rmdemux: add better sipr nibble swap routine

This commit is contained in:
Wim Taymans 2010-05-14 16:02:47 +02:00
parent a68951f0bb
commit 4044046ac1
3 changed files with 122 additions and 18 deletions

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@ -261,6 +261,8 @@ gst_rmdemux_init (GstRMDemux * rmdemux)
rmdemux->first_ts = GST_CLOCK_TIME_NONE; rmdemux->first_ts = GST_CLOCK_TIME_NONE;
rmdemux->base_ts = GST_CLOCK_TIME_NONE; rmdemux->base_ts = GST_CLOCK_TIME_NONE;
rmdemux->need_newsegment = TRUE; rmdemux->need_newsegment = TRUE;
gst_rm_utils_run_tests ();
} }
static gboolean static gboolean

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@ -21,6 +21,7 @@
#include "config.h" #include "config.h"
#endif #endif
#include <string.h>
#include "rmutils.h" #include "rmutils.h"
gchar * gchar *
@ -141,7 +142,69 @@ gst_rm_utils_descramble_dnet_buffer (GstBuffer * buf)
return buf; return buf;
} }
static const gint sipr_swaps[38][2] = { static void
gst_rm_utils_swap_nibbles (guint8 * data, gint idx1, gint idx2, gint len)
{
guint8 *d1, *d2, tmp1, tmp2, tmp1n, tmp2n;
if ((idx2 & 1) && !(idx1 & 1)) {
/* align destination to a byte by swapping the indexes */
tmp1 = idx1;
idx1 = idx2;
idx2 = tmp1;
}
d1 = data + (idx1 >> 1);
d2 = data + (idx2 >> 1);
/* check if we have aligned offsets and we can copy bytes */
if ((idx1 & 1) == (idx2 & 1)) {
if (idx1 & 1) {
/* swap first nibble */
tmp1 = *d1;
tmp2 = *d2;
*d1++ = (tmp2 & 0xf0) | (tmp1 & 0x0f);
*d2++ = (tmp1 & 0xf0) | (tmp2 & 0x0f);
len--;
}
for (; len > 1; len -= 2) {
/* swap 2 nibbles */
tmp1 = *d1;
*d1++ = *d2;
*d2++ = tmp1;
}
if (len) {
/* swap leftover nibble */
tmp1 = *d1;
tmp2 = *d2;
*d1 = (tmp2 & 0x0f) | (tmp1 & 0xf0);
*d2 = (tmp1 & 0x0f) | (tmp2 & 0xf0);
}
} else {
/* preload nibbles from source */
tmp2n = tmp1 = tmp1n = *d1;
tmp2 = *d2;
for (; len > 1; len -= 2) {
/* assemble nibbles */
*d1++ = (tmp2n & 0x0f) | (tmp2 << 4);
tmp1n = *d1;
*d2++ = (tmp1n << 4) | (tmp1 >> 4);
tmp1 = tmp1n;
tmp2n = (tmp2 >> 4);
tmp2 = *d2;
}
if (len) {
/* last leftover */
*d1 = (tmp2 << 4) | (tmp2n & 0x0f);
*d2 = (tmp1 >> 4) | (tmp2 & 0xf0);
} else {
*d1 = (tmp1 & 0xf0) | (tmp2n);
}
}
}
static const gint sipr_swap_index[38][2] = {
{0, 63}, {1, 22}, {2, 44}, {3, 90}, {0, 63}, {1, 22}, {2, 44}, {3, 90},
{5, 81}, {7, 31}, {8, 86}, {9, 58}, {5, 81}, {7, 31}, {8, 86}, {9, 58},
{10, 36}, {12, 68}, {13, 39}, {14, 73}, {10, 36}, {12, 68}, {13, 39}, {14, 73},
@ -161,30 +224,66 @@ gst_rm_utils_descramble_sipr_buffer (GstBuffer * buf)
guint size; guint size;
gint n, bs; gint n, bs;
size = GST_BUFFER_SIZE (buf);
/* split the packet in 96 blocks of nibbles */
bs = size * 2 / 96;
if (bs == 0)
return buf;
buf = gst_buffer_make_writable (buf); buf = gst_buffer_make_writable (buf);
data = GST_BUFFER_DATA (buf); data = GST_BUFFER_DATA (buf);
size = GST_BUFFER_SIZE (buf);
bs = size * 2 / 96;
/* we need to perform 38 swaps on the blocks */
for (n = 0; n < 38; n++) { for (n = 0; n < 38; n++) {
int j; gint idx1, idx2;
int i = bs * sipr_swaps[n][0];
int o = bs * sipr_swaps[n][1];
/* swap 4bit-nibbles of block 'i' with 'o' */ /* get the indexes of the blocks of nibbles that need swapping */
for (j = 0; j < bs; j++, i++, o++) { idx1 = bs * sipr_swap_index[n][0];
int x, y; idx2 = bs * sipr_swap_index[n][1];
x = (data[i >> 1] >> (4 * (i & 1))) & 0xF; /* swap the blocks */
y = (data[o >> 1] >> (4 * (o & 1))) & 0xF; gst_rm_utils_swap_nibbles (data, idx1, idx2, bs);
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; return buf;
} }
void
gst_rm_utils_run_tests (void)
{
#if 0
guint8 tab1[] = { 0x10, 0x32, 0x54, 0x76, 0x98, 0xba, 0xdc, 0xfe };
guint8 tab2[8];
memcpy (tab2, tab1, 8);
gst_util_dump_mem (tab2, 8);
gst_rm_utils_swap_nibbles (tab2, 0, 8, 4);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 0, 8, 5);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 1, 8, 4);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 1, 8, 5);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 0, 9, 4);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 0, 9, 5);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 1, 9, 4);
gst_util_dump_mem (tab2, 8);
memcpy (tab2, tab1, 8);
gst_rm_utils_swap_nibbles (tab2, 1, 9, 5);
gst_util_dump_mem (tab2, 8);
#endif
}

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@ -41,6 +41,9 @@ GstTagList *gst_rm_utils_read_tags (const guint8 * data,
GstBuffer *gst_rm_utils_descramble_dnet_buffer (GstBuffer * buf); GstBuffer *gst_rm_utils_descramble_dnet_buffer (GstBuffer * buf);
GstBuffer *gst_rm_utils_descramble_sipr_buffer (GstBuffer * buf); GstBuffer *gst_rm_utils_descramble_sipr_buffer (GstBuffer * buf);
void gst_rm_utils_run_tests (void);
G_END_DECLS G_END_DECLS
#endif /* __GST_RM_UTILS_H__ */ #endif /* __GST_RM_UTILS_H__ */