Changeset 407 for libmpc/trunk/libmpcdec/mpc_demux.c

Timestamp:

06/02/08 16:23:00 (16 years ago)

Author:

r2d

Message:

added a bound to the seek table size, varying the step between seek points if necessary

File:

• libmpc/trunk/libmpcdec/mpc_demux.c (modified) (6 diffs)

libmpc/trunk/libmpcdec/mpc_demux.c

@@ -42 +42 @@
 #include "mpc_bits_reader.h"
 
+/// maximum number of seek points in the table. The distance between points will
+/// be adapted so this value is never exceeded.
+#define MAX_SEEK_TABLE_SIZE     65536
+
 // streaminfo.c
 mpc_status streaminfo_read_header_sv8(mpc_streaminfo* si,
@@ -205 +209 @@
 static mpc_status mpc_demux_seek_init(mpc_demux * d)
 {
+        size_t seek_table_size;
         if (d->seek_table != 0)
                 return MPC_STATUS_OK;
@@ -211 +216 @@
         if (d->si.block_pwr > d->seek_pwr)
                 d->seek_pwr = d->si.block_pwr;
-        d->seek_table = malloc((size_t)(2 + d->si.samples / (MPC_FRAME_LENGTH << d->seek_pwr)) * sizeof(mpc_seek_t));
+        seek_table_size = (2 + d->si.samples / (MPC_FRAME_LENGTH << d->seek_pwr));
+        while (seek_table_size > MAX_SEEK_TABLE_SIZE) {
+                d->seek_pwr++;
+                seek_table_size = (2 + d->si.samples / (MPC_FRAME_LENGTH << d->seek_pwr));
+        }
+        d->seek_table = malloc((size_t)(seek_table_size * sizeof(mpc_seek_t)));
         if (d->seek_table == 0)
                 return MPC_STATUS_FILE;
@@ -223 +233 @@
 {
         mpc_uint64_t tmp;
-        mpc_seek_t * table;
+        mpc_seek_t * table, last[2];
         mpc_bits_reader r = d->bits_reader;
-        mpc_uint_t i;
+        mpc_uint_t i, diff_pwr = 0, mask;
+        mpc_uint32_t file_table_size;
 
         if (d->seek_table != 0)
@@ -231 +242 @@
 
         mpc_bits_get_size(&r, &tmp);
-        d->seek_table_size = (mpc_seek_t) tmp;
+        file_table_size = (mpc_seek_t) tmp;
         d->seek_pwr = d->si.block_pwr + mpc_bits_read(&r, 4);
+
         tmp = 2 + d->si.samples / (MPC_FRAME_LENGTH << d->seek_pwr);
-        if (tmp < d->seek_table_size) tmp = d->seek_table_size;
-        d->seek_table = malloc((size_t)(tmp * sizeof(mpc_seek_t)));
+        while (tmp > MAX_SEEK_TABLE_SIZE) {
+                d->seek_pwr++;
+                diff_pwr++;
+                tmp = 2 + d->si.samples / (MPC_FRAME_LENGTH << d->seek_pwr);
+        }
+        if ((file_table_size >> diff_pwr) > tmp)
+                file_table_size = tmp << diff_pwr;
+        d->seek_table = malloc((size_t) (tmp * sizeof(mpc_seek_t)));
+        d->seek_table_size = (file_table_size + ((1 << diff_pwr) - 1)) >> diff_pwr;
 
         table = d->seek_table;
         mpc_bits_get_size(&r, &tmp);
-        table[0] = (mpc_seek_t) (tmp + d->si.header_position) * 8;
+        table[0] = last[0] = (mpc_seek_t) (tmp + d->si.header_position) * 8;
 
         if (d->seek_table_size == 1)
@@ -245 +264 @@
 
         mpc_bits_get_size(&r, &tmp);
-        table[1] = (mpc_seek_t) (tmp + d->si.header_position) * 8;
-
-        for (i = 2; i < d->seek_table_size; i++) {
+        last[1] = (mpc_seek_t) (tmp + d->si.header_position) * 8;
+        if (diff_pwr == 0) table[1] = last[1];
+
+        mask = (1 << diff_pwr) - 1;
+        for (i = 2; i < file_table_size; i++) {
                 int code = mpc_bits_golomb_dec(&r, 12);
                 if (code & 1)
                         code = -(code & (-1 << 1));
                 code <<= 2;
-                table[i] = code + 2 * table[i-1] - table[i-2];
+                last[i & 1] = code + 2 * last[(i-1) & 1] - last[i & 1];
+                if ((i & mask) == 0)
+                        table[i >> diff_pwr] = last[i & 1];
         }
 }