Bitwise RLE

Marlin/src/lcd/dogm/marlinui_DOGM.cpp

@@ -127,19 +127,18 @@ bool MarlinUI::detected() { return true; }
         #else
           const u8g_pgm_uint8_t * const bmp = (u8g_pgm_uint8_t*)pgm_read_ptr(&custom_bootscreen_animation[frame]);
         #endif
-      #elif ENABLED(CUSTOM_BOOTSCREEN_RLE)
-        uint8_t bmp[CUSTOM_BOOTSCREEN_BMP_BYTEWIDTH * CUSTOM_BOOTSCREEN_BMPHEIGHT];
+      #elif ANY(CUSTOM_BOOTSCREEN_RLE, CUSTOM_BOOTSCREEN_BITWISE_RLE)
+        #define BMPSIZE (CUSTOM_BOOTSCREEN_BMP_BYTEWIDTH * CUSTOM_BOOTSCREEN_BMPHEIGHT)
+        uint8_t bmp[BMPSIZE];
         uint8_t *bmp_rle = (uint8_t*)custom_start_bmp_rle;
       #else
         const u8g_pgm_uint8_t * const bmp = custom_start_bmp;
       #endif
 
-      UNUSED(frame);
-
       #if ENABLED(CUSTOM_BOOTSCREEN_RLE)
 
         uint8_t bits = 0;                       // Persist the last fetched bitmap byte
-        for (uint8_t *dst = bmp; dst < bmp + sizeof(bmp);) {
+        for (uint8_t *dst = bmp; dst < bmp + BMPSIZE;) {
           uint8_t count = *bmp_rle++;           // Get the count byte
           const bool uniq = bool(count & 0x80); // >= 128 is a distinct run; < 128 is a repeat run
           count = (count & 0x7F) + 1;           // Actual count is 7-bit plus 1
@@ -153,11 +152,39 @@ bool MarlinUI::detected() { return true; }
           }
         }
 
-      #endif // CUSTOM_BOOTSCREEN_RLE
+      #elif ENABLED(CUSTOM_BOOTSCREEN_BITWISE_RLE)
+
+        uint8_t *dst = (uint8_t*)bmp;
+
+        auto rle_nybble = [&](const uint16_t i) {
+          const uint8_t b = bmp_rle[i / 2];
+          return (i & 1 ? b & 0xF : b >> 4);
+        };
+
+        uint8_t workbyte = 0, bitstate = rle_nybble(0) << 7;
+        uint16_t inindex = 1, outindex = 0;
+        while (outindex < BMPSIZE * 8) {
+          int16_t c = rle_nybble(inindex++);
+          if (c == 15) {
+            c = 16 * rle_nybble(inindex) + rle_nybble(inindex + 1) + 15; // From 16 to 270
+            inindex += 2;
+          }
+          while (c-- >= 0) {
+            const uint8_t bitind = outindex & 7,
+                          bitval = bitstate >> bitind;
+            workbyte |= bitval;
+            if (bitind == 7) { *dst++ = workbyte; workbyte = 0; }
+            outindex++;
+          }
+          bitstate ^= 0x80;
+        }
+
+      #endif // CUSTOM_BOOTSCREEN_BITWISE_RLE
 
       u8g.TERN(CUSTOM_BOOTSCREEN_RLE, drawBitmap, drawBitmapP)
         (left, top, CUSTOM_BOOTSCREEN_BMP_BYTEWIDTH, CUSTOM_BOOTSCREEN_BMPHEIGHT, bmp);
 
+      UNUSED(frame);
       #if ENABLED(CUSTOM_BOOTSCREEN_INVERTED)
         if (frame == 0) {
           u8g.setColorIndex(1);

buildroot/share/scripts/rle_compress_bitmap.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# RLE compress a Marlin mono DOGM bitmap.
+# Bitwise RLE compress a Marlin mono DOGM bitmap.
 # Input: An existing Marlin Marlin mono DOGM bitmap .cpp or .h file.
 # Output: A new file with the original and compressed data.
 #
@@ -12,23 +12,21 @@
 def addCompressedData(input_file, output_file):
     ofile = open(output_file, 'wt')
 
