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Jumpback
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Jumpback is an esoteric programming language with no forward jumps.
Instructions
MOV dst, src Copy src to dst ADD dst, src Add src to dst SUB dst, src Subtract src from dst ADDEQ dst, src, cmp Add src to dst if src == cmp ADDNE dst, src, cmp Add src to dst if src != cmp SUBEQ dst, src, cmp Subtract src from dst if src == cmp SUBNE dst, src, cmp Subtract src from dst if src != cmp NEG dst dst = (-1) * dst PSH src Push src to value stack POP dst Pop to dst from value stack LBL Push IP to address stack JEQ a, b Jump if a == b JNE a, b Jump if a != b JLE a, b Jump if a < b JGE a, b Jump if a > g SHOW a Display a
Jumps pop the target from the address stack.
Addressing modes
$ - Immediate # - Memory @ - Memory indirect
i.e.
MOV #0, 1 Writes the number 1 to memory[0] MOV #0, #1 memory[0] = memory[1] MOV #0, @1 memory[0] = memory[memory[1]] MOV @0, @1 memory[memory[0]] = memory[memory[1]]
Examples
MOV #0, 10 MOV #1, 0 LBL SHOW #0 SUB #0, 1 JNE #0, #1
is a countdown from 10 to 0.
The following program prints the first ten Fibonacci numbers:
MOV #0, 0 MOV #1, 1 MOV #2, 2 SHOW #0 SHOW #1 LBL PSH #1 ADD #1, #0 POP #0 SHOW #1 ADD #2, 1 JNE #2, 10
Interpreter
- Common Lisp implementation of the Jumpback programming language.