API Documentation

This section is about the internals of the msp430.asm module. It may be interesting for developers that work on this module or who are interested in using the functions the module provides in their own code.

Object file format

The file format of .o4 files is a bit unusual. It actually contains something that could be labeled as (specialized) Forth code. So the linker is some sort of Forth interpreter. This has the advantage that the object files can be debugged without any special tools, just a text editor. It also makes the format quite universal; it could produce binaries for all sorts of CPUs (single special case: the directive JMP is MSP430 specific).

A list of supported words can be found in the following document:

linker_words

For more details also take a look at the sources of ld.py.

MCU Definition file format

MCU memory definitions can be provided in a file with Forth like syntax.

A list of supported words can be found in the following document:

mcdudef_words

For more details also take a look at the sources of mcu_definition_parser.py.

Modules

msp430.asm

`msp430.asm.as`

msp430.asm.as

This module implements the MSP430(X) assembler. When the module is executed (e.g. using python -m msp430.asm.as), it acts as a command line tool.

__init__(msp430x=False, debug=False)

param msp430x: Set to true to enable MSP430X instruction set.
param debug: When set to true dump some internal data so sys.stderr while compiling.

Create an instance of the assembler.

assemble(f, filename=None, output=sys.stdout)

param f: A file like object that supports iterating over lines.
param filename: An optional string that is used in error messages.
param output: File like object used to write the object code to.

This method takes assembler source and transforms it to object code that can be forwarded to the linker.

AssemblerError

This instances of this class are raised by the MSP430Assembler in case of errors in the source. It may be annotated with the source filename and line number where the error occurred.

filename

line

`msp430.asm.ld`

msp430.asm.ld

This module implements the linker. When the module is executed (e.g. using python -m msp430.asm.ld), it acts as a command line tool.

__init__(name, start_address=None, end_address=None, align=True, programmable=False, little_endian=True, parent=None, mirror_of=None)

__getitem__(segment_name)

param segment_name: name of an sub segment.
raises KeyError: when no segment with given name is found

Easy access to subsegment by name.

sort_subsegments(by_address=False)

param by_address: Sort by address if true, otherwise sort by name.

Sort list of subsegments either by order of definition or by order of start address.

clear()

Clear data. Recursively with all subsegments. Segments are not removed, just their data.

__len__()

Get the number of data bytes contained in the segment.

__cmp__(other)

Compare function that allows to sort segments by their start_address.

__lt__(other)

Compare function that allows to sort segments by their start_address.

print_tree(output, indent='', hide_empty=False)

param output: a file like object (supporting write)
param indent: a prefix put before each line.
param hide_empty: when set to true omit empty segments (no data) in output.

Output segment and subsegments.

shrink_to_fit(address=None)

Modify start- and end_address of segment to fit the data that it contains. Recursively applied to the tree of segments. Typically called with address=None.

write_8bit(value)

param value: an integer (8 significant bits)

Write one byte.

write_16bit(value)

param value: an integer (16 significant bits)

Write two bytes. Order in memory depends on endianness of segment.

write_32bit(value)

param value: an integer (32 significant bits)

Write four bytes. Order in memory depends on endianness of segment.

__init__(instructions)

param instructions: list of directives for the linker

Initialize a linker instance. The given instructions are essentially what is read from a .o4 file as sequence of words.

segments_from_definition(segment_definitions)

param segment_definitions: dictionary describing the memory map

This sets the memory map used for linking. See mcu_definition_parser for a way to load this description.

update_mirrored_segments()

Called before writing the final output. In case the memory map contains segments that mirror the contents of other segments, they are updated. This is typically used for .data_init which contains the initial values that are copied by startup code to the .data segment in RAM.

pass_one()

Run the linkers 1st pass. It iterates through the instructions and places the data into segments.

pass_two()

Run the linkers 2nd pass. It iterates through the instructions and finds all the labels and saves their position.

pass_three()

Run the linkers 3rd pass. It iterates through the instructions and creates the final binary with all known labels set to their target address.

LinkError

Exception object raised when errors during linking occur. May be annotated with the location of the line within the original source file causing the error.

filename

lineno

column

`msp430.asm.cpp`

msp430.asm.cpp

This module implements the preprocessor. When the module is executed (e.g. using python -m msp430.asm.cpp), it acts as a command line tool.

line_joiner(next_line)

Given an iterator for lines, yield lines. It joins consecutive lines with the continuation marker (\\) to a single line.

This object is used by the preprocessor to write out the preprocessed text. It adds notes in the form #line <line> "<filename>". These notes are used by the assembler to know where a source line originally came from (as preprocessed text may contain additional lines etc.)

__init__(output, filename)

param output: file like object to write to
param filename: the filename used in the notes

write(lineno, text)

param linno: line number being written
param text: the actual contents of the line

preprocess(infile, outfile, filename)

param infile: file like object to read from
param outfile: file like object to write to
param filename: original file name of the input (infile)

This runs the preprocessor over the given input.

PreprocessorError

Exception object raised when errors during preprocessing occur.

`msp430.asm.disassemble`

msp430.asm.disassemble

This module implements the disassembler. When the module is executed (e.g. using python -m msp430.asm.disassemble), it acts as a command line tool.

__init__(memory, msp430x=False, named_symbols=None)

param memory: A msp43.memory.Memory instance containing the binary.
param msp430x: Set to true to enable MSP430X instruction set.
param named_symbols: An (optional) instance of NamedSymbols which is used to label peripherals and bits.

Initialize the disassembler with data.

disassemble(output, source_only=False)

param output: A file like object used for the resulting text.
param source_only: When set to true, the address and data columns are omitted from the output.

Run the disassembler, result is written to output.

