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| author | Thomas Martitz <kugel@rockbox.org> | 2012-01-08 00:22:58 +0100 |
|---|---|---|
| committer | Thomas Martitz <kugel@rockbox.org> | 2012-01-22 18:46:45 +0100 |
| commit | c94cf3b8885c8a9e192b95125ce4b8470a1aa3c3 (patch) | |
| tree | 6ca83258616b00428b58e1e31c10dce020fbc310 /firmware/target/arm | |
| parent | 5e9b62cd8ad4d38c7ca43c916b5bc831454bc267 (diff) | |
| download | rockbox-c94cf3b8885c8a9e192b95125ce4b8470a1aa3c3.tar.gz rockbox-c94cf3b8885c8a9e192b95125ce4b8470a1aa3c3.zip | |
Move optimized ffs to firmware/asm, using the new automatic-asm-picking infrastructure.
Change-Id: I5e7bdc8be7de50ef604c16078857fff1b84650dc
Diffstat (limited to 'firmware/target/arm')
| -rw-r--r-- | firmware/target/arm/ffs-arm.S | 75 |
1 files changed, 0 insertions, 75 deletions
diff --git a/firmware/target/arm/ffs-arm.S b/firmware/target/arm/ffs-arm.S deleted file mode 100644 index 4e912c5317..0000000000 --- a/firmware/target/arm/ffs-arm.S +++ /dev/null @@ -1,75 +0,0 @@ -/*************************************************************************** - * __________ __ ___. - * Open \______ \ ____ ____ | | _\_ |__ _______ ___ - * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / - * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < - * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ - * \/ \/ \/ \/ \/ - * $Id$ - * - * Copyright (C) 2008 by Michael Sevakis - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public License - * as published by the Free Software Foundation; either version 2 - * of the License, or (at your option) any later version. - * - * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY - * KIND, either express or implied. - * - ****************************************************************************/ - #include "config.h" - -/**************************************************************************** - * int find_first_set_bit(uint32_t val); - * - * Find the index of the least significant set bit in the 32-bit word. - * - * return values: - * 0 - bit 0 is set - * 1 - bit 1 is set - * ... - * 31 - bit 31 is set - * 32 - no bits set - ****************************************************************************/ - .align 2 - .global find_first_set_bit - .type find_first_set_bit,%function -find_first_set_bit: - @ Standard trick to isolate bottom bit in r0 or 0 if r0 = 0 on entry - rsb r2, r0, #0 @ r1 = r0 & -r0 - ands r1, r0, r2 @ - - @ now r1 has at most one set bit, call this X - -#if ARM_ARCH >= 5 - clz r0, r1 @ Get lead 0's count - rsbne r0, r0, #31 @ lead 0's -> bit index - bx lr @ -#else - @ this is the ffs algorithm devised by D.Seal and posted to - @ comp.sys.arm on 16 Feb 1994. - @ - @ Output modified to suit Rockbox purposes. - - orrne r1, r1, r1, lsl #4 @ r1 = X * 0x11 - orrne r1, r1, r1, lsl #6 @ r1 = X * 0x451 - rsbne r1, r1, r1, lsl #16 @ r1 = X * 0x0450fbaf - - @ now lookup in table indexed on top 6 bits of r1 - ldrb r0, [ pc, r1, lsr #26 ] @ exploit location of table - bx lr @ - -L_ffs_table: - @ 0 1 2 3 4 5 6 7 - @---------------------------------------------- - .byte 32, 0, 1, 12, 2, 6, 0, 13 @ 0- 7 - .byte 3, 0, 7, 0, 0, 0, 0, 14 @ 8-15 - .byte 10, 4, 0, 0, 8, 0, 0, 25 @ 16-23 - .byte 0, 0, 0, 0, 0, 21, 27, 15 @ 24-31 - .byte 31, 11, 5, 0, 0, 0, 0, 0 @ 32-39 - .byte 9, 0, 0, 24, 0, 0, 20, 26 @ 40-47 - .byte 30, 0, 0, 0, 0, 23, 0, 19 @ 48-55 - .byte 29, 0, 22, 18, 28, 17, 16, 0 @ 56-63 -#endif - .size find_first_set_bit, .-find_first_set_bit |