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rm: add function to descramble sipr

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This commit is contained in:
Wim Taymans 2010-05-13 17:57:02 +02:00
parent 7f685c4a21
commit 0b73505c61
2 changed files with 49 additions and 0 deletions
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48
gst/realmedia/rmutils.c
View file

@ -140,3 +140,51 @@ gst_rm_utils_descramble_dnet_buffer (GstBuffer * buf)
}
return buf;
}
static const gint sipr_swaps[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},
{15, 53}, {16, 69}, {17, 57}, {19, 88},
{20, 34}, {21, 71}, {24, 46}, {25, 94},
{26, 54}, {28, 75}, {29, 50}, {32, 70},
{33, 92}, {35, 74}, {38, 85}, {40, 56},
{42, 87}, {43, 65}, {45, 59}, {48, 79},
{49, 93}, {51, 89}, {55, 95}, {61, 76},
{67, 83}, {77, 80}
};
GstBuffer *
gst_rm_utils_descramble_sipr_buffer (GstBuffer * buf)
{
guint8 *data;
guint size;
gint n, bs;
buf = gst_buffer_make_writable (buf);
data = GST_BUFFER_DATA (buf);
size = GST_BUFFER_SIZE (buf);
bs = size * 2 / 96;
for (n = 0; n < 38; n++) {
int j;
int i = bs * sipr_swaps[n][0];
int o = bs * sipr_swaps[n][1];
/* swap 4bit-nibbles of block 'i' with 'o' */
for (j = 0; j < bs; j++, i++, o++) {
int x, y;
x = (data[i >> 1] >> (4 * (i & 1))) & 0xF;
y = (data[o >> 1] >> (4 * (o & 1))) & 0xF;
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))));
}
}
return buf;
}

1
gst/realmedia/rmutils.h
View file

@ -39,6 +39,7 @@ GstTagList *gst_rm_utils_read_tags (const guint8 * data,
GstRmUtilsStringReadFunc func);
GstBuffer *gst_rm_utils_descramble_dnet_buffer (GstBuffer * buf);
GstBuffer *gst_rm_utils_descramble_sipr_buffer (GstBuffer * buf);
G_END_DECLS