hexdraw

#!/usr/libexec/flua

-- Copyright (c) 2013-2014 The FreeBSD Foundation
-- All rights reserved.
--
-- This software was developed by Ed Maste under sponsorship from
-- The FreeBSD Foundation.
--
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions
-- are met:
--
-- 1. Redistributions of source code must retain the above copyright
--    notice, this list of conditions and the following disclaimer.
-- 2. Redistributions in binary form must reproduce the above copyright
--    notice, this list of conditions and the following disclaimer in the
--    documentation and/or other materials provided with the distribution.
--
-- THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
-- ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
-- IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
-- ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
-- FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
-- DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
-- OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
-- HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
-- LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
-- OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
-- SUCH DAMAGE.

-- Convert a hex format font to / from an ASCII-art representation in the same
-- style as hexdraw from GNU unifont.

char_width = 8
char_height = 16

function calculate_char_vals()
    char_width_bytes = math.ceil(char_width / 8)
    char_width_bits = char_width_bytes * 8
    char_bytes = char_width_bytes * char_height
end

function set_width(line, match)
    print (line)
    char_width = match[1]
    calculate_char_vals()
    return true
end

function set_height(line, match)
    print (line)
    char_height = match[1]
    calculate_char_vals()
    return true
end

function hex_to_ascii_art(line, match)
    addr = match[1]
    bytes = match[2]
    if not addr or not bytes then
        print(match)
        return false
    end
    if bytes:len() ~= char_bytes and bytes:len() ~= char_bytes * 2 then
        return false
    end
    addr = tonumber(addr, 16)
    if addr < 0 or addr > 65535 then
        return false
    end

    prefix = string.format("%04X:\t", addr)

    bytes_per_row = bytes:len() / char_height

    repeat
        row = bytes:sub(1, bytes_per_row)
        row = tonumber(row, 16)
        bytes = bytes:sub(bytes_per_row + 1)
        art = ""
        for i = 1, char_width, 1 do
            if row >= 2 ^ (char_width_bits - 1) then
                art = art .. '#'
                row = row - 2 ^ (char_width_bits - 1)
            else
                art = art .. '-'
            end
            row = row * 2
        end
        print(prefix .. art)
        prefix = "\t"
    until bytes:len() == 0
    print()
    return true
end

function ascii_art_line(line, match)
    hexstr = match[1]
    nbits = math.ceil(hexstr:len() / 8) * 8
    hexstr = hexstr .. "        "
    val = 0
    bval = 128
    for i = 1, nbits do
        if hexstr:sub(1, 1) == "#" then
            val = val + bval
        end
        hexstr = hexstr:sub(2)
        bval = bval / 2
        if bval < 1 then
            io.write(string.format("%02X", val))
            val = 0
            bval = 128
        end
    end
    return true
end

function ascii_art_start(line, match)
    io.write(match[1] .. ":")
    return ascii_art_line(line, {match[2]})
end

expressions = {
    ["# Width: (%d+)"] = set_width,
    ["# Height: (%d+)"] = set_height,
    ["(%x+):(%x+)"] = hex_to_ascii_art,
    ["^(%x+):%s*([-#]+)"] = ascii_art_start,
    ["^%s*([-#]+)"] = ascii_art_line
}

calculate_char_vals()

for line in io.lines(arg[1]) do
    found = false
    for exp,fn in pairs(expressions) do
        match = {line:match(exp)}
        if next(match) ~= nil and fn(line, match) then
            found = true
            break
        end
    end
    if not found then
        print (line)
    end
end