rmutil: WIP try to make a better reorder functionreorder

1 files changed, 108 insertions, 13 deletions

diff --git a/gst/realmedia/rmutils.c b/gst/realmedia/rmutils.c
index b1184257..d8c5110f 100644
--- a/gst/realmedia/rmutils.c
+++ b/gst/realmedia/rmutils.c
@@ -141,7 +141,7 @@ gst_rm_utils_descramble_dnet_buffer (GstBuffer * buf)
   return buf;
 }
 
-static const gint sipr_swaps[38][2] = {
+static const gint sipr_swap_index[38][2] = {
   {0, 63}, {1, 22}, {2, 44}, {3, 90},
   {5, 81}, {7, 31}, {8, 86}, {9, 58},
   {10, 36}, {12, 68}, {13, 39}, {14, 73},
@@ -154,37 +154,132 @@ static const gint sipr_swaps[38][2] = {
   {67, 83}, {77, 80}
 };
 
+#define NIBBLE_BYTE(d,idx)    (d[(idx)>>1])
+#define NIBBLE_BMASK(d,idx)   (NIBBLE_BYTE(d,idx) & (0xf << ((!((idx)&1))<<2)))
+#define NIBBLE_INSERT(v,idx)  ((v) << (((idx)&1)<<2))
+#define NIBBLE_EXTRACT(v,idx) ((v) >> (((idx)&1)<<2))
+#define NIBBLE_GET(d,idx)     (NIBBLE_EXTRACT (NIBBLE_BYTE (d,idx), idx))
+#define NIBBLE_PUT(d,idx,v)   (NIBBLE_BYTE (d,idx) = NIBBLE_BMASK(d,idx) | NIBBLE_INSERT (v,idx))
+
+typedef struct
+{
+  guint8 *data;
+  guint offset;
+  guint8 byte;
+  guint8 store;
+} NibbleParse;
+
+static void
+nibble_parse_init (NibbleParse * parse, guint8 * data, guint nibble)
+{
+  parse->data = data;
+  parse->offset = nibble;
+  parse->byte = data[nibble >> 1];
+  parse->store = parse->byte;
+}
+
+static guint8
+nibble_parse_get (NibbleParse * parse)
+{
+  return parse->byte & 0xf;
+}
+
+static void
+nibble_parse_next (NibbleParse * parse)
+{
+  guint8 res;
+
+  if (parse->offset & 1) {
+    parse->byte >>= 4;
+  } else {
+    parse->byte = parse->data[parse->offset >> 1];
+    parse->store = parse->byte;
+  }
+  parse->offset++;
+
+  return res;
+}
+
+static void
+nibble_parse_store (NibbleParse * parse, guint8 value)
+{
+  parse->store = (parse->store << 4) | value;
+
+  parse->offset++;
+  if (parse->offset & 1) {
+    parse->data[parse->offset >> 1] = parse->byte;
+  }
+}
+
 GstBuffer *
 gst_rm_utils_descramble_sipr_buffer (GstBuffer * buf)
 {
   guint8 *data;
   guint size;
   gint n, bs;
+  NibbleParse pi, po;
 
   buf = gst_buffer_make_writable (buf);
 
   data = GST_BUFFER_DATA (buf);
   size = GST_BUFFER_SIZE (buf);
 
+  /* split the packet in 96 nibbles */
   bs = size * 2 / 96;
 
+  /* we need to swap the nibles of the blocks */
   for (n = 0; n < 38; n++) {
-    int j;
-    int i = bs * sipr_swaps[n][0];
-    int o = bs * sipr_swaps[n][1];
+    gint j, i_idx, o_idx;
+
+    /* get the indexes of the blocks of nibbles that need swapping */
+    i_idx = bs * sipr_swap_index[n][0];
+    o_idx = bs * sipr_swap_index[n][1];
+
+#if 0
+    /* check if we have byte aligned offsets and we can copy bytes */
+    if ((i_idx & 1) == 0 && (o_idx & 1) == 0) {
+      guint8 *i, *o, tmp1, tmp2;
+
+      i = data + (i_idx >> 1);
+      o = data + (o_idx >> 1);
+
+      for (j = bs >> 1; j > 0; j--, i++, o++) {
+        tmp = *i;
+        *i = *o;
+        *o = tmp;
+      }
+      if (bs & 1) {
+        tmp = *i;
+        tmp2 = *o;
+        *i = (tmp2 & 0xf0) | (tmp1 & 0x0f);
+        *o = (tmp1 & 0xf0) | (tmp2 & 0x0f);
+      }
+    } else {
+      for (j = 0; j < bs; j++, i_idx++, o_idx++) {
+        int i, o;
+
+        i = NIBBLE_GET (data, i_idx);
+        o = NIBBLE_GET (data, o_idx);
+
+        NIBBLE_PUT (data, i_idx, o);
+        NIBBLE_PUT (data, o_idx, i);
+      }
+    }
+#else
 
-    /* swap 4bit-nibbles of block 'i' with 'o' */
-    for (j = 0; j < bs; j++, i++, o++) {
-      int x, y;
+    nibble_parse_init (&pi, data, i_idx);
+    nibble_parse_init (&po, data, o_idx);
 
-      x = (data[i >> 1] >> (4 * (i & 1))) & 0xF;
-      y = (data[o >> 1] >> (4 * (o & 1))) & 0xF;
+    for (j = bs; j > 0; j--) {
+      guint8 tmp1, tmp2;
 
-      data[o >> 1] = (x << (4 * (o & 1))) |
-          (data[o >> 1] & (0xF << (4 * !(o & 1))));
-      data[i >> 1] = (y << (4 * (i & 1))) |
-          (data[i >> 1] & (0xF << (4 * !(i & 1))));
+      tmp1 = nibble_parse_next (&pi);
+      tmp2 = nibble_parse_next (&po);
+
+      nibble_parse_store (&pi, tmp2);
+      nibble_parse_store (&po, tmp1);
     }
+#endif
   }
   return buf;
 }