preprocess.py

from . import nocomment
from .util import split_tokens


class RTC_Macros:
    @staticmethod
    def READ_RTC_REG(rtc_reg, low_bit, bit_width):
        return '\treg_rd ' + ', '.join((
            rtc_reg,
            '%s + %s - 1' % (low_bit, bit_width),
            low_bit
        ))

    @staticmethod
    def WRITE_RTC_REG(rtc_reg, low_bit, bit_width, value):
        args = (
            rtc_reg,
            '%s + %s - 1' % (low_bit, bit_width),
            low_bit,
            value
        )
        return '\treg_wr ' + ', '.join(args)

    @staticmethod
    def READ_RTC_FIELD(rtc_reg, low_bit):
        return RTC_Macros.READ_RTC_REG(rtc_reg, low_bit, 1)

    @staticmethod
    def WRITE_RTC_FIELD(rtc_reg, low_bit, value):
        return RTC_Macros.WRITE_RTC_REG(rtc_reg, low_bit, 1, value + ' & 1')


class Preprocessor:
    def __init__(self):
        self._defines = {}

    def parse_defines(self, content):
        result = {}
        for line in content.splitlines():
            line = line.strip()
            if not line.startswith("#define"):
                # skip lines not containing #define
                continue
            line = line[8:].strip()  # remove #define
            parts = line.split(None, 1)
            if len(parts) != 2:
                # skip defines without value
                continue
            identifier, value = parts
            tmp = identifier.split('(', 1)
            if len(tmp) == 2:
                # skip parameterised defines (macros)
                continue
            value = "".join(nocomment.remove_comments(value)).strip()
            result[identifier] = value
        self._defines = result
        return result

    def expand_defines(self, line):
        found = True
        while found:  # do as many passed as needed, until nothing was replaced anymore
            found = False
            tokens = split_tokens(line)
            line = ""
            for t in tokens:
                lu = self._defines.get(t, t)
                if lu != t:
                    found = True
                line += lu

        return line

    def expand_rtc_macros(self, line):
        clean_line = line.strip()
        if not clean_line:
            return line

        macro = clean_line.split('(', 1)
        if len(macro) != 2:
            return line

        macro_name, macro_args = macro

        macro_fn = getattr(RTC_Macros, macro_name, None)
        if macro_fn is None:
            return line

        macro_args, _ = macro_args.rsplit(')', 1)  # trim away right bracket. safe as comments already stripped
        macro_args = macro_args.split(',')  # not safe when args contain ',' but we should not have those
        macro_args = [x.strip() for x in macro_args]

        return macro_fn(*macro_args)

    def preprocess(self, content):
        self.parse_defines(content)
        lines = nocomment.remove_comments(content)
        result = []
        for line in lines:
            line = self.expand_defines(line)
            line = self.expand_rtc_macros(line)
            result.append(line)
        result = "\n".join(result)
        return result


def preprocess(content):
    return Preprocessor().preprocess(content)