keychron_qmk_firmware/docs/quantum_painter_rle.md
2024-05-30 12:00:41 +10:00

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# QMK QGF/QFF RLE data schema {#qmk-qp-rle-schema}
There are two "modes" to the RLE algorithm used in both [QGF](quantum_painter_qgf)/[QFF](quantum_painter_qff):
* Non-repeating sections of octets, with associated length of up to `128` octets
* `length` = `marker - 128`
* A corresponding `length` number of octets follow directly after the marker octet
* Repeated octet with associated length, with associated length of up to `128`
* `length` = `marker`
* A single octet follows the marker that should be repeated `length` times.
Decoder pseudocode:
```
while !EOF
marker = READ_OCTET()
if marker >= 128
length = marker - 128
for i = 0 ... length-1
c = READ_OCTET()
WRITE_OCTET(c)
else
length = marker
c = READ_OCTET()
for i = 0 ... length-1
WRITE_OCTET(c)
```