High-level assembler

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For the language, see High Level Assembly.
For the IBM product, see IBM High-Level Assembler.

High-level assemblers in computing are assemblers for assembly language that incorporate features found in high-level programming languages.

The earliest high-level assembler was probably Burroughs ESPOL in about 1960, which provided an ALGOL-like syntax around explicitly-specified B5000 machine instructions. This was followed by Niklaus Wirth's PL360 in 1968, this replicated the Burroughs facilities- with which he was familiar- on an IBM S/360. More recent high-level assemblers are Borland's TASM, NASM, Microsoft's MASM, IBM's HLASM (for z/Architecture systems), Alessandro Ghignola's Linoleum and Ziron.

High-level assemblers typically provide instructions that directly assemble one-to-one into low-level machine code as in any assembler, plus control statements such as IF, WHILE, REPEAT...UNTIL, and FOR, macros, and other enhancements. This allows the use of high-level control statement abstractions wherever maximal speed or minimal space is not essential; low-level statements that assemble directly to machine code can be used to produce the fastest or shortest code. The end result is assembly source code that is far more readable than standard assembly code while preserving the efficiency inherent with using assembly language.

High-level assemblers generally provide information-hiding facilities and the ability to call functions and procedures using a high-level-like syntax (i.e., the assembler automatically produces code to push parameters on the stack rather than the programmer having to manually write the code to do this).

High-level assemblers also provide data abstractions normally found in high level languages. Examples include structures, unions, classes, and sets. Some high level assemblers (e.g., TASM and HLA) support object-oriented programming.

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