h2md

#!/bin/bash
shopt -s extglob
# Convert a header file into a markdown file.
# Pass the header file to convert as first argument.
# Markdown text sent to standard output.
typeset -i comment=0
typeset -i endcomment=0
typeset -i newpar=0
typeset -i verbatim=0
preline=
while IFS= read -r newline ; do  # Read standard input stream
  preline="$preline${newline%"\\"}"  # Aggregate lines ending with \
  if [[ "$newline" == *"\\" ]] ; then
    continue
  else
    line="$preline"
    preline=
  fi
  if (( comment )) && [[ "$line" == *([[:blank:]]) ]] ; then   # An empty line starts a new paragraph.
    echo
    newpar=1
    verbatim=0
  fi
  if (( comment )) && (( newpar )) && [[ "$line" == +([[:blank:]])!([[:blank:]])* ]] ; then  # A new paragraph starting with spaces is treated as verbatim (snippets of code inside comments).
    newpar=0
    verbatim=1
  fi
  while ! [[ "$line" == *([[:blank:]]) ]] ; do  # Not a blank line
          if ! (( comment )) && [[ "$line" == *"/*"*"*/"* ]] ; then
            a="${line#*"/*"}"                              # what is after /*
            a="${a%%"*/"*}"                                # what if before */
            a="${a##+("*")*([[:blank:]])}"                 # what if after ****
            a="${a%%*([[:blank:]])+("*")}"                 # what if before ****
            a="${a/%"."*([[:blank:]])/".\n\n"}"            # add a \n after . followed by spaces
            echo -e "${a#+([[:blank:]])}"
            code="$code ${line%%"/*"*}"                    # what is before /* is code, a space replaces the comment in the code
            line="${line#*"*/"}"                           # what is after */ is code or comments
          elif ! (( comment )) && [[ "$line" == *"/*"* ]] ; then
            comment=1
            a="${line#*"/*"}"                              # what is after /*
            a="${a##+("*")*([[:blank:]])}"                 # what if after ****
            a="${a%%*([[:blank:]])+("*")}"                 # what if before ****
            a="${a/%"."*([[:blank:]])/".\n\n"}"            # add a \n after . followed by spaces
            echo -e "${a#+([[:blank:]])}"
            code="$code${line%%"/*"*}"                     # what is before /* is code
            line=""
          elif (( comment )) && [[ "$line" == *"*/"* ]] ; then
            comment=0
            a="${line%%"*/"*}"                             # what if before */
            a="${a%%*([[:blank:]])+("*")}"                 # what if before ****
            if ! (( verbatim )) ; then
                    a="${a/%"."*([[:blank:]])/".\n\n"}"    # add a \n after . followed by spaces
                    echo -e "${a#+([[:blank:]])}"
            else                                           # verbatim
                    echo -n -e "\t" ; echo -E "${a%%+([[:blank:]])}"
            fi
            line="${line#*"*/"}"                           # what is after */ is code or comments
            code="$code "                                  # a space replaces the comment in the code
          elif (( comment )) ; then
            a="$line"
            if ! (( verbatim )) ; then
                    a="${a##*([[:blank:]])+("*")*([[:blank:]])}"         # what if after ****
                    a="${a%%*([[:blank:]])+("*")}"         # what if before ****
                    a="${a/%"."*([[:blank:]])/".\n\n"}"    # add a \n after . followed by spaces
                    echo -e "${a#+([[:blank:]])}"
            else                                           # verbatim
                    echo -n -e "\t" ; echo -E "${a%%+([[:blank:]])}"
            fi
            line=""
          elif ! (( comment )) && [[ "$line" == *"//"* ]] ; then
            a="${line#*"//"}"                              # what is after //
            a="${a/%"."*([[:blank:]])/".\n\n"}"            # add a \n after . followed by spaces
            echo -e "${a#+([[:blank:]])}"
            code="$code${line%%"//"*}"
            line=""
          else
            code="$code$line"
            line=""
          fi
  done
  ## Code between comments
  if (( comment )) ; then continue ; fi
  if [[ "$code" == "#"*([[:blank:]])"include"+([[:blank:]])* ]] ; then  # '#include'
    code="${code//"\\"/"\\\\"}"
    code="${code//"*"/"\\*"}"
    code="${code//"_"/"\\_"}"
    echo -n -e "\n| Include |\n| - |\n| "
    echo -n -E "${code#"#"*([[:blank:]])"include"+([[:blank:]])}"
    echo -e " |\n"
  elif [[ "$code" == "#"*([[:blank:]])"define"+([[:blank:]])* ]] ; then  # '#define'
    code="${code//"\\"/"\\\\"}"
    code="${code//"*"/"\\*"}"
    code="${code//"_"/"\\_"}"
    code="${code#"#"*([[:blank:]])"define"+([[:blank:]])}"
    echo -n -e "\n| Define | Value |\n| - | - |\n| "
    echo -n -E "${code/+([[:blank:]])/" | "}"
    echo -e " |\n"
  elif [[ "$code" == "#"* ]] ; then
    :
  elif [[ "$code" == *([[:blank:]])"typedef"+([[:blank:]])* ]] ; then  # 'typedef'
    code="${code//"\\"/"\\\\"}"
    code="${code//"*"/"\\*"}"
    code="${code//"_"/"\\_"}"
    code="${code#*([[:blank:]])"typedef"+([[:blank:]])}"
    code="${code%";"*([[:blank:]])}"
    echo -n -e "\n| Type definition |\n| - |\n| "
    echo -n -E "$code"
    echo -e " |\n"
  elif [[ "$code" != *([[:blank:]]) ]] ; then              # code
    echo -e '```c'
    echo -E "$code"
    echo -e '```'
  fi
  code=""
done < "$1"
echo
echo -----
echo -e "*This page was generated automatically from \`${1##*/}\` by \`${0##*/}\`.*"