More README updates
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Rob McMullen
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README.rst
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README.rst
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@ -8,18 +8,20 @@ AsmGen
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Abstract
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========
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AsmGen - code generator for sprites, fonts, and images for Apple ][ hi-res and
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Atari 8-bit computers
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AsmGen - 6502 assembly code generator for sprites, fonts, and images for Apple
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][ hi-res and Atari 8-bit computers
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This program creates 6502 (or 65c02) code for several tasks, including a sprite
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complier (based on `HiSprite <https://github.com/blondie7575/HiSprite>`_) that
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hardcodes sprite data in unrolled loops for each shifted shape. By removing
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image lookups and loops, sprites can be drawn much faster than otherwise
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possible.
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This program creates 6502 (or 65c02) code for several tasks, including a high
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speed font rendering engine and a sprite compiler. The font rendered can plot
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font glyphs (or game tiles) much faster than normal tile drawing routines. The
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sprite complier (based on `HiSprite
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<https://github.com/blondie7575/HiSprite>`_) hardcodes sprite data in unrolled
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loops for each shifted shape. By removing image lookups and loops, sprites can
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be drawn much faster than otherwise possible.
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Other utilities include generating code for reporting screen damage, a fast
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bitmap font renderer, and generation for all the row/column lookup tables for
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each supported bitmap mode.
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Other utilities include generating code for reporting screen damage, screen
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clearing, screen scrolling, and generation for all the row/column lookup tables
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for each supported bitmap mode.
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Installation
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@ -32,7 +34,8 @@ that can use python. It requires:
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* numpy
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* pypng
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Install using the Python package manager::
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the latter two of which will be installed automatically when using the Python
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package manager::
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pip install asmgen
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@ -40,19 +43,35 @@ Starting with version 2.0, python 2 support has been dropped.
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Installing From Source
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======================
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----------------------
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To contribute bug fixes or enhancements, it would be useful to get an account
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on github and clone the source to your own account. You can then send me pull
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requests for any modifications you would like to see included.
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If you just want to clone my source to look at it, use::
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If you just want to clone the source to look at it, use::
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git clone https://github.com/robmcmullen/asmgen.git
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Using the Code Generator
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==========================
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The code generator is a command line tool that creates text files that can be
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used as source code for assemblers. Its general usage is::
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asmgen.py [OPTIONS] -o ROOTNAME
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which will create one file called ''ROOTNAME-driver.s'' and one or more files
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containing generated code as specified by ''OPTIONS''. This driver file is a
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convenience that only exists to include all the other generated files. This
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means that your build process only needs to include ``ROOTNAME-driver.s``
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instead of needing to be updated if you add aditional code generation options.
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Assembler Support
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=================
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-----------------
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Code generation is supported for the following assemblers:
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* cc65 (the default)
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* MAC/65
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@ -61,7 +80,7 @@ Contributors welcome for other assemblers, like Merlin, MADS, dasm, xasm, etc.
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Code Generation Capabilities
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============================
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----------------------------
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* Transposed font code generator
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* Sprite compiler
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@ -77,30 +96,44 @@ Experimental (and unsupported)
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* Merge two hi-res images, switching images at specified scan line
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Running the Code Generator
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==========================
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You will use
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Transposed Font
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===============
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To generate source code for a fast font renderer, you will need a binary font
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file that is required in order to transpose the font characters and embed them
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in the source code. Then::
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file. The code generator will embed the binary data as ``.byte`` directives (or equivalent for the chosen assembler) because the transposition requires reordering of the data. The usage is::
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asmgen.py -f FONTFILENAME -o OUTPUTFILEROOT
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asmgen.py -f FONTFILENAME -o ROOTNAME
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It will create two source files, the main one of interest is called
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OUTPUTFILEROOT-fastfont.s which contains the generated code and data for use of
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the transposed font. All you need is to include this file in your source and
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it's ready to go. No need to include a binary of the font file, as it's already
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included in byte data.
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It will create two source files, the ``ROOTNAME-driver.s`` file described
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above, and the file of interest called ``ROOTNAME-fastfont.s`` which contains
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the generated code and data for use of the transposed font. The entry point
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look like this::
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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
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FASTFONT_H1 ; A = character, X = column, Y = row; A is clobbered, X&Y are not
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pha
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lda FASTFONT_H1_JMP_HI,y
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sta FASTFONT_H1_JMP+2
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lda FASTFONT_H1_JMP_LO,y
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sta FASTFONT_H1_JMP+1
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sty scratch_0
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pla
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tay
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FASTFONT_H1_JMP
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jmp $ffff
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called OUTPUFILEROOT-driver.s that will include all the other generated files, and the specific font file source
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``FASTFONT_H1_JMP`` is a jump table, broken into high and low bytes.
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The input is described in the comment: the glyph in the accumulator, column
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value (0-39) in the X register, and row value (0-23) in the Y register. Note
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that no error checking is done here, so it will happily trash data in some
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unintended part of RAM if you pass it values that are out of range.
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Use it like this::
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lda #65 ; ASCII character 'A'
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ldx #20 ; column 20 (counting from zero)
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ldy #5 ; row 5 (counting from zero)
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jsr FASTFONT_H1
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