Flow control is implemented by means of three pairs of instructions.
Flow Control
befunge
Memory Input/Output
Memory input and output is accomplished through the abuse of six G1
instructions (dealing with indexed register memory access). The G1 instructions
incorporate and subsume the ALU instruction. As such
they could be seen as 66 different instructions, but this author will
Literals
Loading registers with literal values is needed by any self respecting architecture. Like the MIPS R×000, Fungus has a fixed single-word instruction length, which precludes loading an entire literal word into a register. A pair of instructions are therefore provided, but, in true Fungus fashion, they are not what the MIPS
Arithmetic and Logic Unary Operations
Instructions in this category are cascaded extensions of the ALU
instruction, where the ALU operation is 111 and the B instruction field selects
a unary ALU operation instead of a register. These are, of course, G1 instructions.
Arithmetic and Logic Binary Operations
All instructions in this category are G1 instructions. In fact, they are the
same instruction: ALU, engaging the ALU in different operation modes. For
the programmer's convenience, the ALU instruction is assembled and
disassembled as different sub-instructions, depending on the contents of the
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