===========
AsmGen
===========



Abstract
========

AsmGen - code generator for sprites, fonts, and images for Apple ][ hi-res and
Atari 8-bit computers

This program creates 6502 (or 65c02) code for several tasks, including a sprite
complier (based on `HiSprite <https://github.com/blondie7575/HiSprite>`_) that
hardcodes sprite data in unrolled loops for each shifted shape. By removing
image lookups and loops, sprites can be drawn much faster than otherwise
possible.

Other utilities include generating code for reporting screen damage, a fast
bitmap font renderer, and generation for all the row/column lookup tables for
each supported bitmap mode.


Installation
============

The autogenerator code is written in Python and should run on any platform
that can use python. It requires:

* python 3.6 (and above)
* numpy
* pypng

Install using the Python package manager::

    pip install asmgen

Starting with version 2.0, python 2 support has been dropped.


Installing From Source
======================

To contribute bug fixes or enhancements, it would be useful to get an account
on github and clone the source to your own account. You can then send me pull
requests for any modifications you would like to see included.

If you just want to clone my source to look at it, use::

    git clone https://github.com/robmcmullen/asmgen.git


Assembler Support
=================

* cc65 (the default)
* MAC/65

Contributors welcome for other assemblers, like Merlin, MADS, dasm, xasm, etc.


Code Generation Capabilities
============================

* Transposed font code generator
* Sprite compiler
* Screen clearing
* Screen vertical scrolling
* Hi-res row lookup table generation

Experimental (and unsupported)
------------------------------

* Font compiler (slower than the transposed font code)
* Run-length encoding of images
* Merge two hi-res images, switching images at specified scan line


Running the Code Generator
==========================

You will use


Transposed Font
===============

To generate source code for a fast font renderer, you will need a binary font
file that is required in order to transpose the font characters and embed them
in the source code. Then::

    asmgen.py -f FONTFILENAME -o OUTPUTFILEROOT

It will create two source files, the main one of interest is called
OUTPUTFILEROOT-fastfont.s which contains the generated code and data for use of
the transposed font. All you need is to include this file in your source and
it's ready to go. No need to include a binary of the font file, as it's already
included in byte data.

The otherother will be a parent file that contains ``include`` statement for all the generated files from this run of ``asmgen.py``. In this case it only has one include, but if you also generate a clear screen routine and some sprite compiling, it will contain all those

called OUTPUFILEROOT-driver.s that will include all the other generated files, and the specific font file source



Fork me!
========

The source is free and open, and lives on `github
<https://github.com/robmcmullen/asmgen>`_, so clone and enhance at will!


History
=======

This program started life as a friendly fork of Quinn Dunki's `HiSprite
<https://github.com/blondie7575/HiSprite>`_ that she presented at KansasFest
2017.

Her conclusion was that it was not that practical for the Apple II because of
the limited memory and the number of sprite shifts needed. I wanted to port
this to the Atari because it would require fewer shifted shapes in most of the
graphics modes (e.g. only 4 shifted shapes for the commonly used ANTIC modes 13
and 14) She told me that she was unlikely to continue work on sprite compiling
but encouraged me to continue development.


Additional Credits
==================

The sample font is modified from Michael Pohoreski's `excellent tutorial on
Apple II fonts <https://github.com/Michaelangel007/apple2_hgr_font_tutorial>`_.


Disclaimer
==========

AsmGen, the 6502 code generator sponsored by the Player/Missile Podcast
Copyright (c) 2017-2018 Rob McMullen

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.


Generated Code License
----------------------

While the code for AsmGen itself is licensed under the GPLv3, the code it
produces is licensed under the the Creative Commons Attribution 4.0
International (CC BY 4.0), so you are free to use the generated code for
commercial or non-commercial purposes.