Better support for HP PA-RISC architecture

[XVilka]

PA-RISC is an instruction set architecture (ISA) developed by Hewlett-Packard. As the name implies, it is a reduced instruction set computer (RISC) architecture, where the PA stands for Precision Architecture. The design is also referred to as HP/PA for Hewlett Packard Precision Architecture.

The architecture was introduced on 26 February 1986, when the HP 3000 Series 930 and HP 9000 Model 840 computers were launched featuring the first implementation, the TS1.

PA-RISC has been succeeded by the Itanium (originally IA-64) ISA, jointly developed by HP and Intel. HP stopped selling PA-RISC-based HP 9000 systems at the end of 2008 but supported servers running PA-RISC chips until 2013.

A significant amount of the proprietary and valuable software was created for this platform thus might be of interest for the reverse engineers.

Rizin currently supports disassembly of PA-RISC, but it's based on binutils, and no analysis. Ideally, it should be reimplemented in LGPL-compatible license: LGPL itself or MIT.

PA-RISC 1.1 Architecture and Instruction Set Reference Manual
PA-RISC 2.0 Architecture and Instruction Set Reference Manual

See also:

• https://github.com/NationalSecurityAgency/ghidra/tree/master/Ghidra/Processors/PA-RISC
• https://parisc.wiki.kernel.org
• http://www.parisc-linux.org/index.html
• https://www.debian.org/ports/hppa/

See also rizinorg/rizin#1927