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5.3 Assembler Instructions

In QSMM, there are three categories of assembler instructions: built-in instructions, user instructions, and mixed-type instructions.

The built-in instructions are case, choice, end, jmp, joe, jprob, and stt. The assembler understands the built-in instructions without a prior definition of corresponding instruction classes and meta-classes. The built-in instructions do not necessarily induce code for execution by some kind of a machine; they can be the control words affecting the structure of a machine.

User instructions are assembler instructions with application-specific behavior. You declare a custom set of user instructions in an application program by registering instruction classes and meta-classes. You implement the execution of actions associated with the user instructions in the event handlers of instruction meta-classes.

The mixed-type instructions are abort, lookup, nop, and nop1. The disassembler can generate abort, lookup, and nop1 instructions, but assembling them requires defining the corresponding instruction classes and meta-classes. Their implementation can be specific to an application program. In certain cases, the assembler may implicitly generate nop instructions, but assembling them fails without a definition of the corresponding instruction class and meta-class.

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