50 lines
1.2 KiB
Markdown
50 lines
1.2 KiB
Markdown
# picview.asm (c) 2019 Thomas Bernard
|
|
|
|
This is a C64 image depacker and viewer designed to build self-displaying
|
|
.prg pictures files.
|
|
One has to concatenate the data to the viewer machine code to build a .prg
|
|
file.
|
|
|
|
## Data format
|
|
- 1 byte for mode
|
|
- then one or several blocks, composed of :
|
|
1. 1 byte TP header :
|
|
- upper nibble T is type
|
|
- lower nibble P is packing
|
|
2. n bytes data load, depending of type and packing
|
|
|
|
### Mode byte
|
|
0EBM0000 E=Extended Background mode. B=Bitmap Mode. M=Multicolor.
|
|
|
|
### TP byte
|
|
- T = type
|
|
- 0 - end of file
|
|
- 1 - bitmap 8000 bytes
|
|
- 2 - screen ram 1000 bytes
|
|
- 3 - color ram 1000 bytes at $D800
|
|
- 4 - border/background etc. 15 bytes at $D020
|
|
- P = packing
|
|
- 0 - no packing
|
|
- 1 - RLE packing
|
|
- 2 - color ram RLE packing
|
|
|
|
All other values are reserved.
|
|
|
|
|
|
## border/backgrounds at $D020, 15 bytes
|
|
- BO BORDER
|
|
- BA BACKGROUND
|
|
- E1 Extra background color #1
|
|
- E2 Extra background color #2
|
|
- E3 Extra background color #3
|
|
- SE1 sprite extra color #1
|
|
- SE2 sprite extra color #2
|
|
- S0 sprite #0
|
|
- S1 sprite #1
|
|
- S2 sprite #2
|
|
- S3 sprite #3
|
|
- S4 sprite #4
|
|
- S5 sprite #5
|
|
- S6 sprite #6
|
|
- S7 sprite #7
|