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-rw-r--r--firmware/asm/SOURCES1
-rw-r--r--firmware/asm/arm/ffs.S75
-rw-r--r--firmware/asm/ffs.c56
-rw-r--r--firmware/asm/m68k/ffs.S78
-rw-r--r--firmware/asm/mips/ffs.S59
5 files changed, 269 insertions, 0 deletions
diff --git a/firmware/asm/SOURCES b/firmware/asm/SOURCES
index f56d99a7de..23563d11d8 100644
--- a/firmware/asm/SOURCES
+++ b/firmware/asm/SOURCES
@@ -1,3 +1,4 @@
1ffs.c
1memset16.c 2memset16.c
2#if (CONFIG_PLATFORM & PLATFORM_NATIVE) || defined(HAVE_ROCKBOX_C_LIBRARY) 3#if (CONFIG_PLATFORM & PLATFORM_NATIVE) || defined(HAVE_ROCKBOX_C_LIBRARY)
3memcpy.c 4memcpy.c
diff --git a/firmware/asm/arm/ffs.S b/firmware/asm/arm/ffs.S
new file mode 100644
index 0000000000..4e912c5317
--- /dev/null
+++ b/firmware/asm/arm/ffs.S
@@ -0,0 +1,75 @@
1/***************************************************************************
2 * __________ __ ___.
3 * Open \______ \ ____ ____ | | _\_ |__ _______ ___
4 * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
5 * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
6 * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
7 * \/ \/ \/ \/ \/
8 * $Id$
9 *
10 * Copyright (C) 2008 by Michael Sevakis
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version 2
15 * of the License, or (at your option) any later version.
16 *
17 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
18 * KIND, either express or implied.
19 *
20 ****************************************************************************/
21 #include "config.h"
22
23/****************************************************************************
24 * int find_first_set_bit(uint32_t val);
25 *
26 * Find the index of the least significant set bit in the 32-bit word.
27 *
28 * return values:
29 * 0 - bit 0 is set
30 * 1 - bit 1 is set
31 * ...
32 * 31 - bit 31 is set
33 * 32 - no bits set
34 ****************************************************************************/
35 .align 2
36 .global find_first_set_bit
37 .type find_first_set_bit,%function
38find_first_set_bit:
39 @ Standard trick to isolate bottom bit in r0 or 0 if r0 = 0 on entry
40 rsb r2, r0, #0 @ r1 = r0 & -r0
41 ands r1, r0, r2 @
42
43 @ now r1 has at most one set bit, call this X
44
45#if ARM_ARCH >= 5
46 clz r0, r1 @ Get lead 0's count
47 rsbne r0, r0, #31 @ lead 0's -> bit index
48 bx lr @
49#else
50 @ this is the ffs algorithm devised by D.Seal and posted to
51 @ comp.sys.arm on 16 Feb 1994.
52 @
53 @ Output modified to suit Rockbox purposes.
54
55 orrne r1, r1, r1, lsl #4 @ r1 = X * 0x11
56 orrne r1, r1, r1, lsl #6 @ r1 = X * 0x451
57 rsbne r1, r1, r1, lsl #16 @ r1 = X * 0x0450fbaf
58
59 @ now lookup in table indexed on top 6 bits of r1
60 ldrb r0, [ pc, r1, lsr #26 ] @ exploit location of table
61 bx lr @
62
63L_ffs_table:
64 @ 0 1 2 3 4 5 6 7
65 @----------------------------------------------
66 .byte 32, 0, 1, 12, 2, 6, 0, 13 @ 0- 7
67 .byte 3, 0, 7, 0, 0, 0, 0, 14 @ 8-15
68 .byte 10, 4, 0, 0, 8, 0, 0, 25 @ 16-23
69 .byte 0, 0, 0, 0, 0, 21, 27, 15 @ 24-31
70 .byte 31, 11, 5, 0, 0, 0, 0, 0 @ 32-39
71 .byte 9, 0, 0, 24, 0, 0, 20, 26 @ 40-47
72 .byte 30, 0, 0, 0, 0, 23, 0, 19 @ 48-55
73 .byte 29, 0, 22, 18, 28, 17, 16, 0 @ 56-63
74#endif
75 .size find_first_set_bit, .-find_first_set_bit
diff --git a/firmware/asm/ffs.c b/firmware/asm/ffs.c
new file mode 100644
index 0000000000..f68a9cef8c
--- /dev/null
+++ b/firmware/asm/ffs.c
@@ -0,0 +1,56 @@
1/***************************************************************************
2 * __________ __ ___.
