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Library and utilities for working with NES data and ROMS

A library for working with NES CHR data and ROM files.

chrutil

Utility to work with CHR files and related data.

  • Converting bitmaps to the CHR format
  • Converting CHR files to PNG
  • Selecting which tiles to export (Range or individual IDs)
  • Tile de-duplication (with ID mappings exported)
  • Multiple input bitmaps into a single CHR
  • Multiple inputs to multiple outputs
  • 8x16 sprite mode (per-input file)
  • Target start ID for given input
  • Allow CHR files as input for concatenation
  • Output as binary CHR file or assembly source
  • Destination tile ID override

Custom rolled flag parsing (only chrutil)

Three main sections (or "targets") of data: default, global, and per-input.

Default is defined at compile-time, while the global and per-input are defined at runtime.

All command line options have a target, with the default (first) target "global". Retrieving a value for a target will first look in the current target scope, fall back to the global target if nothing was found, then finally fall back to the default target.

Each target should have a reference to the higher target scope. The default target will not have a reference anywhere as all options will be expected to have been defined in the default target scope.

Multiple input files

The order of commands and input files matters. Options given before an input file are global for all input files, unless overwritten later.

$ chrutil input_a.bmp input_b.bmp --b-option
$ chrutil input_a.bmp --a-option input_b.bmp
$ chrutil input_a.bmp --a-option input_b.bmp --b-option

$ chrutil \
    --global-option \
    input_a.bmp \
    input_b.bmp --b-option

$ chrutil \
    --global-option \
    input_a.bmp --global-override-for-a \
    input_b.bmp --b-option

For this command, main.chr will not contain the data from input_b.bmp.

$ chrutil \
    --output main.chr \
    input_a.bmp \
    input_b.bmp --output only_b.chr \
    input_c.bmp

Options are per-input file or global. If an option is defined once globally and once for an input file, the global value is overwritten with the input file's value.

If an option is given more than once for the same scope the last value will be used.

Multiple input and output files

Multiple input files with the same output file will be combined into that output file.

$ chrutil \
    input_a.bmp --output ab.chr \
    input_b.bmp --output ab.chr \
    input_c.bmp --output cd.chr \
    input_d.bmp --output cd.chr

Selecting which tiles to export

Either a range or a list of tile IDs. Accept either decimal or hex ($##) notation.

$ chrutil --tile-ids 2-14
$ chrutil --tile-ids 2,4,8,10

$ chrutil --tile-ids $02-$0D
$ chrutil --tile-ids $02,$04,$08,$0A

CHR as input

This will append font.chr to the end of main.chr after input_a.bmp has been converted and written.

$ chrutil \
    --output main.chr \
    input_a.bmp \
    font.chr

This will append the converted input_a.bmp CHR data to the end of main.chr after font.chr.

$ chrutil \
    --output main.chr \
    font.chr \
    input_a.bmp

fontutil

Takes a font in an image and removes blank tiles. This can also output ca65 remapping commands so ascii typed in source files will be able to use the generated font without any modification.

fontutil --input font.bmp --output converted.chr \
         --remap character-remappings.i \
         --widths character-widths.i \
         --space-width 5 \
         --input-offset 0 \
         --input-length 0

--input and --output are the only required options.

An --input-length of zero disables the length check and will process all the characters in the font.

metatiles

Convert metatiles in an image to tile-reduced CHR data and metadata that can be used to re-construct the metatiles. The positional arguments are required, all the others are optional.

$ metatiles input.bmp output.chr metadata.i
$ metatiles input.bmp output.chr metadata.i \
            --tile-size 2x2 \
            --count 2 \
            --offeset 1 \
            --pad 16

--tile-size defaults to 2x2. This option accepts a single number (square metatile) or a WxH value.

--count will process only the given number of metatiles. A value of 0 will process all metatiles found in the input file.

--offset will start processing metatiles after the given number of metatiles (not individual 8x8 tiles).

--pad will pad the output CHR to contain at least the given number of 8x8 tiles.

Output Metadata

This data is used to reconstruct the metatiles from individual 8x8 pixel tiles. The data consists of two tables. The first is a list of addresses (pointers) to data for each metatile.

The data for each mitatile consists of a few vaules:

; width, height
.byte 2, 2
; palette, total tiles (W*H)
.byte 0, 4
; list of tile IDs
.byte 128, 129, 128, 129

romutil

Utility to work directly with ROM files.

  • Unpack ROM into PRG and CHR
  • Option to split PRG and CHR into banks
  • Pack ROM from unpacked data
  • ROM info printout (header info, hashes, etc)

Command line

General command format.

$ romutil <command> <input> [options]

Unpack a ROM into PRG and CHR binary files and a header.json file.

$ romutil unpack input.nes

Re-pack an unpacked ROM.

$ romutil pack unpacked_data_directory/

Print mapper info and CRC32 hashes

$ romutil info input.nes

sbutil

An (unfinished) utility to pack and unpack StudyBox rom files.

text2chr

Create a tile-reduced text image. Letters are assumed to be variable width.

$ text2chr --font font.bmp --metadata text.i --input "Hello world" --chr output.chr

The file font.bmp is the font to use for the conversion and the text to convert is provided with the --input option. Metadata is written to text.i and CHR data to output.chr. The metadata consists of a data length (one byte) followed by that number tile IDs.

usage

Create an image showing the usage of a ROM.

$ usage --chr-size 8 input.nes output.png

The output image is made up of columns of data. Each column represents 16k and is 16 bytes wide. Each pixel in the image is a single bit in the ROM.

CHR data is also written out to a set of images. By default, the images are split into 8k chunks. Valid sizes are: 8, 4, 2, 1, & 0. A value of "0" will not split the CHR data into chunks and will write a single image.

Currently, the output filenames for the CHR data conforms to "chr_%04d.png". This will be configurable, eventually.