The Independent JPEG Group's JPEG software v1

1 files changed, 106 insertions, 0 deletions

diff --git a/jutils.c b/jutils.c
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+/*
+ * jutils.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 miscellaneous utility routines needed for both
+ * compression and decompression.
+ * Note we prefix all global names with "j" to minimize conflicts with
+ * a surrounding application.
+ */
+
+#include "jinclude.h"
+
+
+GLOBAL long
+jround_up (long a, long b)
+/* Compute a rounded up to next multiple of b; a >= 0, b > 0 */
+{
+  a += b-1;
+  return a - (a % b);
+}
+
+
+GLOBAL void
+jcopy_sample_rows (JSAMPARRAY input_array, int source_row,
+		   JSAMPARRAY output_array, int dest_row,
+		   int num_rows, long num_cols)
+/* Copy some rows of samples from one place to another.
+ * num_rows rows are copied from input_array[source_row++]
+ * to output_array[dest_row++]; these areas should not overlap.
+ * The source and destination arrays must be at least as wide as num_cols.
+ */
+{
+  /* On normal machines we can use memcpy().  This won't work on 80x86 because
+   * the sample arrays are FAR and we're assuming a small-pointer memory model.
+   */
+  register JSAMPROW inptr, outptr;
+#ifdef NEED_FAR_POINTERS
+  register long count;
+#else
+  register size_t count = num_cols * SIZEOF(JSAMPLE);
+#endif
+  register int row;
+
+  input_array += source_row;
+  output_array += dest_row;
+
+  for (row = num_rows; row > 0; row--) {
+    inptr = *input_array++;
+    outptr = *output_array++;
+#ifdef NEED_FAR_POINTERS
+    for (count = num_cols; count > 0; count--)
+      *outptr++ = *inptr++;	/* needn't bother with GETJSAMPLE() here */
+#else
+    memcpy((void *) outptr, (void *) inptr, count);
+#endif
+  }
+}
+
+
+GLOBAL void
+jcopy_block_row (JBLOCKROW input_row, JBLOCKROW output_row, long num_blocks)
+/* Copy a row of coefficient blocks from one place to another. */
+{
+  /* On normal machines we can use memcpy().  This won't work on 80x86 because
+   * the block arrays are FAR and we're assuming a small-pointer memory model.
+   */
+#ifdef NEED_FAR_POINTERS
+  register JCOEFPTR inptr, outptr;
+  register int i;
+  register long count;
+
+  for (count = num_blocks; count > 0; count--) {
+    inptr = *input_row++;
+    outptr = *output_row++;
+    for (i = DCTSIZE2; i > 0; i--)
+      *outptr++ = *inptr++;
+  }
+#else
+    memcpy((void *) output_row, (void *) input_row,
+	   (size_t) (num_blocks * (DCTSIZE2 * SIZEOF(JCOEF))));
+#endif
+}
+
+
+GLOBAL void
+jzero_far (void FAR * target, size_t bytestozero)
+/* Zero out a chunk of FAR memory. */
+/* This might be sample-array data, block-array data, or alloc_medium data. */
+{
+  /* On normal machines we can use MEMZERO().  This won't work on 80x86
+   * because we're assuming a small-pointer memory model.
+   */
+#ifdef NEED_FAR_POINTERS
+  register char FAR * ptr = (char FAR *) target;
+  register size_t count;
+
+  for (count = bytestozero; count > 0; count--) {
+    *ptr++ = 0;
+  }
+#else
+  MEMZERO((void *) target, bytestozero);
+#endif
+}