3 * Open \______ \ ____ ____ | | _\_ |__ _______ ___
4 * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
5 * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
6 * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
7 * \/ \/ \/ \/ \/
8 * $Id$
9 *
10 * Copyright (C) 2008 by Michael Sevakis
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version 2
15 * of the License, or (at your option) any later version.
16 *
17 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
18 * KIND, either express or implied.
19 *
20 ****************************************************************************/
21#include "config.h"
22#include <inttypes.h>
23
24/* find_first_set_bit() - this is a C version of the ffs algorithm devised
25 * by D.Seal and posted to comp.sys.arm on 16 Feb 1994.
26 *
27 * Find the index of the least significant set bit in the word.
28 * return values:
29 * 0 - bit 0 is set
30 * 1 - bit 1 is set
31 * ...
32 * 31 - bit 31 is set
33 * 32 - no bits set
34 */
35
36/* Table shared with assembly code */
37const uint8_t L_ffs_table[64] ICONST_ATTR =
38{
39/* 0 1 2 3 4 5 6 7 */
40/* ----------------------------------------- */
41 32, 0, 1, 12, 2, 6, 0, 13, /* 0- 7 */
42 3, 0, 7, 0, 0, 0, 0, 14, /* 8-15 */
43 10, 4, 0, 0, 8, 0, 0, 25, /* 16-23 */
44 0, 0, 0, 0, 0, 21, 27, 15, /* 24-31 */
45 31, 11, 5, 0, 0, 0, 0, 0, /* 32-39 */
46 9, 0, 0, 24, 0, 0, 20, 26, /* 40-47 */
47 30, 0, 0, 0, 0, 23, 0, 19, /* 48-55 */
48 29, 0, 22, 18, 28, 17, 16, 0, /* 56-63 */
49};
50
51#if !defined(CPU_COLDFIRE)
52int find_first_set_bit(uint32_t val)
53{
54 return L_ffs_table[((val & -val)*0x0450fbaf) >> 26];
55}
56#endif
diff --git a/firmware/asm/m68k/ffs.S b/firmware/asm/m68k/ffs.S
new file mode 100644
index 0000000000..2a39ae5bcd
--- /dev/null
+++ b/firmware/asm/m68k/ffs.S
@@ -0,0 +1,78 @@
1/***************************************************************************
2 * __________ __ ___.
3 * Open \______ \ ____ ____ | | _\_ |__ _______ ___
4 * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
5 * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
6 * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
7 * \/ \/ \/ \/ \/
8 * $Id$
9 *
10 * Copyright (C) 2008 by Michael Sevakis
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version 2
15 * of the License, or (at your option) any later version.
16 *
17 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
18 * KIND, either express or implied.
19 *
20 ****************************************************************************/
21 #include "config.h"
22
23/****************************************************************************
24 * int find_first_set_bit(uint32_t val);
25 *
26 * Find the index of the least significant set bit in the 32-bit word.
27 *
28 * return values:
29 * 0 - bit 0 is set
30 * 1 - bit 1 is set
31 * ...
32 * 31 - bit 31 is set
33 * 32 - no bits set
34 ****************************************************************************/
35 .text
36 .align 2
37 .global find_first_set_bit
38 .type find_first_set_bit,@function
39find_first_set_bit:
40 | this is a coldfire version of the ffs algorithm devised by D.Seal
41 | and posted to comp.sys.arm on 16 Feb 1994.
