devs/foxbox
1
0
Fork 0
forked from len0rd/rockbox
Code Pull requests Activity

Back to byte-aligned bitswapping

Browse source 
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@2519 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Linus Nielsen Feltzing 2002-10-08 07:43:52 +00:00
parent 591f3ac129
commit 03c13a1a3b
2 changed files with 89 additions and 76 deletions
Download patch file Download diff file Expand all files Collapse all files

39
firmware/bitswap.S
View file

@ -25,36 +25,27 @@
/* Registers used:
*
* r0 Temporary (required by some instructions)
* r1 Low byte
* r2 High byte
* r3 Result after flip
* r4 Data
* r5 Length
* r6 Current (position in Data)
* r7 Flip table
* r1 Flip table
* r4 Argument: Data pointer
* r5 Argument: Length (in bytes)
*/
/* TODO: Optimize for DRAM burst operation by reading and writing in chunks
We do not want to optimize by reading/writing words, because the data
pointer may be odd */
_bitswap:
mov.l .fliptable,r7
mov r4,r6
add r5,r6 /* goto end of buffer */
add r5,r6 /* (direction IS important) */
mov.l .fliptable,r1
add r4,r5 /* Calculate end of buffer */
bra .init
.loop:
mov.w @r4,r1 /* data to flip */
swap.b r1,r2
extu.b r2,r0 /* high byte */
mov.b @(r0,r7),r2
extu.b r2,r0 /* remove any sign extend */
swap.b r0,r3 /* put high byte in result */
extu.b r1,r0 /* low byte */
mov.b @(r0,r7),r1
extu.b r1,r0 /* remove any sign extend */
or r0,r3 /* put low byte in result */
mov.w r3,@r4 /* store result */
add #2,r4
mov.b @r4,r0 /* Data to flip */
extu.b r0,r0 /* Zero extend */
mov.b @(r0,r1),r0 /* Look up in the flip table */
mov.b r0,@r4 /* Store result */
add #1,r4
.init:
cmp/gt r4,r6 /* while (data < start+length*2) */
cmp/gt r4,r5 /* while (dataptr < start+length) */
bt .loop
rts

40
firmware/mpeg.c
View file

@ -35,7 +35,7 @@
#include "file.h"
#endif
extern void bitswap(unsigned short *data, int length);
extern void bitswap(unsigned char *data, int length);
#define MPEG_CHUNKSIZE 0x180000
#define MPEG_SWAP_CHUNKSIZE 0x8000
@ -465,9 +465,30 @@ static void mas_poll_start(int interval_in_ms)
TSR1 &= ~0x02;
TIER1 = 0xf9; /* Enable GRA match interrupt */
TSTR |= 0x02; /* Start timer 2 */
TSTR |= 0x02; /* Start timer 1 */
}
#ifdef DEBUG
static void dbg_timer_start(void)
{
/* We are using timer 2 */
TSTR &= ~0x04; /* Stop the timer */
TSNC &= ~0x04; /* No synchronization */
TMDR &= ~0x44; /* Operate normally */
TCNT1 = 0; /* Start counting at 0 */
TCR1 = 0x03; /* Sysclock/8 */
TSTR |= 0x04; /* Start timer 2 */
}
static int dbg_cnt2us(unsigned int cnt)
{
return (cnt * 10000) / (FREQ/800);
}
#endif
static int get_unplayed_space(void)
{
int space = mp3buf_write - mp3buf_read;
@ -704,7 +725,7 @@ static int new_file(int steps)
}
else
{
/* skip past id3v2 tag (to an even byte) */
/* skip past id3v2 tag */
lseek(mpeg_file,
id3tags[new_tag_idx]->id3.id3v2len,
SEEK_SET);
@ -827,9 +848,9 @@ static void mpeg_thread(void)
set_elapsed(id3);
}
else {
/* skip past id3v2 tag (to an even byte) */
/* skip past id3v2 tag */
lseek(mpeg_file,
id3tags[tag_read_idx]->id3.id3v2len & ~1,
id3tags[tag_read_idx]->id3.id3v2len,
SEEK_SET);
}
@ -1046,8 +1067,6 @@ static void mpeg_thread(void)
newpos = id3->id3v2len;
}
newpos = newpos & ~1;
if (mpeg_file >= 0)
curpos = lseek(mpeg_file, 0, SEEK_CUR);
else
@ -1196,8 +1215,7 @@ static void mpeg_thread(void)
DEBUGF("B %x\n", amount_to_swap);
t1 = current_tick;
bitswap((unsigned short *)(mp3buf + mp3buf_swapwrite),
(amount_to_swap+1)/2);
bitswap(mp3buf + mp3buf_swapwrite, amount_to_swap);
t2 = current_tick;
DEBUGF("time: %d\n", t2 - t1);
@ -2054,6 +2072,10 @@ void mpeg_init(int volume, int bass, int treble, int balance, int loudness, int
memset(id3tags, sizeof(id3tags), 0);
memset(_id3tags, sizeof(id3tags), 0);
#ifdef DEBUG
dbg_timer_start();
#endif
}
/* -----------------------------------------------------------------