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https://github.com/irmen/prog8.git
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141 lines
6.9 KiB
Lua
141 lines
6.9 KiB
Lua
%target cx16
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%import graphics
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%import textio
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%import diskio
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%option no_sysinit
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; CommanderX16 Image file format. (EXPERIMENTAL/ UNFINISHED)
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; Numbers are encoded in little endian format (lsb first).
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;
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; offset value
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; -----------------
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; HEADER (12 bytes):
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; 0-1 'CI' in petscii , from "CommanderX16 Image".
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; 2 Size of the header data following this byte (always 9, could become more if format changes)
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; 3-4 Width in pixels (must be multiple of 8)
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; 5-6 Height in pixels
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; 7 Bits-per-pixel (1, 2, 4 or 8) (= 2, 4, 16 or 256 colors)
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; this also determines the number of palette entries following later.
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; 8 Settings bits.
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; bit 0 and 1 = compression. 00 = uncompressed
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; 01 = RLE [TODO not yet implemented]
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; 10 = LZSA [TODO not yet implemented]
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; 11 = Exomizer [TODO not yet implemented]
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; bit 2 = palette format. 0 = 4 bits/channel (2 bytes per color, $0R $GB)
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; 1 = 8 bits/channel (3 bytes per color, $RR $GG $BB)
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; 4 bits per channel is what the Vera in the Cx16 supports.
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; bit 3 = bitmap format. 0 = raw bitmap pixels
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; 1 = tile-based image [TODO not yet implemented]
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; bit 4 = hscale (horizontal display resulution) 0 = 320 pixels, 1 = 640 pixels
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; bit 5 = vscale (vertical display resulution) 0 = 240 pixels, 1 = 480 pixels
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; bit 6,7: reserved, set to 0
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; 9-11 Size of the bitmap data following the palette data.
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; This is a 24-bits number, can be 0 ("unknown", in which case just read until the end).
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;
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; PALETTE (always present but size varies):
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; 12-... Color palette. Number of entries = 2 ^ bits-per-pixel. Number of bytes per
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; entry is 2 or 3, depending on the chosen palette format in the setting bits.
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;
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; BITMAPDATA (size varies):
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; After this, the actual image data follows.
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; If the bitmap format is 'raw bitmap pixels', the bimap is simply written as a sequence
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; of bytes making up the image's scan lines. #bytes per scan line = width * bits-per-pixel / 8
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; If it is 'tiles', .... [TODO]
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; If a compression scheme is used, the bitmap data here has to be decompressed first.
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; TODO: with compressed files, store the data in compressed chunks of max 8kb uncompressed?
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; (it is a problem to load let alone decompress a full bitmap at once because there will likely not be enough ram to do that)
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; (doing it in chunks of 8 kb allows for sticking each chunk in one of the banked 8kb ram blocks, or even copy it directly to the screen)
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ci_module {
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%option force_output
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ubyte[256] buffer
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ubyte[256] buffer2 ; add two more buffers to make enough space
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ubyte[256] buffer3 ; to store a 256 color palette
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ubyte[256] buffer4 ; .. and some more to be able to store 1280=
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ubyte[256] buffer5 ; two 640 bytes worth of bitmap scanline data
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sub show_image(uword filename) -> ubyte {
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ubyte read_success = false
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uword bitmap_load_address = progend()
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; uword max_bitmap_size = $9eff - bitmap_load_address
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if(diskio.f_open(8, filename)) {
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uword size = diskio.f_read(buffer, 12) ; read the header
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if size==12 {
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if buffer[0]=='c' and buffer[1]=='i' and buffer[2] == 9 {
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uword width = mkword(buffer[4], buffer[3])
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uword height = mkword(buffer[6], buffer[5])
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ubyte bpp = buffer[7]
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uword num_colors = 2 ** bpp
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ubyte flags = buffer[8]
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ubyte compression = flags & %00000011
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ubyte palette_format = (flags & %00000100) >> 2
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ubyte bitmap_format = (flags & %00001000) >> 3
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; ubyte hscale = (flags & %00010000) >> 4
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; ubyte vscale = (flags & %00100000) >> 5
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uword bitmap_size = mkword(buffer[10], buffer[9])
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uword palette_size = num_colors*2
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if palette_format
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palette_size += num_colors ; 3
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if width > graphics.WIDTH {
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txt.print("image is too wide for the display!\n")
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} else if compression!=0 {
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txt.print("compressed image not yet supported!\n") ; TODO implement the various decompressions
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} else if bitmap_format==1 {
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txt.print("tiled bitmap not yet supported!\n") ; TODO implement tiled image
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} else {
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size = diskio.f_read(buffer, palette_size)
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if size==palette_size {
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if compression {
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txt.print("todo: compressed image support\n")
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} else {
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; uncompressed bitmap data. read it a scanline at a time and display as we go.
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; restrict height to the maximun that can be displayed
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if height > graphics.HEIGHT
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height = graphics.HEIGHT
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graphics.enable_bitmap_mode()
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if palette_format
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palette.set_rgb8(buffer, num_colors)
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else
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palette.set_rgb4(buffer, num_colors)
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graphics.clear_screen(1,0)
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cx16.r0 = 0
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cx16.r1 = 0
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cx16.FB_cursor_position()
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uword scanline_size = width * bpp / 8
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ubyte y
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for y in 0 to lsb(height)-1 {
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void diskio.f_read(buffer, scanline_size)
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when bpp {
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8 -> cx16.FB_set_pixels_from_buf(buffer, scanline_size) ; FB_set_pixels in rom v38 crashes with a size > 255 so we use our own replacement for now
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4 -> display_scanline_16c(buffer, scanline_size)
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2 -> display_scanline_4c(buffer, scanline_size)
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1 -> display_scanline_2c(buffer, scanline_size)
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}
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}
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read_success = true
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}
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}
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}
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}
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}
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diskio.f_close()
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}
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return read_success
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}
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sub display_scanline_16c(uword dataptr, uword numbytes) {
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; TODO
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}
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sub display_scanline_4c(uword dataptr, uword numbytes) {
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; TODO
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}
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sub display_scanline_2c(uword dataptr, uword numbytes) {
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; TODO
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}
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}
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