42 |
43 | Output modified to suit rockbox purposes.
44
45 | Standard trick to isolate bottom bit in r0 or 0 if r0 = 0 on entry
46 move.l 4(%sp), %d1 | %d1 = %d1 & -%d1
47 lea.l L_ffs_table, %a0 | %a0 = table address
48 move.l %d1, %d0 |
49 neg.l %d1 |
50 and.l %d0, %d1 |
51
52 | now %d1 has at most one set bit, call this X
53
54 move.l #0x0450fbaf, %d0 | %d0 = multiplier
55 mulu.l %d0, %d1 | %d1 = X * 0x0450fbaf
56
57 | now lookup in table indexed on top 6 bits of %d0
58 moveq.l #26, %d0 | %d0 = final shift count
59 lsr.l %d0, %d1 |
60
61 | the top 24 bits of d0 are 0 so just load the value over it
62 move.b (%a0, %d1.l), %d0 |
63 rts |
64
65 .section .irodata
66L_ffs_table:
67 | 0 1 2 3 4 5 6 7
68 |----------------------------------------------
69 .byte 32, 0, 1, 12, 2, 6, 0, 13 | 0- 7
70 .byte 3, 0, 7, 0, 0, 0, 0, 14 | 8-15
71 .byte 10, 4, 0, 0, 8, 0, 0, 25 | 16-23
72 .byte 0, 0, 0, 0, 0, 21, 27, 15 | 24-31
73 .byte 31, 11, 5, 0, 0, 0, 0, 0 | 32-39
74 .byte 9, 0, 0, 24, 0, 0, 20, 26 | 40-47
75 .byte 30, 0, 0, 0, 0, 23, 0, 19 | 48-55
76 .byte 29, 0, 22, 18, 28, 17, 16, 0 | 56-63
77
78 .size find_first_set_bit, .-find_first_set_bit
diff --git a/firmware/asm/mips/ffs.S b/firmware/asm/mips/ffs.S
new file mode 100644
index 0000000000..a2a82a6a32
--- /dev/null
+++ b/firmware/asm/mips/ffs.S
@@ -0,0 +1,59 @@
1/***************************************************************************
2 * __________ __ ___.
3 * Open \______ \ ____ ____ | | _\_ |__ _______ ___
4 * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
5 * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
6 * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
7 * \/ \/ \/ \/ \/
8 * $Id$
9 *
10 * Copyright (C) 2009 by Maurus Cuelenaere
11 * based on ffs-arm.S by Michael Sevakis
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version 2
16 * of the License, or (at your option) any later version.
17 *
18 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19 * KIND, either express or implied.
20 *
21 ****************************************************************************/
22
23#include "config.h"
24#include "mips.h"
25
26/****************************************************************************
27 * int find_first_set_bit(uint32_t val);
28 *
29 * Find the index of the least significant set bit in the 32-bit word.
30 *
31 * return values:
32 * 0 - bit 0 is set
33 * 1 - bit 1 is set
34 * ...
35 * 31 - bit 31 is set
36 * 32 - no bits set
37 ****************************************************************************/
38 .align 2
39 .global find_first_set_bit
40 .type find_first_set_bit, %function
41 .set noreorder
42 .set noat
43
44find_first_set_bit:
45 beqz a0, l # if(a0 == 0) goto l
46 nop #
47 negu t0, a0 # t0 = -a0
48 and t0, a0, t0 # t0 = a0 & t0
49 clz v0, t0 # get lead 0's count
50 li t0, 31 # t0 = 31
51 jr ra #
52 subu v0, t0, v0 # v0 = t0 - v0
53
54l:
55 jr ra #
56 li v0, 32 # v0 = 32
57
58 .set reorder
59 .set at
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