objasm2gas

Migrate legacy ObjASM syntax assembly (as used on RISC OS) to GNU syntax (GAS).

Usage

objasm2gas.pl [<options>] <file1> [<file2>...]

Options

Switch	Descriptions
--compatible	Keeps compatibility with armclang assembler
-h, --help	Show this help text
-v, --verbose	Show a message on every non-trivial conversion
-n, --no-comment	Discard all the comments in output
-o, --output=<file>	Specify the output filename
-r, --return-code	Print return code definitions
-s, --strict	Error on directives that have no equivalent counterparts
-V, --version	Show version info
-w, --no-warning	Suppress all warning messages
-x, --suffix=<string>	Suffix of the output filename [default: '.out']
--inline	Process the GET and INCLUDE inline as objasm, rather than generating a GNU as include
--simple-conditions	Leave conditions in GNU as form (default is to interpret objasm conditionals
--test-expr=<expr>	Diagnostics for exercising the expression parser
--gas=<gas-binary>	GNU as to invoke to create ELF file, after conversion; output file will be the output from GNU as
--bin	When used with --gas, create a binary file (default is to produce an ELF file)
--predefine=<asm>	Pre-execute a SETA, SETL or SETS directive.
-i <paths>	Comma separated list of paths to search for inclues
--32	Select 32 bit mode
--64	Select 64 bit mode
--util	Create a Utility file, using 'riscos64-link'
--aif	Create a AIF Absolute file, using 'riscos64-link'
--rmf	Create a Relocatable Module file, using 'riscos64-link'

Supported conversions

• Comments

• Labels

• Numeric local labels

• Functions

• Sections

• Symbols with special characters

• Numeric literals

• Operators

• Aligment

• PC-relative addressing

• Directives: Conditional

• Directives: Data definition

• Directives: Instruction set

• Directives: Symbol definition

• Directives: Miscellaneous

• GET and INCLUDE inline

• RISC OS format filename handling

• Macro expansion

• Local variables within macros

• Conditionals with expressions

• WHILE loops

Extensions

In addition to the standard operations, the conversion includes a few extensions to make using ObjAsm syntax a little easier.

Expression parsing:

• $regs :REGLISTLEFT: $num - a binary operator which returns the left most $num registers from the supplied register list.
• $regs :REGLISTRIGHT: $num - a binary operator which returns the right most $num registers from the supplied register list.
• $regs :REGLISTSKIP: $num - a binary operator which returns the supplied register list without the first $num registers.
• $regs :REGLISTTRIM: $num - a binary operator which returns the supplied register list without the last $num registers.

Demo

Conversion result of demo.s:

Command-line output:

$ /objasm2gas.pl -v demo/demo.s
INFO: demo/demo.s:33 -> demo/demo.s.out:37: Converting '2_11001010' to hexadecimal literal '0xCA'

Cautions

By default (without --strict), for those directives that have no equivalent GNU format, objasm2gas will try best to convert and generate warning information on the specific line. Therefore, a 'warning' does NOT necessarily mean no issue, please check the conversion result to ensure it works as expected.

Note that objasm2gas assumes that the input file is in the correct syntax, otherwise, the conversion result is UNEXPECTED

TODO

• Loops