#!/bin/sh
# genfont - generate font converted to code from pure font data
# author Neil Franklin, last modification 2008.10.12


### ------ configuration for this site

# first CONF_*  various site or user dependant user config variables
# then  DEBUG_* various debugging settings
# last  SYS_*   various system internal values

# input file, ASCII drawings of characters pixel maps
CONF_INFILE=vga_text_font.fon

# output file, AVR code for including
CONF_OUTFILE=vga_text_font.inc


### ------ actual implementation from here on
# no user settings any more below this point

set -e


# --- get ready to work
# sanitise this place, else some commands may fail
PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin
export PATH


# stuff that goes wrong, not expected by user, not in data output, use >&2
#   so also with $0 in case this script was called by an other script
# something within the system that user does not expect, give up
CMD_FATAL="echo $0: FATAL:"
# something from users input, user will correct this and continue
CMD_ERROR="echo $0: ERROR:"
# something we can continue with, but may be wrong, and user may not suspect it
CMD_WARNING="echo $0: WARNING:"
# something most likely not wrong, but tell user for the odd case it is wrong
CMD_NOTE="echo $0: NOTE:"

# normal stuff users expect, so to stdout as normal output, no $0, no marking
CMD_INFO="echo"
# stuff users asked for, so add to stdout as normal output, no $0, but mark it
CMD_DEBUG="echo DEBUG:"


# --- check input
if [ ! -f "${CONF_INFILE}" ] ; then
  # input file nonexistant, so we can not work on it
  ${CMD_ERROR} "no input file ${CONF_INFILE} to process" >&2
fi
${CMD_INFO} "generating include ${CONF_OUTFILE} from font ${CONF_INFILE}" >&2


# --- remove existing output file, as later all is >> additions

rm -f "${CONF_OUTFILE}"


# --- make output file header

echo "; ${CONF_OUTFILE} - font for generating VGA text - converted to code" \
  >> "${CONF_OUTFILE}"
echo "; generated from ${CONF_INFILE}, last generation `date "+%Y.%m.%d"`" \
  >> "${CONF_OUTFILE}"


# --- process font
cat "${CONF_INFILE}" | while read LINE ; do

  if [ "${LINE}" = "" ] ; then
    # blank line: pass trough into font
    echo "${LINE}" >> "${CONF_OUTFILE}"

  elif [ "`echo "${LINE}" | cut -c 1`" = "#" ] ; then
    # comment: drop it, not in font, do nothing
    true

  elif [ "`echo "${LINE}" | cut -c 1-5`" = "CHAR " ] ; then
    # character definition: process that character into font
    #   output progress info, one dot per character processed
    echo -n "." >&2
    #   first also output its intro line as comment
    echo "  ; ${LINE}" >> "${CONF_OUTFILE}"
    #   then separator line
    echo >> "${CONF_OUTFILE}"
    #   then process the 8 lines of pixel data to segments
    for SEGMENT in 0x00 0x10 0x20 0x30 0x40 0x50 0x60 0x70 ; do

      read PIXELS

      # first pixel with pattern behind it as comment, rest without
      if [ "`echo "${PIXELS}" | cut -c 1-2`" = "()" ] ; then
        echo "  out VGADPORT,FORE ; ${PIXELS}" >> "${CONF_OUTFILE}"
      else
        echo  "  out VGADPORT,BACK ; ${PIXELS}" >> "${CONF_OUTFILE}"
      fi

      echo "  ld ZL,X+" >> "${CONF_OUTFILE}"

      if [ "`echo "${PIXELS}" | cut -c 3-4`" = "()" ] ; then
        echo "  out VGADPORT,FORE" >> "${CONF_OUTFILE}"
      else
        echo  "  out VGADPORT,BACK" >> "${CONF_OUTFILE}"
      fi

      echo "  mov ZH,ZL" >> "${CONF_OUTFILE}"
      echo "  andi ZH,0x3F" >> "${CONF_OUTFILE}"

      if [ "`echo "${PIXELS}" | cut -c 5-6`" = "()" ] ; then
        echo "  out VGADPORT,FORE" >> "${CONF_OUTFILE}"
      else
        echo  "  out VGADPORT,BACK" >> "${CONF_OUTFILE}"
      fi

      echo "  andi ZL,0x80" >> "${CONF_OUTFILE}"
      echo "  ori ZL,${SEGMENT}" >> "${CONF_OUTFILE}"

      if [ "`echo "${PIXELS}" | cut -c 7-8`" = "()" ] ; then
        echo "  out VGADPORT,FORE" >> "${CONF_OUTFILE}"
      else
        echo  "  out VGADPORT,BACK" >> "${CONF_OUTFILE}"
      fi

      echo "  ijmp" >> "${CONF_OUTFILE}"

      # fill up 16 instructions with nop
      for NOP in 0 1 2 3 4 5 ; do
        echo "  nop" >> "${CONF_OUTFILE}"
      done

      # separator from segment of next line of pixel data
      echo >> "${CONF_OUTFILE}"

    done

  else
    # random text: convert to comment lines in font
    echo "  ; ${LINE}" >> "${CONF_OUTFILE}"

  fi

done

# finish off progress info output dots with newline
echo >&2