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Accelerated bit swapping

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@1075 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Linus Nielsen Feltzing 2002-06-19 12:44:32 +00:00
parent c57dbe78fa
commit a124e87f84
1 changed files with 19 additions and 3 deletions
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22
firmware/mpeg.c
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@ -119,6 +119,8 @@ static unsigned char fliptable[] =
0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff
};
static unsigned short big_fliptable[65536];
static struct event_queue mpeg_queue;
static int mpeg_stack[MPEG_STACK_SIZE/sizeof(int)];
@ -138,6 +140,16 @@ static bool filling; /* We are filling the buffer with data from disk */
static int mpeg_file;
static void create_fliptable(void)
{
int i;
for(i = 0;i < 65536;i++)
{
big_fliptable[i] = fliptable[i & 0xff] | (fliptable[i >> 8] << 8);
}
}
static void mas_poll_start(int interval_in_ms)
{
unsigned int count;
@ -207,12 +219,12 @@ static void dma_tick(void)
}
}
static void bitswap(unsigned char *data, int length)
static void bitswap(unsigned short *data, int length)
{
int i = length;
while(i--)
{
data[i] = fliptable[data[i]];
data[i] = big_fliptable[data[i]];
}
}
@ -393,7 +405,9 @@ static void mpeg_thread(void)
if(len > 0)
{
DEBUGF("B\n");
bitswap(mp3buf + mp3buf_write, len);
bitswap((unsigned short *)(mp3buf + mp3buf_write),
(len+1)/2);
mp3buf_write += len;
if(mp3buf_write >= mp3buflen)
@ -609,6 +623,8 @@ void mpeg_init(void)
mp3buflen = mp3end - mp3buf;
create_fliptable();
queue_init(&mpeg_queue);
create_thread(mpeg_thread, mpeg_stack, sizeof(mpeg_stack));