-    c_data_section = False
-    c_skip_data = False
-    c_footer = False
     datatype = "uint8_t"
     bytewidth = 16
     raw_data = []
-    rle_value = []
-    rle_count = []
     arrname = ''
 
-    line = input_file.readline()
-    while line:
+    c_data_section = False ; c_skip_data = False ; c_footer = False
+    while True:
+        line = input_file.readline()
+        if not line: break
+
         if not c_footer:
             if not c_skip_data: ofile.write(line)
 
-        mat = re.match(r'CUSTOM_BOOTSCREEN_BMPWIDTH\s+(\d+)', line)
-        if mat: bytewidth = int(mat[1]) / 16
+        mat = re.match(r'.+CUSTOM_BOOTSCREEN_BMPWIDTH\s+(\d+)', line)
+        if mat: bytewidth = (int(mat[1]) + 7) // 8
 
         if "};" in line:
             c_skip_data = False
@@ -58,89 +56,129 @@ def addCompressedData(input_file, output_file):
                 arrname = line.split('[')[0].split(' ')[-1]
                 print("Found data array", arrname)
 
-        line = input_file.readline()
-
     input_file.close()
 
+    #print("\nRaw Bitmap Data", raw_data)
+
     #
-    # RLE (run length) encoding
-    # Convert data from raw mono bitmap to a simple run-length-encoded format.
-    # - Each sequence begins with a count byte N.
-    #   - If the high bit is set in N the run contains N & 0x7F + 1 unique bytes.
+    # Bitwise RLE (run length) encoding
+    # Convert data from raw mono bitmap to a bitwise run-length-encoded format.
+    # - The first byte is the starting bit state. Changing this byte inverts the bitmap.
+    # - Next bytes each contain two run counts, encoding from 1 to 15 bits
+    #   so a single byte can encode up to 4 bytes, saving 3 bytes.
+    #   - If the high bit is set in N the run contains N & 0xF + 1 unique bytes.
     #   - Otherwise it repeats the following byte N + 1 times.
     #
-    def rle_encode(data):
+    def bitwise_rle_encode(data):
         warn = "This may take a while" if len(data) > 300000 else ""
         print("Compressing image data...", warn)
-        rledata = []
-        distinct = []
+
+        def get_bit(data, n): return 1 if (data[n // 8] & (0x80 >> (n & 7))) else 0
+
+        bitslen = len(data) * 8
+        bitstate = get_bit(data, 0)
+        rledata = [ bitstate ]
+
         i = 0
-        while i < len(data):
-            v = data[i]
+        runlen = -1
+        while i <= bitslen:
+            if i < bitslen: b = get_bit(data, i)
+            runlen += 1
+            if bitstate != b or i == bitslen:
+                if i > 11 * 56 * 8: print(f'Bit change at index {i} with runlen={runlen}')
+                if runlen >= 16:
+                    rledata += [ 15, runlen // 16 - 1, runlen % 16 ]
+                    if i > 11 * 56 * 8: print(f'Storing {[ 15, runlen // 16 - 1, runlen % 16 ]}')
+                else:
+                    rledata += [ runlen - 1 ]
+                    if i > 11 * 56 * 8: print(f'Storing {[ runlen ]}')
+                bitstate ^= 1
+                runlen = 0
             i += 1
-            rsize = 1
-            for j in range(i, len(data)):
-                if v != data[j]: break
-                i += 1
-                rsize += 1
-                if rsize >= 128: break
-
-            # If the run is one, add to the distinct values
-            if rsize == 1: distinct.append(v)
-
-            # If distinct length >= 127, or the repeat run is 2 or more,
-            # store the distinct run.
-            nr = len(distinct)
-            if nr and (nr >= 128 or rsize > 1 or i >= len(data)):
-                rledata += [(nr - 1) | 0x80] + distinct
-                distinct = []
-
-            # If the repeat run is 2 or more, store the repeat run.
-            if rsize > 1: rledata += [rsize - 1, v]
-
-        return rledata
-
-    def append_byte(data, byte, cols=bytewidth):
-        if data == '': data = '  '
-        data += ('0x{0:02X}, '.format(byte)) # 6 characters
-        if len(data) % (cols * 6 + 2) == 0: data = data.rstrip() + "\n  "
-        return data
 
