Changeset 15312 for branches/eam_branch_20071015/Ohana/src/libfits/doc/notes-compress.txt

Timestamp:

Oct 14, 2007, 1:54:24 PM (19 years ago)

Author:

eugene

Message:

cleanup libfits header, some apis (gfits_matrix_size to gfits_data_size), adding bits for reading compressed images

File:

• branches/eam_branch_20071015/Ohana/src/libfits/doc/notes-compress.txt (modified) (3 diffs)

branches/eam_branch_20071015/Ohana/src/libfits/doc/notes-compress.txt

@@ +1 @@
+
+TFORMn : rPt(e_max)
+r is 0, 1, or absent
+P is literal
+t is datatype character for binary tables
+e_max is the largest record in the column
+
+data column actually contains: 2 32bit values:
+Length + Offset
+
+THEAP : offset from start of data to start of heap
+(note that the heap starts at NAXIS1 x NAXIS2, not Nx2880 bytes). 
+
+total size of heap segment (gap + heap data) is PCOUNT
 
 I need to implement (at least) support for read of compressed images.
@@ -16 +30 @@
     level ones as needed.
 
-* possible needed APIs:
+* possible needed APIs & upgrades:
 
   - gfits_image_is_compressed (Header *header) 
@@ -30 +44 @@
     compress the given image returning the table data
 
+  o include PCOUNT in data area size (gfits_matrix_size)
 
+  o read heap when reading table (gfits_fread_table_data)
+
+  - void *gfits_varlength_column_pointer (FTable *ftable, VarLengthColumn *column, int row);
+
+  o int gfits_varlength_column_define (FTable *ftable, VarLengthColumn *def, int column);
+
+