value to (memval AND value)
• If Conditional jump: if memval is not 0, add value to current program position pointer
• IntIO If value equals 0, read an integer from standard input stream and assign it to memval, otherwise print memval as an integer
• AscIO If value equals 0, read a character from standard input stream and assign its ASCII-code to memval, otherwise print memval as a character

Math ring:

• Noop No action
• Load Set value to memval
• Store Set memval to value
• Add Set value to value + memval
• Mult Set value to value * memval
• Div Set value to value / memval
• Zero Set value to 0
• < Set value to 1, if value < memval, and 0 otherwise
• > Set value to 1, if value > memval, and 0 otherwise
• = Set value to 1, if value = memval, and 0 otherwise
• Not Set value to 1, if value = 0, and 0 otherwise
• Neg Multiply value by -1