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84 lines
2.4 KiB
Lua
84 lines
2.4 KiB
Lua
%target cx16
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%import gfx2
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%import diskio
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%import palette
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koala_module {
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const uword load_location = $6000
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sub show_image(uword filenameptr) -> ubyte {
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ubyte load_ok=false
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if diskio.f_open(8, filenameptr) {
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uword size = diskio.f_read(load_location, 2) ; skip the first 2 bytes (load address)
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if size==2 {
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diskio.f_read_exact(load_location, 10001)
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; set a better C64 color palette, the Cx16's default is too saturated
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palette.set_c64pepto()
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convert_koalapic()
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load_ok = true
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}
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diskio.f_close()
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}
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return load_ok
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}
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sub convert_koalapic() {
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ubyte cy
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ubyte @zp cx
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uword @zp cy_times_forty = 0
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ubyte @zp d
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uword bitmap_ptr = load_location
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; theoretically you could put the 8-pixel array in zeropage to squeeze out another tiny bit of performance
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ubyte[8] pixels
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gfx2.clear_screen()
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uword offsety = (gfx2.height - 200) / 2
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for cy in 0 to 24*8 step 8 {
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uword posy = cy + offsety
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for cx in 0 to 39 {
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uword posx = cx as uword * 8
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for d in 0 to 7 {
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gfx2.position(posx, posy + d)
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get_8_pixels()
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gfx2.next_pixels(pixels, 8)
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}
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}
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cy_times_forty += 40
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}
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sub get_8_pixels() {
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ubyte bm = @(bitmap_ptr)
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ubyte @zp m = mcol(bm)
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pixels[7] = m
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pixels[6] = m
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bm >>= 2
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m = mcol(bm)
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pixels[5] = m
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pixels[4] = m
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bm >>= 2
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m = mcol(bm)
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pixels[3] = m
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pixels[2] = m
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bm >>= 2
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m = mcol(bm)
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pixels[1] = m
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pixels[0] = m
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bitmap_ptr++
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sub mcol(ubyte b) -> ubyte {
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ubyte @zp color
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when b & 3 {
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0 -> color = @(load_location + 8000 + 1000 + 1000) & 15
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1 -> color = @(load_location + 8000 + cy_times_forty + cx) >>4
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2 -> color = @(load_location + 8000 + cy_times_forty + cx) & 15
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else -> color = @(load_location + 8000 + 1000 + cy_times_forty + cx) & 15
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}
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return color
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}
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}
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}
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}
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