-    def rle_emit(ofile, arrname, rledata, rawsize):
+        print("\nrledata", rledata)
+
+        encoded = []
+        ri = 0
+        rlen = len(rledata)
+        while ri < rlen:
+            v = rledata[ri] << 4
+            if (ri < rlen - 1): v |= rledata[ri + 1]
+            encoded += [ v ]
+            ri += 2
+
+        print("\nencoded", encoded)
+        return encoded
+
+    def bitwise_rle_decode(rledata, invert=0):
+        expanded = []
+        for n in rledata: expanded += [ n >> 4, n & 0xF ]
+
+        decoded = []
+        bitstate = 0 ; workbyte = 0 ; outindex = 0
         i = 0
-        outstr = ''
-        size = 0
-        while i < len(rledata):
-            rval = rledata[i]
+        while i < len(expanded):
+            c = expanded[i]
             i += 1
-            if rval & 0x80:
-                count = (rval & 0x7F) + 1
-                outstr = append_byte(outstr, rval)
-                size += 1
-                for j in range(count):
-                    outstr = append_byte(outstr, rledata[i + j])
-                    size += 1
-                i += count
-            else:
-                outstr = append_byte(outstr, rval)
-                outstr = append_byte(outstr, rledata[i])
-                i += 1
-                size += 2
 
-        outstr = outstr.rstrip()[:-1]
+            if i == 1: bitstate = c ; continue
+
+            if c == 15:
+                c = 16 * expanded[i] + expanded[i + 1] + 15
+                i += 2
+
+            for _ in range(c, -1, -1):
+                bitval = 0x80 >> (outindex & 7)
+                if bitstate: workbyte |= bitval
+                if bitval == 1:
+                    decoded += [ workbyte ]
+                    workbyte = 0
+                outindex += 1
+
+            bitstate ^= 1
+
+        print("\nDecoded RLE data:")
+        pretty = [ '{0:08b}'.format(v) for v in decoded ]
+        rows = [pretty[i:i+bytewidth] for i in range(0, len(pretty), bytewidth)]
+        for row in rows: print(f"{''.join(row)}")
+
+        return decoded
+
+    def rle_emit(ofile, arrname, rledata, rawsize):
+
+        outstr = ''
+        rows = [ rledata[i:i+16] for i in range(0, len(rledata), 16) ]
+        for i in range(0, len(rows)):
+            rows[i] = [ '0x{0:02X}'.format(v) for v in rows[i] ]
+            outstr += f"  {', '.join(rows[i])},\n"
+
+        outstr = outstr[:-2]
+        size = len(rledata)
         ofile.write("\n// Saves %i bytes\n%s %s_rle[%d] PROGMEM = {\n%s\n};\n" % (rawsize - size, datatype, arrname, size, outstr))
 
     # Encode the data, write it out, close the file
-    rledata = rle_encode(raw_data)
+    rledata = bitwise_rle_encode(raw_data)
     rle_emit(ofile, arrname, rledata, len(raw_data))
     ofile.close()
 
+    # Validate that code properly compressed (and decompressed) the data
+    checkdata = bitwise_rle_decode(rledata)
+    badindex = -1
+    for i in range(0, len(checkdata)):
+        if raw_data[i] != checkdata[i]:
+            badindex = i
+            break
+    if badindex >= 0: print(f'Data mismatch at byte {badindex}')
+
 if len(sys.argv) <= 2:
     print('Usage: rle_compress_bitmap.py INPUT_FILE OUTPUT_FILE')
     exit(1)
 
 output_cpp = sys.argv[2]
 inname = sys.argv[1].replace('//', '/')
-input_cpp = open(inname)
-print("Processing", inname, "...")
-addCompressedData(input_cpp, output_cpp)
+try:
+    input_cpp = open(inname)
+    print("Processing", inname, "...")
+    addCompressedData(input_cpp, output_cpp)
+except OSError:
+    print("Can't find input file", inname)