bhdr: zrle flag

jmode.c

@@ -230,17 +230,18 @@ static int read_header_from_map(mmap_t map, int force, int ifactor_override) {
   return parse_header(out, force, ifactor_override);
 }
 #endif
-typedef struct { u32 bytes, crc; } block_hdr;
+typedef struct { u32 bytes, crc; bool zrle; } block_hdr;
 static void write_block_header(FILE * des, block_hdr h) {
-  u8 b[8]; b[0] = 'X';
+  u8 b[8]; b[0] = 'X' + zrle; // X/Y.
   if (h.bytes > 0xFFFFFF)
     FATAL("Could not write the header: block too big.");
   b[1] = h.bytes >> 16; b[2] = h.bytes >> 8; b[3] = h.bytes;
   b[4] = h.crc >> 24; b[5] = h.crc >> 16; b[6] = h.crc >> 8; b[7] = h.crc;
   xfwrite(b, 8, des);
 }
 static block_hdr parse_block_header(u8 b[8], bool force) {
-  block_hdr h;  bool valid = b[0] == 'X';
+  block_hdr h;  bool valid = b[0] == 'X' || b[0] == 'Y';
+  h.zrle = b[0] == 'Y';
   if (!valid) {
     FATAL_UNLESS("Invalid block header.", !force);
     h.bytes = 0xFFFFFF; h.crc = 0; return h;
@@ -264,7 +265,7 @@ static void encode4(FILE * in, FILE * out, int ifactor) {
     Fi(ibs, rse32(in_buffer + i * K, o1 + i * N));
     do_interlacing(o1, o2, ifactor);
     xfwrite(o2, ibs * N, out);
-    bhdr.bytes = n; bhdr.crc = crc32c(in_buffer, n);
+    bhdr.bytes = n; bhdr.crc = crc32c(in_buffer, n); bhdr.zrle = false;
     write_block_header(out, bhdr);
   }
   free(in_buffer), free(o1), free(o2); xfclose(out);
@@ -286,7 +287,7 @@ static void encode3(mmap_t in, FILE * out, int ifactor) {
     Fi(ibs, rse32(in_buffer + i * K, o1 + i * N));
     do_interlacing(o1, o2, ifactor);
     xfwrite(o2, ibs * N, out);
-    bhdr.bytes = n; bhdr.crc = crc32c(in_buffer, n);
+    bhdr.bytes = n; bhdr.crc = crc32c(in_buffer, n); bhdr.zrle = false;
     write_block_header(out, bhdr);
   }
   free(in_buffer), free(o1), free(o2); xfclose(out);