Design

Note: Information on this page is no longer accurate.

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Organisation

General structure

1. Preprocess: process command-line arguments, read input file into Line and check the existing output cubin.
2. Process: calls the default Master Parser to process the lines.
3. Postprocess: write assembled opcode into cubin

Master Parser

The master parser calls the line parser once for each line.

Master parsers are active parsers, which are given a starting line number and are then free to jump between lines and do the necessary processing.

Line Parser

Note: Currently the default Line Parser is implemented inside the default Master Parser itself. This may change in the future.

    if(line is directive)
        directive_parser(line);
    else
    {
        break the line into multiple instructions separated by ';'
        instruction_parser(each instruction);
    }

The Line parser receives a line, makes a judgement about whether this line is a directive or an instruction, and then

• Asks the directive parser to parse the line, if the line is a directive, or
• Asks the instruction parser to parse the processed parts of the line, if the line is an instruction.

Line parsers are passive parsers, which parse only one line that is given by the caller.

Instruction Parser

An instruction parser is a passive parser. It receives a single instruction from the caller (line parser), and then analyses the instruction to produce the correct opcode. It then appends the opcode to a list and increase an offset count by the byte length of the opcode.

The default instruction parser, upon receiving the instruction line, would check against a list of known instruction rules and treat the instruction operands in accordance with the rules specified under the corresponding instruction name.

For more details of the instructions, see SourceFormat

Directive Parser

A directive parser is a passive parser. It receives a single command (a single line) from the caller (line parser), and does the corresponding changes to the assembler's states.

It is also in charge of registering the labels found into a list along with its current instruction offset.

The default directive parser, upon receiving the directive line, would check against a list of known directive rules and treat the arguments of the directive in accordance with the rules specified under the corresponding directive name.

For more details of the directives, see SourceFormat

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Extensibility

Default master, line and instruction parsers can be replaced by custom parsers under the request of specific directives. See Directives#Set_current_parsers

With this feature, asfermi could process non-standard lines of code. This feature could be used to support some high-level style coding.