Changeset 148

Timestamp:

06/08/10 04:01:54 (3 years ago)

Author:

faltet

Message:

Introduced BLOSC_MAX_OVERHEAD symbol that is the maximum overhead introduced by Blosc during compression.

Location:

trunk

Files:

• bench/bench.c (modified) (2 diffs)
• src/blosc.c (modified) (2 diffs)
• src/blosc.h (modified) (2 diffs)

trunk/bench/bench.c

@@ -164 +164 @@
   memcpy(srccpy, src, size);
   for (j = 0; j < nchunks; j++) {
-    /* 16 additional bytes should be enough for encoding everything */
-    dest[j] = malloc(size+16);
+    dest[j] = malloc(size+BLOSC_MAX_OVERHEAD);
   }
 
@@ -212 +211 @@
       for (j = 0; j < nchunks; j++) {
         cbytes = blosc_compress(clevel, doshuffle, elsize, size, src,
-                                dest[j], size);
+                                dest[j], size+BLOSC_MAX_OVERHEAD);
       }
     }

trunk/src/blosc.c

@@ -612 +612 @@
 
   /* Last chance for fitting `src` buffer in `dest` */
-  if ((ntbytes == 0) && (nbytes+16 <= maxbytes)) {
+  if ((ntbytes == 0) && (nbytes+BLOSC_MAX_OVERHEAD <= maxbytes)) {
     /* Specify that this buffer is memcpy'ed (bit 2 set to 1 in flags) */
     _dest = (uint8_t *)(dest);
     _dest[2] = 0x2;
-    memcpy(dest+16, src, nbytes);
-    ntbytes = nbytes+16;
+    memcpy(dest+BLOSC_MAX_OVERHEAD, src, nbytes);
+    ntbytes = nbytes+BLOSC_MAX_OVERHEAD;
   }
 
@@ -657 +657 @@
   /* Check whether this buffer is memcpy'ed */
   if (flags == 0x2) {
-    memcpy(dest, src+16, nbytes);
+    memcpy(dest, src+BLOSC_MAX_OVERHEAD, nbytes);
     return nbytes;
   }

trunk/src/blosc.h

@@ -27 +27 @@
 #define BLOSC_VERSION_CFORMAT (BLOSC_VERSION_FORMAT << 8) & (BLOSCLZ_VERSION_FORMAT)
 
+/* The maximum overhead during compression in bytes */
+#define BLOSC_MAX_OVERHEAD 16
 
 /**
@@ -58 +60 @@
 
   The `dest` buffer must have at least the size of `maxbytes`.  Blosc
-  guarantees that if you set `maxbytes` at least to `nbytes` + 16, the
-  compression will always succeed.  The `src` buffer and the `dest`
-  buffer can not overlap.
+  guarantees that if you set `maxbytes` to, at least,
+  (`nbytes`+BLOSC_MAX_OVERHEAD), the compression will always succeed.
+  The `src` buffer and the `dest` buffer can not overlap.
 
   If `src` buffer cannot be compressed into `maxbytes`, the return