add sprites library and Xmas demo

utils/png2pict.py

@@ -0,0 +1,110 @@
+#!/usr/bin/python3
+import sys
+import png
+
+def process_pixdata(outfile, pixdata, frameindex = 0, pix_w=640, pix_h=400):
+
+    pixmask = 15
+    y = pix_h * frameindex
+    max_y = y + pix_h - 1
+
+    while y <= max_y:
+        x = 0
+        max_x = pix_w - 1
+        pixline = pixdata[y]
+        while x <= max_x:
+            px1 = pixline[x+0] & pixmask
+            px2 = pixline[x+1] & pixmask
+            px3 = pixline[x+2] & pixmask
+            px4 = pixline[x+3] & pixmask
+            px5 = pixline[x+4] & pixmask
+            px6 = pixline[x+5] & pixmask
+            px7 = pixline[x+6] & pixmask
+            px8 = pixline[x+7] & pixmask
+            vmem_word = (px1 << 28) | (px2 << 24) | (px3 << 20) | (px4 << 16) | \
+                        (px5 << 12) | (px6 << 8)  | (px7 << 4)  | px8
+
+            outfile.write(vmem_word.to_bytes(4, 'big'))
+            x += 8
+        y += 1
+
+
+def process_palette(outfile, palette):
+    for r,g,b in palette:
+        r4 = r >> 4
+        g4 = g >> 4
+        b4 = b >> 4
+        c12 = r4 << 8 | g4 << 4 | b4
+
+        outfile.write(c12.to_bytes(4, 'big'))
+
+
+def write_header(outfile):
+    magic = b'PIct'
+    mode = 1
+    outfile.write(magic);
+    outfile.write(mode.to_bytes(4, 'big'))
+
+
+def write_sprite_header(outfile):
+    magic = b'SPRT'
+    mode = 1
+    outfile.write(magic);
+    outfile.write(mode.to_bytes(4, 'big'))
+
+
+def write_pict_file(width, height, px, metadata, outfile):
+    print("processing as PICT file...")
+    if width != 640:
+        print("width must be 640, aborting")
+        sys.exit(1)
+    pixdata = list(px)
+    palette = metadata['palette']
+
+    if len(palette) != 16:
+        print("palette must have 16 colors, aborting")
+        sys.exit(0)
+
+    with open(outfile,'wb') as f:
+        write_header(f)
+        process_palette(f, palette)
+        process_pixdata(f, pixdata)
+
+
+def write_sprite_file(width, height, px, metadata, outfile):
+    sprite_height=16
+
+    print("processing as SPRT file with {} sprites...".format(height//sprite_height))
+    if width != 16:
+        print("width must be 16, aborting")
+        sys.exit(1)
+    pixdata = list(px)
+    palette = metadata['palette']
+
+    if len(palette) != 16:
+        print("palette must have 16 colors, aborting")
+        sys.exit(0)
+
+    with open(outfile,'wb') as f:
+        write_sprite_header(f)
+        process_pixdata(f, pixdata, pix_w=16, pix_h=height)
+
+
+if __name__ == '__main__':
+    if len(sys.argv) != 3:
+        print("Usage: {} <infile> <outfile>".format(sys.argv[0]))
+        sys.exit(1)
+
+    infile = sys.argv[1]
+    outfile = sys.argv[2]
+
+    r = png.Reader(infile)
+    p = r.read()
+    width, height, px, metadata = p
+    if width == 640:
+        write_pict_file(width, height, px, metadata, outfile)
+    elif width == 16:
+        write_sprite_file(width, height, px, metadata, outfile)
+    else:
+        print("Can't handle this file, need a width of\n640 or 16 pixels with 16 color palette.")
+