| == architecture == | |
| - three storage regions | |
| - memory with 15-bit address space storing 16-bit values | |
| - eight registers | |
| - an unbounded stack which holds individual 16-bit values | |
| - all numbers are unsigned integers 0..32767 (15-bit) | |
| - all math is modulo 32768; 32758 + 15 => 5 | |
| == binary format == | |
| - each number is stored as a 16-bit little-endian pair (low byte, high byte) | |
| - numbers 0..32767 mean a literal value | |
| - numbers 32768..32775 instead mean registers 0..7 | |
| - numbers 32776..65535 are invalid | |
| - programs are loaded into memory starting at address 0 | |
| - address 0 is the first 16-bit value, address 1 is the second 16-bit value, etc | |
| == execution == | |
| - After an operation is executed, the next instruction to read is immediately after the last argument of the current operation. | |
| If a jump was performed, the next operation is instead the exact destination of the jump. | |
| - Encountering a register as an operation argument should be taken as reading from the register or setting into the register as appropriate. | |
| == hints == | |
| - Start with operations 0, 19, and 21. | |
| - Here's a code for the challenge website: jTTockJlJiOC | |
| - The program "9,32768,32769,4,19,32768" occupies six memory addresses and should: | |
| - Store into register 0 the sum of 4 and the value contained in register 1. | |
| - Output to the terminal the character with the ascii code contained in register 0. | |
| == opcode listing == | |
| halt: 0 | |
| stop execution and terminate the program | |
| set: 1 a b | |
| set register <a> to the value of <b> | |
| push: 2 a | |
| push <a> onto the stack | |
| pop: 3 a | |
| remove the top element from the stack and write it into <a>; empty stack = error | |
| eq: 4 a b c | |
| set <a> to 1 if <b> is equal to <c>; set it to 0 otherwise | |
| gt: 5 a b c | |
| set <a> to 1 if <b> is greater than <c>; set it to 0 otherwise | |
| jmp: 6 a | |
| jump to <a> | |
| jt: 7 a b | |
| if <a> is nonzero, jump to <b> | |
| jf: 8 a b | |
| if <a> is zero, jump to <b> | |
| add: 9 a b c | |
| assign into <a> the sum of <b> and <c> (modulo 32768) | |
| mult: 10 a b c | |
| store into <a> the product of <b> and <c> (modulo 32768) | |
| mod: 11 a b c | |
| store into <a> the remainder of <b> divided by <c> | |
| and: 12 a b c | |
| stores into <a> the bitwise and of <b> and <c> | |
| or: 13 a b c | |
| stores into <a> the bitwise or of <b> and <c> | |
| not: 14 a b | |
| stores 15-bit bitwise inverse of <b> in <a> | |
| rmem: 15 a b | |
| read memory at address <b> and write it to <a> | |
| wmem: 16 a b | |
| write the value from <b> into memory at address <a> | |
| call: 17 a | |
| write the address of the next instruction to the stack and jump to <a> | |
| ret: 18 | |
| remove the top element from the stack and jump to it; empty stack = halt | |
| out: 19 a | |
| write the character represented by ascii code <a> to the terminal | |
| in: 20 a | |
| read a character from the terminal and write its ascii code to <a>; it can be assumed that once input starts, it will continue until a newline is encountered; this means that you can safely read whole lines from the keyboard and trust that they will be fully read | |
| noop: 21 | |
| no operation |