1 files changed, 133 insertions, 0 deletions
diff --git a/jdsample.c b/jdsample.c
new file mode 100644
index 0000000..15dbf4f
--- /dev/null
+++ b/jdsample.c
@@ -0,0 +1,133 @@
+/*
+ * jdsample.c
+ *
+ * Copyright (C) 1991, Thomas G. Lane.
+ * This file is part of the Independent JPEG Group's software.
+ * For conditions of distribution and use, see the accompanying README file.
+ *
+ * This file contains un-subsampling routines.
+ * These routines are invoked via the unsubsample and
+ * unsubsample_init/term methods.
+ */
+
+#include "jinclude.h"
+
+
+/*
+ * Initialize for un-subsampling a scan.
+ */
+
+METHODDEF void
+unsubsample_init (decompress_info_ptr cinfo)
+{
+  /* no work for now */
+}
+
+
+/*
+ * Un-subsample pixel values of a single component.
+ * This version only handles integral sampling ratios.
+ */
+
+METHODDEF void
+unsubsample (decompress_info_ptr cinfo, int which_component,
+	     long input_cols, int input_rows,
+	     long output_cols, int output_rows,
+	     JSAMPARRAY above, JSAMPARRAY input_data, JSAMPARRAY below,
+	     JSAMPARRAY output_data)
+{
+  jpeg_component_info * compptr = cinfo->cur_comp_info[which_component];
+  short h_expand, v_expand, h, v;
+  int inrow, outrow;
+  long incol;
+  JSAMPROW inptr, outptr;
+  JSAMPLE invalue;
+
+  /* TEMP FOR DEBUGGING PIPELINE CONTROLLER */
+  if (input_rows != compptr->v_samp_factor ||
+      output_rows != cinfo->max_v_samp_factor ||
+      (input_cols % compptr->h_samp_factor) != 0 ||
+      (output_cols % cinfo->max_h_samp_factor) != 0 ||
+      output_cols*compptr->h_samp_factor != input_cols*cinfo->max_h_samp_factor)
+    ERREXIT(cinfo->emethods, "Bogus unsubsample parameters");
+
+  h_expand = cinfo->max_h_samp_factor / compptr->h_samp_factor;
+  v_expand = cinfo->max_v_samp_factor / compptr->v_samp_factor;
+
+  outrow = 0;
+  for (inrow = 0; inrow < input_rows; inrow++) {
+    for (v = 0; v < v_expand; v++) {
+      inptr = input_data[inrow];
+      outptr = output_data[outrow++];
+      for (incol = 0; incol < input_cols; incol++) {
+	invalue = GETJSAMPLE(*inptr++);
+	for (h = 0; h < h_expand; h++) {
+	  *outptr++ = invalue;
+	}
+      }
+    }
+  }
+}
+
+
+/*
+ * Un-subsample pixel values of a single component.
+ * This version handles the special case of a full-size component.
+ */
+
+METHODDEF void
+fullsize_unsubsample (decompress_info_ptr cinfo, int which_component,
+		      long input_cols, int input_rows,
+		      long output_cols, int output_rows,
+		      JSAMPARRAY above, JSAMPARRAY input_data, JSAMPARRAY below,
+		      JSAMPARRAY output_data)
+{
+  if (input_cols != output_cols || input_rows != output_rows) /* DEBUG */
+    ERREXIT(cinfo->emethods, "Pipeline controller messed up");
+
+  jcopy_sample_rows(input_data, 0, output_data, 0, output_rows, output_cols);
+}
+
+
+
+/*
+ * Clean up after a scan.
+ */
+
+METHODDEF void
+unsubsample_term (decompress_info_ptr cinfo)
+{
+  /* no work for now */
+}
+
+
+
+/*
+ * The method selection routine for unsubsampling.
+ * Note that we must select a routine for each component.
+ */
+
+GLOBAL void
+jselunsubsample (decompress_info_ptr cinfo)
+{
+  short ci;
+  jpeg_component_info * compptr;
+
+  if (cinfo->CCIR601_sampling)
+    ERREXIT(cinfo->emethods, "CCIR601 subsampling not implemented yet");
+
+  for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
+    compptr = cinfo->cur_comp_info[ci];
+    if (compptr->h_samp_factor == cinfo->max_h_samp_factor &&
+	compptr->v_samp_factor == cinfo->max_v_samp_factor)
+      cinfo->methods->unsubsample[ci] = fullsize_unsubsample;
+    else if ((cinfo->max_h_samp_factor % compptr->h_samp_factor) == 0 &&
+	     (cinfo->max_v_samp_factor % compptr->v_samp_factor) == 0)
+      cinfo->methods->unsubsample[ci] = unsubsample;
+    else
+      ERREXIT(cinfo->emethods, "Fractional subsampling not implemented yet");
+  }
+
+  cinfo->methods->unsubsample_init = unsubsample_init;
+  cinfo->methods->unsubsample_term = unsubsample_term;
+}