Tonic
An Elixir DSL for conveniently loading binary data/files.
The DSL is designed to closely represent the structure of the actual binary data layout. So it aims to be easy to read, and easy to change.
The DSL defines functionality to represent types, endianness, groups, chunks, repeated data, branches, optional segments. Where the majority of these functions can be further extended to customize the behaviour and result.
The default behaviour of these operations is to remove the data that was read from the
current binary data, and append the value to the current block. Values by default are
in the form of a tagged value if a name is supplied { :name, value }, otherwise are
simply value if no name is supplied. The default return value behaviour can be
overridden by passing in a function.
The most common types are defined in Tonic.Types for convenience. These are
common integer and floating point types, and strings. The behaviour of types can
further be customized when used otherwise new types can be defined using the type/2
function.
To use the DSL, call use Tonic in your module and include any additional type modules
you may require. Then you are free to write the DSL directly inside the module. Certain
options may be passed to the library on use, to indicate additional behaviours. The
currently supported options are:
optimize: which can be passed true to enable all optimizations, or a keyword list
enabling the specific optimizations. Enabling optimizations may make debugging issues
trickier, so best practice is to enable after it's been tested. Current specific
optimizations include:
:reduce #Enables the code reduction optimization, so the generated code is reduced as much as possible.
Example
defmodule PNG do
use Tonic, optimize: true
endian :big
repeat :magic, 8, :uint8
repeat :chunks do
uint32 :length
string :type, length: 4
chunk get(:length) do
on get(:type) do
"IHDR" ->
uint32 :width
uint32 :height
uint8 :bit_depth
uint8 :colour_type
uint8 :compression_type
uint8 :filter_method
uint8 :interlace_method
"gAMA" ->
uint32 :gamma, fn { name, value } -> { name, value / 100000 } end
"cHRM" ->
group :white_point do
uint32 :x, fn { name, value } -> { name, value / 100000 } end
uint32 :y, fn { name, value } -> { name, value / 100000 } end
end
group :red do
uint32 :x, fn { name, value } -> { name, value / 100000 } end
uint32 :y, fn { name, value } -> { name, value / 100000 } end
end
group :green do
uint32 :x, fn { name, value } -> { name, value / 100000 } end
uint32 :y, fn { name, value } -> { name, value / 100000 } end
end
group :blue do
uint32 :x, fn { name, value } -> { name, value / 100000 } end
uint32 :y, fn { name, value } -> { name, value / 100000 } end
end
"iTXt" ->
string :keyword, ?\0
string :text
_ -> repeat :uint8
end
end
uint32 :crc
end
end
#Example load result:
#{{:magic, [137, 80, 78, 71, 13, 10, 26, 10]},
# {:chunks,
# [{{:length, 13}, {:type, "IHDR"}, {:width, 48}, {:height, 40},
# {:bit_depth, 8}, {:colour_type, 6}, {:compression_type, 0},
# {:filter_method, 0}, {:interlace_method, 0}, {:crc, 3095886193}},
# {{:length, 4}, {:type, "gAMA"}, {:gamma, 0.45455}, {:crc, 201089285}},
# {{:length, 32}, {:type, "cHRM"}, {:white_point, {:x, 0.3127}, {:y, 0.329}},
# {:red, {:x, 0.64}, {:y, 0.33}}, {:green, {:x, 0.3}, {:y, 0.6}},
# {:blue, {:x, 0.15}, {:y, 0.06}}, {:crc, 2629456188}},
# {{:length, 345}, {:type, "iTXt"}, {:keyword, "XML:com.adobe.xmp"},
# {:text,
# <<0, 0, 0, 0, 60, 120, 58, 120, 109, 112, 109, 101, 116, 97, 32, 120, 109, 108, 110, 115, 58, 120, 61, 34, 97, 100, 111, 98, 101, 58, 110, 115, 58, 109, 101, 116, 97, 47, 34, ...>>},
# {:crc, 1287792473}},
# {{:length, 1638}, {:type, "IDAT"},
# [88, 9, 237, 216, 73, 143, 85, 69, 24, 198, 241, 11, 125, 26, 68, 148, 25,
# 109, 4, 154, 102, 114, 192, 149, 70, 137, 137, 209, 152, 152, 24, 19, 190,
# 131, 75, 22, 234, 55, 224, 59, ...], {:crc, 2269121590}},
# {{:length, 0}, {:type, "IEND"}, [], {:crc, 2923585666}}]}}To-Do
- Automatically use loader on extension and magic number match
- Convenient types
- New function: Seek. Ability to seek certain points in the data
- Change repeat step callback to pass in current length
- Add a repeat/5 where you can pass in the option whether the list should be reversed or not
Installation
defp deps do
[{ :tonic, "~> 0.2.2" }]
end
