Introduce fast paths to speed up NULL color conversion somewhat, particularly when using 64-bit code; on the decompression side, the "slow path" also now use an approach similar to that of the compression side (with the component loop outside of the column loop rather than inside.) This is faster when using 32-bit code.

git-svn-id: svn://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1520 632fc199-4ca6-4c93-a231-07263d6284db

1 files changed, 42 insertions, 12 deletions

diff --git a/jdcolor.c b/jdcolor.c
index 779fa51..38db90f 100644
--- a/jdcolor.c
+++ b/jdcolor.c
@@ -6,7 +6,7 @@
  * Modified 2011 by Guido Vollbeding.
  * libjpeg-turbo Modifications:
  * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
- * Copyright (C) 2009, 2011-2012, 2014, D. R. Commander.
+ * Copyright (C) 2009, 2011-2012, 2014-2015, D. R. Commander.
  * Copyright (C) 2013, Linaro Limited.
  * For conditions of distribution and use, see the accompanying README file.
  *
@@ -364,23 +364,53 @@ null_convert (j_decompress_ptr cinfo,
               JSAMPIMAGE input_buf, JDIMENSION input_row,
               JSAMPARRAY output_buf, int num_rows)
 {
-  register JSAMPROW inptr, outptr;
-  register JDIMENSION count;
+  register JSAMPROW inptr, inptr0, inptr1, inptr2, inptr3, outptr;
+  register JDIMENSION col;
   register int num_components = cinfo->num_components;
   JDIMENSION num_cols = cinfo->output_width;
   int ci;
 
-  while (--num_rows >= 0) {
-    for (ci = 0; ci < num_components; ci++) {
-      inptr = input_buf[ci][input_row];
-      outptr = output_buf[0] + ci;
-      for (count = num_cols; count > 0; count--) {
-        *outptr = *inptr++;     /* needn't bother with GETJSAMPLE() here */
-        outptr += num_components;
+  if (num_components == 3) {
+    while (--num_rows >= 0) {
+      inptr0 = input_buf[0][input_row];
+      inptr1 = input_buf[1][input_row];
+      inptr2 = input_buf[2][input_row];
+      input_row++;
+      outptr = *output_buf++;
+      for (col = 0; col < num_cols; col++) {
+        *outptr++ = inptr0[col];
+        *outptr++ = inptr1[col];
+        *outptr++ = inptr2[col];
       }
     }
-    input_row++;
-    output_buf++;
+  } else if (num_components == 4) {
+    while (--num_rows >= 0) {
+      inptr0 = input_buf[0][input_row];
+      inptr1 = input_buf[1][input_row];
+      inptr2 = input_buf[2][input_row];
+      inptr3 = input_buf[3][input_row];
+      input_row++;
+      outptr = *output_buf++;
+      for (col = 0; col < num_cols; col++) {
+        *outptr++ = inptr0[col];
+        *outptr++ = inptr1[col];
+        *outptr++ = inptr2[col];
+        *outptr++ = inptr3[col];
+      }
+    }
+  } else {
+    while (--num_rows >= 0) {
+      for (ci = 0; ci < num_components; ci++) {
+        inptr = input_buf[ci][input_row];
+        outptr = *output_buf;
+        for (col = 0; col < num_cols; col++) {
+          outptr[ci] = inptr[col];
+          outptr += num_components;
+        }
+      }
+      output_buf++;
+      input_row++;
+    }
   }
 }