High Level Assembly - High Vs. Low-level Assembler

High Vs. Low-level Assembler

The HLA v2.x assembler supports the same low-level machine instructions as a regular, low-level, assembler. The difference is that high-level assemblers (such as HLA, MASM, or TASM on the x86) also support high-level-language-like statements such as IF, WHILE, and so on, and fancier data declaration directives, such as structures/records, unions, and even classes.

Unlike most other assembler tools, the HLA compiler includes a Standard Library: thousands of functions, procedures, and macros that can be used to create full applications with the ease of a high-level language. While assembly language libraries are not new, a language that includes a large standardized library makes programmers far more likely to use such library code rather than simply writing their own library functions.

HLA supports all the same low-level machine instructions as other x86 assemblers and, indeed, HLA's high-level control structures are based on the ones found in MASM and TASM (whose HLL-like features predated the arrival of HLA by several years). One can write low-level assembly code in HLA just as easily as with any other assembler by simply ignoring the HLL-control constructs. Indeed, in contrast to HLLs like Pascal and C(++), HLA doesn't require inline asm statements. HLL-like features appear in HLA to provide a learning aid for beginning programmers by smoothing the learning curve, with the assumption that they will discontinue the use of those statements once they master the low-level instruction set (in practice, many experienced programmers continue to use HLL-like statements in HLA, MASM, and TASM, long after they've mastered the low-level instruction set, but this is usually done for readability purposes).

Of course, as the earlier "Hello World" example demonstrates, it is possible to write "high-level" programs using HLA, avoiding much of the tedium of low-level assembly language programming. Some assembly language programmers reject HLA out of hand because it allows programmers to do this. However, supporting both high-level and low-level programming gives any language an expanded range of applicability. If one must do only low-level-only coding, that is possible. If one must write more readable code, using higher-level statements is an option.