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- == 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
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