`msp430.asm.rpn`

msp430.asm.rpn

This module implements the an RPN calculator. The calculator can be tested by executing the module (e.g. using python -m msp430.asm.rpn).

This class is used to wrap words so that their source location can be tracked. This is useful for error messages.

__new__(cls, word, filename, lineno, text)

param cls: Class for __new__
param word: The word (unicode)
param filename: Filename where the word was read from.
param lineno: Line number within the file.
param text: The complete line (or context).
type filename: unicode or None
type lineno: int or None
type text: unicode or None

Create new instance with a word that was read from given location.

An RPN calculator. It provides a data stack and implements a number of basic operations (arithmetical and stack)

interpret(next_word)

param next_word: A function return the next word from input when called.

Interpret a sequence of words given by the iterator next_word.

annotated_words(sequence, filename=None, lineno=None, offset=None, text=None)

Create an generator for Word, all annotated with the given information.

words_in_string(data, name='<string>')

param data: String with (lines) of text.
param name: Optional name, used in error messages.

Create a generator for annotated Word in string (splitlines() is used).

words_in_file(filename)

param filename: Name of a file to read from.

Create a generator for annotated Word read from file given by name.

rpn_function(code)

param code: A string in RPN notation
return: A Python function.

Return a wrapper - a function that evaluates the given RPN code when called. This can be used to insert functions implemented as RPN into the name space.

word(name)

Function decorator used to tag methods that will be visible in the RPN built-in name space.

val(words, stack=[], namespace={})

param words: Sequence of words.
param stack: Optional initial stack.
param namespace: Optional namespace.
return: The top element from the stack

Evaluate sequence of words.

python_function(code, namespace={})

param code: RPN code to execute.
param namespace: Optional namespace.
return: A python function that executes code when called.

Create a Python function that will execute given code when called. All parameters given to the Python function will be placed on the stack and the top of stack will be returned.

interpreter_loop(namespace={}, debug=False)

Run an interactive loop. Can be used as calculator.

RPNError

Exception type used for errors when parsing or executing RPN code. It may be annotated with the source position where the word causing the error came from.

filename

lineno

offset

text

`msp430.asm.peripherals`

msp430.asm.peripherals

This module implements a parser for a file format describing the peripherals and their bits of a MCU. The module can be executed (e.g. using python -m msp430.asm.peripherals) to test definition files.

This class implements the parser and keeps the result. It inherits from RPN.

load_symbols(filename)

param filename: Load symbols from a file named like this.
return: instance of SymbolDefinitions

Load definitions from a file of given name.

load_internal(name)

param name: Name of an internal file.
return: instance of SymbolDefinitions

This tries to load internal data (using pkgutil).

SymbolError

Exception object used for errors in the definition file.

`msp430.asm.mcu_definition_parser`

msp430.asm.mcu_definition_parser

This module implements the a parser for files describing the memory map of a CPU. The module can be executed (e.g. using python -m msp430.asm.mcu_definition_parser) to test definition files.

This class implements the parser and keeps the result. It inherits from msp430.asm.rpn.RPN. Loaded definitions may contain the memory maps of many MCUs and also partial maps (that may depend on each other).

load_from_file(filename)

param filename: Load definitions from file of given name.
return: instance of MCUDefintitions

load_internal()

return: instance of MCUDefintitions

Load internal list. The default list is included in msp430/asm/definitions/msp430-mcu-list.txt

expand_definition(memory_maps, name)

param memory_maps: Memory map descriptions.
param name: Name of an MCU that should be extracted
type memory_maps: MCUDefintitions
return: Dictionary with recursively expanded memory map.

Return the memory map of a specific MCU. If the definition depends on others, it is expanded so that a single, complete description is returned.

`msp430.asm.infix2postfix`

msp430.asm.infix2postfix

This module implements a converter that can translate infix (arithmetical) notation to postfix notation (RPN). It is used by the preprocessor and assembler when evaluating expressions.

infix2postfix(expression, variable_prefix='', scanner=Scanner, precedence=default_precedence)

param expression: Input string in infix notation.
param variable_prefix: A string that is prepended to symbols found in the expression.
param scanner: The class that is used to parse the expression.
param precedence: A dictionary returning the priority given an operator as key.
return: A string with the expression in postfix notation.

convert_precedence_list(precedence_list)

param precedence_list: A list of lists that defines operator priorities.
return: A dictionary mapping operators to priorities.

Input will look like this:

default_precedence_list = [
        # lowest precedence
        ['or'],
        ['and'],
        ['not'],
        ['<', '<=', '>', '>=', '==', '!='],
        ['|', '^', '&'],
        ['<<', '>>'],
        ['+', '-'],
        ['*', '/', '%'],
        ['~', 'neg', '0 +'],
        ['(', ')'],
        # highest precedence
    ]

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api.rst

api.rst

API Documentation

Object file format

MCU Definition file format

Modules

`msp430.asm.as`

`msp430.asm.ld`

`msp430.asm.cpp`

`msp430.asm.disassemble`

`msp430.asm.rpn`

`msp430.asm.peripherals`

`msp430.asm.mcu_definition_parser`

`msp430.asm.infix2postfix`

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api.rst

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API Documentation

Object file format

MCU Definition file format

Modules

msp430.asm.as

msp430.asm.ld

msp430.asm.cpp

msp430.asm.disassemble

msp430.asm.rpn

msp430.asm.peripherals

msp430.asm.mcu_definition_parser

msp430.asm.infix2postfix

`msp430.asm.as`

`msp430.asm.ld`

`msp430.asm.cpp`

`msp430.asm.disassemble`

`msp430.asm.rpn`

`msp430.asm.peripherals`

`msp430.asm.mcu_definition_parser`

`msp430.asm.infix2postfix`