Changeset 41474 for trunk/Ohana/src/libfits/matrix/F_compress_M.c

Timestamp:

Jan 24, 2021, 3:37:52 PM (5 years ago)

Author:

eugene

Message:

clarify in comments the buffers and pixel sizes used in the different stages of compression/uncompression; catch unimplemented compression cases; fix error in pixel size for RICE1; cleanup verbose code; use correct sscanf format code in ASCII table reading code

File:

• trunk/Ohana/src/libfits/matrix/F_compress_M.c (modified) (4 diffs)

trunk/Ohana/src/libfits/matrix/F_compress_M.c

@@ -76 +76 @@
   if (!gfits_modify (theader, "ZCMPTYPE", "%s", 1, zcmptype)) ESCAPE;
 
-  // define compression-specific keywords, update header as needed.
-  if (!strcasecmp(zcmptype, "GZIP_1") || !strcasecmp(zcmptype, "GZIP_2")) {
-    if ((header[0].bitpix == -32) || (header[0].bitpix == -64)) {
-      if (!gfits_modify (theader, "ZQUANTIZ", "%s", 1, "NONE")) ESCAPE;
-    }
-  }
-
   if (!gfits_modify_alt (theader, "ZSIMPLE", "%t", 1, TRUE)) ESCAPE;
   // gfits_modify (header, "ZTENSION", "%s", 1, exttype);
@@ -124 +117 @@
   int oblank = 32767;
   // gfits_modify (header, "BLANK", "%d", 1, oblank);
+
+  // define compression-specific keywords, update header as needed.
+  if (!strcasecmp(zcmptype, "GZIP_1") || !strcasecmp(zcmptype, "GZIP_2")) {
+    if ((header[0].bitpix == -32) || (header[0].bitpix == -64)) {
+      if (!gfits_modify (theader, "ZQUANTIZ", "%s", 1, "NONE")) ESCAPE;
+    }
+  }
 
 # if (0)
@@ -159 +159 @@
   unsigned long int max_tile_size = gfits_imtile_maxsize (matrix, ztile);
 
-  // size of a pixel in the raw pixel buffer (before compression)
-  int raw_pixsize = gfits_uncompressed_data_pixsize (zcmptype, header[0].bitpix, NULL, NULL, 0);
-  int raw_bitpix  = gfits_uncompressed_data_bitpix (zcmptype, header[0].bitpix, NULL, NULL, 0);
+  // size of a pixel in the compressed data (cmp_pixsize), used for byteswap below
   int cmp_pixsize = gfits_compressed_data_pixsize (zcmptype, header[0].bitpix, NULL, NULL, 0);
+
+  // size of a pixel in the raw pixel buffer (before compression) (last option says RICE uses header.bitpix)
+  int raw_pixsize = gfits_uncompressed_data_pixsize (zcmptype, header[0].bitpix, NULL, NULL, 0, TRUE);
+
+  // we also need the bitpix value for the raw uncompressed buffer to distinguish int and floats
+  int raw_bitpix  = gfits_uncompressed_data_bitpix (zcmptype, header[0].bitpix, NULL, NULL, 0, TRUE);
 
   // define compression-specific keywords, update header as needed.
@@ -237 +241 @@
     }
 
-    // GZIP_1 is swapped before compression; GZIP_2 implies swapping.  All other
-    // compression modes require swapping after compression (compresssion & decompression
-    // operate on native ENDIAN)
-    if (strcasecmp(zcmptype, "NONE_2") && // strcasecmp(zcmptype, "NONE") && 
-        strcasecmp(zcmptype, "GZIP_1") && 
-        strcasecmp(zcmptype, "GZIP_2") && 
-        strcasecmp(zcmptype, "RICE_1") && 
-        strcasecmp(zcmptype, "RICE_ONE")) {
-      // Nzdata is number of bytes
-      if (!gfits_byteswap_zdata (zdata, Nzdata, cmp_pixsize)) ESCAPE;
-    }
+    // BYTESWAP the compressed data after compressing.  Compression algorithms which do
+    // not need to byteswap here return 1 for cmp_pixsize.  GZIP_1 is swapped before
+    // compression; GZIP_2 implies swapping.  All other compression modes require swapping
+    // after compression (the compresssion & decompression functions operate on native
+    // ENDIAN data values).
+    if (!gfits_byteswap_zdata (zdata, Nzdata, cmp_pixsize)) ESCAPE;
 
     if (VERBOSE_DUMP && (i == 0)) {