This publication describes the assembly language supported by the IRIX operating system, its syntax rules, and how to write assembly programs. For information about assembling and linking an assembly language program, see the MIPSpro N32/64 Compiling and Performance Tuning Guide.

This book assumes that you are an experienced assembly language programmer. The assembler produces object modules from the assembly instructions that the C and Fortran compilers generate. It therefore lacks many of the functions normally present in an assembler. You should use the assembler only when you must:

The assembler converts assembly language statements into machine code. In most assembly languages, each instruction corresponds to a single machine instruction; however, some assembly language instructions can generate several machine instructions. This feature results in assembly programs that can run without modification on future machines, which might have different machine instructions.

In this release, the assembler supports compilations in -o32, -n32, and -64 mode. Some of the implications of these different data sizes are explained in this book. For more information, see the MIPSpro 64-Bit Porting and Transition Guide.

Many assembly language instructions have direct equivalents to machine instructions. For more information about the operations of a specific architecture, see the book that is appropriate for your hardware type.

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