2.6 KiB
Instructions
Instructions are the base of all casio_asm programs. They are what instructs the processor to act.
Instructions can be represented in their assembler form or in their bytecode form.
Instructions are described in detail in opcode.list and implemented in executerImp.c.
Instruction execution
An instruction may take one or two arguments from registers, an immediate argument or none at all. All required arguments that are not explicitly supplied are popped from the stack.
Instruction families
There are several instruction families for different purposes. Here are some examples:
Arithmetic instructions
These instructions end in _i or _d and represent a basic arithmetic operation, like an addition. They take one or two arguments.
Examples include add_i, div_d and mod_i.
bitwise instructions
These instructions represent bitwise operations, like a bitshift or an exclusive or. They take one or two arguments.
Examples include shlt, xor and not.
Logic instructions
These instructions end in _l and represent logic operations, like negation. They take one or two arguments.
Examples include and_l, not_l and xor_l.
Comparison instructions
These instructions end in _i or _d and represent arithmetic comparison. They take two arguments.
Examples include eq_i, ge_d and neq_i.
Stack control instructions
These instructions are used to control the stack.
Examples include push, swap and top.
Flow control instructions
These instructions are used to jump conditionally or unconditionally to other points in the program. Their first argument is the jump address.
Examples include call, jmp and jif.
Register control instructions
These instructions are used to manage data contained in registers. They are the only ones (except puind) to alter their content.
Examples include store, swregi and puind.
Processor control instructions
These instructions alter the status of the processor, be it the status register, interrupts or idle state. The ext instruction is used to call external functions.
Examples include stat_s, halt and inth.
Memory manipulation
These instructions allow for direct access to the managed RAM. Write instructions take two arguments and read instructions take a single argument.
Examples include mem_wr, lastad and mem_bw.
Value managment instructions
These instructions are used to convert from one data type to another. They take one argument.
Examples include i2d and d2i.