Chicken is an esoteric programming language by Torbjörn Söderstedt, in which "chicken" is the only valid symbol.

Language overview

A chicken program consists of the tokens "chicken", " " and "

". Every line has a number of chickens separated by spaces. The number of chickens corresponds to an opcode. Trailing newlines are significant, as an empty line will produce a "0" opcode.

Instructions are loaded onto the stack and executed there directly, which allows for injecting arbitrary code and executing it through a jump. Self-modifying code is also possible because the program stack is not bounded.

The user is able to supply an input value before executing the program. This input is stored in one of the two registers.

Memory model

The stack (represents the memory of the program) has three segments.

The first segment contains two registers. The first register just points to the stack itself (by reference). The second register contains the user input, which is usually a string. These registers are used by the LOAD instruction.

The second segment contains the loaded code. For each line of the code there is a cell on the stack containing the amount of chickens on that line. This segment is directly used for execution. It is automatically padded with a single EXIT instruction.

The third segment contains the actual program stack. As instructions are executed, they will push and pop values in this space. Since the segments are not isolated, it is possible to modify values in the code space or execute in the user stack space.

Instructions

Chicken supports the following instructions:

Opcode Name Name (chicken) Description 0 exit axe Stop execution. 1 chicken chicken Push the string "chicken" onto the stack. 2 add add Add two top stack values. 3 subtract fox Subtract two top stack values. 4 multiply rooster Multiply two top stack values. 5 compare compare Compare two top stack values for equality, push truthy or falsy result onto the stack. 6 load pick Double wide instruction. Next instruction indicates source to load from. 0 loads from stack, 1 loads from user input. Top of stack points to address/index to load onto stack. 7 store peck Top of stack points to address/index to store to. The value below that will be popped and stored. 8 jump fr Top of stack is a relative offset to jump to. The value below that is the condition. Jump only happens if condition is truthy. 9 char BBQ Interprets the top of the stack as ascii and pushes the corresponding character. 10+ push Pushes the literal number n-10 onto the stack.

Examples

chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken chicken

chicken

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MiniChicken

MiniChicken is a version of chicken created by Cortex. Numbers in MiniChicken are equivalent to a line of that many chicken s in Chicken, and a space is equivalent to a newline in Chicken. However, for no other reason than so it can make a quine, the number 1 pushes the number 1 onto the stack instead of the string "chicken".

Cat program

11 6 0

Quine

1