Faster, 8-bit bitswap by Magnus Holmgren

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@1819 a1c6a512-1295-4272-9138-f99709370657

3 files changed, 104 insertions, 61 deletions

diff --git a/firmware/Makefile b/firmware/Makefile
index 7d09809..aab5249 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -35,7 +35,7 @@ endif
 
 SRC := $(wildcard drivers/*.c common/*.c *.c)
 
-OBJS := $(SRC:%.c=$(OBJDIR)/%.o) $(OBJDIR)/crt0.o
+OBJS := $(SRC:%.c=$(OBJDIR)/%.o) $(OBJDIR)/crt0.o $(OBJDIR)/bitswap.o
 DEPS:=.deps
 DEPDIRS:=$(DEPS) $(DEPS)/drivers $(DEPS)/common $(DEPS)/malloc
 
diff --git a/firmware/bitswap.S b/firmware/bitswap.S
new file mode 100644
index 0000000..5f94fed
--- /dev/null
+++ b/firmware/bitswap.S
@@ -0,0 +1,101 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2002 by Magnus Holmgren
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+	.section	.icode,"ax",@progbits
+    	.global		_bitswap
+	.align 		4
+	.type		_bitswap,@function
+
+/* 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
+ */
+
+_bitswap:
+	mov.l	.fliptable,r7
+	mov	r4,r6
+	add	r5,r6				/* goto end of buffer */
+	add	r5,r6				/* (direction IS important) */
+	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
+.init:
+	cmp/gt	r4,r6				/* while (data < start+length*2) */
+	bt	.loop
+	rts
+
+	.align	4
+
+.fliptable:
+	.long	_fliptable
+
+_fliptable:
+	.byte	0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0
+	.byte	0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0
+	.byte	0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8
+	.byte	0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8
+	.byte	0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4
+	.byte	0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4
+	.byte	0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec
+	.byte	0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc
+	.byte	0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2
+	.byte	0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2
+	.byte	0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea
+	.byte	0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa
+	.byte	0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6
+	.byte	0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6
+	.byte	0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee
+	.byte	0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe
+	.byte	0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1
+	.byte	0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1
+	.byte	0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9
+	.byte	0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9
+	.byte	0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5
+	.byte	0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5
+	.byte	0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed
+	.byte	0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd
+	.byte	0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3
+	.byte	0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3
+	.byte	0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb
+	.byte	0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb
+	.byte	0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7
+	.byte	0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7
+	.byte	0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef
+	.byte	0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff
+
+.end:
+	.size	_bitswap,.end-_bitswap
diff --git a/firmware/mpeg.c b/firmware/mpeg.c
index a3fdf21..a49f444 100644
--- a/firmware/mpeg.c
+++ b/firmware/mpeg.c
@@ -35,6 +35,8 @@
 #include "file.h"
 #endif
 
+extern void bitswap(unsigned short *data, int length);
+
 #define MPEG_CHUNKSIZE  0x180000
 #define MPEG_SWAP_CHUNKSIZE  0x8000
 #define MPEG_HIGH_WATER  2
@@ -347,44 +349,6 @@ static unsigned int prescale_table[] =
 };
 #endif
 
-static unsigned char fliptable[] =
-{
-    0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0, 
-    0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0, 
-    0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8, 
-    0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8, 
-    0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4, 
-    0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4, 
-    0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec, 
-    0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc, 
-    0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2, 
-    0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2, 
-    0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea, 
-    0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa, 
-    0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6, 
-    0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6, 
-    0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee, 
-    0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe, 
-    0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1, 
-    0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1, 
-    0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9, 
-    0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9, 
-    0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5, 
-    0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5, 
-    0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed, 
-    0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd, 
-    0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3, 
-    0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3, 
-    0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb, 
-    0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb, 
-    0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7, 
-    0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7, 
-    0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef, 
-    0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff
-};
-
-static unsigned short big_fliptable[65536];
-
 static struct event_queue mpeg_queue;
 static char mpeg_stack[DEFAULT_STACK_SIZE + 0x1000];
 static char mpeg_thread_name[] = "mpeg";
@@ -407,16 +371,6 @@ 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;
@@ -518,16 +472,6 @@ static void dma_tick(void)
     }
 }
 
-static void bitswap(unsigned short *data, int length) __attribute__ ((section (".icode")));
-static void bitswap(unsigned short *data, int length)
-{
-    int i = length;
-    while(i--)
-    {
-        data[i] = big_fliptable[data[i]];
-    }
-}
-
 static void reset_mp3_buffer(void)
 {
     mp3buf_read = 0;
@@ -1621,8 +1565,6 @@ void mpeg_init(int volume, int bass, int treble, int balance, int loudness, int
     
     mp3buflen = mp3end - mp3buf;
 
-    create_fliptable();
-    
     queue_init(&mpeg_queue);
     create_thread(mpeg_thread, mpeg_stack,
                   sizeof(mpeg_stack), mpeg_thread_name);